-
- Downstream Interface Configuration
- Upstream Interface Configuration
- DOCSIS Interface and Fiber Node Configuration
- Service Group Based Configuration of the Cisco cBR Router
- DOCSIS Load Balancing Groups
- DOCSIS Load Balancing Movements
- DOCSIS 3.0 Downstream Bonding
- DOCSIS 2.0 A-TDMA Modulation Profiles
- Downstream Resiliency Bonding Group
- Downstream Channel ID Assignment
- Upstream Channel Bonding
- Spectrum Management and Advanced Spectrum Management
- Upstream Scheduler Mode
- Generic Routing Encapsulation
- Transparent LAN Service over Cable
- Downgrading Channel Bonding in Battery Backup Mode
- Upstream Bonding Support for D-PON
- Energy Management Mode
- Cable Modem Steering
-
- IP Access Control Lists
- Creating an IP Access List and Applying It to an Interface
- Creating an IP Access List to Filter IP Options, TCP Flags, Noncontiguous Ports
- Refining an IP Access List
- IP Named Access Control Lists
- IPv4 ACL Chaining Support
- IPv6 ACL Chaining with a Common ACL
- Commented IP Access List Entries
- Standard IP Access List Logging
- IP Access List Entry Sequence Numbering
- ACL IP Options Selective Drop
- ACL Syslog Correlation
- IPv6 Access Control Lists
- IPv6 Template ACL
- IPv6 ACL Extensions for Hop by Hop Filtering
-
- Call Home
- SNMP Support over VPNs—Context-Based Access Control
- SNMP Engine Enhancement
- Onboard Failure Logging
- Control Point Discovery
- IPDR Streaming Protocol
- Usage-Based Billing (SAMIS)
- Frequency Allocation Information for the Cisco CMTS Routers
- Flap List Troubleshooting
- Maximum CPE and Host Parameters
- SNMP Background Synchronization
- Online Offline Diagnostics
Cisco cBR Converged Broadband Routers DOCSIS Software Configuration Guide for Cisco IOS XE Everest 16.5.1
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- Updated:
- June 6, 2017
Chapter: Fairness Across DOCSIS Interfaces
- Hardware Compatibility Matrix for Cisco cBR Series Routers
- Prerequisites for Fairness Across DOCSIS Interfaces
- Restrictions for Fairness Across DOCSIS Interfaces
- Information About Fairness Across DOCSIS Interfaces
- How to Configure Fairness Across DOCSIS Interfaces
- Verifying the Fairness Across DOCSIS Interfaces
- Configuration Examples for Fairness Across DOCSIS Interfaces
- Additional References
- Feature Information for Fairness Across DOCSIS Interfaces
Fairness Across DOCSIS Interfaces
The Fairness Across DOCSIS Interfaces feature introduces an adaptive mechanism to effectively distribute reservable bandwidth for committed information rate (CIR) flows and fair bandwidth for best-effort (BE) service flows across adjacent bonding groups (BGs).
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/. An account on http://www.cisco.com/ is not required.
Contents
- Hardware Compatibility Matrix for Cisco cBR Series Routers
- Prerequisites for Fairness Across DOCSIS Interfaces
- Restrictions for Fairness Across DOCSIS Interfaces
- Information About Fairness Across DOCSIS Interfaces
- How to Configure Fairness Across DOCSIS Interfaces
- Verifying the Fairness Across DOCSIS Interfaces
- Configuration Examples for Fairness Across DOCSIS Interfaces
- Additional References
- Feature Information for Fairness Across DOCSIS Interfaces
Hardware Compatibility Matrix for Cisco cBR Series Routers
 Note | The hardware components introduced in a given Cisco IOS-XE Release are supported in all subsequent releases unless otherwise specified. |
Prerequisites for Fairness Across DOCSIS Interfaces
Note | The term ‘Bonding Group (BG)’ is used in this document to refer to all the integrated-cable (IC) and wideband-cable (WC) interfaces in the context of Fairness Across DOCSIS Interfaces feature context. The IC interfaces are considered as a single-channel BG. |
Restrictions for Fairness Across DOCSIS Interfaces
- The CIR flows cannot reserve all the RF bandwidth. The CIR flows can only reserve 90 percent1 of the RF bandwidth that is not statically reserved by the “bandwidth-percent”, in addition to the legacy CIR bandwidth.
- It is recommended that the CIR reservation be cleared before disabling Fairness Across DOCSIS Interfaces feature to ensure that the CIR reservation is not more than the static reservable bandwidth specified by the “bandwidth-percent” in legacy configuration. This is to prevent CIR over-subscription after disabling Fairness Across DOCSIS Interfaces feature.
- The effect of Fairness Across DOCSIS Interfaces feature depends on topology and flow distribution. In certain cases, Fairness Across DOCSIS Interfaces feature may not achieve BE fairness or maximum CIR utilization.
- Fairness Across DOCSIS Interfaces feature applies only to dynamic bandwidth sharing (DBS) enabled IC and WB interfaces.
Information About Fairness Across DOCSIS Interfaces
The Fairness Across DOCSIS Interfaces feature is an enhancement over the DOCSIS WFQ scheduler. It enables downstream CIR service flows to be admitted on the interfaces over the thresholds defined in the legacy configuration (that is, “bandwidth-percent” or “max-reserved-bandwidth”). For example, the feature enables large CIR flows (like multicast service flows) to be admitted when the current parameters cannot guarantee enough bandwidth. However, its success rate depends on the allocation and reservation of the bandwidth for cable interfaces within common RF channels.
This feature also ensures fair bandwidth for downstream BE service flows across cable interfaces with common RF channels. The per-flow bandwidth of all active service flows on the adjacent BGs are balanced periodically. The weights (DOCSIS traffic priority (traffic priority + 1)) of all the BGs are equal for downstream BE service flows. The bandwidth, available for BE traffic, can be used to admit additional CIR flows.
Note | For information about DOCSIS traffic priority, see DOCSIS WFQ Scheduler on the Cisco CMTS Routers guide. |
On-demand CIR Acquisition
When multiple bonding groups sharing the RF-channel bandwidth and the current bonding group's guaranteed bandwidth is insufficient, this feature can "borrow" neighbor bonding group's non-reserved guaranteed bandwidth for current bonding group's CIR.
This feature is only used by multicast service flow.
Fairness Across Bonding Groups
Fairness Across DOCSIS Interfaces feature use the weight value of the aggregated active flow count, that is EIR demand, to periodically re-balance the reservable bandwidth. So that the service flows with the same weight in different bonding groups will have roughly the same throughput.
OFDM Channels
OFDM Channel
DOCSIS 3.1 introduces modes for higher throughput and higher spectral efficiency while still allowing backward compatibility to DOCSIS 3.0. OFDM Channel support includes 1 OFDM channel per port with channel bandwidth from 24 MHz to 192 MHz wide. In Cisco IOS-XE 16.5.1, a bonding group can consist of SC-QAMs and OFDM channels. An OFDM channel can have multiple profiles configured, and each profile may have different rate. The OFDM Channel rate can vary constantly depending on the profiles being used. For more information on OFDM channels, see OFDM Channel Configuration Guide.
OFDM Channel Rate
An OFDM channel can have multiple profiles configured, and each profile can have different rates. For example, with a 96MHz OFDM channel that is configured with profile A (Control Profile) with modulation 1024-QAM, profile B with modulation 2048-QAM, and profile C with modulation 4096-QAM, the profile rates of profile A, B, and C are 616Mbps, 680Mbps, and 736Mbps respectively.
In Cisco IOS-XE 16.5.1, if an OFDM channel has both Control Profile (profile A) and Data Profiles (profile B, C, and so on) configured, the lowest Data Profile rate is used for Fairness Across DOCSIS Interface calculation. Otherwise, the Control Profile rate is used.
Interface Bandwidth
A Wideband-Cable (WB) interface can consist of both SC-QAMs and OFDM channels. If it contains OFDM channels, the highest profile rates are used to calculate the interface bandwidth.
For example, with a 96MHz OFDM channel that is configured with profile A having modulation 1024-QAM, profile B with modulation 2048-QAM, and profile C with modulation 4096-QAM, the profile rates of profile A, B, and C are 616Mbps, 680Mbps, and 736Mbps respectively. Here, 736Mbps is used to calculate the interface bandwidth.
How to Configure Fairness Across DOCSIS Interfaces
This section describes the following tasks that are required to implement Fairness Across DOCSIS Interfaces feature:
- Configuring Fairness Across DOCSIS Interfaces
- Configuring Maximum Excess Information Rate Ratio
- Configuring Constant Excess Information Rate Demand
- Configuring Maximum Bonus Bandwidth
Configuring Fairness Across DOCSIS Interfaces
This section describes how to enable Fairness Across DOCSIS Interfaces feature on the cable interfaces. The configuration is applied to all WB or IC interfaces on the router.
We recommend that you clear the CIR reservation before disabling the Fairness Across DOCSIS Interfaces feature to ensure that CIR reservation is not more than the static reservable bandwidth specified by the “bandwidth-percent” in the legacy configuration.
Configuring Maximum Excess Information Rate Ratio
This section describes how to configure the maximum Excess Information Rate (EIR) ratio between the BE bandwidth among adjacent BGs.
The EIR ratio is used to maintain the maximum EIR bandwidth difference between BGs. It helps to prevent BGs (which has only a few active BE service flows) from getting very low or zero EIR bandwidth. Otherwise, these BGs will not be able to admit CIR flows as they get only very low EIR bandwidth.
For example, there are two BGs sharing the same RF channel, with BG1 having 1000 active BE service flows and BG2 having none. If “max-eir-ratio” is not used, BG1 gets all the bandwidth leaving no bandwidth for BG2. When a voice CIR tries for bandwidth at BG2, it will get rejected. If “max-eir-ratio” is set at 10, BG2 gets about 10 percent of the QAM that is sufficient to admit the voice CIR. The ‘max-eir-ratio’ is a trade-off between perfect fairness and CIR utilization. It means, compromising 'flow fairness' to prevent some BGs from getting all the bandwidth leaving the other BGs with none.
Configuring Constant Excess Information Rate Demand
This section describes how to configure the constant excess information rate (EIR) demand for a bonding group (BG). EIR demand is a unitless value that is used to determine relative bandwidth ratio between BGs.
An active EIR flow with DOCSIS priority-0 is given 1000 units of demand in ACFE module. Therefore a BG with constant-eir-demand set to 1 will get no more than 1/1000 of the bandwidth of a single service flow.
Configuring Maximum Bonus Bandwidth
This section describes how to configure the maximum usable bonus bandwidth for a BG.
Bonus bandwidth is the additional bandwidth provided by the Fairness Across DOCSIS Interfaces feature to each BG for CIR reservation. In the default maximum bonus bandwidth configuration, a single BG can reserve all the underlying RF bandwidth. When the maximum bonus is set, the AC module will not admit CIR flows above that setting even if the scheduler has guaranteed more bandwidth. This will effectively prevent BGs from being starved for CIR flows.
Note | The cable acfe max-bonus-bandwidth command configuration is applicable only for the new incoming CIR flows. It will not terminate the existing CIR flows that exceeds the max-bonus-bandwidth . |
If the maximum bonus bandwidth is less than the current CIR reservation on an interface, no new CIR flows are admitted until the CIR reservation drops below the maximum bonus bandwidth configuration.
Verifying the Fairness Across DOCSIS Interfaces
To monitor the Fairness Across DOCSIS Interfaces feature, use the following procedures:
- Verifying Reservable Bandwidth
- Verifying Global Fairness Across DOCSIS Interfaces Status and Statistics
- Verifying Per-Controller Fairness Across DOCSIS Interfaces Status and Statistics
- Verifying Per-Interface Fairness Across DOCSIS Interfaces Status and Statistics
Verifying Reservable Bandwidth
To display the reserved and reservable bandwidth for a particular interface, use the show interface {wideband-cable | modular-cable | integrated-cable} command as shown in the example:
Router# show interfaces wideband-cable 1/0/0:1 downstream Total downstream bandwidth 1875 Kbps Total downstream reserved/reservable bandwidth 20000/1500 Kbps Total downstream guaranteed/non-guaranteed bonus bandwidth 20760/9741 Kbps Router#
The “reservable bandwidth” is a part of the guaranteed bandwidth from the legacy configuration. When the Fairness Across DOCSIS Interfaces feature is disabled, values of both the “guaranteed bonus bandwidth” and “non-guaranteed bonus bandwidth” is zero. When the feature is enabled, the “reservable bandwidth” and “guaranteed bonus bandwidth” represents the maximum CIR that can be reserved on the interface. Unicast CIR flows exceeding this limit are rejected. The additional “non-guaranteed bonus bandwidth” allows the multicast CIR flows to pass the AC module. However, the service flow may not be created successful because the bandwidth comes from the shared pool.
To display the reserved and reservable bandwidth for a particular interface, use the show cable admission-control interface command as shown in the example:
Router#show cable admission-control interface wideband-Cable 1/0/0:0 Interface Wi1/0/0:0 BGID: 28673 Resource - Downstream Bandwidth ------------------------------- App-type Name Reservation/bps Exclusive 1 0 Not configured 2 0 Not configured 3 0 Not configured 4 0 Not configured 5 0 Not configured 6 0 Not configured 7 0 Not configured 8 20000000 Not configured Max Reserved BW = 1500000 bps Total Current Reservation = 20000000 bps Guaranteed Bonus BW = 20760000 bps Non-guaranteed Bonus BW = 9741000 bps Subset BGs: In1/0/0:8 In1/0/0:9 In1/0/0:10 In1/0/0:11 In1/0/0:12 Superset BGs: N/A Overlapping BGs: Wi1/0/0:8 Wi1/0/0:9 Wi1/0/0:10 Router#
Effective with Cisco IOS-XE Release 3.18.0SP, Capacity BW is also displayed. It is a summation of the channel capacity of the RF channels in this interface, and the capacity of OFDM channels is calculated considering the lowest profile rate.
Router#show cable admission-control interface wideband-Cable 2/0/0:1 Interface Wi2/0/0:1 BGID: 8194 Resource - Downstream Bandwidth ------------------------------- App-type Name Reservation/bps Maximum Rejected 1 4000 90% 0 2 0 N/A 0 3 0 90% 0 4 0 N/A 0 5 0 N/A 0 6 0 90% 0 7 0 N/A 0 8 0 87% 0 Max Reserved BW = 11424000 bps Total Current Reservation = 4000 bps Guaranteed Bonus BW = 884352000 bps Non-guaranteed Bonus BW = 225904000 bps Capacity BW = 1428000000 bps Subset BGs: In2/0/0:0 In2/0/0:1 In2/0/0:2 In2/0/0:3 In2/0/0:4 In2/0/0:5 In2/0/0:6 In2/0/0:7 In2/0/0:158 Wi2/0/0:0 Superset BGs: N/A
Verifying Global Fairness Across DOCSIS Interfaces Status and Statistics
To display the global status and statistics of the Fairness Across DOCSIS Interfaces feature, use the show cable acfe summary command as shown in the example:
Router# show cable acfe summary ACFE state: Enabled EIR Rebalance period (secs): 5 EIR Rebalance invocations: 254 CIR Acquire rate/limit: 100/100 CIR Acquire invocations: 0 CIR Acquire throttled: 0 CIR Oversubscriptions: 0 Maximal EIR ratio: 10 Constant EIR demand: 2
Verifying Per-Controller Fairness Across DOCSIS Interfaces Status and Statistics
To display the status and statistics for each controller interface, use the show cable acfe controller command as shown in the following example:
Router# show cable acfe controller integrated-Cable 1/0/0 EIR Rebalance invoked: 450963 Adaptive CIR granted: 20 Adaptive CIR rejected: 1 Total clusters: 9 RF FlexBW 8 36376 9 36376 10 32625 ......
The BG clusters span across multiple channels and are used as a means to share the underlying RF channel bandwidth dynamically.
Use the show controllers integrated-Cable acfe cluster command to show Per-controller statistics and clusters and checking the bandwidth information as follows:
Router# show controllers integrated-Cable 1/0/0 acfe cluster 0 Integrated-Cable 1/0/0 status: Topology changed: No ========Cluster 0======== Number of RF: 2 RF FlexBW WB ExcessBW Quanta 0 35625 - 35438 35438 0 187 187 1 35250 0 35250 35250 Number of BG: 2 Intf Demand CIR Max CstrMin Alloc NBonus Ratio WB0 1000 0 70875 35250 35437 35438 14855190400 IC0 1000 0 35625 0 35438 187 14855609600
Verifying Per-Interface Fairness Across DOCSIS Interfaces Status and Statistics
To display the status and statistics for each interface, use the show cable acfe interface command as shown in the following example:
Router# show cable acfe interface wideband-cable 1/0/0:1 EIR Demand (raw/scale): 0/1 Per-Flow EIR BW (kbps): 19125 Guar Bonus BW (kbps): 19125 Non-guar Bonus BW (kbps): 38250 Reserved Bonus BW (kbps): 0 !
Configuration Examples for Fairness Across DOCSIS Interfaces
This section lists the following sample configurations for the Fairness Across DOCSIS Interfaces feature on a Cisco CMTS router:
- Example: Fairness Across DOCSIS Interfaces
- Example: Maximum EIR Demand Ratio
- Example: Constant EIR Demand
- Example: Maximum Bonus Bandwidth
Example: Fairness Across DOCSIS Interfaces
The following sample configuration shows Fairness Across DOCSIS Interfaces feature enabled on the router:
Current configuration : 39682 bytes ! ! Last configuration change at 04:30:02 UTC Wed Jan 19 2 ! NVRAM config last updated at 04:23:17 UTC Wed Jan 19 2 ! version 12.2 ! cable clock dti cable acfe enable ! . . .
Example: Maximum EIR Demand Ratio
The following sample configuration shows maximum EIR demand ratio configured on the router:
Building configuration... Current configuration : 54253 bytes ! version 12.2 ! cable clock dti cable acfe enable cable acfe max-eir-ratio 20 !
The effect of the cable acfe max-eir-ratio command is demonstrated using a simple BG cluster.
! interface integrated-Cable1/0/0:0 cable bundle 1 cable rf-bandwidth-percent 10 ! interface Wideband-Cable9/0/0:0 cable bundle 1 cable rf-channels channel-list 0 bandwidth-percent 1 end !
On this RF channel, 20 percent of the bandwidth is reserved by the ‘bandwidth-percent’ allowing Fairness Across DOCSIS Interfaces feature to use 27 Mbps, that is: (100 - 20) * 90 * 37.5). If the ‘max-eir-ratio’ is above 100 and the WB interface has 99 active BE flows and the IC interface has only 1 BE flow, then IC interface gets only 270 kbps, that is 1/(1+99)*27 of the bonus bandwidth. The BE traffic enjoys perfect fairness here. However, it is not possible to admit a unicast CIR flow beyond 270 kbps on the IC interface, as it would exceed the bonus bandwidth. If the ‘max-eir-ratio’ is set to 10, then the IC interface is treated to have 99/10 flows on it, resulting in a higher bonus bandwidth allocation. The ‘max-eir-ratio’ is a trade-off between perfect fairness and CIR utilization.
Example: Constant EIR Demand
The following sample configuration shows constant EIR demand on the router:
Building configuration... Current configuration : 54253 bytes ! version 12.2 ! cable clock dti cable acfe enable cable acfe max-eir-ratio 20 cable acfe constant-eir-demand 2 !
! interface integrated-Cable1/0/0:0 cable bundle 1 cable rf-bandwidth-percent 10 cable acfe constant-eir-demand 2 ! interface Wideband-Cable9/0/0:0 cable bundle 1 cable rf-channels channel-list 0 bandwidth-percent 1 cable acfe constant-eir-demand 2 end !
Example: Maximum Bonus Bandwidth
The following sample configuration shows the maximum bonus bandwidth enabled on the router:
Building configuration... Current configuration : 274 bytes ! interface Wideband-Cable1/0/0:0 cable bundle 1 cable rf-channel 0 bandwidth-percent 10 cable acfe max-bonus-bandwidth 10000 end !
In this per-interface configuration, even if the Fairness Across DOCSIS Interfaces feature guarantees more than 10 Mbps for a WB interface, the AC module will not pass more than 10 Mbps bandwidth above the legacy reservable bandwidth.
! . . .
Additional References
Technical Assistance
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Feature Information for Fairness Across DOCSIS Interfaces
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note | The table below lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. |
|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
Fairness Across DOCSIS Interfaces |
Cisco IOS-XE 3.15.0S |
This feature was introduced on the Cisco cBR Series Converged Broadband Router. |
|
Fairness Across DOCSIS Interfaces |
Cisco IOS-XE 3.17.0S |
On-demand CIR acquisition and Fairness across bonding groups were supported. The following commands were modified: |
|
Hierarchical QoS |
Cisco IOS-XE 3.18.0SP |
This feature was introduced on the Cisco cBR Series Converged Broadband Router. |
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