-
Cisco IOS Multiservice Applications Configuration Guide, Release 12.1
-
About the Cisco IOS Software Documentation
-
Using Cisco IOS Software
-
Multiservice Applications Overview
-
Part 1: Voice
-
Configuring Voice over IP
-
Configuring Voice Ports for Voice over IP
-
Configuring Gatekeepers (Multimedia Conference Manager)
-
Configuring Interactive Voice Response
-
Configuring Debit Card for Packet Telephony
-
Configuring Settlement for Packet Telephony
-
Managing Cisco AS5300 Voice Feature Cards
-
Configuring Voice over Frame Relay
-
Configuring Voice over ATM
-
Configuring Voice over HDLC
-
Configuring Voice-Related Support Features
-
Configuring PBX Signaling
-
Configuring Store and Forward Fax
-
- Part 2: Video
- Part 3: Broadband
- Part 4: Appendix
-
Table Of Contents
Configuring Headend Broadband Access Router Features
Weighted Random Early Detection
Cable Modem and Multicast Authentication Using RADIUS
Operations and Provisioning Features
Downstream Channel ID Configuration
Cable Modem and Host Subnet Addressing
Per-Modem and per-Host Access Lists
Inter-Switch Link Bridging on Noncable Interfaces
Headend Broadband Access Router Configuration Prerequisites
Headend Broadband Access Router Configuration Tasks
Configuring the Downstream Cable Interface
Activating the Downstream Carrier
Verifying the Downstream Carrier
Setting the Downstream Center Frequency
Verifying the Downstream Center Frequency
Setting the Downstream Channel ID
Verifying the Downstream Channel ID
Setting the Downstream MPEG Framing Format (Annex B)
Verifying the Downstream MPEG Framing Format
Setting the Downstream Modulation
Verifying the Downstream Modulation
Setting the Downstream Interleave Depth
Verifying the Downstream Interleave Depth
Setting the Downstream Helper Address
Verifying the Downstream Helper Address
Setting Downstream Rate Limiting
Verifying Downstream Rate Limiting
Configuring the Upstream Cable Interface
Setting the Upstream Frequency
Verifying the Upstream Frequency
Setting the Upstream Channel Width
Verifying Upstream Channel Width
Setting the Upstream Input Power Level
Verifying the Upstream Input Power Level
Activating Upstream Admission Control
Verifying Upstream Admission Control
Specifying Upstream Minislot Size
Verifying Upstream Minislot Size
Activating the Upstream Scrambler
Verifying the Upstream Scrambler
Activating Upstream Differential Encoding
Verifying Upstream Differential Encoding
Activating Upstream Rate Limiting
Verifying Upstream Rate Limiting
Activating Upstream Frequency Adjustment
Verifying Upstream Frequency Adjustment
Activating Upstream Power Adjustment
Verifying Upstream Power Adjustment
Activating Upstream Timing Adjustment
Verifying Upstream Timing Adjustment
Setting Upstream Backoff Values
Verifying Upstream Data Backoff Automatic
Configuring and Activating Baseline Privacy
Configuring and Activating Frequency Agility
Determining the Upstream Ports Assigned to a Combiner Group
Configuring and Activating Spectrum Groups
Verifying Spectrum Group Configuration
Configuring Spectrum Group Characteristics
Verifying Spectrum Group Characteristics
Assigning the Spectrum Group and the Upstream Ports
Verifying Spectrum Group and Upstream Port Assignments
Activating IP Address Resolution Protocol
Activating Host-to-Host Communication (Proxy ARP)
Activating Cable Proxy ARP Requests
Verifying Cable Proxy ARP Requests
Verifying DHCP giaddr Activation
Setting Optional IP Parameters
Configuring Cable Modulation Profiles
Verifying Cable Modulation Profiles
Enforcing a QoS Profile Assignment
Verifying a QoS Profile Assignment
Managing Cable Modems on the HFC Network
Configuring Sync Message Interval
Verifying Sync Message Interval
Activating Cable Modem Authentication
Verifying Cable Modem Authentication
Activating Cable Modem Upstream Address Verification
Verifying Cable Modem Upstream Address Verification
Activating Cable Modem Insertion Interval
Verifying Cable Modem Insertion Interval
Configuring the Maximum Number of Hosts Attached to a Cable Modem
Verifying the Maximum Number of Hosts
Configuring Cable Modem Registration Timeout
Verifying Registration Timeout
Clearing and Resetting Cable Modems
Verifying Cable Modem Clearing and Resetting
Verifying that Cable Modem Counters are Cleared
Headend Broadband Access Router Configuration Examples
Spectrum Management Configuration Example
Virtual Private Network Configuration Example
Telco Return Configuration Example
QoS Profile Enforcement Configuration Example
Troubleshooting Using Cable Flap Lists
Verifying Cable Flap List Aging
Setting Cable Flap List Insertion Time
Verifying Cable Flap List Insertion Time
Setting Cable Flap List Power Adjustment Threshold
Verifying Cable Flap List Power Adjustment Threshold
Setting Cable Flap List Miss Threshold
Verifying Cable Flap List Miss Threshold
Verifying Cable Flap List Size
Configuring Headend Broadband Access Router Features
This chapter contains procedures for configuring the Cisco uBR7200 series universal broadband routers using the Cisco command-line interface (CLI). For detailed descriptions of the commands used, refer to the Cisco IOS Multiservice Applications Command Reference publication.
This chapter includes the following sections:
•
Operations and Provisioning Features
•
•
•
•
•
•
•
•
•
•
•
•
Headend Overview
Cisco uBR7200 series universal broadband routers are Data-over-Cable Service Interface Specifications (DOCSIS)-based cable modem termination systems (CMTSs) that typically serve as interfaces between a WAN backbone and a hybrid fiber-coaxial (HFC) cable network. Installed at a Community Antenna Television (CATV) head-end facility or distribution hub, the Cisco uBR7200 series is often located with the following Internet service provider (ISP)-related components:
•
•
•
•
The Ethernet switch is used to reduce traffic on the WAN backbone.
The proxy server usually functions as a Web cache for host computers and as the Dynamic Host Control Protocol/Trivial File Transfer Protocol (DHCP/TFTP) server for cable modems. DHCP for host computers in the HFC plant is often handled over the WAN. The WAN router provides a gateway to the data network.
For more information on these components and their requirements, refer to the "Supported System Configurations" section of the "Cisco uBR7200 Series Overview" chapter of the Cisco uBR7200 Series Hardware Installation Guide.
Note
On the RF side, the downstream port on the Cisco uBR7200 series router is assigned a 6 MHz channel slot at a standard broadcast CATV frequency. An upconverter device is used to convert the 44 MHz intermediate frequency (IF) output to the assigned slot. In North America, carrier frequencies in the forward plant are assigned from 54 MHz to 860 MHz. After upconversion, the signal is combined with other analog TV or digital TV signals and sent to the transmit input of a fiber transceiver.
The receive input of the fiber transceiver is connected to an upstream port of the Cisco uBR7200 series router. The upstream port is assigned a 0.2 MHz to 3.2 MHz frequency band in the reverse plant. In North America, carrier frequencies in the reverse plant are between 5 MHz and 42 MHz.
The fiber transceiver is connected to up to 80 kilometers of optical fiber. Signals are carried in analog form to a neighborhood, where they terminate in a fiber node. The fiber node, located on a telephone pole or in an underground box, converts the optical signal back to an electrical signal, which is then passed on to a two-way distribution amplifier system. The distribution amplifier system passes through the neighborhood, where it is tapped off to individual CATV subscribers.
A coaxial cable delivers the signal from the tap to a drop box located on the subscriber premises. From the drop box, the signal is split and cabled to consumer CATV appliances. One cable goes to the television or set-top box; the other cable goes to a cable modem appliance such as a Cisco uBR900 series cable access router, providing data and IP telephony services.
Figure 106 illustrates the topology of a typical HFC network supporting basic data services.
Figure 106 Topology of a Typical Broadband Network
Cisco uBR7200 series routers support the DOCSIS 1.0 specifications (and static multiple service identifiers (SIDs) for voice) for the following high-speed data-over-cable interfaces:
•
•
•
•
•
Cisco cable modem cards residing in the Cisco uBR7200 series routers provide the interface between the protocol control information (PCI) bus on the router and the RF signal on the HFC network. The subscriber-end cable modems and Cisco cable access routers are connected to the HFC network through upconverters and the Cisco cable modem cards.
The Cisco uBR7200 series routers support a variety of cable modem cards with different upstream and downstream transmission capabilities and features. You must install at least one Cisco cable modem card in the Cisco uBR7200 series chassis to establish communication between the Cisco uBR7200 series and the HFC network. For detailed information, refer to the Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide.
Voice over IP Services
Figure 107 shows a typical two-way configuration involving Voice over IP (VoIP) telephony services. The Cisco uBR7200 series supports the transmission of digitized voice and facsimile traffic over the cable and IP backbone network.
Figure 107 Two-Way IP Telephony Network Diagram
The Cisco uBR7200 series equipment and DOCSIS-based cable modems supporting IP telephony can be configured to treat VoIP and regular data traffic separately. The system can be configured to keep regular data on a default class of service, while using a higher priority for the VoIP traffic that originates on the VoIP ports of the cable modem.
When creating a configuration for remote cable modems, the Cisco uBR7200 series system administrator typically configures extra classes of service. These secondary classes of service are expected to be higher QoS classes that are used by higher priority traffic such as voice. These classes have a minimum upstream rate specified for the channel.
System administrators can associate unique packet flows with a unique SID. These images support multiple SIDs per cable modem.
Note
Telco Return
Cisco uBR7200 series routers can register third-party DOCSIS-based telco return cable modems based on the DOCSIS telco return specification. This feature enables the HFC network to support both two-way and telco return cable modems.
In telco return configurations, the Cisco uBR7200 series router provides downstream dataflow from cable modem cards connected to the cable system and accepts upstream traffic via a combination of the local public switched telephone network (PSTN) and IP network path that terminates at the Cisco uBR7200 series input/output (I/O) controller or applicable port adapter. Upstream data is through a telephone modem typically connected to an analog telephone line. (The telephone modem can be external or internal to a cable modem, or a cable modem card in a PC, based on the third-party cable modem vendor.) Telco return gives cable companies that have not upgraded their cable plants or specific service areas to support two-way RF transmission the ability to offer fast downstream data services via the cable plant and upstream transmission via the PSTN.
Figure 108 illustrates a telco return application.
Figure 108 Telco Return Network Diagram
Downstream traffic must be precluded by Telephony Channel Descriptor (TCD) messages to enable upstream telco return traffic. TCD messages contain information necessary for the telco return cable modem to access the headend/ISP network access server (for example, a Cisco AS5300 or Cisco AS5800) over the PSTN.
TCD packets contain three critical telco return elements:
•
•
•
When connected, the network access server feeds the subscriber username and password to a RADIUS dial security server. Access is granted or denied. When access has been attained, the network server sets up a PPP negotiation and connection.
QoS Features
The Cisco uBR7200 series universal broadband routers support QoS as defined by the DOCSIS 1.0 specification. Service class profiles can be configured through the Cisco CLI to support the QoS profile number, traffic priority, maximum upstream bandwidth, guaranteed upstream bandwidth, maximum downstream bandwidth, maximum transmit burst length, baseline privacy enable/disable, and type of service (ToS) overwrite byte.
The QoS Profile Enforcement feature allows you to control the QoS to eliminate any interference from improper local-rate limiting implemented on the cable modem. The CMTS provisions a registering cable modem with a default DOCSIS 1.0 service class assigned by the operator, overriding any service class that previously existed on the modem. This service class has no upstream or downstream rate limits so that the CMTS can do traffic shaping based on the QoS profile enforced by the operator.
As part of this functionality, Cisco uBR7200 series routers support multiple service classes per cable modem by providing multiple static QoS service identifiers (SIDs). The multiple SIDs feature allows the Cisco uBR7200 series CMTS to dynamically allocate and delete service flows for voice and fax transmissions.
These features are described in more detail in the following sections. For additional information on QoS, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Service Class Profiles
Cisco uBR7200 series routers allow you to create multiple service class profiles with the following characteristics:
•
•
•
•
•
Using these service class profiles, you can define the following:
•
•
Both of these classes can be used to get an indication whether the grant server in MAPs is not serving bandwidth requests from cable modems subscribing to the particular service.
Note
Multiple Service IDs
The Cisco uBR7200 series routers allow you to statically define multiple service IDs (SIDs) on the upstream, enabling multiple service classes per cable modem. Multiple SIDs allow you to specify priority service flows higher than those specified in DOCSIS 1.0.
Multiple SIDs provide the following functionality:
•
•
The CMTS treats the primary and secondary SIDs independently for issuing grants. Each SID of a cable modem has an independent state machine. Channel access for each SID is independent of the other SID.
Note
QoS Profile Enforcement
QoS profile enforcement allows you to override the provisioned service class of a cable modem with a static CMTS-defined QoS profile. A static CMTS-defined QoS profile gives you control of the cable modem QoS and eliminates any interference from improper local-rate limiting implemented on the cable modem.
When this feature is enabled, the CMTS provisions each registering cable modem with a default DOCSIS 1.0 service class that is assigned by the CMTS operator. The operator-defined service class is enforced on cable modems attempting to register with the CMTS regardless of the provisioned class of service. The default service class has no upstream or downstream rate limits.
When the cable modem sends data upstream, it makes bandwidth requests without throttling or dropping packets because of its own rate-policing algorithm. The CMTS does traffic shaping based on the QoS profile enforced by the operator.
Note
TAG/NetFlow Switching
TAG switching and Netflow switching provide high performance for network layer services, enabling per-flow application of network services such as security and traffic accounting. The following data is collected for each flow:
•
•
•
•
•
•
•
•
•
•
•
Tag Switching
Tag switching is a Cisco-developed technology that implements a next-generation architecture for the Internet backbone and large intranets. Tags placed on the fronts of packets contain forwarding information used for making switching decisions and applying network services.
Tag switching has become the foundation for flexible Layer 3 virtual private networks (VPNs), QoS handling, and traffic engineering. It also forms the basis for the emerging Internet Engineering Task Force (IETF) standard for Multiprotocol Label Switching (MPLS).
A tag switching infrastructure combines with advanced routing protocol capabilities to define IP VPNs by selectively advertising IP reachability information to just those subscribers within the same VPN or extranet, thus keeping different VPN traffic logically separate. The subscribers are then all connected via tag switch paths (TSPs).
Forwarding is based entirely upon the assigned tag values (rather than IP destination prefixes), eliminating the requirement for uniqueness in the IP addresses that are used. This feature means subscribers to different VPNs need not concern themselves with the problems that would otherwise occur when connecting networks with different subnetworks into an integrated network.
Netflow Switching
NetFlow switching is a high-performance, network-layer switching path that provides network administrators with access to "call detail recording" information from their data networks; this information includes details such as user, protocol, port, ToS information, and the duration of the communication. This data can be used for a variety of purposes, including billing, enterprise accounting, network planning and performance analysis, QoS bandwidth management, security policies, and data warehousing/mining for marketing purposes.
The collected NetFlow data is sent out via UDP packets to a workstation running the Netflow Flowcollector server, which can collect data from multiple routers for later analysis by a user running the Netflow Flowanalyzer application. Through the NetFlow Data Export feature, traffic information can also be passed to external applications that perform functions such as billing or network performance analysis.
NetFlow also provides a highly efficient mechanism that can process security access lists without incurring the same performance penalty as other available switching methods. In conventional switching at the network layer, each incoming packet is handled on an individual basis with a series of functions to perform access list checks, capture accounting data, and switch the packet. In contrast, after NetFlow switching identifies a flow and processes the access list for the first packet of the flow, all subsequent packets are handled on a "connection-oriented" basis as part of the flow. This process avoids further access list checks on the flow, and packet switching and statistics capture are performed in tandem.
Weighted Random Early Detection
Weighted Random Early Detection (WRED) enables you to specify traffic handling policies to maximize throughput under congestion conditions. Random early detection (RED) works in conjunction with TCP to intelligently avoid network congestion. WRED combines IP precedence and RED capabilities to provide differentiated performance characteristics for different classes of service, thus providing preferential traffic handling for higher priority traffic. You can define minimum and maximum queue depth thresholds and drop probabilities for each class of service.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Weighted Fair Queueing
Weighted Fair Queueing (WFQ) performs priority output queueing and custom queueing to grant resources to important sessions when network bandwidth is saturated; it is typically used for digitized voice packets to help reduce delay. WFQ provides expeditious handling for high priority traffic, requiring low delay, while fairly sharing the remaining bandwidth between lower priority traffic. WFQ divides link traffic into high and low priority flows based on metrics including IP precedence and traffic volume.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Resource Reservation Protocol
Resource Reservation Protocol (RSVP) works in conjunction with WFQ; it helps the router establish a weight for different types of packets that affect the order in which the packets enter the output queue and are placed on the cable network for transmission. Voice packets are routed through the interface with a QoS method that allows the packets to receive priority over standard data frames. A router that supports RSVP gives priority to packets that fall into a reservation within RSVP.
For more information on this feature, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.
Committed Access Rate (CAR)
Committed Access Rate (CAR) provides the means to allocate and limit bandwidth to traffic sources and destinations, and specify policies to handle traffic exceeding the bandwidth allocation. CAR policies can be utilized at the ingress or egress of the network. CAR uses token bucket filters to measure traffic load and limit sources to bandwidth allocations.
Security Features
The following sections describe features that enhance the security of devices attached to the Cisco uBR7200 series cable access routers.
DOCSIS Baseline Privacy
The Cisco uBR7200 series routers support DOCSIS baseline privacy (BPI). When BPI is enabled, the Cisco uBR7200 series generates Traffic Encryption Keys (TEKs) for each applicable SID. The router uses the keys to encrypt downstream data and decrypt upstream traffic from two-way cable modems.
The Cisco uBR7200 series supports both 40-bit and 56-bit encryption/decryption. When BPI is enabled, 56-bit encryption/decryption is the default. A configuration command allows an administrator to manually force the Cisco uBR7200 series to generate a 40-bit DES key, where the DES key that is generated and returned masks the first 16 bits of the 56-bit key to 0 in software.
Note
The Cisco uBR7200 series router generates keys for unicast, broadcast, and multicast operation as appropriate. Keys are refreshed periodically and have a default lifetime of 12 hours.
Cable Modem and Multicast Authentication Using RADIUS
As an enhancement to baseline privacy, Cisco uBR7200 series universal broadband routers can be configured for cable modem and multicast authentication using the RADIUS protocol, an access server authentication, authorization, and accounting (AAA) protocol originally developed by Livingston, Inc. The Cisco uBR7200 series also supports additional vendor-proprietary RADIUS attributes.
When a cable modem comes online or when an access request is sent through a multicast data stream, the Cisco uBR7200 series sends relevant information to RADIUS servers for cable modem/host authentication. This feature can be configured on a per-interface basis.
An IETF draft standard, RFC 2138, defines the RADIUS protocol. RFC 2139 defines the corresponding RADIUS accounting protocol. Additional RFC drafts define vendor-proprietary attributes and MIBs that can be used with a Simple Network Management Protocol (SNMP) manager.
Upstream Address Verification
Upstream address verification prevents the spoofing of IP addresses by comparing the source IP address with the MAC address of the cable modem, thus verifying that each upstream data packet comes from the cable modem known to be associated with the source IP address in the packet. The cable source-verify [dhcp] cable interface command specifies that DHCP lease query requests are sent to verify any unknown source IP address found in upstream data packets. This feature requires a DHCP server that supports the LEASEQUERY message type.
Note
Traffic Shaping Features
Traffic shaping is a Cisco patent-pending feature that conserves bandwidth by reducing the chances that information will be retransmitted to hosts on the HFC network. Traffic shaping in the upstream direction delays the scheduling of the upstream packet, causing the packet to be buffered on the cable CPE device instead of being dropped. Traffic shaping allows the TCP/IP stack to pace the application traffic appropriately and approach throughput commensurate with the QoS levels defined for the subscriber.
Without traffic shaping, the Cisco uBR7200 series software drops bandwidth requests from cable modems that are found to have exceeded their configured peak upstream transmission rate. Dropping bandwidth requests (and eventually upstream packets) from a rate-exceeding cable modem causes TCP-related timeouts which cause the host sending the information to resend its information. Resent information wastes bandwidth on the network.
The Cisco uBR7200 series supports the following traffic shaping features:
•
Downstream rate shaping enables you to partition downstream traffic for a cable modem into multiple classes of service and multiple data rates by using the three precedence bits in the ToS byte in the IP header to specify a class of service assignment for each packet. Those packets with the precedence bit set in the ToS field are given higher priority.
Using the ToS byte, you can also calculate the data rate for a specified flow in addition to the data rate configured on a per-cable modem basis. By specifying a maximum data rate for a particular ToS, you can override the common maximum downstream data rate.
Note
•
Token bucket policing with shaping is the per-upstream default rate-limiting setting at the CMTS. Shaping can be enabled or disabled for the token-bucket algorithm.
Operations and Provisioning Features
The following sections describe operational and provisioning features and enhancements of the Cisco uBR7200 series cable access routers.
Dynamic Ranging
The dynamic ranging feature is a Cisco patent-pending feature that supports quick restoration of service following a catastrophic plant failure. With dynamic ranging, hundreds of cable modems can come back online quickly. The time that the cable modems spend deferring contention ranging slots is minimized, significantly reducing cable modem reinitialization time.
Downstream Channel ID Configuration
Downstream channel ID configuration allows all cable modems on the HFC network to identify themselves via unique downstream channel IDs instead of their downstream frequencies. Cable modems communicate their downstream ID when making a connection, not their downstream frequency. This feature allows system administrators to enter a configurable downstream channel ID to a value other than the default. Thus, each downstream channel ID can be unique on a cable network.
Downstream Frequency Override
Cisco uBR7200 series routers are able to change the downstream frequency for any or all cable modems, overriding the DOCSIS configuration file settings.
CPE Limitation
Cisco uBR7200 series routers can report and limit the number of CPE devices per cable modem using CLI commands or SNMP.
Note
Burst Profile Configuration
For each modulation/burst profile configuration, Cisco uBR7200 series universal broadband routers will support burst profile number, burst profile interval usage code, burst type, preamble length and unique word length, differential encoding enable/disable, forward error correction (FEC) correctable bytes value, FEC code word length, scrambler seed value, maximum burst size, guard time size, last code word shortened/lengthened, and scrambler enable/disable.
Note
Cable Modem and Host Subnet Addressing
The Cisco uBR7200 series cable access routers can manipulate the GIADDR field of DHCPDISCOVER and DHCPREQUEST packets with a Relay IP address before they are forwarded to the DHCP server.
By modifying the GIADDR field based on whether the source is a cable modem or a host, the Cisco uBR7200 series provides hints to the DHCP server as to where (that is, on which IP subnet) the server should allocate addresses to the requesting client.
Per-Modem and per-Host Access Lists
Per-modem and per-host access lists allow Cisco uBR7200 series routers to filter incoming packets from individual hosts or cable modems based on the source MAC or IP address. Access lists can thus be specified on a per-interface or a per-address basis. The packets received from cable modems or individual hosts are filtered based on the cable modem or host from which the packets are received.
You can preconfigure the filters by using the CLI following standard Cisco IOS access list and access group configuration procedures. You can assign these filters to a user or modem by using the CLI or SNMP.
This feature also supports traps to inform the CMTS about the online/offline status of modems.
Basic Wiretap Support
Cisco uBR7200 series routers provide support for a basic wiretap facility for VoIP calls, as required by the United States Federal Communications Assistance for Law Enforcement Act (CALEA). The wiretap facility is based on the MAC address of the cable modem, so it can be used for either data or digitized voice connections.
The feature is controlled by the cable intercept command, which requires a MAC address, an IP address, and a UDP port number as its parameters. When activated, the Cisco uBR7200 series universal broadband router examines each packet for the desired MAC address; when a matching MAC address is found (for either the origination or destination endpoint), a copy of the packet is encapsulated into a UDP packet, which is then sent to the specified server at the given IP address and port.
Inter-Switch Link Bridging on Noncable Interfaces
Inter-Switch Link (ISL) is a Cisco protocol used to interconnect multiple routers and switches and maintain virtual LAN (VLAN) information as traffic passes between routers and switches.
Integrated Time-of-Day Server
Cisco uBR7200 series routers are able to obtain the correct time-of-day (ToD) and respond to (RFC 868) queries from cable modems during the registration process.
Integrated DHCP Server
Cisco uBR7200 series routers offer an integrated DHCP server to simplify the provisioning of cable modems.
Spectrum Management
Due to the nature of CATV technology, upstream noise management is a significant issue. Frequency bands must have a sufficient carrier-to-noise ratio (CNR) and carrier-to-ingress power ratio to support the transmission of quadrature phase-shift keying (QPSK) and quadrature amplitude modulation (QAM) data. The DOCSIS specification sets the minimum value for both of these parameters to 25 dB in the 5-MHz to 42-MHz frequency range. If the CNR drops below this value on a particular channel due to noise, the cable modem on that channel will drop off of the HFC network.
We recommend that system administrators use upstream frequency hopping as a countermeasure to long-term narrowband noise. To provide this capability, Cisco uBR7200 series routers contain a spectrum manager that continuously monitors the noise in unused upstream channels. If the CNR reaches an unacceptable level on a particular channel, the spectrum manager will automatically assign a new upstream channel to the cable modem using that channel. This is referred to as frequency agility.
Cisco uBR7200 series routers support the following techniques for upstream frequency hopping when no clean frequency band is available:
•
•
•
•
Note
The Cisco uBR7200 series allows you to create up to 32 cable spectrum groups, each containing multiple upstream ports. The configured channel width is used for each upstream. In addition, the router maintains a flap list containing the MAC address for each cable modem having problems maintaining its connection. (A "flapping modem" is a cable modem that rapidly disconnects and reconnects to the CMTS.)
Note
Headend Broadband Access Router Configuration Prerequisites
Before you can configure Cisco uBR7200 series universal broadband router features, you must first perform the following tasks:
•
–
–
Note
–
–
•
–
–
–
For information about installing and configuring port adapters, refer to the installation and configuration guide for the port adapter(s) you are using.
•
Headend Broadband Access Router Configuration Tasks
The Cisco IOS software CLI is used to configure the Cisco cable modem card for correct operation on the HFC network. To configure the Cisco cable modem card, perform the tasks described in the following sections. For some tasks, the default values are adequate to configure the device; these configuration tasks are optional.
•
•
•
•
•
•
•
•
•
Configuring the Downstream Cable Interface
The first step in configuring the Cisco cable modem interface is to configure the downstream cable interface. The downstream direction refers to the data flow from the Cisco cable modem card in a Cisco uBR7200 series to the subscriber's cable modem. Data passing through the Cisco cable modem card is converted to IF and then passed through an upconverter to transform the signal to RF. This RF signal is then sent down the line to the subscriber's cable modem. Downstream cable interface commands configure the frequency, symbol rate, compression, and modulation of the downstream signal.
To configure the downstream cable interface, perform the following tasks:
•
•
•
•
•
•
•
•
Note
Activating the Downstream Carrier
To activate a downstream port on a Cisco uBR7200 series cable modem card for digital data transmissions over the HFC network, use the following commands:
Verifying the Downstream Carrier
To verify whether the downstream carrier is active (up), enter the show controllers cable command for the downstream port that you just configured:
CMTS01# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
Setting the Downstream Center Frequency
Downstream frequency is an information-only parameter that must match the digital carrier frequency, which is the center frequency of the downstream RF carrier (the channel) for a particular downstream port. The configuration controlling the digital carrier frequency is performed in the IF-to-RF upconverter that must be installed in the downstream path from the Cisco uBR7200 series. Refer to the documentation for your upconverter for information about configuring the upconverter.
Enter the fixed center frequency of the downstream RF carrier for the downstream port. You can also select a default that does not set a specific fixed value. The valid range for a fixed center frequency is 54,000,000 to 1,020,000,000 Hz.
The digital carrier frequency is specified to be the center of a 6.0 MHz channel. For example, EIA channel 95 spans 90.000 to 96.000 MHz. The center frequency is 93.000 MHz, which is the digital carrier frequency that should be configured as the downstream frequency. The typical range for current CATV headends is 88,000,000 to 860,000,000 Hz. The DOCSIS specification is 91,000,000 to 857,000,000 Hz:
•
•
Note
Note
To set the downstream center frequency, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable downstream frequency down-freq-hz
Sets the fixed center frequency for your downstream RF carrier in Hz.
Verifying the Downstream Center Frequency
To verify the current value of the center frequency, enter the show controllers cable command for the downstream port that you have just configured.
•
router# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4•
router# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency is not set. Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting the Downstream Channel ID
To assign a numeric channel ID to the downstream port on the Cisco cable modem card, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable downstream channel-id id
Specifies the downstream channel ID. Acceptable range is 0 to 255.
Verifying the Downstream Channel ID
To verify the downstream channel ID, enter the show controllers cable command for the downstream port you have just configured:
CMTS01# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting the Downstream MPEG Framing Format (Annex B)
The Moving Pictures Experts Group (MPEG) framing format must be compatible with your local standards and specifications for downstream MPEG framing. Annex B is the DOCSIS MPEG framing format standard for North America; Annex A is the European standard.
In Cisco IOS Release 12.1, only the Annex B MPEG framing format is supported.
Note
To set the downstream MPEG framing format, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable downstream annex B
Sets the downstream MPEG framing format.
Verifying the Downstream MPEG Framing Format
To verify the downstream MPEG framing format setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting the Downstream Modulation
By setting the downstream modulation, you define the speed in symbols per second at which data travels downstream to the subscriber cable modem. A symbol is the basic unit of modulation. QPSK encodes 2 bits per symbol, 16-QAM encodes 4 bits per symbol, 64-QAM encodes 6 bits per symbol, and 256-QAM encodes 8 bits per symbol.
The valid modulation rates for a downstream port on a Cisco cable modem card are 64 QAM (6 bits per downstream symbol rate) and 256 QAM (8 bits per downstream symbol rate).
Note
To set the downstream modulation, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable downstream modulation 64qam
Sets the downstream modulation. The standard DOCSIS modulation rate (and the Cisco default) is 64qam.
Verifying the Downstream Modulation
To verify the downstream modulation setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
•
Setting the Downstream Interleave Depth
Set the interleave depth for the downstream port on the Cisco cable modem card. A higher interleave depth provides more protection from bursts of noise on the HFC network; however, it will increase downstream latency. The valid values are 8, 16, 32 (default), 64, and 128.
To set the downstream interleave depth, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable downstream interleave-depth {8|16|32|64|128}
Sets the downstream interleave depth in milliseconds.
Verifying the Downstream Interleave Depth
To verify the downstream interleave depth setting, enter the show controllers cable command for the downstream port you have just configured:
router# show controllers cable 6/0 downstreamCable6/0 Downstream is upFrequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 MspsFEC ITU-T J.83 Annex B, R/S Interleave I=32, J=Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting the Downstream Helper Address
Specify an IP address of a DHCP server where UDP broadcast (DHCP) packets will be sent. You can specify a DHCP server for UDP broadcast packets from cable modems and a DHCP server for UDP broadcast packets from hosts.
To set a downstream helper address, use one of the following commands in cable interface configuration mode:
Verifying the Downstream Helper Address
To verify the downstream helper address setting, enter the show running-config command and look for ip helper-address in the cable interface configuration information:
CMTS01# show running-configBuilding configuration...Current configuration:!interface Cable4/0ip address 10.254.254.254 255.0.0.0no ip directed-broadcastip helper-address 192.168.1.1no keepaliveTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting Downstream Rate Limiting
Downstream rate limiting enables you to use the token bucket policing algorithm with traffic shaping options or the weighted discard policing algorithm to buffer, shape, or discard packets that exceed a set bandwidth. Downstream rate limiting is disabled by default.
To enable downstream rate limiting for a downstream port on a Cisco cable modem card, use one of the following commands in cable interface configuration mode:
Verifying Downstream Rate Limiting
To verify whether or not downstream rate limiting has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If downstream rate limiting has been configured and enabled, a rate limiting entry will be displayed in the output; if downstream rate limiting is disabled, no rate limiting entry will be displayed.
CMTS01# show running-configBuilding configuration...Current configuration:!interface Cable4/0ip address 10.254.254.254 255.0.0.0no ip directed-broadcastip helper-address 192.168.1.1no keepalivecable downstream rate-limit token-bucket shapingcable downstream annex Bcable downstream modulation 64qamTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
•
Configuring the Upstream Cable Interface
The upstream direction refers to the data flow from a subscriber cable modem to the cable modem card in a Cisco uBR7200 series router. The subscriber cable modem sends an RF signal back to the Cisco cable modem card, which translates the RF signal back to data format. Upstream cable interface commands configure the frequency and input power level of the upstream signal, in addition to error detection and correction of the upstream signal.
The configuration of the upstream cable interface depends on the characteristics of the cable operator's physical plant.
To configure the upstream cable interface, perform the following tasks:
•
•
•
•
•
•
•
•
•
•
•
•
•
Setting the Upstream Frequency
The upstream channel frequency of your RF output must be set to comply with the expected input frequency of your Cisco cable modem card. To configure upstream channel frequencies, you may configure a fixed frequency of 5 to 42 MHz and enable the upstream port, or create a global spectrum group, assign the interface to it, and enable the upstream port.
You can also select a default that does not set a specific fixed value.
Note
The cable modem card receiver accepts time-division multiplexed burst transmissions from cable modems that are DOCSIS compliant. The upstream port becomes "up" when it is assigned an upstream frequency and is configured to be administratively up.
The upstream port is frequency-agile. The frequency can change while the interface is up and carrying traffic, if you define spectrum groups. See the "Configuring and Activating Frequency Agility" section later in this chapter for details.
Upstream burst parameters can be configured by defining individual modulation profiles. A modulation profile consists of a table of physical layer characteristics for the different types of upstream bursts; for example, initial maintenance, long grant, request/data, request, short grant, and station maintenance.
Note
If you are setting a fixed upstream frequency, make sure that the frequency selected does not interfere with the frequencies used for any other upstream applications running in the cable plant.
Note
To set a fixed upstream frequency, use the following commands in cable interface configuration mode:
To configure the default upstream frequency (which is no fixed frequency), enter the cable upstream usport frequency command without specifying a center frequency.
Verifying the Upstream Frequency
To verify the current value of the upstream frequency, enter the show controllers cable command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0Cable6/0 Upstream 0 is upFrequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 MspsSpectrum Group is overriddenSNR 33.2560 dBNominal Input Power Level 0 dBmV, Tx Timing Offset 2288Ranging Backoff automatic (Start 0, End 3)Ranging Insertion Interval automatic (60 ms)Tx Backoff Start 0, Tx Backoff End 4Modulation Profile Group 1
Note
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
•
Setting the Upstream Channel Width
Enter the channel width in Hz. Valid values are 200000 Hz (160 kilosymbols per second, or ksps), 400000 Hz (320 ksps), 800000 Hz (640 ksps), 1600000 Hz (1280 ksps), and 3200000 Hz (2560 ksps). The default is 1600000 Hz.
Note
Note
To set the upstream channel width, use the following command in cable interface configuration mode:
Verifying Upstream Channel Width
To verify the current value of the upstream channel width, enter the show controllers cable command for the upstream port you just configured:
CMTS01# show controllers cable 6/0 u0Cable6/0 Upstream 0 is upFrequency 24.016 MHz, Channel Width 0.800 MHz, QPSK Symbol Rate 0.640 MspsSpectrum Group is overriddenSNR 33.2560 dBNominal Input Power Level 0 dBmV, Tx Timing Offset 2288Ranging Backoff automatic (Start 0, End 3)Ranging Insertion Interval automatic (60 ms)Tx Backoff Start 0, Tx Backoff End 4Modulation Profile Group 1Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting the Upstream Input Power Level
The Cisco uBR7200 series controls the output power levels of the cable modems to meet the desired upstream input power level. The nominal input power level for the upstream RF carrier is specified in decibels per millivolt (dBmV). The default setting of 0 dBmV is the optimal setting for the upstream power level.
The valid range for the input power level depends on the data rate. At 1.6 MHz, the valid range is -10 dBmV to 25 dBmV. If your power levels operate at greater than the maximum valid level, you must use an inline attenuator to bring the power level to within the valid range.
Caution
You should not adjust your input power level by more than 5 dB in a 30-second interval. If you increase the power level by more than 5 dB within 30 seconds, cable modem service on your network will be disrupted. If you decrease the power level by more than 5 dB within 30 seconds, cable modems on your network will be forced offline.
Note
To set the upstream input power level, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable upstream usport power-level dbmv
Sets the upstream input power level. Enter the upstream power level in dBmV. Default = 0 dBmV.
Verifying the Upstream Input Power Level
To verify the current value of the upstream input power level, enter the show controllers cable command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0Cable6/0 Upstream 0 is upFrequency 24.016 MHz, Channel Width 0.800 MHz, QPSK Symbol Rate 0.640 MspsSpectrum Group is overriddenSNR 33.2560 dBNominal Input Power Level 0 dBmV, Tx Timing Offset 2288Ranging Backoff automatic (Start 0, End 3)Ranging Insertion Interval automatic (60 ms)Tx Backoff Start 0, Tx Backoff End 4Modulation Profile Group 1Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Activating Upstream Admission Control
The admission control is set as a percentage of the specified upstream channel capacity. The acceptable range is from 10 to 1000 percent. Admission control is disabled by default.
To set the upstream admission control, use the following command in cable interface configuration mode:
Verifying Upstream Admission Control
To verify whether or not upstream admission control has been configured and activated, enter the show running-config command in privileged EXEC mode and look for the cable interface configuration information. If upstream admission control has been configured and enabled, an admission control entry will be displayed in the show running-config output, indicating the user-defined percentage of upstream channel capacity allowable. If upstream admission control is disabled, no admission control entry will be displayed in the output.
CMTS01# show running-configTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream FEC
The Cisco uBR7200 series uses forward error correction (FEC) to attempt to correct any upstream data that might have been corrupted. FEC is activated by default and should not be disabled. When FEC is activated, all cable modems on the network also activate FEC.
Note
To activate the upstream forward error correction, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable upstream usport fec
Enables FEC. This is the default setting.
Verifying Upstream FEC
To verify if FEC is activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If FEC is enabled, an FEC entry will be displayed in the show running-config output. If FEC is disabled, no FEC entry will be displayed in the output. The following is an excerpt from the more system:running-config command output.
router# more system:running-configBuilding configuration...!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Specifying Upstream Minislot Size
To specify the minislot size (in ticks) for specific upstream cable interfaces, use the following command in cable interface configuration mode:
Verifying Upstream Minislot Size
To verify upstream minislot size, enter the show controllers cable 6/0 u0 command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0Cable6/0 Upstream 0 is upFrequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 MspsSpectrum Group is overriddenSNR 33.2560 dBNominal Input Power Level 0 dBmV, Tx Timing Offset 2288Ranging Backoff automatic (Start 0, End 3)Ranging Insertion Interval automatic (60 ms)Tx Backoff Start 0, Tx Backoff End 4Modulation Profile Group 1part_id=0xFFFF, rev_id=0xFF, rev2_id=0xFFnb_agc_thr=0x0000, nb_agc_nom=0x0000Range Load Reg Size=0x58Request Load Reg Size=0x0EMinislot Size in number of Timebase Ticks is = 8Minislot Size in Symbols = 64Bandwidth Requests = 0xFEPiggyback Requests = 0xDInvalid BW Requests= 0x2Minislots Requested= 0x2963Minislots Granted = 0x2963Minislot Size in Bytes = 16Map Advance = 4000 usecsUCD Count = 32964DES Ctrl Reg#0 = C000C043, Reg#1 = 0Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating the Upstream Scrambler
The scrambler on the upstream RF carrier enables cable modems on the HFC network to use built-in scrambler circuitry for upstream data transmissions. The scrambler circuitry improves reliability of the upstream receiver on the cable modem card. The upstream scrambler is activated by default and should not be disabled under normal circumstances.
Caution
To activate the upstream scrambler after it has been disabled, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable upstream usport scrambler
Enables the scrambler. This is the default.
Verifying the Upstream Scrambler
To verify whether or not the upstream scrambler is activated, enter the more system:running-config command and look for the cable interface configuration information. The following is an excerpt from the more system:running-config command output:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream Differential Encoding
To enable differential encoding on upstream traffic to a specified cable interface, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable upstream usport differential-encoding
Enables differential encoding.
Upstream differential encoding is disabled by default.
Verifying Upstream Differential Encoding
To verify whether or not upstream differential encoding is activated, enter the show running-config command and look for the cable interface configuration information. If upstream differential encoding is enabled, a differential encoding entry will be displayed in the show running-config output. If upstream differential encoding is disabled, no differential encoding entry will be displayed in the output.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream Rate Limiting
Upstream rate limiting allows upstream bandwidth requests from rate-exceeding cable modems to be buffered without incurring TCP-related timeouts and retransmits. The CMTS can thus enforce the peak upstream rate for each cable modem without degrading overall TCP performance for the subscriber CPE devices. Upstream grant shaping is per cable modem (SID).
Token bucket policing with shaping is the per-upstream default rate-limiting setting at the CMTS. Shaping can be enabled or disabled for the token bucket algorithm.
To enable upstream rate limiting for an upstream port on a Cisco cable modem card, use one of the following commands in cable interface configuration mode:
To disable upstream traffic shaping for an upstream port, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport rate-limitVerifying Upstream Rate Limiting
To verify whether or not upstream rate limiting has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream rate limiting has been configured and enabled, a rate limiting entry will be displayed in the show running-config output. If upstream rate limiting is disabled, no cable upstream rate-limit will be displayed in the output.
You can also perform the following tasks to verify that rate limiting is enabled on the upstream channel:
Step 1
Step 2
Use the show interface cx/y sid counters command to see the bandwidth request drops. See that the upstream rate received by that modem is in fact less than its configured peak rate due to the timeouts and backoffs produced by the drop in bandwidth requests. To see the input rate at the CMTS in bps, enter the show interface cx/y sid command.Step 3
Step 4
Let the pings run for a few minutes (to let averages at CMTS settle); then see the upstream rate received by this single modem. Use the show interface cx/y command and observe the input rate in bps. This value should be close to the modem's peak upstream rate. Also observe the drop counts for the modem's SID by using the show interface sid counters command and see that CMTS no longer drops the bandwidth requests from the cable modem.The bandwidth request drop count (from previous nonshaping test) remains unchanged when upstream rate shaping is used, indicating that the CMTS is actually shaping (buffering) the grants for the modem. See that the input rate at the CMTS (from the single rate-exceeded cable modem) stabilizes close to the configured peak rate of 128 kbps.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream Frequency Adjustment
To enable automatic upstream frequency adjustment for a specified cable interface, use the following command in cable interface configuration mode:
To return the automatic upstream frequency adjustment percentage to the default value of 30 percent, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport frequency-adjust averagingVerifying Upstream Frequency Adjustment
To verify whether or not upstream frequency adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream frequency adjustment is enabled, frequency adjustment entries will be displayed in the show running-config output. If frequency adjustments have been disabled, no frequency adjustment entry will be displayed in the output.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream Power Adjustment
To enable upstream power adjustment for a specified cable interface, use the following commands in cable interface configuration mode:
To return the automatic upstream power adjustment ranging value to the default of 2 dB, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport power-adjust continueTo return the automatic upstream power adjustment noise value to the default of 30 percent, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport power-adjust noiseTo return the upstream power adjustment threshold value to the default of 1 dB, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport power-adjust thresholdVerifying Upstream Power Adjustment
To verify whether or not upstream power adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream power adjustment is enabled, any or all three of the continue, noise, and threshold power adjustment entries will be displayed in the show running-config output. If all three continue, noise, and threshold upstream power adjustments have been disabled, no power adjustment entry will be displayed in the show running-config output.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating Upstream Timing Adjustment
To enable upstream timing adjustment for a specified cable interface, use the following commands in cable interface configuration mode:
To return the upstream time adjustment ranging value to the default of 2 seconds, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport time-adjust continueTo return the upstream time adjustment threshold value to the default of 1 second, enter the following command in cable interface configuration mode:
CMTS01(config-if)# no cable upstream usport time-adjust thresholdVerifying Upstream Timing Adjustment
To verify whether or not upstream timing adjustment has been configured and activated, enter the show running-config command and look for the cable interface configuration information. If upstream timing adjustment is enabled, either or both of the continue and threshold timing adjustment entries will be displayed in the show running-config output. If both the continue and threshold upstream timing adjustments have been disabled, no timing adjustment entry will be displayed in the show running-config output.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Activating the Upstream Ports
Each upstream port must be activated to enable upstream data transmission from the cable modems on the HFC network to the Cisco uBR7200 series router.
Note
To activate the upstream ports, use the following commands beginning in global configuration mode:
Verifying the Upstream Ports
To verify whether the upstream ports are activated or deactivated, enter the show interface cable command for the upstream port that you have just configured:
router# show interface cable 6/0Cable6/0 is up, line protocol is upHardware is BCM3210 FPGA, address is 00e0.1e5f.7a60 (bia 00e0.1e5f.7a60)Internet address is 1.1.1.3/24MTU 1500 bytes, BW 27000 Kbit, DLY 1000 usec, rely 255/255, load 1/255Encapsulation, loopback not set, keepalive not setARP type: ARPA, ARP Timeout 04:00:00Last input 00:00:25, output 00:00:00, output hang neverLast clearing of "show interface" counters neverQueueing strategy: fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 dropsTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Setting Upstream Backoff Values
The DOCSIS-specified method of contention resolution for cable modems wishing to transmit data or requests on the upstream channel is a truncated binary exponential backoff, with the initial backoff window and the maximum backoff window controlled by the CMTS. The Cisco uBR7200 series router specifies backoff window values for both data and initial ranging, and sends these values downstream as part of the Bandwidth Allocation Map (MAP) MAC message. The values are configurable on the Cisco uBR7200 series and are power-of-two values. For example, a value of 4 indicates a window from 0 to 15; a value of 10 indicates a window from 0 to 1023.
You can set fixed start and end values for data backoff on the upstream ports, or you can set the upstream ports for automatic data backoff. You have the same options for ranging backoff. For both backoff windows, the default start value is 0; the default end value is 4. Valid values are from 0 to 15.
To set data or ranging backoff values for an upstream port, use one or more of the following commands, beginning in cable interface configuration mode:
When considering whether or not to adjust backoff values, note the following:
•
–
–
–
–
–
•
Note
Verifying Upstream Data Backoff Automatic
To verify backoff window settings, enter the show controllers cable 6/0 u0 command for the upstream port you have just configured:
CMTS01# show controllers cable 6/0 u0Cable6/0 Upstream 0 is upFrequency 24.016 MHz, Channel Width 1.600 MHz, QPSK Symbol Rate 1.280 MspsSpectrum Group is overriddenSNR 33.2560 dBNominal Input Power Level 0 dBmV, Tx Timing Offset 2288Ranging Backoff automatic (Start 0, End 3)Ranging Insertion Interval automatic (60 ms)Tx Backoff Start 0, Tx Backoff End 4Modulation Profile Group 1part_id=0x3137, rev_id=0x03, rev2_id=0xFFnb_agc_thr=0x0000, nb_agc_nom=0x0000Range Load Reg Size=0x58Request Load Reg Size=0x0EMinislot Size in number of Timebase Ticks is = 8Minislot Size in Symbols = 64Bandwidth Requests = 0xFEPiggyback Requests = 0xDInvalid BW Requests= 0x2Minislots Requested= 0x2963Minislots Granted = 0x2963Minislot Size in Bytes = 16Map Advance = 4000 usecsUCD Count = 32964DES Ctrl Reg#0 = C000C043, Reg#1 = 0Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
–
–
–
–
Configuring and Activating Baseline Privacy
To encrypt upstream and downstream data, you need to configure and activate baseline privacy. Baseline privacy on an HFC network is configured with key encryption keys (KEKs) and traffic encryption keys (TEKs). The encryption is based on 40-bit or 56-bit data encryption standard (DES) encryption algorithms.
A KEK is assigned to a cable modem based on the cable modem SID and permits the cable modem to connect to the Cisco uBR7200 series when baseline privacy is activated. The TEK is assigned to a cable modem when its KEK has been established. The TEK is used to encrypt data traffic between the cable modem and the Cisco uBR7200 series.
KEKs and TEKs can be set to expire based on a grace-time or a life-time value. A grace-time key is used to assign a temporary key to a cable modem to access the network. A life-time key is used to assign a more permanent key to a cable modem. Each cable modem that has a life-time key assigned will request a new life-time key from the Cisco uBR7200 series before the current one expires.
Note
Note
The configuration and activation of baseline privacy depends on each cable operator physical plant.
To configure and activate baseline privacy, perform the following tasks:
Configuring KEK Privacy
A grace-time KEK can be set from 300 to 1800 seconds. A life-time KEK can be set from 86,400 to 6,048,000 seconds. If you do not set a KEK value, the default values are used.
To configure KEK data privacy on the HFC network, use the following commands in cable interface configuration mode:
Verifying KEK Privacy
To verify the KEK life-time or grace-time values that have been set, enter the show cable privacy kek command:
CMTS01# show cable privacy kekConfigured KEK life time value = 750000Configured KEK grace time value = 800Troubleshooting Tips
To troubleshoot the configuration, make sure you have entered a valid value for grace time or life time.
Configuring TEK Privacy
A grace-time TEK can be set from 300 to 1800 seconds. A life-time TEK can be set from 1800 to
604,800 seconds. If you do not set a TEK value, the defaults are used.To configure TEK data privacy on the HFC network, use one of the following commands in cable interface configuration mode:
Verifying TEK Privacy
To verify the TEK life-time or grace-time values that have been set, enter the show cable privacy tek command:
CMTS01# show cable privacy tekConfigured TEK life time value = 56000Configured TEK grace time value = 900Troubleshooting Tips
To troubleshoot the configuration, make sure you have entered a valid value for grace time or life time.
Activating Baseline Privacy
After the KEK and TEK values have been set, activate encryption on the HFC network by using the following commands in cable interface configuration mode:
Verifying Baseline Privacy
To verify whether or not baseline privacy is activated, enter the cable privacy enable or cable privacy mandatory command. By default, cable privacy is enabled and can only be disabled with the no cable privacy command.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Configuring and Activating Frequency Agility
The Cisco uBR7200 series universal broadband routers divide a cable plant into downstream channels. Downstream channels contain upstream segments.
Each upstream segment typically serves more than one fiber node. Upstream segments can be defined as one of the following:
•
•
Note
Defining sparse segments allows the cable operator to share upstream bandwidth among fiber nodes with fewer subscribers. Defining dense segments allows the cable operator to provide larger upstream bandwidth to fiber nodes with many subscribers. Figure 109 illustrates sparse versus dense segments.
Figure 109 Sparse Versus Dense Segment Illustrations
As shown in Figure 109, the downstream segment can contain multiple upstream segments. Two fiber nodes can be in one downstream segment but in different upstream segments.
An upstream frequency has an associated upstream input power level in dBmV. Cable operators must make noise measurements and determine the cable plant spectrum management policy. Different modulation schemes and symbol rates can be used based on the characteristics of the cable plant and the cable modem card contained in the Cisco uBR7200 series chassis. Bits are encoded into a two-dimensional mapping called a constellation. A good carrier-to-noise ratio is needed to properly decode symbols into bits.
Combiner Groups
The return path of several fiber nodes can be combined at a single point to form a single RF frequency domain called a combiner group. The Cisco uBR7200 series software allows a frequency hop table called a spectrum group to be associated with a combiner group.
Note
The Cisco uBR7200 series routers support up to 32 spectrum groups. Each spectrum group defines the table of frequencies to be used in a specific frequency plan. Cisco cable modem cards interface the downstream and upstream ports to the cable plant, while port adapters connect to the IP backbone and external networks.
Frequency Management Policy
Upstream port frequency should be set to a fixed value during system installation and testing. This value is chosen from the allocation plan for the RF domain for the RF plant segment connected to the upstream.
Note
When the system has reached sufficient stability, the RF domain topology can be entered into the Cisco IOS configuration file to enable RF spectrum management. This management feature—also called frequency agility—applies a common frequency management policy to a set of upstream ports.
Spectrum management or frequency agility is configured and activated using spectrum groups. A spectrum group is a frequency hop table that can be used by upstream ports to implement a frequency-hopping policy. There are four types of frequency-hopping policies: blind, scheduled, combined blind and scheduled, and guided.
Note
Note
In general, when defining your spectrum use the following guidelines:
•
•
•
•
•
Frequency agility is configured and activated using spectrum groups that are controlled by the spectrum manager. You can create from 1 to 32 spectrum groups for each Cisco uBR7200 series cable modem card upstream port.
To configure and activate frequency agility, perform the tasks in the following sections:
•
•
•
•
Determining the Upstream Ports Assigned to a Combiner Group
Following is an example topology for a Cisco uBR7223 with combiner groups designated A through J. Combiner groups C and E have multiple upstream ports that should be configured in a shared spectrum group. The other upstreams should be configured in a nonshared spectrum group.
In this example, ten combiner groups are served with frequency hop tables from three spectrum groups:
Cable3/0DS +-----+ Upconverter +----- laser group 1U0 +----- combiner group AU1 +----- combiner group BU2 +------combiner group CU3 +------combiner group CU4 +----- combiner group DU5 +------combiner group ECable4/0DS +-----+ Upconverter +----- laser group 2U0 +------combiner group EU1 +----- combiner group FU2 +----- combiner group GU3 +----- combiner group HU4 +----- combiner group IU5 +----- combiner group JThe laser group term refers to the set of fiber nodes that share the same downstream signal. An optical splitter is often used to create individual feeds per node.
In the downstream direction, two 6 MHz channel slots are assigned. All fiber nodes in combiner groups A through E should have a channel slot containing the downstream signal from Cable3/0. Combiner groups A through E are said to belong to laser group 1.
All fiber nodes in combiner groups E through J should have a channel slot containing the downstream signal from Cable4/0. Combiner groups E through J are said to belong to laser group 2.
Because combiner group E belongs to two laser groups, there should be two different downstream channel slots for Cable3/0 and Cable4/0.
Creating Spectrum Groups
To create a spectrum group, use one of the following commands in global configuration mode:
Verifying Spectrum Groups
To verify that a spectrum group has been created, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-groupspectrum-group 1spectrum-group 2spectrum-group 3Troubleshooting Tips
To troubleshoot the configuration, make sure you have entered a valid spectrum group number and type.
Configuring and Activating Spectrum Groups
After you create a spectrum group, you need to configure a list of upstream frequencies and optional nominal power levels that each spectrum group can use when an upstream frequency change is necessary. Each spectrum group should have its own list of upstream frequencies. Valid frequencies are 5,000,000 to 42,000,000 Hz; valid power levels at a channel width of 1.6 MHz are -10 dBmV to 25 dBmV.
To configure and activate a spectrum group, use one of the following commands in global configuration mode:
Note
You must repeat the command described above for each frequency or power level that you want to add to a spectrum group's list of valid values.If your cable plant has an upstream noise characteristic on a weekly cycle, use time-scheduled spectrum allocation. An example follows:
CMTS01(config)# cable spectrum-group 1 time Mon 08:00:00 frequency 21600000Deletion is performed using the delete keyword:
CMTS01(config)# cable spectrum-group 1 time Mon 18:00:00 delete frequency 21600000The following is an example of a spectrum group configuration that is designed to perform minor equalization as a function of frequency.
CMTS01(config)# cable spectrum-group 1 frequency 21600000CMTS01(config)# cable spectrum-group 1 frequency 24800000 1CMTS01(config)# cable spectrum-group 1 frequency 28000000 2In this example, the upstream port nominal receive power at 21.6 MHz is 0 dBmV, at 24.8 MHz is 1 dBmV, and at 28.0 MHz is 2 dBmV. At any time, the power level set in the interface configuration overrides the spectrum group power level.
The following example enables spectrum management for all upstream ports, assuming that all combiner groups use the frequency band from 20 to 26 MHz:
CMTS01(config)# cable spectrum-group 1 band 20000000 26000000CMTS01(config)# cable spectrum-group 2 sharedCMTS01(config)# cable spectrum-group 2 band 20000000 26000000CMTS01(config)# cable spectrum-group 3 sharedCMTS01(config)# cable spectrum-group 3 band 20000000 26000000CMTS01(config)# interface Cable3/0CMTS01(config-if)# cable spectrum-group 1CMTS01(config-if)# cable upstream 2 spectrum-group 2CMTS01(config-if)# cable upstream 3 spectrum-group 2CMTS01(config-if)# cable upstream 5 spectrum-group 3CMTS01(config-if)# exitCMTS01(config)# interface Cable4/0CMTS01(config-if)# cable spectrum-group 1CMTS01(config-if)# cable upstream 0 spectrum-group 3A description of the spectrum groups 1 through 3 follows:
•
Upstream Port RF DomainCable3/0 U0 combiner group ACable3/0 U1 combiner group BCable3/0 U4 combiner group DCable4/0 U1 combiner group FCable4/0 U2 combiner group GCable4/0 U3 combiner group HCable4/0 U4 combiner group ICable4/0 U5 combiner group J•
Upstream Port RF DomainCable3/0 U2 combiner group CCable3/0 U3 combiner group C•
Upstream Port RF DomainCable3/0 U5 combiner group ECable4/0 U0 combiner group EFor the 20 to 26 MHz band of each RF domain, the spectrum is channelized according to the channel width settings of each member port. For example, if the ports U2 and U3 of Cable3/0 are set to 3.2 MHz and 1.6 MHz channel widths, respectively, then spectrum group 2 uses the following channelization:
> Channel Width Start Stop Center> (Mhz) (Mhz) (Mhz) (Mhz)> 1 3.2 20.0 23.2 21.6> 2* 1.6 20.0 21.6 20.8> 3* 1.6 21.6 23.2 22.4> 4 1.6 23.2 24.8 24.0
Note
Because the group is shared, ports U2 and U3 will be assigned channels 1 and 4, respectively, to prevent overlap.
Note
> Channel Width Start Stop Center> (Mhz) (Mhz) (Mhz) (Mhz)> 1 3.2 20.0 23.2 21.6> 2 3.2 23.2 26.4 24.8> 3 1.6 20.0 21.6 20.8> 4 1.6 21.6 23.2 22.4> 5 1.6 23.2 24.8 24.0> 6 1.6 24.8 26.4 25.6> 7 1.6 26.4 28.0 27.4Care should be taken to reduce the spectrum allocation when used with small channel widths. Otherwise, there will be a large number of upstream channel slots.
For example, if the allocation is from 20.0 to 28.0 MHz and an upstream port has its channel width set to 0.2 MHz, then there will be 40 possible slots for that channel width. Blind frequency hopping may require several minutes to find the clean slot because it will try each available slot, one at a time for several seconds each try.
Verifying Spectrum Group Configuration
To verify if spectrum groups have been configured and activated, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-group22:07:46: %SYS-5-CONFIG_I: Configured from console by consoleGroup Frequency Upstream Weekly Scheduled Power SharedNo. Band Port Availability Level Spectrum(Mhz) From Time: To Time: (dBmV)1 5.000-15.000 0 Yes1 12.000 0 Yes1 22.000 7 Yes2 29.000 6 No2 26.000 0 No3 35.000-41.000 0 No3 16.000-19.000 5 No5* 5.000-10.000 Thu 21:50:00 Thu 21:45:00 0 YesVerifying Frequency Hopping
To verify frequency hopping on the Cisco uBR7200 series router, note the following:
•
•
After you have established basic operation, inject a tone to the upstream port. For example, if the upstream frequency is 22.4 MHz, inject a 22.4 MHz tone at approximately the same power level as the modem. (If the power level at the modem is 40 dBmV, set the tone power to 40 dBmV.) The interfering carrier should shut down the channel and cause the frequency to change to the next configured value. In this example, the next configured value is 24.0 MHz.
If you do not have an RF tone generator, use another line card and modem that carries traffic. Connect the upstream to the same combiner group, and use the data carrier as an interfering signal by setting it to the same frequency. For example, to test frequency hopping on c3/0, install c4/0 and connect both upstreams together using a combiner. If the upstream frequency of c3/0 is 22.4 MHz, set c4/0 to 22.4 MHz while c4/0 is carrying traffic. This should force c3/0 to change the frequency to the next configured value.
Troubleshooting Tips
To troubleshoot the configuration, make sure you entered a valid spectrum group number, time, frequency, and input power level. Also, when defining your spectrum, use the following guidelines:
•
•
•
•
•
Configuring Spectrum Group Characteristics
Once you have created spectrum groups for your cable network, you can add characteristics to them, providing you with more definitive control over frequency usage and frequency hopping.
As stated in Section 6.3.2.2 of the DOCSIS RFI specification, RF channel migration occurs by broadcasting a change in the upstream channel descriptor (UCD) message to all cable modems. The UCD message contains the upstream frequency and transmission parameters associated with an upstream channel.
The speed of channel migration via the UCD message is typically less than 20 ms. During this time, upstream transmission is interrupted until the cable modem transmitter adjusts to its new frequency. Data is stored in the cable modem buffers during this time and is sent when the frequency hop is complete.
Also, per the DOCSIS RFI, station maintenance intervals are used to perform per-modem "keepalive" polling. The Cisco uBR7200 series routers poll each cable modem at a default rate of once every 10 seconds. When ingress noise causes loss of keepalive messages from a configurable percentage of all cable modems, resulting in those cable modems going offline, a new frequency is selected from the allocation table and a UCD update is performed.
The migration time is 10 seconds (maximum) for the decision and 20 ms for the frequency hop. The percentage threshold method prevents a single failing cable modem from affecting service to other operational cable modems. The system will not hop endlessly because one cable modem is generating 90 percent of the errors and 90 percent of the traffic.
The minimum period between frequency hops is also configurable, with a default setting of 300 seconds. If the destination channel is expected to be impaired, the minimum period between frequency hops can be reduced to a small value such as 10 seconds. Reducing the time between frequency hops allows the frequency hop to continue more rapidly until a clear channel is found. If excessive frequency hop is a concern, the minimum period between hops can be increased.
To adjust the frequency hop threshold percentage or the minimum period between frequency hops, use the following commands in global configuration mode:
The current implementation is known as blind frequency hop because there is no "look-ahead" mechanism. In this case, the search time is 0 seconds and the switching time is 20 ms.
To specify that a particular spectrum group is a shared RF spectrum group, use the following command in global configuration mode:
Verifying Spectrum Group Characteristics
To verify spectrum group characteristics and whether or not a spectrum group is shared, enter the show cable spectrum-group command:
CMTS01# show cable spectrum-group22:07:46: %SYS-5-CONFIG_I: Configured from console by consoleGroup Frequency Upstream Weekly Scheduled Power SharedNo. Band Port Availability Level Spectrum(Mhz) From Time: To Time: (dBmV)1 5.000-15.000 0 Yes1 12.000 0 Yes1 22.000 7 Yes2 29.000 6 No2 26.000 0 No3 35.000-41.000 0 No3 16.000-19.000 5 No5* 5.000-10.000 Thu 21:50:00 Thu 21:45:00 0 YesTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Assigning the Spectrum Group and the Upstream Ports
To configure a frequency hop table after you have determined which upstream ports you want assigned to a combiner group, use the following commands:
Verifying Spectrum Group and Upstream Port Assignments
To display the current allocation table and frequency assignments, use the show cable spectrum-group command.
Activating IP Address Resolution Protocol
Address Resolution Protocol (ARP) is an Internet protocol used to map IP addresses to MAC addresses on computers and other equipment installed in a network. You need to activate ARP requests on the cable interface so that the Cisco uBR7200 series can perform IP address resolution on the downstream path.
Note
Activating Cable ARP Requests
To activate ARP requests, use the following command in cable interface configuration mode:
Verifying ARP Requests
To verify whether or not cable ARP has been activated, enter the more system:running-config command and look for the cable interface configuration information. If ARP has been activated, it does not appear in this output. If ARP has been deactivated, it will appear in the output as no cable arp as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepaliveno cable arpcable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure you entered the correct port and cable modem card slot number when you activated ARP and when you entered the show interface cable command.
Activating Host-to-Host Communication (Proxy ARP)
Cable proxy ARP allows the Cisco uBR7200 series to issue cable ARP requests on behalf of cable modems on the same cable network subnet.
Note
Note
Activating Cable Proxy ARP Requests
To activate cable proxy ARP for host-to-host communications, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable proxy-arp
Enables proxy ARP on the cable interface. This is the default.
Verifying Cable Proxy ARP Requests
To verify whether or not cable proxy ARP has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If cable proxy ARP has been activated, it does not appear in the output. If cable proxy ARP has been deactivated, it appears in the output as no cable proxy-arp as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepaliveno cable proxy-arpcable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure you entered the correct port and cable modem card slot number when you activated cable proxy ARP.
Configuring DHCP Options
The following sections describe configurable DHCP options for the Cisco uBR7200 series.
Activating Cable Relay Agent
The cable relay agent is for use with DOCSIS-based DHCP servers that use option 87 to automatically map the Ethernet MAC address of a host (end user PC) with the cable modem to which it is connected.
With the cable relay agent activated, the Cisco uBR7200 series will insert the cable modem MAC address into a DHCP packet when a packet is received from a cable modem or another host. The Cisco uBR7200 series will then forward the packet to a DHCP server.
To activate the cable relay agent, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable relay-agent-option
Activates the cable relay agent. This is the default.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Activating DHCP giaddr
Configure the Cisco uBR7200 series so it will either assign primary addresses to both cable modems and remote hosts, or assign primary addresses to cable modems and secondary addresses to remote hosts.
To configure cable DHCP giaddr functionality, use one of the following commands in cable interface configuration mode:
To disable cable DHCP giaddr functionality (the default) after it has been enabled, enter the no cable dhcp-giaddr command in cable interface configuration mode.
Verifying DHCP giaddr Activation
To verify whether DHCP giaddr has been activated, enter the show running-config command and look for the cable interface configuration information. If DHCP giaddr has been activated, a notation will appear in this output. If DHCP giaddr has been deactivated, it will not appear in the output.
Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Setting Service Options
The following sections describe configurable service options for the Cisco uBR7200 series.
Configuring ToD Service
To activate ToD service for the Cisco uBR7200 series, use the following command in global configuration mode:
CMTS01(config)# cable time-server enable
Enables ToD service for the Cisco uBR7200 series.
To disable ToD service (the default) after it has been enabled, enter the no cable time-server command or the cable time-server disable command in global configuration mode.
Verifying ToD Service
To verify whether or not ToD service has been activated, enter the show running-config command and look for the global cable configuration information. If ToD service has been activated, an entry will appear in this output. If ToD service has been deactivated, no entry will appear in this output.
Troubleshooting Tips
To troubleshoot the configuration, make sure you are in global configuration mode.
Setting Optional IP Parameters
Additional IP parameters can be set to enable downstream echoing of upstream data. To configure these optional IP parameters, perform the tasks in the following sections:
Note
Activating IP Multicast Echo
The Cisco uBR7200 series echoes IP multicast packets by default. To activate IP multicast echo if it has been previously disabled, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable ip-multicast-echo
Enables IP multicast echo. This is the default.
To disable IP multicast echo, enter the no cable ip-multicast-echo command in cable interface configuration mode.
Verifying IP Multicast Echo
To verify whether IP multicast echo has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If IP multicast echo is activated, there is no notation in the output as this is the default setting. If IP multicast echo has been deactivated, a notation appears in the output as shown in the following command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepaliveno cable ip-multicast-echocable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure you entered the correct slot and port numbers when you entered cable interface configuration mode.
Activating IP Broadcast Echo
By default, the Cisco uBR7200 series does not echo IP broadcast packets. To activate IP broadcast echo, use the following command in cable interface configuration mode:
To disable IP broadcast echo (the default setting), enter the no cable ip-broadcast-echo command in cable interface configuration mode.
Verifying IP Broadcast Echo
To verify whether IP broadcast echo has been activated or deactivated, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in the following command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable ip-broadcast-echocable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you entered cable interface configuration mode.
Configuring Cable Profiles
The following sections describe optional cable profile configuration tasks:
•
•
•
•
Configuring Cable Modulation Profiles
This section describes how to define the elements that are used in a cable modulation profile. The Cisco uBR7200 series router supports up to eight cable modulation profiles. Profile 1 is the default.
Caution
The following modulation profile values can be changed:
•
•
•
•
•
•
•
•
•
•
•
•
To create or change a cable modulation profile, use the following command in global configuration mode:
In the following example, the request burst for cable modulation profile 2 is defined to have 0 fec-tbytes, 16 KB fec-len, a burst-len of 1, a guard time of 8, a mod value of qpsk, scrambler enabled with a seed value of 152, differential encoding disabled, a preamble length of 64 bits, a fixed code-word length, and 8-bit unique words for upstream unique word length.
CMTS01(config)# cable modulation-profile 2 request 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8To remove a cable modulation profile, use the no cable modulation-profile profile command in global configuration mode. You can use this command to remove all modulation profiles except for modulation profile 1. Entering the no cable modulation-profile 1 command sets all of the parameters in profile 1 to the default values.
Verifying Cable Modulation Profiles
To verify whether or not a cable modulation profile has been created and to see how it is configured, enter the show cable modulation-profile command:
CMTS01# show cable modulation-profileMo IUC Type Preamb Diff FEC err FEC Scrambl Max Guard Last Scrambl Preamb length enco correct T seed B time CW offset bytes size size short1 request qpsk 64 no 0x0 0x10 0x152 1 8 no yes 56 1 initial qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0 1 station qpsk 128 no 0x5 0x22 0x152 0 48 no yes 0 1 short qpsk 72 no 0x5 0x4B 0x152 0 8 no yes 48Troubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
Configuring QoS Profiles
The Cisco uBR7200 series router supports multiple QoS profiles. QoS profile 1 is used during cable modem registration; QoS profile 2 is the default QoS profile. Both of these profiles are preconfigured and cannot be removed. However, you can modify these profiles and create additional QoS profiles for various traffic flows.
To create or change a QoS profile, use the first command in the following table, plus as many of the additional commands as are necessary to make the changes you require. All of the QoS profile commands are global configuration commands.
Note
Use the no cable qos-profile groupnum command to remove an optional QoS profile, or in the case of QoS profiles 1 and 2, to return the parameters to their default values.
Verifying QoS Profiles
To verify whether or not a QoS profile has been created, and to see how it is configured, enter the show cable qos profile command:
CMTS01# show cable qos profileService Prio Max Guarantee Max Max tx TOS TOS Create Bclass upstream upstream downstream burst mask value by privbandwidth bandwidth bandwidth enab1 0 0 0 0 0 0x0 0x0 cmts no2 0 64000 0 1000000 0 0x0 0x0 cmts no3 0 1000 0 1000 0 0x0 0x0 cmts no4 7 2000000 100000 4000000 0 0x0 0x0 cm yesTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
•
Setting QoS Permission
The Cisco uBR7200 series router supports the creation of QoS table entries by SNMP or by cable modem registration requests. You can also configure the Cisco uBR7200 series to dynamically update QoS table entries via SNMP.
To set QoS table access, use one or more of the following commands in global configuration mode:
Verifying QoS Permission
To verify QoS permissions, enter the show cable qos permission command:
CMTS01# show cable qos permissionCreate by SNMP Update by SNMP Create by modemsno no yesTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
Enforcing a QoS Profile Assignment
To override the provisioned QoS profile of the cable modems connecting to the Cisco uBR7200 series and enforce a CMTS-specified QoS profile, use the following command in global configuration mode:
CMTS01(config)# cable qos permission enforce index
Assigns the QoS profile, specified by the index number, to all cable modems attempting to connect to the Cisco uBR7200 series.
Verifying a QoS Profile Assignment
To verify a QoS profile assignment, perform the following steps:
Step 1
Notice that the modems are getting their provisioned class of service as indicated by the show cable modem and show cable qos profile commands.
Step 2
Step 3
Step 4
Notice that the cable modems are assigned temporarily the CMTS-defined PRE_REGISTRATION QoS profile with index 2 until the cable modems register with the CMTS.
Step 5
Notice that at the end of the registration, the modem gets the user-enforced QoS profile as indicated by the show cable modem and show cable qos profile commands.
For additional information, refer to the cable qos permission enforce command reference page in the Cisco IOS Multiservice Applications Command Reference.
Managing Cable Modems on the HFC Network
You can manage the cable modems connected to the Cisco uBR7200 series on the HFC network by performing the optional tasks in the following sections:
•
•
•
•
•
•
•
•
•
•
Note
Configuring Sync Message Interval
To specify the interval between successive sync message transmissions from the Cisco uBR7200 series, use the following command in cable interface configuration mode:
To return the sync message interval to its default value of 10 ms, enter the no cable sync-interval command in cable interface configuration mode.
Verifying Sync Message Interval
To verify whether a sync message interval has been configured, enter the show running-config command and look for the cable interface configuration information. If a sync message interval has been configured, it will appear in this output. If the sync message interval has been deactivated or reset to its default value, no sync interval command line will appear in the output.
Troubleshooting Tips
To troubleshoot the configuration, make sure you entered the correct slot and port numbers when you entered cable interface configuration mode.
Configuring Telco Return
The Cisco uBR7200 series routers support both two-way communication and DOCSIS-based telco return communication from remote cable modems.
Note
For detailed instructions on configuring telco return, refer to the document Telephone Return for the Cisco uBR7200 Series Cable Router on CCO. You will find this document on the index page for Cisco IOS software under the section "New Features for Cisco IOS Release 12.0(5)T."
Activating Cable Modem Authentication
The Cisco uBR7200 series can be configured to require all cable modems to return a known text string in order to register with the CMTS and gain access to the network. The text string can be from 1 to 80 characters in length.
To activate cable modem authentication, use the following command in cable interface configuration mode:
Verifying Cable Modem Authentication
To verify whether cable modem authentication has been activated or deactivated, enter the more system:running-config command and look for the cable interface configuration information. If cable modem authentication has been activated, it does not appear in this output. If cable modem authentication has been deactivated, it appears in this output as no cable secret-shared as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepaliveno cable secret-sharedcable insertion-interval 150000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
Note
Activating Cable Modem Upstream Address Verification
Cable modem upstream address verification ensures that only known cable modems that have received DHCP leases through the Cisco uBR7200 series can access the HFC network. The Cisco uBR7200 series will discard all packets received for or from hosts that have not received DHCP-assigned addresses.
To activate cable modem upstream address verification, use the following command in cable interface configuration mode:
To deactivate cable modem upstream address verification (the default), enter the no cable source-verify command.
Verifying Cable Modem Upstream Address Verification
To verify whether cable modem upstream verification has been activated or deactivated, enter the more system:running-config command and look for a cable source-verify notation in the cable interface configuration information:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable source-verifycable insertion-interval 2000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
•
Activating Cable Modem Insertion Interval
When a cable modem is ready to join the HFC network and send data, it requests an upstream frequency from the Cisco uBR7200 series. You can limit the amount of time that a cable modem can request an upstream frequency from the Cisco uBR7200 series for the first time. The initial request of a cable modem to join the network is known as initial ranging. The default insertion interval setting (automatic) configures the Cisco uBR7200 series to automatically vary the initial ranging times available to new cable modems that attempt to join the network.
Note
To configure the cable modem insertion interval, use one of the following commands in cable interface configuration mode:
To ignore any minimum or maximum insertion intervals and return to the automatic setting, enter the no cable insertion-interval command.
Verifying Cable Modem Insertion Interval
To verify that a cable modem insertion interval has been set, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable insertion-interval 2000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
Configuring the Maximum Number of Hosts Attached to a Cable Modem
To specify the maximum number of hosts that can be attached to a subscriber cable modem, use the following command in cable interface configuration mode:
CMTS01(config-if)# cable max-hosts n
Specifies the maximum number of hosts that can be attached to a cable modem on this interface. Valid range is from 0 to 255 hosts. Default = 0.
Verifying the Maximum Number of Hosts
To verify the maximum number of hosts that can be attached to a cable modem on a particular interface, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable insertion-interval 2000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
Configuring Cable Modem Registration Timeout
By default, registered cable modems that have no upstream activity for three minutes are timed out and disconnected from the Cisco uBR7200 series. This timeout interval can be decreased to two minutes or increased to 60 minutes.
To specify the registration timeout interval for cable modems connected to the Cisco uBR7200 series, use the following command in cable interface configuration mode:
Verifying Registration Timeout
To verify the registration timeout interval for a cable modem on a particular interface, enter the more system:running-config command and look for a notation in the cable interface configuration information as shown in this command output excerpt:
CMTS01# more system:running-configBuilding configuration...Current configuration:!interface Cable6/0ip address 1.1.1.1 255.255.255.0no keepalivecable insertion-interval 2000cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream symbol-rate 5056941cable upstream 0 frequency 15008000cable upstream 0 feccable upstream 0 scramblerno cable upstream 0 shutdownTroubleshooting Tips
To troubleshoot the configuration, make sure that you entered the correct slot and port numbers when you typed the command.
Clearing and Resetting Cable Modems
To remove a single cable modem (or all cable modems) from the Station Maintenance List and reset the cable modem (or all cable modems) on the network, use one of the following commands in cable interface configuration mode:
Verifying Cable Modem Clearing and Resetting
To verify whether the clear cable modem reset command has removed a cable modem from the Station Maintenance List and forced it to start a reset sequence, enter the show cable modem command:
CMTS01# show cable modem 1.1.1.5Interface US Online Timing SID QoS IP address MAC addressState OffsetTroubleshooting Tips
To troubleshoot the configuration, perform the following tasks:
•
•
Note
Clearing Cable Modem Counters
To clear the counters for a cable modem (or for all cable modems) in the Station Maintenance List, use one of the following commands in cable interface configuration mode:
Verifying that Cable Modem Counters are Cleared
To verify whether the counters in the Station Maintenance List have been cleared, enter the show cable flap list command. The station maintenance list counter will be 0.
CMTS01# show cable flap listTroubleshooting Tips
To troubleshoot the configuration, make sure you entered the correct cable modem MAC address or IP address when you typed the command.
Using Ping DOCSIS
To ping a specific cable modem to determine if it is online, use the following command in EXEC mode:
CMTS01# ping docsis addr
Ping the cable modem with a specific MAC address or IP address to see if it is online.
Verifying Ping DOCSIS
The output from the ping docsis command indicates whether or not the cable modem you were trying to contact was found on the network:
CMTS01# ping docsis 10.1.1.0Queueing 5 MAC-layer station maintenance intervals, timeout is 25 msec:!!!!!Success rate is 100 percent (5/5)Troubleshooting Tips
To troubleshoot the configuration, make sure you are using a valid MAC or IP address for the cable modem you want to ping.
Headend Broadband Access Router Configuration Examples
For most of the commands described in this document, the default values are adequate to configure the Cisco uBR7200 series router. To view the current configuration of a Cisco uBR7200 series, enter the show running-config command at the CLI prompt in EXEC mode or privileged EXEC mode.
Headend broadband access router configuration examples are provided in the following sections:
•
•
•
•
Spectrum Management Configuration Example
In the following example, the Cisco uBR7200 series is configured to support spectrum management and modulation profiles.
!version 12.1no service padservice timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname uBR7246!boot system flash slot0:ubr7200-p-mz.120-4.Tboot system flash!cable spectrum-group 1 frequency 40000000cable spectrum-group 1 frequency 20000000 2cable modulation-profile 3 request 0 16 1 8 16qam scrambler 152 no-diff 128 fixed uw16cable modulation-profile 3 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 3 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 3 short 5 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 3 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8no cable qos permission createno cable qos permission updatecable qos permission modemsip subnet-zeroip dhcp relay information option!interface FastEthernet0/0ip address 10.1.70.2 255.255.255.0no ip directed-broadcastno ip mroute-cache!!interface Ethernet2/3ip address 1.3.59.1 255.255.0.0no ip directed-broadcast!interface Cable5/0ip address 172.1.71.1 255.255.255.0 secondaryip address 10.1.71.1 255.255.252.0no ip directed-broadcastno ip route-cacheno ip mroute-cacheno keepaliveno cable proxy-arpcable helper-address 10.1.70.30cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable upstream 0 spectrum-group 1cable upstream 0 modulation-profile 3cable downstream frequency 531000000cable upstream 0 frequency 28000000cable upstream 0 power-level 0no cable upstream 0 shutdowncable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown!!router eigrp 100network 10.0.0.0!ip classlessno ip http server!!!line con 0password ciscologintransport input noneline aux 0line vty 0 4password ciscologin!endVirtual Private Network Configuration Example
VPN support enables you to offer private network connections to telecommuters and other business-oriented customers. In the following configuration example, a VPN is set up between two peer termination points: one at a remote cable modem and the other at a VPN gateway residing at a corporate office firewall. To properly transmit and receive encrypted/decrypted traffic, each peer in the VPN must activate encryption/decryption and have matching access key strings.
Note
!version 12.1no service padservice timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname uBR7246!boot system flash slot0:ubr7200-k1p-mz_120-4_XI1enable password ****!username smith privilege 15 password ****cable flap-list aging 1cable spectrum-group 1 band 20000000 26400000cable spectrum-group 2 frequency 20000000cable spectrum-group 2 frequency 20000000 2cable spectrum-group 2 frequency 20000000 -2cable spectrum-group 2 frequency 22000000cable spectrum-group 2 frequency 22000000 2cable spectrum-group 2 frequency 22000000 3no cable qos permission createno cable qos permission updatecable qos permission modemsip subnet-zeroip host abrick 223.255.254.254!!!interface FastEthernet0/0ip address 10.30.0.1 255.255.0.0no ip directed-broadcastfull-duplexno cdp enable!interface FastEthernet1/0ip address 10.31.0.1 255.255.0.0ip helper-address 10.0.0.101no ip directed-broadcastfull-duplexno cdp enable!interface Ethernet2/0ip address 10.32.0.1 255.255.0.0no ip directed-broadcastno cdp enable!interface Ethernet2/1no ip addressno ip directed-broadcastshutdownno cdp enable!interface Ethernet2/2no ip addressno ip directed-broadcastshutdownno cdp enable!interface Ethernet2/3no ip addressno ip directed-broadcastshutdownno cdp enable!interface Cable3/0mac-address 1033.0000.1c30ip address 10.33.0.1 255.255.0.0no ip redirectsno ip directed-broadcastip helper-address 10.0.0.101load-interval 30no keepalivecable spectrum-group 1cable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 453000000no cable upstream 0 shutdowncable upstream 1 frequency 18000000cable upstream 1 power-level 0no cable upstream 1 shutdowncable upstream 2 frequency 18000000cable upstream 2 power-level 0no cable upstream 2 shutdowncable upstream 3 frequency 18000000cable upstream 3 power-level 0no cable upstream 3 shutdowncable upstream 4 frequency 18000000cable upstream 4 power-level 0no cable upstream 4 shutdowncable upstream 5 frequency 18000000cable upstream 5 power-level 0no cable upstream 5 shutdown!interface Cable4/0no ip addressno ip directed-broadcastno keepaliveshutdowncable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable upstream 0 shutdowncable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown!ip classlessip route 0.0.0.0 0.0.0.0 10.30.0.10ip route 10.51.0.0 255.255.0.0 10.32.0.10ip route 10.100.1.0 255.255.255.248 10.33.1.10ip flow-export destination 10.32.0.8 9995ip http serverip http authentication local!no cdp runsnmp-server engineID local 00000009020000905F0E7800snmp-server community public RW!tftp-server flash slot0:basic.cfgtftp-server flash slot0:boot.tfttftp-server flash slot0:bootmin.tftpalias exec shcm show cable modem!line con 0exec-timeout 0 0transport input noneline aux 0line vty 0 1exec-timeout 0 0password labloginlength 0line vty 2exec-timeout 0 0password labloginline vty 3exec-timeout 0 0password labloginlength 0line vty 4exec-timeout 0 0password lablogin!endVoIP Configuration Example
Following is a sample VoIP configuration file for a Cisco uBR7200 series cable router:
Caution
version 12.1no service padservice timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname twoslot!enable password ****!cable modulation-profile 2 request 0 16 1 8 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 2 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 2 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8cable modulation-profile 3 initial 5 34 0 48 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 3 station 5 34 0 48 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 3 short 5 75 6 8 16qam scrambler 152 no-diff 80 shortened uw8cable modulation-profile 3 long 8 220 0 8 16qam scrambler 152 no-diff 80 shortened uw8cable modulation-profile 4 request 0 16 1 8 qpsk scrambler 152 no-diff 64 shortened uw16cable modulation-profile 4 initial 5 34 0 48 qpsk scrambler 152 no-diff 128 shortened uw16cable modulation-profile 4 station 5 34 0 48 qpsk scrambler 152 no-diff 128 shortened uw16cable modulation-profile 4 short 5 75 6 8 qpsk scrambler 152 no-diff 72 shortened uw8cable modulation-profile 4 long 8 220 0 8 qpsk scrambler 152 no-diff 80 shortened uw8cable modulation-profile 5 request 0 16 2 8 qpsk scrambler 152 no-diff 64 fixeduw8cable modulation-profile 5 initial 5 34 0 48 qpsk scrambler 152 no-diff 128 fixed uw16cable modulation-profile 5 short 5 78 8 8 16qam scrambler 152 no-diff 144 shortened uw8cable modulation-profile 5 long 10 235 8 8 16qam scrambler 152 no-diff 160 shortened uw8cable modulation-profile 6 request 0 16 1 8 16qam scrambler 152 no-diff 128 shortened uw16cable modulation-profile 6 initial 5 34 0 48 16qam scrambler 152 no-diff 256 shortened w16cable modulation-profile 6 station 5 34 0 48 16qam scrambler 152 no-diff 256 shortened uw16cable modulation-profile 6 short 6 75 6 8 16qam scrambler 152 no-diff 144 shortened uw8cable modulation-profile 6 long 8 220 0 8 16qam scrambler 152 no-diff 160 shortened uw8cable modulation-profile 7 request 0 16 1 8 16qam scrambler 152 no-diff 128 fixed uw16cable modulation-profile 7 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 7 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 7 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 7 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8cable modulation-profile 8 request 0 16 1 8 qpsk scrambler 152 no-diff 64 fixed uw8cable modulation-profile 8 initial 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 8 station 5 34 0 48 16qam scrambler 152 no-diff 256 fixed uw16cable modulation-profile 8 short 6 75 6 8 16qam scrambler 152 no-diff 144 fixed uw8cable modulation-profile 8 long 8 220 0 8 16qam scrambler 152 no-diff 160 fixed uw8no cable qos permission createno cable qos permission updatecable qos permission modems!!!!ip subnet-zerono ip domain-lookupip host abrick 223.255.254.254ip host muck 255.255.255.255ip host keyer 223.255.254.254ip host bell 223.255.254.253!!!interface FastEthernet0/0ip address 2.2.2.2 255.255.255.0no ip directed-broadcastno ip mroute-cacheshutdown!interface Ethernet1/0ip address 1.11.8.1 255.255.0.0ip broadcast-address 1.11.255.255ip helper-address 223.255.254.254no ip directed-broadcastno ip mroute-cache!interface Ethernet1/1ip address 10.20.122.2 255.255.255.192ip helper-address 10.0.0.2no ip directed-broadcast!interface Ethernet1/2no ip addressno ip directed-broadcastshutdown!interface Ethernet1/3no ip addressno ip directed-broadcastshutdown!interface Cable2/0ip address 20.20.20.20 255.255.255.0no ip directed-broadcastno keepalivecable downstream modulation 64qamcable upstream 0 frequency 10000000cable upstream 0 power-level 0no cable upstream 0 shutdowncable upstream 1 frequency 10000000cable upstream 1 power-level 0no cable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown!ip default-gateway 1.11.0.1ip classlessip route 0.0.0.0 0.0.0.0 10.20.122.1ip route 223.255.254.254 255.255.255.255 1.11.0.1ip http server!!tftp-server flash slot1:ubr920-y5-mz.euro alias ubr900!!line con 0exec-timeout 0 0transport input noneline aux 0line vty 0 4loginline vty 5 11login!endTelco Return Configuration Example
Following is a sample configuration file displaying critical elements of a telco return network configuration for the Cisco uBR7200 series, including the following:
•
•
•
•
Note
version 12.1service timestamps debug uptimeservice timestamps log uptimeservice password-encryption!hostname uBR7246!boot system flash slot0:ubr7200-p-mz.**********boot system flashlogging buffered 100000 debuggingaaa new-modelaaa authentication login default radius enableaaa authentication login vty lineaaa accounting update newinfoaaa accounting exec default start-stop radiusaaa accounting commands 15 default start-stop radiusaaa accounting network default start-stop radiusaaa accounting system default start-stop radiusenable secret guess_my_password_ha_ha_ha.!no cable qos permission createno cable qos permission updatecable qos permission modemsip subnet-zerono ip fingerno ip domain-lookup!!interface Loopback0ip address 24.1.2.246 255.255.255.0no ip directed-broadcast!interface FastEthernet0/0no ip addressno ip directed-broadcastshutdownmedia-type MIIfull-duplex!interface Hssi1/0ip unnumbered Loopback0no ip directed-broadcast!interface Cable3/0ip address 10.1.1.1 255.255.255.0no ip directed-broadcastip helper-address 24.1.1.84no keepalivecable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 687000000cable upstream 0 frequency 13008000no cable upstream 0 shutdowncable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown!interface Cable6/0ip address 172.16.1.1 secondaryip address 10.1.1.1no ip directed-broadcastip helper-address 24.1.1.84no keepalivecable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 687000000cable upstream 0 frequency 13008000no cable upstream 0 shutdowncable telco-return enablecable telco-return spd 1 factory-defaultcable telco-return spd 1 dhcp-authenticatecable telco-return spd 1 dhcp-server 24.1.1.84cable telco-return spd 1 ppp-authenticate chapcable telco-return spd 1 phonenum 918005555555cable telco-return spd 1 phonenum 18005555555cable telco-return spd 1 username testcable telco-return spd 1 password test!router ospf 100network 10.0.0.0 0.255.255.255 area 0network 24.1.0.0 0.0.255.255 area 0!ip classlessip route 0.0.0.0 0.0.0.0 24.1.2.21!logging 24.1.1.78snmp-server community public ROsnmp-server community favorite_server_community RWsnmp-server location favorite_location!radius-server host 24.1.1.78 auth-port 1645 acct-port 1646radius-server key radius_server_key!line con 0password No need to change; this is encrypted already.transport input noneflowcontrol softwareline aux 0password No need to change; this is encrypted already.flowcontrol hardwareline vty 0 4password No need to change; this is encrypted already.login authentication vtyendQoS Profile Enforcement Configuration Example
The following example shows how a cable modem with a QoS profile of 4, created by the cable modem (cm), is reset to use QoS profile 225 enforced by the Cisco uBR7200 series (management):
CMTS01# show cable modemInterface SID Online Timing Receive QoS IP address MACaddressState Offset PowerCable6/0/U0 1 online 2848 0.00 4 19.2.20.139 0010.7b6b.7215CMTS01# show cable qos profile 4Service Prio Max Guarantee Max Max tx TOS TOS Create Bclass upstream upstream downstream burst mask value by privbandwidth bandwidth bandwidth enab4 7 128000 64000 2048000 255 0x0 0x0 cm noCMTS01(config)# cable qos profile 225 max-upstream 256CMTS01(config)# cable qos permission enforce 225CMTS01# clear cable modem all resetCMTS01# show cable modemInterface SID Online Timing Receive QoS IP address MACaddressState Offset PowerCable6/0/U0 1 offline 2848 0.25 2 19.2.20.139 0010.7b6b.7215CMTS01# debug cable reg....00:15:59: Finished parsing REG Request00:15:59: Overriding Provisioned QoS Parameters In REG-REQ....CMTS01# show cable modemInterface SID Online Timing Receive QoS IP address MACaddressState Offset PowerCable6/0/U0 1 online 2852 0.00 225 19.2.20.139 0010.7b6b.7215CMTS01# show cable qos profile 225Service Prio Max Guarantee Max Max tx TOS TOS Create Bclass upstream upstream downstream burst mask value by privbandwidth bandwidth bandwidth enab225 0 256000 0 0 0 0x0 0x0 management noTroubleshooting Using Cable Flap Lists
A cable flap list is a table maintained by the Cisco uBR7200 series for every cable modem (active or not active) that is having difficulties communicating with the headend. Flapping refers to the rapid disconnecting and reconnecting of a cable modem. The flap list contains cable modem MAC addresses and logs the time of the most recent activity. You can configure the size, recording duration, and entry thresholds for the flap list.
The following tips and scenarios allow you to use the flap list in the most effective way:
•
•
•
•
•
•
•
•
•
•
•
•
Setting Cable Flap List Aging
You can specify the number of days to record and retain flapping activity on cable modems currently in the flap list table. This value is known as the age of the flap list. The valid range is from 1 to 60 days.
To set the age of the flap list, use the following command in global configuration mode:
CMTS01(config)# cable flap-list aging days
Specifies the number of days to record and retain flapping activity for the cable modems connected to this Cisco uBR7200 series router.
Verifying Cable Flap List Aging
To verify that cable flap list aging is set, enter the show cable flap list command:
CMTS01# show cable flap listMac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:500010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:520010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:550010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:520010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16Setting Cable Flap List Insertion Time
You can set the cable flap list insertion time. When a cable modem makes an insertion request more frequently than the amount of insertion time defined by this command, the cable modem is placed in the flap list for activity recording. The valid range is from 60 to 86400 seconds.
To set the cable flap list insertion time, use the following command in global configuration mode:
Verifying Cable Flap List Insertion Time
To verify cable flap list insertion time, enter the show cable flap list command:
CMTS01# show cable flap listMac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:500010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:520010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:550010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:520010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16Setting Cable Flap List Power Adjustment Threshold
You can specify the power adjustment threshold that will cause a flap list event to be recorded. When the power adjustment of a cable modem meets or exceeds the threshold, the cable modem is placed in the flap list. The valid range is from 1 to 10 dBmV.
Note
To set the power adjustment threshold for flap list events, use the following command in global configuration mode:
CMTS01(config)# cable flap-list power-adjust threshold dbmv
Specifies the minimum power adjustment that will constitute a flap list event.
Verifying Cable Flap List Power Adjustment Threshold
To verify the cable flap list power adjustment threshold, enter the show cable flap list command:
CMTS01# show cable flap listMac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:500010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:520010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:550010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:520010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16Setting Cable Flap List Miss Threshold
You can specify the miss threshold for recording a flap list event. A miss is the number of times a cable modem does not acknowledge a MAC-layer keepalive message from a cable modem card. An 8 percent miss rate is normal for the Cisco cable modem cards. When the number of misses exceeds the threshold, the cable modem is placed in the flap list.
Note
To set the miss threshold for recording a flap list event, use the following command in global configuration mode:
CMTS01(config)# cable flap-list miss-threshold misses
Specifies the number of MAC-layer keepalive misses that will result in the cable modems being place in the flap list.
Verifying Cable Flap List Miss Threshold
To verify the cable flap list miss threshold, enter the show cable flap list command:
CMTS01# show cable flap listMac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:500010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:520010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:550010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:520010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16Setting Cable Flap List Size
You can specify the maximum number of cable modems that can be listed in the cable flap list tables. The valid range is from 1 to 8192 cable modems. The default is 8192 cable modems.
To specify the maximum number of cable modems that can be recorded in the flap list, use the following command in global configuration mode:
CMTS01(config)# cable flap-list size number
Specifies the maximum size of the flap list.
Verifying Cable Flap List Size
To verify the cable flap list size, enter the show cable flap list command:
CMTS01# show cable flap listMac Addr CableIF Ins Hit Miss CRC P-Adj Flap Time0010.7b6b.5d1d C3/0 U0 0 688 169 0 0 3 Nov 5 12:28:500010.7b6b.5e15 C3/0 U0 1 707 185 0 0 5 Nov 5 12:29:520010.7b6b.5e27 C3/0 U0 1 707 198 0 0 5 Nov 5 12:29:550010.7b6b.5d29 C3/0 U0 1 709 205 0 0 5 Nov 5 12:29:520010.7b6b.5e2b C3/0 U0 1 710 204 0 0 7 Nov 5 12:30:16Clearing Cable Flap List
To remove a single cable modem from the flap list or to remove all cable modems from the flap list, use one of the following commands in global configuration mode:
