Table Of Contents
Multiservice Interchange (MIX) for
Cisco 3600 Series Multiservice PlatformsCircuit Emulation Service (CES)
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Adding DSPs to the DSP Resource Pool
Activating the Connection for Drop and Insert
Example 1: Internal Source for Network Clocking
Example 2: External Source for Network Clocking
Drop and Insert of Voice or Data
DSP Resource Pool with PRI Support
Multiservice Interchange (MIX) for
Cisco 3600 Series Multiservice Platforms
Multiservice interchange (MIX) adds TDM connection capabilities to Cisco 3600 series multiservice platforms. On the Cisco 3660, MIX requires the installation of a multiservice interchange card, also called a MIX module (MIX-3660-64). On Cisco 3620 and Cisco 3640 platforms, MIX features are software only. MIX features support applications that are sensitive to time delay, such as voice and video. MIX enables the combination of different types of traffic on a single T1 or E1 connection, giving customers the flexibility to manage traffic through their routers efficiently, as either traditional TDM connections or in packet-based format.
On all Cisco 3600 series multiservice platforms, MIX allows connection of TDM streams between two voice/WAN interface cards (VWICs) on the same Fast Ethernet network module (NM-xFE2W).
On the Cisco 3660, the MIX module also enables the following features:
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Connection of TDM streams between separate MIX-enabled network modules. The following network modules are currently MIX-enabled: High-Density Voice (NM-HDV), Fast Ethernet Mixed Media (NM-xFE2W), and ATM OC-3 CES (NM-1AOC3-XX-1V)
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In addition, extended availability drop and insert (EADI) capabilities have been enhanced to allow MIX connections across slots to stay up through a router reload if they have been saved in the NVRAM.
This document includes the following sections:
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Feature Overview
On Cisco 3660 multiservice platforms, the MIX module enables the connection of TDM traffic from any port on a MIX-enabled network module to any other port on another MIX-enabled network module. The following network modules are currently MIX-enabled:
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In addition, TDM connections between ports on the same Fast Ethernet Mixed Media card are now supported on the Cisco 3620 and Cisco 3640 multiservice platforms.
The MIX feature also enhances extended availability drop and insert (EADI) functionality to ensure that TDM connections across slots survive a software reload if they have been saved in NVRAM. This means that the data or voice connections carried over TDM will survive even if the router goes down and comes back up again. No separate configuration is necessary for EADI, but to ensure that the TDM connections are not interrupted, their connect commands must be saved to NVRAM by writing the configuration. Other types of MIX connections, such as CES connections and voice connections that terminate on the router, will not survive a software reboot or reload.
MIX functionality is used to support the following general applications, which are discussed in the next section:
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Drop and Insert
Drop and insert (D&I) is a telephony term that refers to the cross-connecting of TDM circuits. In the context of using Cisco routers for voice traffic, the term refers to the cross-connecting of a TDM stream from one port to another on the router. Drop and insert allows you to take 64Kb DS0 channels from one T1 and digitally cross-connect them to 64Kb DS0 channels on another T1. Individual 64Kb DS0 channels can be transparently passed, uncompressed, between T1/E1 ports without DSP processing because D&I uses circuit switching, which does not require the DSPs that VoIP technology employs.
On all Cisco 3600 series multiservice platforms, MIX allows connection of TDM streams between two voice/WAN interface cards (VWICs) on the same Fast Ethernet network module (NM-xFE2W). On Cisco 3660 multiservice platforms equipped with a MIX module, you can also connect ports on different MIX-enabled network modules to each other.
Drop-and-insert connecting is one way to integrate traditional circuit-based PBX technologies with VoIP. Channel traffic is sent between a PBX and CO switch or other telephony device, allowing the use, for example, of some PBX channels for long-distance service through the PSTN, while the router compresses others for interoffice VoIP calls. In addition, drop and insert can cross-connect a telephony switch (from the CO or PSTN) to a channel bank to provide external analog connectivity.
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Figure 1 MIX enables drop and insert between two different network modules
Circuit Emulation Service (CES)
The MIX feature on the Cisco 3660 gives you the ability to route cross-connected TDM streams out over CES-enabled network modules to an ATM WAN for toll bypass or other WAN services.
CES, or circuit emulation service, is based on ATM Forum standards that allow communications to take place between AAL1 CES and ATM UNI interfaces; that is, between non-ATM telephony devices (such as classic PBXs) and ATM devices (such as Cisco 3600 series routers). Thus, a Cisco 3660 router equipped with an ATM OC-3 CES network module offers a migration path from classic T1/E1 data communications service to emulated CES T1/E1 unstructured (clear channel) services or structured (N x 64) services in an ATM network. Although standard CES supports ATM AAL1 structured and unstructured CES, the MIX module on the Cisco 3660 supports only structured ATM AAL1.
Clocking and bit integrity are maintained in this application, which is critical for interconnections of existing T1 or E1 interfaces and other kinds of constant bit rate (CBR) equipment. Circuit emulation service includes such features as PBX interconnect, consolidated voice and data traffic, and video conferencing.
In addition to supporting ATM CES on the two T1/E1 ports of its own VWIC, the ATM OC-3 CES network module supports two additional physical T1/E1 ports from another network module (for example, from a Fast Ethernet Mixed Media card). Note that the following limitations apply when an ATM OC-3 CES network module is supporting ATM CES on T1/E1s from other network modules:
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OC-3/STM-1 ATM Circuit Emulation Service Network Module.Figure 2 MIX enables routing of TDM traffic for circuit emulation service
DSP Resource Pool
Digital signal processors (DSPs) contain specialized electronics to handle the complex computational processing needed for VoIP, such as compression and coding/decoding. The number of DSP resources required on a router depends on the codec complexities and number of timeslots you are using. Without MIX functionality, the DSP resources on a network module are restricted to serving only the traffic that comes in or goes out over that particular network module. This means that each TDM stream with DSP processing requirements must be routed through a network module with adequate DSP resources to handle those requirements.
In contrast, on a Cisco 3660 equipped with a MIX switching module and MIX bus you can create a pool of DSP resources from selected network modules with excess DSP capacity. Then, when you configure DS0 groups or PRI groups, you can assign the DSP resources in this pool to TDM streams from other network modules that need the DSP resources but do not have them locally available on their own network modules.
Each network module can be individually configured to participate or to not participate in the DSP resource pool (the default is to not participate). If a module participates, its DSP resources are available for assignment to any traffic on the MIX bus. If the module does not participate, its DSP resources are reserved only for the traffic from the module's own interfaces.
When a DSP resource pool has been enabled, it is possible for T1/E1 interfaces in network modules without DSP resources to pass CAS, CCS, and PRI traffic by using the DSPs in another network module.
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Figure 3 MIX allows creation of DSP resource pools to process TDM streams on network modules without DSPs
Benefits
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Restrictions
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Related Features and Technologies
Configuration of MIX-enabled network modules and VWICs is described in these documents:
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OC-3/STM-1 ATM Circuit Emulation Service Network Module, Cisco IOS Release 12.1(2)T•
Cisco IOS Multiservice Applications Configuration Guide, Release 12.1, "Configuring Voice over IP"•
V.54/BERT, Multi-SCC for 1- and 2-Port T1/E1 Multiflex VWICs, Cisco IOS Release 12.1(1)TRelated Documents
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Installing the Multiservice Interchange Card in Cisco 3660 Routers•
Cisco IOS Multiservice Applications Configuration Guide, Release 12.1, "Configuring Digital T1 Packet Voice Trunk Network Modules on Cisco 2600 and 3600 Series Routers"•
Q.931 User-Side and Network-Side Switch Support, Cisco IOS Release 12.1(2)XHThe following documents provide information to help you set up a network and make TDM connections:
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Supported Platforms
TDM cross-connect across ports on the same Fast Ethernet Mixed Media card:
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TDM cross-connect across ports on different MIX-enabled network modules, CES connections, and DSP resource pool:
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Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
Cisco 3620 and Cisco 3640:
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Cisco 3660:
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Configuration Tasks
See the following sections for multiservice interchange configuration tasks. Each task in the list includes the supported platform and is identified as optional or required. Note that each of the network modules being connected must first be configured for the type of traffic it will handle. For those instructions, see the documentation for the particular module, listed in the "Related Features and Technologies" section.
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Configuring Network Clock Use
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On a Cisco 3660 with a MIX module, network modules that are cross-connected carry traffic that is sensitive to time delay, such as voice and video. To prevent mismatches and data slips, cross-connected network modules must synchronize their data flows to a single clock source. This is done by configuring both of the module slots to participate in network clocking before making the connection between the two slots.
When you configure network clock use, you select which modules participate and what the source of the network clock will be. Potential clock sources include internal generation from a module's own PLL or external retrieval from PSTN or PBX clocks over trunk lines. If you specify more than one network clock source, you will assign each source a different priority level. The highest priority level indicates the clock you most prefer to be the source of timing for the modules you name to participate in network clocking. If the highest-priority clock becomes unavailable, the second highest priority level takes over automatically as the network clock, and so forth for lower priority levels.
The important point is that all network modules that are used for drop and insert across network modules must be configured to use the same clock, which is then called the network clock.
Adding DSPs to the DSP Resource Pool
To add a network module's DSP resources to the DSP resource pool on a Cisco 3660 with a MIX module, follow this procedure.
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Setting Framer Type for CES
On a Cisco 3660 with a MIX module, if you are making E1 CES connections over ATM OC-3 CES network modules that do not contain Cisco T1/E1 multiflex voice/WAN interface cards (VWICs), you must manually set the framer type to E1 before making the TDM connection through the MIX bus. You do not need to use this command in T1 configurations because t1 is the default for framer type.
Activating the Connection for Drop and Insert
To activate a drop-and-insert connection, complete the following task, beginning in global configuration mode.
Note
After you issue the connect command, the router changes to TDM connect configuration mode or to CES connect configuration mode, depending on whether you are configuring a TDM or ATM connection, as shown in the following configuration excerpts
Router(config)# connect tdm1 t1 2/0 0 t1 2/1 0Router(config-tdm-conn)#Router(config-tdm-conn)# exitRouter(config)#Router(config)# connect ces1 t1 2/0 1 atm1/0 1/100Router(config-ces-conn)#Router(config-ces-conn)# exitRouter(config)#Verifying MIX Connections
To verify MIX settings and connections, use the following commands.
Troubleshooting Tips
The following table lists debug and show commands to help analyze problems with your configuration.
The following example shows output for the show diag command:
Router# show diag3660 Chassis type:ENTERPRISEc3600 Backplane EEPROM:Hardware Revision :1.0Part Number :800-04740-02Board Revision :A0Deviation Number :0-0Fab Version :02PCB Serial Number :HAD03411035RMA Test History :00RMA Number :0-0-0-0RMA History :00Chassis Serial Number :JAB034585UXChassis MAC Address :0030.9405.1530MAC Address block size :112Manufacturing Test Data :00 00 00 00 00 00 00 00Fab Part Number :28-2651-02Number of Slots :6EEPROM format version 4EEPROM contents (hex):0x00:04 FF 40 00 C8 41 01 00 C0 46 03 20 00 12 84 020x10:42 41 30 80 00 00 00 00 02 02 C1 8B 48 41 44 300x20:33 34 31 31 30 33 35 03 00 81 00 00 00 00 04 000x30:C2 8B 4A 41 42 30 33 34 35 38 35 55 58 C3 06 000x40:30 94 05 15 30 43 00 70 C4 08 00 00 00 00 00 000x50:00 00 85 1C 0A 5B 02 01 06 FF FF FF FF FF FF FF0x60:FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0x70:FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FFBackplane MIX Module:Hardware Revision :1.0Part Number :800-03700-01Board Revision :A0Deviation Number :0-0Fab Version :02PCB Serial Number :JAB9801ABCDRMA Test History :00RMA Number :0-0-0-0RMA History :00EEPROM format version 4EEPROM contents (hex):0x00:04 FF 40 01 E1 41 01 00 C0 46 03 20 00 0E 74 010x10:42 41 30 80 00 00 00 00 02 02 C1 8B 4A 41 42 390x20:38 30 31 41 42 43 44 03 00 81 00 00 00 00 04 000x30:FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FFConfiguration Examples
This section provides the following configuration examples:
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Network Clock Configuration
As mentioned, when cross-connecting time-delay-sensitive traffic such as voice and video, you must make sure the data flows are synchronized. This is done by first configuring the cross-connected modules to participate in network clocking, and then specifying the sources and priorities to be used for network clocking. Two examples are shown:
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Example 1: Internal Source for Network Clocking
This example uses the MIX module internal backplane clock on a Cisco 3660 as a source for network clocking; this is the default if no clock source is explicitly configured. The example configures the modules in slots 2 and 6 to participate in network clocking.
!version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname Router3660-1!enable secret 5 $1$iEoB$MSs93cmIErxxBp9RcIJl41enable password cisco!!!network-clock-participate slot 2
!ces 1/0framer-type t1!voice-card 3dspfarm!voice-card 4dspfarm!ip subnet-zerono ip routing...To verify the network clock(s) that has been configured and the network clock that is currently being used, enter the show network-clocks command.
Router3660-1# show network-clocksNetwork Clock Configuration---------------------------Priority Clock Source Clock State Clock Type9 Backplane Good PLLCurrent Primary Clock Source---------------------------Priority Clock Source Clock State Clock Type9 Backplane Good PLLExample 2: External Source for Network Clocking
This example configures two external clock sources with different priority levels on a Cisco 3660.
!version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname Router3660-1!enable secret 5 $1$iEuB$MVs93cmICrxxBy9RcIJl41enable password cisco!!!network-clock-participate slot 2network-clock-participate slot 6!ces 1/0framer-type t1!voice-card 3dspfarm!voice-card 4dspfarm!ip subnet-zerono ip routing...To verify the network clock(s) that have been configured and the network clock that is currently being used, enter the show network-clocks command. This example shows the highest priority clock is in use.
Router3660-1# show network-clocksNetwork Clock Configuration---------------------------Priority Clock Source Clock State Clock Type3 E1 6/2 GOOD E15 T1 2/0 GOOD T19 Backplane Good PLLCurrent Primary Clock Source---------------------------Priority Clock Source Clock State Clock Type3 E1 6/2 GOOD E1Drop and Insert of Voice or Data
This example shows drop and insert of time slots 1-12 of T1 1/0 to time slots 1-12 of T1 2/0. The TDM groups are defined by the command tdm-group 0 timeslots 1-12 type e&m under controller t1. The drop and insert connection is made by the command connect tdm t1 1/0 0 t1 2/0 0. The time slots can carry either voice or data. When they carry voice, then the tdm-group definition should include the type of signaling being used.
!version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname aurora!enable password lab!!!!!voice-card 3dspfarm!!ip subnet-zerono ip domain-lookupip host igloo 192.168.254.254!!!!controller T1 1/0framing esfclock source internallinecode b8zsTDM Connections with CES
In this example, a CES connection is being established on a Cisco 3660. A TDM group is defined under controller command, specifying the time slots that need to be carried over ATM PVC, and a CES PVC is specified under the ATM interface. The command connect ces1 atm3/0 1/100 t1 1/2 0 then establishes the connection.
!version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname aurora!enable password lab!!!!!ces 5/0!ip subnet-zerono ip domain-lookupip host igloo 192.168.254.254!!!!!controller T1 1/0!controller T1 1/1!controller T1 1/2framing esfclock source internallinecode b8zsDSP Resource Pool
In this example, slot 2 is a Fast Ethernet WAN network module and slot 3 is a digital T1/E1 packet voice trunk network module. The DSP on slot 3 is included in the DSP resource pool, making it available to be configured to support traffic from any slot and port on a Cisco 3660.
!version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname aurora!enable password lab!!!!!network-clock-participate slot 1voice-card 3DSP Resource Pool with PRI Support
In this example from a Cisco 3660, slot 3 contains a Fast Ethernet WAN network module, and slot 1 contains a digital T1/E1 packet voice trunk network module. The DSP on slot 1 is used in a DSP resource pool to provide DSP resources for the traffic in slot 3. This is the ISDN configuration.
version 12.1service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname aurora!enable password lab!!!!!voice-card 1!isdn switch-type primary-5essisdn voice-call-failure 0call rsvp-sync!!!!!!!controller T1 1/0!controller T1 1/1!controller T1 3/0framing esflinecode b8zsCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
dspfarm (voice-card)
To add the specified voice card to those participating in the DSP resource pool, use the dspfarm voice-card configuration command. To remove the specified card from participation in the DSP resource pool, use the no form of this command.
dspfarm
no dspfarm
Syntax Description
This command has no arguments or keywords.
Defaults
The default behavior is that a card participates in the DSP resource pool.
Command Modes
Voice-card configuration
Command History
Usage Guidelines
This command is used on Cisco 3660 routers with a MIX module installed.
To reach voice-card configuration mode for a particular voice card, enter voice-card and the card number while in global configuration mode.
The assignment of DSP resources in the resource pool to particular TDM streams is based on the order in which the streams are configured with the ds0-group command (T1/E1) or the pri-group command (PRI). It is not a dynamic assignment during call signaling.
Examples
The following example adds the voice card in slot 5 to the group of voice cards participating in the DSP resource pool:
!voice-card 5dspfarmRelated Commands
framer-type
To set the framer type of supported CES MIX connections to T1 or E1, use the framer-type CES configuration command.
This command is needed only with CES-enabled network modules (ATM OC-3 CES network modules) that do not contain Cisco T1/E1 multiflex voice/WAN interface cards (VWICs) on the Cisco 3660. Other network modules set their framer type automatically, and therefore do not require use of this command. It is also not necessary to use this command for T1 connections, because t1 is the default argument.
framer-type {t1 | e1}
Syntax Description
t1
The framer type of supported CES connections is T1.
e1
The framer type of supported CES connections is E1.
Defaults
The default behavior is that the framer type is set to T1.
Command Modes
CES configuration
Command History
Usage Guidelines
This command is used on Cisco 3660 series routers with CES-enabled network modules (ATM OC-3 CES network modules) that do not contain Cisco T1/E1 multiflex voice/WAN interface cards (VWICs).
To reach CES configuration mode for a particular slot, enter ces and the slot number/port number while in global configuration mode. Note that the port value is always 0, as the interface configuration applies to all ports in the slot.
Examples
The following example sets the framer type of the CES card in slot 1 to E1:
!ces 1/0framer-type e1Related Commands
network-clock-participate
To enable a network module to receive clock signals from the MIX module on the Cisco 3660, use the network-clock-participate global configuration command. To restrict the network module to use only its own clock signals, use the no form of this command.
network-clock-participate slot slot
no network-clock-participate slot slot
Syntax Description
slot
Keyword indicating the value that follows is a slot number.
slot
Slot number of the network module. Values are 1 to 6 for the Cisco 3660.
Defaults
No network clocking is enabled; interfaces are restricted to using the clocking generated on their own modules.
Command Modes
Global configuration
Command History
Usage Guidelines
This command is used on Cisco 3660 routers with a MIX module installed.
Examples
To allow the network module in slot 5 to participate in network clocking, the following command was used:
network-clock-participate slot 5Related Commands
network-clock-select
To name a source to provide timing for the network clock and to specify the selection priority for this clock source, use the network-clock-select global configuration command. To cancel the network clock selection, use the no form of this command.
Cisco 3660 with MIX module
network-clock-select priority {t1 | e1} slot /port
no network-clock-select priority {t1 | e1} slot/port
Cisco MC3810
network-clock-select priority {serial 0 | system | controller}
no network-clock-select priority {serial 0 | system | controller}
Syntax Description
Defaults
Cisco 3660
The network clock source is the backplane PLL with priority 9.
Cisco MC3810
No network clock source is specified.
Command Modes
Global configuration
Command History
11.3 MA
This command was introduced for the Cisco MC3810.
12.1(5)XM
This command was introduced for the Cisco 3660.
Usage Guidelines
Cisco 3660
This command is used on Cisco 3660 routers with a MIX card installed to select the controller to provide the clock to the backplane, and in turn to all the network modules that are participating in network clocking.
Cisco MC3810
This command applies to Voice over Frame Relay, Voice over ATM, and Voice over HDLC on the Cisco MC3810.
Examples
Cisco 3660
This example selects the controller in slot 5/port 1 to provide the clock at priority 3:
network-clock-select 3 t1 5/1Cisco MC3810
The following example sets the priority of four network clock sources. When the clock source with the highest priority (controller T1 0) fails, the Cisco MC3810 switches the clock source to the second highest priority (controller T1 1).
network-clock-select 1 T1 0network-clock-select 2 T1 1network-clock-select 3 serial 0network-clock-select 4 SystemRelated Commands
Debug Commands
This section documents new or modified debug commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
debug ces-conn
To display information from CES clients, use debug ces-conn. To disable debug mode, use the no form of the command.
debug ces-conn [all | errors | events]
no debug ces-conn
Syntax Description
all
Displays all error and event information
errors
Displays only error information
events
Displays only event information
Command History
Examples
The following example shows debug output for a CES connection.
Router# debug ces-conn allCES all debugging is onRouter#Router# conf tEnter configuration commands, one per line. End with CNTL/Z.Router(config)# connect conn1 t1 3/0 1 atm1/0 1/100Router(config-ces-conn)# exitRouter(config)#*Mar 6 18:32:27:CES_CLIENT:vc QoS parameters are PCR = 590, CDV =5000, CAS_ENABLED = 1,partial fill = 0, multiplier = 8,cbr rate = 64,clock recovery = 0,service_type = 3, error method = 0,sdt_size = 196,billing count = 0*Mar 6 18:32:27:CES_CLIENT:attempt 1 to activate segment>debug conn
To display information from the connection manager, TDM and DSP clients, use debug conn. To disable debug mode, use the no form of the command.
debug conn
no debug conn
Syntax Description
This command has no arguments or keywords.
Command History
Examples
The following example shows connection manager debugging output.
Router# debug connConnection Manager debugging is onRouter# conf tEnter configuration commands, one per line. End with CNTL/Z.Router(config)# connect conn1 t1 3/0 1 t1 4/0 1Router(config-tdm-conn)# exit*Mar 6 18:30:59:%CONN TDM:Segment attached to dsx1*Mar 6 18:30:59:%CONN TDM:Parsed segment 1*Mar 6 18:30:59:%CONN TDM:Segment attached to dsx1*Mar 6 18:30:59:%CONN TDM:Parsed segment 2*Mar 6 18:30:59:%CONN:Creating new connectionRouter(config)#*Mar 6 18:31:01:%CONN TDM:Interwork Segments*Mar 6 18:31:01:CONN TDM:Init Segment @ 61C26980*Mar 6 18:31:01:CONN TDM:Init Segment @ 61C26A44*Mar 6 18:31:01:%CONN TDM:Activating Segment @ 61C26980*Mar 6 18:31:01:%CONN:Segment alarms for conn conn1 are 2*Mar 6 18:31:01:%CONN TDM:Activating Segment @ 61C26A44*Mar 6 18:31:01:%CONN:Segment alarms for conn conn1 are 0*Mar 6 18:31:01:%CONN TDM:Connecting Segments*Mar 6 18:31:01:%CONN TDM:MAKING CONNECTION*Mar 6 18:31:01:%CONN:cm_activate_connection, stat = 5Router(config)#Glossary
AAL1—ATM adaptation layer 1. One of four AALs recommended by the ITU-T. AAL1 is used for connection-oriented, delay-sensitive services requiring constant bit rates, such as uncompressed video and other isochronous traffic.
ATM—Asynchronous Transfer Mode. A high-bandwidth, low-delay, packet-switching, and multiplexing technique used to transfer voice, video, image, and character-based data in 53-byte cells over various media, including synchronous optical network (SONET), synchronous digital hierarchy (SDH), and digital cross-connect (DCC) systems.
CES—Circuit Emulation Service. ATM emulation of TDM circuits over AAL1.
channel—Term used to describe a group of time slots that are combined to form a point-to-point HDLC data path or a VoIP data path. Also, the smallest subdivision of a circuit or transmission system in which a single type of communication service is provided (for example, a voice or data channel).
channelized E1/T1—An E1 or T1 interface with 31 or 24 time slots respectively. Channels may be assigned one or more time-arbitrary time slots. Multiple channels may be assigned to a single E1 or T1 as long as the time slots allocated do not overlap.
CLI—Command Language Interpreter. Basic Cisco IOS configuration and management interface.
CO—Central office. A telephone operating company facility where local subscriber loops are collected, controlled, and switched to other destinations in the public switched network system. A central office is the site where a local telephone company terminates subscriber lines and houses the switching equipment that interconnects those lines to the local network or a long distance network. CO is frequently used as a synonym for the switching equipment itself.
D&I—Drop and insert. Method of time-switching channels between T1/E1 time slots on different streams. This is also sometimes called "pass-through" or "TDM cross-connect."
DS0—Digital Signal Level 0. Framing specification used in transmitting digital signals over a single channel at 64-kbps on a T1 facility. Often used to refer to a single 64 Kbps channel, designed for digital voice, which is the building block of a T1 transmission line. Twenty-four DS0 channels make up one T1 line, and thirty-two DS0 channels make up one E1 (European) line.
DS1—Digital Signal Level 1. Framing specification used in transmitting digital signals at 1.544 Mbps on a T1 facility (in the United States) or at 2.108 Mbps on an E1 facility (in Europe). Often used to refer to a T1 line that contains 24 DS0-formatted channels.
DSP—Digital Signal Processor. Its primary function is to provide stream-to-packet signal processing functionality that includes voice compression, echo cancellation, and tone and voice activity detection.
DSP resource pool—A collection of DSP resources available to any network module on the router.
E1—Wide-area digital transmission scheme. E1 is the European equivalent of a T1 line. The higher E1 clock rate (2.048 MHz) allows for 32 64-kbps time slots, including one time slot (typically time slot 0) for framing and one time slot (typically time slot 16) for D-channel information.
EADI—Extended availability drop and insert. Ability of TDM drop-and-insert connections to remain active through software reboots or reloads.
framer—A hardware device that converts between the raw E1 or T1 bit stream and 8-bit DS0 streams. The framer also extracts and inserts signaling information.
HDLC—High-level Data Link Control. A standard set of protocols for carrying data over a link with error and flow control.
ITU-T—Telecommunication standardization sector of the International Telecommunication Union, the telecommunications agency of the United Nations established to provide worldwide standard communications practices and procedures.
MIX—Multiservice Interchange. Feature that allows TDM connections between MIX-enabled ports.
NM—Network Module. Modular plug-in device that provides a physical connection to a network medium, either a local-area network or a wide-area network.
OC3—Optical Carrier level 3. The optical interface designed with synchronous transport signal (STS-3) rate in SONET (synchronous optical network).
PCI—Peripheral component interconnect. Specification that defines the PCI Local bus.
POTS—Plain old telephone service.
PSTN—Public switched telephone network.
PVC—Permanent virtual circuit made between two data terminal equipment (DTE) lines established by configuration.
T1—The basic 24-channel, 1.544 Mbps pulse code modulation (PCM) system used in the United States.
TDM—Time-division multiplexing. Technique in which information from multiple channels can be allocated bandwidth on a single wire based on preassigned time slots. Bandwidth is allocated to each channel regardless of whether the station has data to transmit.
TDM bus—A structure for passing telephony sample data between interfaces. Typically data is channelized to the level of a single telephone call.
time slot—Continuously repeating interval of time in which two devices are able to interconnect. In time-division multiplexing (TDM), describes the individual "voice channels" in a T1 or E1 signal. T1 has 24 time slots numbered 1 through 24, all of which are available for voice or data. E1 has 32 time slots numbered 0 through 31, but time slot 0 is dedicated to framing and time slot 16 is dedicated to channel-associated signaling in voice applications. Data-only applications can use time slot 16 if desired.
VIC—Voice interconnect card. Provides voice-specific ports, including FXS, FXO, E&M, and BRI.
VWIC—A card that can operate as a VIC or as a WIC, providing physical connection to WAN or voice networks.
VoIP—Voice over IP. The ability to carry normal telephony-style voice over an IP-based Internet with POTS-like functionality, reliability, and voice quality. VoIP is a blanket term that generally refers to the Cisco standards-based (H.323, etc.) approach to IP voice traffic.
WIC—WAN (wide area network) interconnect card.
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