2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers This feature module describes the Two-port STM-1/OC-3 Channelized E1/T1 line card and its use in the Cisco 12000 series Internet Routers. This document includes information on the following topics: Feature Overview, page 1 Supported Platforms, page 4 Supported Standards, MIBs, and RFCs, page 5 Configuration Tasks, page 6 Monitoring and Maintaining Operation, page 13 Configuration Examples, page 15 Command Reference, page 18 Glossary, page 91 Feature Overview The Two-port STM-1/OC-3 Channelized E1/T1 line card provides E1/DS1 aggregation for the Cisco 12000 series Internet Router. The Two-port STM-1/OC-3 Channelized E1/T1 line card interfaces with the 12000 series Internet Router switch fabric and provides two OC-3/STM-1 duplex SC single-mode intermediate-reach optical interfaces. When configured for operation in a Synchronous Digital Hierarchy (SDH) environment, each STM-1 port is capable of supporting channelization into either 63 independent E1s through VC-12 ETSI mapping, or 84 J1 (Japanese T1 equivalent) channels through VC-11 ANSI mapping. When configured for operation in a Synchronous Optical Network (SONET) environment, each OC-3 port is capable of supporting channelization into 84 independent DS1 (VT1.5 mapping or CT3 mapping into STS-1) channels. Fractional E1 and individual 64 kbps channels can also be configured, up to the limit of 105 channel definitions per STM-1 (35 per TUG-3). Fractional T1 and individual DS0 channels can also be configured, up to the limit of 35 channel definitions per STS-1 (210 per line card). Each Two-port STM-1/OC-3 Channelized E1/T1 line card supports up to 126 E1s when configured for SDH operation, 168 DS1 connections when configured for SONET operation, or any combination of 64 kbps/ds0, fractional E1/T1, or E1/T1 interface definitions, up to the limit of 210 per line card. 1

Feature Overview 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers SDH STM-1 Multiplexing Hierarchy Figure 1 illustrates the SDH STM-1 multiplexing hierarchy supported on the Two-port STM-1/OC-3 Channelized E1/T1 line card. The multiplexing hierarchy is the ITU-T SDH multiplexing hierarchy defined in ITU-T G.707. Figure 1 SDH STM-1 Multiplexing Hierarchy VC-3 x1 TU-3 x1 TUG-3 x3 VC-4 x1 AU-4 x1 E3/DS3 45 45 Mbps Mbps C-3 VC-3 x1 x7 x1 AU-3 x3 AUG x1 STM-1 E1 2.048 Mbps DS1 J1 1.544 Mbps C-12 C-11 VC-12 VC-11 TU-12 TU-11 x3 x4 TUG-2 x7 Multiplexing Aligning Mapping 57106 At the lowest level, PDH signals are mapped into containers (C). The mapping process uses bit stuffing to generate synchronous containers with a common bit rate. Overhead bytes are then added to create virtual containers (VCs). The VCs are then aligned into tributary units (TUs) where pointer processing operations are implemented. This allows the TUs to be synchronously multiplexed into TU groups (TUGs). The TUGs are then multiplexed to become the payload of a High Order VC (HOVC) that includes its own overhead bytes. The HOVC is aligned into an administrative units (AUs) by adding the AU pointer, then multiplexed into an AU group (AUG). Finally, the frame of an SDH Synchronous Transport Module level N (STM-N) is created by multiplexing N AUGs and adding the Multiplexer Section and Regenerator Section Overhead bytes (MSOH and RSOH). SONET OC-3 Multiplexing Hierarchy Figure 2 illustrates the SONET OC-3 multiplexing hierarchy supported on the Two-port STM-1/OC-3 Channelized E1/T1 line card. DS1 signals are multiplexed in one of two methods: Virtual Tributary Group structure VT1.5 mapping, which is used for DS1 transport, or T1 PDH M13 mapping, which multiplexes DS1 signals asynchronously to form a DS3 signal. 2

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Feature Overview Figure 2 SONET OC-3 Multiplexing Hierarchy DS1 VT1.5 SPE VT1.5 SPE x4 VT group x7 T1 VT1.5 mapping DS1 M13 multiplex DS3 STS1 SPE x1 x3 STS-1 STS-3 T1 PDH M13 mapping OC-3 57107 In VT1.5 mapping, each DS1signal is individually mapped into a Virtual Tributary 1.5 (VT1.5) Synchronous Payload Envelope (SPE). Overhead bytes are added to the payload, the VTs are aligned using a VT pointer, and then synchronously multiplexed into a VT group (VTG). VTGs are further multiplexed to form the payload of an STS-1 SPE. The addition of overhead bytes, and alignment by using a pointer, completes the STS-1 signal. Three STS-1 signals are then synchronously multiplexed and complemented by Line and Section overhead bytes to form an STS-3 frame, which is then converted from electrical to optical to form an OC-3 signal. In T1 PDH M13 mapping, DS1 signals can be multiplexed asynchronously to form a DS3 signal, which is then mapped directly into an STS-1 SPE. Three STS-1s are then combined to form the OC-3 signal. Benefits The Two-port STM-1/OC-3 Channelized E1/T1 line card concentrates up to 168 DS-1s in one line card. This level of aggregation increases per-rack density and overall router capacity, enabling service providers to scale networks in a cost-effective manner. Restrictions The following qualifications apply when you are configuring a Two-port STM-1/OC-3 Channelized E1/T1 line card: Because a single clock line times all tributary channels on the Two-port STM-1/OC-3 Channelized E1/T1 line card, both ports of a card must be configured for the same channelization either E1 channelization or T1 channelization. You cannot configure one port for E1 channelization and the other port for T1 channelization. The maximum number of channel groups per STS-1, AU-3, or TUG-3 is 35; full channelization to DS0 is not supported. The idle timeslot pattern, set using the idle pattern pattern command, affects a pair of STS-1s, AU-3s, or TUG-3s. The following pairs use the same idle timeslot pattern: Port 0, path 1 port 0, path 2 Port 0, path 3 port 1, path 1 Port 1, path 2 port 1, path 3 MLPPP bundles must be contained within a single line card. Links in a bundle can be assigned to different ports on the same card, but assigning links from different line cards to one bundle is not supported. 3

Supported Platforms 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Related Features and Technologies Weighted Random Early Detection (WRED) Modified Deficient Round Robin (MDRR) Multilink Point-to-Point Protocol (MLPPP) Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs) for MPLS Multilink Frame Relay (MLFR) Multichannel STM-1 Port Adapter (PA-MC-STM1) See the Related Documents in the next section for a list of documents that describe these features and technologies. Related Documents The following documents provide additional information about installing and configuring Two-port STM-1/OC-3 Channelized E1/T1 line cards: 2-port STM-1/OC-3 Channelized E1/T1 Line Card Installation and Configuration Release Notes for Cisco IOS Release 12.0 ST Release Notes for Cisco 7000 Family and Cisco 12000 Series Routers for Cisco IOS Release 12.0 S Weighted Random Early Detection on the Cisco 12000 Series Router Configuring Media-Independent PPP and Multilink PPP Multiprotocol Label Switching on Cisco Routers MPLS Virtual Private Networks Multilink Frame Relay (FRF.16) You can also find additional information in the installation and configuration guide for your Cisco 12000 series Internet Router, and in the Cisco IOS Release 12.0 documentation set. Supported Platforms Cisco 12008 Internet Router Cisco 12012 Internet Router Cisco 12016 Internet Router Cisco 12410 Internet Router Cisco 12416 Internet Router The Two-port STM-1/OC-3 Channelized E1/T1 line card is compatible with any Cisco 12000 series Internet Router that is operating with the following system software: Cisco IOS Release 12.0(17)S or later, or Cisco IOS Release 12.0(17)ST or later. 4

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Supported Standards, MIBs, and RFCs Supported Standards, MIBs, and RFCs Standards Packet-over-SONET/SDH (POS), ITU-T G.957, ITU-T G.958 as applicable Cisco HDLC Layer 3 routing protocols, including BGPv4, OSPF, IS-IS, EIGRP, RIP, Distributed FIB IP switching, CDP, ICMP, RRR, and others Multicast forwarding with support for source and shared distribution trees, and the following protocols: PIM-DIM, PIM-SM, AutoRP, IGMPv1/v2, CGMP, MBGP, MSDP, and others Comprehensive MPLS support, including MPLS-VPN Multilink Frame Relay (MLFR) Traffic engineering using Routing with Resource Reservation (RRR) At the E1 level: ITU-T G.703 support, framing support for CRC-4 and no-crc-4 in conformance with ITU-T G.703 and ITU-T G.704 At the DS1level: Superframe (SF) and Extended Superframe (ESF) support, ANST T1.403 FDL support MIBs In addition to industry-standard SNMP and other MIBs supported on the Cisco 12000 series Internet Router, the Two-port STM-1/OC-3 Channelized E1/T1 line card also supports the following: SONET/SDH MIB (RFC 2558, formerly RFC 1595) DS3 MIB (RFC 2496) DS1/E1 MIB (RFC 2495) 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 IETF RFC 1490, Frame Relay Encapsulation RFC 1619, Point-to-Point Protocol over SONET/SDH RFC 1662, Point-to-Point Protocol in HDLC-like Framing RFC 2615, PPP over SONET/SDH 5

Configuration Tasks 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Tasks See the following sections for configuration tasks for the Two-port STM-1/OC-3 Channelized E1/T1 line card. Each task in the list is identified as either optional or required. Configuring the SONET Controller, page 6 Configuring STS-1 Path Attributes under SONET Framing, page 6 Configuring Administrative Unit Group (AUG) Mapping under SDH Framing, page 8 Configuring the SONET Controller To configure the SONET controller on the Two-port STM-1/OC-3 Channelized E1/T1 line card, perform the following steps: Command Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing {sonet sdh} Specify the framing type. Step 3 Router(config-controller)# clock source {internal line} Set the clock source for the selected OC-3/STM-1 port. Step 4 Router(config-controller)# description string (Optional) Add a description for the controller. Step 5 Router(config-controller)# report {all event} (Optional) Enable reporting of selected alarm and signal events. Step 6 Router(config-controller)# threshold type value (Optional) Set threshold values for the BER Threshold Crossing Alarms. Configuring STS-1 Path Attributes under SONET Framing To enter STS-1 path configuration mode to configure an STS-1 path under SONET framing on the Two-port STM-1/OC-3 Channelized E1/T1 line card, perform the following steps: Command Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing sonet Specify SONET as the framing type. Step 3 Router(config-controller)# sts-1 number Enter STS-1 path configuration mode. 6

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Tasks Configuring the Mode of Operation DS1 signals are multiplexed in one of two methods: Virtual Tributary Group (VTG) structure VT1.5 mapping, which is used for DS1 transport, or T1 PDH M13 mapping (channelized T3, or CT3), which multiplexes DS1 signals asynchronously to form a DS3 signal. To configure the STS-1 mode of operation under SONET framing on the Two-port STM-1/OC-3 Channelized E1/T1 line card, perform the following steps: Command Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing sonet Specify SONET as the framing type. Step 3 Router(config-controller)# sts-1 number Enter STS-1 path configuration mode. Step 4 Router(config-crtlr-sts1)# mode {vt-15 ct3} Specify the mode of operation for the STS-1. Configuring T3 Links Under SONET Framing When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SONET framing, and have selected ct3 as the STS-1 mode of operation, you can configure the T3 link using the following steps: Command Step 1 Router(config-crtlr-sts1)# t3 framing [auto-detect c-bit m23] Step 2 Router(config-crtlr-sts1)# t3 clock source [internal line] Purpose Specify the framing type for the T3 link. Set the clock source for the selected T3 link. Configuring T1 Links Under SONET Framing When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SONET framing, and have selected vt-15 as the STS-1 mode of operation, you can configure the T1 link using the following steps: Step 1 Step 2 Step 3 Command Router(config-crtlr-sts1)# vtg vtg-number t1 t1-line-number channel-group channel-group-number timeslots list-of-timeslots [speed {56 64}] Router(config-crtlr-sts1)# vtg vtg-number t1 t1-line-number framing {esf sf [hdlc-idle {0x7E 0xFF}]} Router(config-crtlr-sts1)# vtg vtg-number t1 t1-line-number clock source {internal line} Purpose Create a logical channel group on a T1 line. Specify the T1 framing format. Set the internal or line (network) clock source. 7

Configuration Tasks 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SONET framing, and have selected ct3 as the STS-1 mode of operation, you can configure the T1 link using the following steps: Step 1 Step 2 Step 3 Command Router(config-crtlr-sts1)# t1 t1-line-number channel-group channel-group-number timeslots list-of-timeslots [speed {56 64}] Router(config-crtlr-sts1)# t1 t1-line-number framing {esf sf [hdlc-idle {0x7E 0xFF}]} Router(config-crtlr-sts1)# t1 t1-line-number clock source {internal line} Purpose Create a logical channel group on a T1 line. Specify the T1 framing format. Set the internal or line (network) clock source. Configuring an Interface under SONET Framing After a T1 channel group is configured, it appears to the Cisco IOS software as a serial interface; therefore, all the configuration commands for a serial interface are available, but not all commands are applicable to the T1 channel group. All the encapsulation formats, such as PPP, HDLC, and Frame Relay are applicable to the configured T1 channel group. Be sure that you are in serial interface configuration mode when you set the encapsulation format. All the switching types that are applicable to a serial interface are also applicable to the configured T1 channel group. To configure a serial interface, use one of the following commands: Command Router(config)# interface serial slot/port.sts1-number/ vtg-number/t1-number:channel-group-number Router(config)# interface serial slot/port.sts1-number/ t1-number:channel-group-number Purpose In VT1.5 mode, select the line card interface to be configured. In CT3 mode, select the line card interface to be configured. Configuring Administrative Unit Group (AUG) Mapping under SDH Framing In SDH, there are two possible mapping/multiplexing schemes for most payload types: ANSI and ETSI. In ANSI mapping, the Low Order payloads are aggregated into a VC-3 High Order Path. An AU pointer is added to the VC-3 to create an AU-3 (Administrative Unit type 3). Three such AU-3s are then synchronously multiplexed into an AUG (AU group). The multiplexing scheme is as follows: VC-3 < > AU-3 (x3) < > AUG < > STM-1 SDH ANSI mapping is very similar to the SONET frame structure. In ETSI mapping, the Low Order payloads are aggregated into a VC-4 High Order Path. An AU pointer is added to the VC-4 to create an AU-4 (Administrative Unit type 4). One AU-4 is multiplexed into an AUG (AU group), which is to say, the AUG is, in fact, equivalent to an AU-4. The multiplexing scheme is as follows: TUG-3 (x3) < > VC-4 < > AU-4 (x1) < > STM-1 8

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Tasks To specify the AUG mapping under SDH framing on the Two-port STM-1/OC-3 Channelized E1/T1 line card, perform the following steps: Command Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing sdh Specify SDH as the framing type. Step 3 Router(config-controller)# aug mapping {au-3 au-4} Select AU-3 or AU-4 AUG mapping. Note When configured for SDH framing, the Two-port STM-1/OC-3 Channelized E1/T1 line card supports channelization to E1s when the AUG mapping is set to AU-4, and channelization to T1s when the AUG mapping is set to AU-3. Different combinations of payload types and AUG mappings are not supported. Configuring an AU-3 Entering AU-3 Configuration Mode Under SDH framing with AUG mapping set to AU-3, each VC-3 High Order Path can be configured to carry up to 28 T1s, mapped into VC-11s. The mode of operation of an AU-3 is not configurable, and defaults to mode c-11. When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SDH framing, and have selected au-3 as the mode of operation, you can configure an AU-3 using the following steps: Command Configuring a T1 Line in AU-3 Configuration Mode Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing sdh Specify SDH as the framing type. Step 3 Router(config-controller)# aug mapping au-3 Select AU-3 AUG mapping. Step 4 Router(config-controller)# au-3 number Select the AU-3 to be configured and enter AU-3 configuration mode. When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SDH framing, and have selected au-3 as the mode of operation, you can configure a T1 line using the following steps: Step 1 Step 2 Step 3 Command Router(config-crtlr-au3)# tug-2 tug-2-number t1 t1-line-number channel-group channel-group-number timeslots list-of-timeslots [speed {56 64}] Router(config-crtlr-au3)# tug-2 tug-2-number t1 t1-line-number framing {esf sf [hdlc-idle {0x7E 0xFF}]} Router(config-crtlr-au3)# tug-2 tug-2-number t1 t1-line-number clock source {internal line} Purpose Create a logical channel group on a T1 line. Specify the T1 framing format. Set the internal or line (network) clock source. 9

Configuration Tasks 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuring an Interface under SDH with AU-3 AUG Mapping Command Router(config)# interface serial slot/port.au-3-number/ tug-2-number/t1-number:channel-group-number Purpose Select the line card interface. Configuring a TUG-3 under AU-4 AUG Mapping Entering TUG-3 Configuration Mode Under SDH framing with AUG mapping set to AU-4, the VC-4 High Order Path comprises three TUG-3s. Each TUG-3 can be configured to carry up to 21 E1s, mapped into VC-12s. The mode of operation of a TUG-3 is not configurable, and defaults to mode c-12. When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SDH framing, and have selected au-4 as the mode of operation, you can configure a TUG-3 using the following steps: Command Configuring an E1 Line in TUG-3 Configuration Mode Purpose Step 1 Router(config)# controller sonet slot/port Select the physical port you want to configure. Step 2 Router(config-controller)# framing sdh Specify SDH as the framing type. Step 3 Router(config-controller)# aug mapping au-4 Select AU-4 AUG mapping. Step 4 Router(config-controller)# au-4 1 tug-3 number Select the TUG-3 to be configured and enter TUG-3 configuration mode. When you are configuring the Two-port STM-1/OC-3 Channelized E1/T1 line card for SDH framing, and have selected AU-4 AUG mapping, you can configure an E1 line using the following steps: Step 1 Step 2 Step 3 Step 4 Step 5 Command Router(config-crtlr-tug3)# tug-2 tug-2-number e1 e1-line-number channel-group channel-group-number timeslots list-of-timeslots Router(config-crtlr-tug3)# tug-2 tug-2-number e1 e1-line-number unframed Router(config-crtlr-tug3)# tug-2 tug-2-number e1 e1-line-number framing {crc4 no-crc4} Router(config-crtlr-tug3)# tug-2 tug-2-number e1 e1-line-number clock source {internal line} Router(config-crtlr-tug3)# tug-2 tug-2-number e1 e1-line-number national bits pattern Purpose Create a logical channel group on an E1 line. (Optional) Configure the E1 line as an unframed E1 line. Specify the E1 framing format. Set the internal or line (network) clock source. Configure the national reserve bit pattern. 10

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Tasks Configuring an Interface under SDH with AU-4 AUG Mapping Command Router(config)# interface serial slot/port.au-4-number/ tug-3-number/tug-2-number/e1-number:channel-group-number Purpose Select the line card interface. 11

Configuration Tasks 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Verifying Operation To verify the operation of the controllers and interfaces configured on the Two-port STM-1/OC-3 Channelized E1/T1 line card, perform the following steps: Command Purpose Step 1 Router# show version Displays the configuration of the system hardware, the software release, the names and sources of configuration files, and the boot images. Verify that the list includes the newly configured Two-port STM-1/OC-3 Channelized E1/T1 line card ports and interfaces. Step 2 Router# show controllers sonet slot/port [brief tabular] Displays an exhaustive list of information about a SONET port, including information about all the configured channels. When framing is SDH and AUG mapping is AU-4, the slot/port argument takes the form: slot/port.au-4-number/tug-3-number/tug-2-number/ e1-line-number When framing is SDH and AUG mapping is AU-3, the slot/port argument takes the form: slot/port.au-3-number/tug-2-number/t1-line-number When framing is SONET and the mode is CT3, the slot/port argument takes the form: slot/port.sts1-number/t1-line-number When framing is SONET and the mode is VT1.5, the slot/port argument takes the form: slot/port.sts1-number/vtg-number/t1-line-number Step 3 Router# show interfaces Displays status and configuration of interfaces. Step 4 Router# show protocols Displays information about the protocols configured for the system as a whole, and for specific interfaces. 12

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Monitoring and Maintaining Operation Monitoring and Maintaining Operation See the following sections for monitoring and maintenance tasks for the Two-port STM-1/OC-3 Channelized E1/T1 line card. Using clear Commands on Serial Interfaces, page 13 Using Loopbacks, page 13 Using BER Tests, page 14 Using clear Commands on Serial Interfaces Command Router# clear interface serial slot/port.path:channel-group-number Router# clear counters serial slot/port.path:channel-group-number Purpose Reset the hardware logic for a serial interface, where path depends on the interface configuration: When framing is SDH and AUG mapping is AU-4, path takes the form: au-4-number/tug-3-number/tug-2-number/e1-linenumber When framing is SDH and AUG mapping is AU-3, path takes the form: au-3-number/tug-2-number/t1-line-number When framing is SONET and the mode is CT3, path takes the form: sts1-number/t1-line-number When framing is SONET and the mode is VT1.5, path takes the form: sts1-number/vtg-number/t1-line-number Initialize the counters for a serial interface. Using Loopbacks The Two-port STM-1/OC-3 Channelized E1/T1 line card supports loopback tests at the OC-3/STM-1 port level, as well as at the T3, T1, and E1 link level. To set a loopback at one of those levels, use one of the following commands: Command Router (config-controller)# loopback [local network] Router (config-ctrlr-sts1)# t3 loopback [local network remote] Router (config-ctrlr-sts1)# vtg number t1 t1-line-number loopback [local network {line payload} remote {line fdl {ansi bellcore} payload [fdl] [ansi]}] Purpose Set a loopback to test the OC-3/STM-1 port. Set a loopback to test a T3 link. In vt-15 mode, set a loopback to test a T1 link. 13

Monitoring and Maintaining Operation 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Command Router (config-ctrlr-sts1)# t1 t1-line-number loopback [local network {line payload} remote {line fdl {ansi bellcore} payload [fdl] [ansi]}] Router (config-ctrlr-au3)# tug-2 tug-2-number t1 t1-line-number loopback [local network {line payload} remote {line fdl {ansi bellcore} payload [fdl] [ansi]}] Router (config-ctrlr-tug3)# tug-2 tug-2-number e1 e1-line-number loopback {local network {line payload}} Purpose In ct3 mode, set a loopback to test a T1 link. When framing is SDH with AU-3 AUG mapping, set a loopback to test a T1 link. When framing is SDH with AU-4 AUG mapping, set a loopback to test a E1 link. Using BER Tests The Two-port STM-1/OC-3 Channelized E1/T1 line card supports BER tests at the T1 and E1 link level. To enable a BERT at one of those levels, use one of the following commands: Command Router (config-ctrlr-sts1)# vtg vtg-number t1 t1-line-number bert pattern pattern interval time Router (config-ctrlr-sts1)# t1 t1-line-number bert pattern pattern interval time Router (config-ctrlr-au3)# tug-2 tug-2-number t1 t1-line-number bert pattern pattern interval time Router (config-ctrlr-tug3)# tug-2 tug-2-number e1 e1-line-number bert pattern pattern interval time Purpose In vt-15 mode, enable a BERT on a T1 link. In ct3 mode, enable a BERT on a T1 link. When framing is SDH with AU-3 AUG mapping, enable a BERT on a T1 link. When framing is SDH with AU-4 AUG mapping, enable a BERT on an E1 link. 14

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Examples Configuration Examples This section provides the following configuration examples: Configuring for SONET Framing and CT3 Mode of Operation, page 15 Configuring for SONET Framing and VT1.5 Mode of Operation, page 16 Configuring for SDH Framing with AU-4 AUG Mapping, page 17 Configuring for SONET Framing and CT3 Mode of Operation In the following example, port 0 of a Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 2 of a Cisco 12000 series Internet Router is configured for SONET framing with CT3 mode of operation. This example is an excerpt from a larger example that configures 168 T1s for CT3 and VT1.5 operation, and shows only the configuration for the first STS-1 (one of three). controller SONET 2/0 clock source line framing sonet! sts-1 1 mode ct3 t3 framing m23 t3 clock source line t1 1 clock source Line t1 1 channel-group 0 timeslots 1-24 t1 2 clock source Line t1 2 channel-group 0 timeslots 1-24 t1 3 clock source Line t1 3 channel-group 0 timeslots 1-24... t1 28 clock source Line t1 28 channel-group 0 timeslots 1-24!! interface Serial2/0.1/1:0! STS-1 1, T1 1 ip address 20.141.20.1 255.255.255.252 no ip directed-broadcast...! interface Serial2/0.1/28:0! STS-1 1, T1 28 ip address 20.141.20.109 255.255.255.252 no ip directed-broadcast (Additional display text is not shown.) 15

Configuration Examples 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuring for SONET Framing and VT1.5 Mode of Operation In the following example, port 1 of a Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 2 is configured for SONET framing with VT1.5 mode of operation. This example is an excerpt from a larger example that configures 168 T1s for CT3 and VT1.5 operation, and shows only the configuration for the first STS-1 (one of three). controller SONET 2/1 clock source line framing sonet! sts-1 1 mode vt-15 vtg 1 t1 1 clock source Line vtg 1 t1 1 channel-group 0 timeslots 1-24 vtg 1 t1 2 clock source Line vtg 1 t1 2 channel-group 0 timeslots 1-24 vtg 1 t1 3 clock source Line vtg 1 t1 3 channel-group 0 timeslots 1-24 vtg 1 t1 4 clock source Line vtg 1 t1 4 channel-group 0 timeslots 1-24... vtg 7 t1 1 clock source Line vtg 7 t1 1 channel-group 0 timeslots 1-24 vtg 7 t1 2 clock source Line vtg 7 t1 2 channel-group 0 timeslots 1-24 vtg 7 t1 3 clock source Line vtg 7 t1 3 channel-group 0 timeslots 1-24 vtg 7 t1 4 clock source Line vtg 7 t1 4 channel-group 0 timeslots 1-24!! interface Serial2/1.1/1/1:0! STS-1 1, VTG 1, T1 1 ip address 20.141.23.1 255.255.255.252 no ip directed-broadcast...! interface Serial2/1.1/1/4:0! STS-1 1, VTG 1, T1 4 ip address 20.141.23.13 255.255.255.252 no ip directed-broadcast...! interface Serial2/1.1/7/1:0! STS-1 1, VTG 7, T1 1 ip address 20.141.23.97 255.255.255.252 no ip directed-broadcast...! interface Serial2/1.1/7/4:0! STS-1 1, VTG 7, T1 4 ip address 20.141.23.109 255.255.255.252 no ip directed-broadcast (Additional display text is not shown.) 16

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Configuration Examples Configuring for SDH Framing with AU-4 AUG Mapping In the following example, port 0 of a Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 2 is configured for SDH framing with AU-4 AUG mapping. This example is excerpted from a larger example that configures 126 E1s, and shows only the configuration of the first TUG-3. controller SONET 2/0 clock source line framing sdh aug mapping au-4! au-4 1 tug-3 1 mode c-12 tug-2 1 e1 1 clock source Line tug-2 1 e1 1 channel-group 0 timeslots 1-31 tug-2 1 e1 2 clock source Line tug-2 1 e1 2 channel-group 0 timeslots 1-31 tug-2 1 e1 3 clock source Line tug-2 1 e1 3 channel-group 0 timeslots 1-31... tug-2 7 e1 1 clock source Line tug-2 7 e1 1 channel-group 0 timeslots 1-31 tug-2 7 e1 2 clock source Line tug-2 7 e1 2 channel-group 0 timeslots 1-31 tug-2 7 e1 3 clock source Line tug-2 7 e1 3 channel-group 0 timeslots 1-31! interface Serial2/0.1/1/1/1:0! AU-4 1, TUG-3 1, TUG-2 1, E1 1 ip address 20.141.20.1 255.255.255.252 no ip directed-broadcast ip load-sharing per-packet... interface Serial2/0.1/1/7/1:0! AU-4 1, TUG-3 1, TUG-2 7, E1 1 ip address 20.141.20.73 255.255.255.252 no ip directed-broadcast! interface Serial2/0.1/1/1/2:0! AU-4 1, TUG-3 1, TUG-2 1, E1 2 ip address 20.141.20.5 255.255.255.252 no ip directed-broadcast ip load-sharing per-packet... interface Serial2/0.1/1/7/2:0! AU-4 1, TUG-3 1, TUG-2 7, E1 2 ip address 20.141.20.77 255.255.255.252 no ip directed-broadcast! interface Serial2/0.1/1/1/3:0! AU-4 1, TUG-3 1, TUG-2 1, E1 3 ip address 20.141.20.9 255.255.255.252 no ip directed-broadcast... interface Serial2/0.1/1/7/3:0! AU-4 1, TUG-3 1, TUG-2 7, E1 3 ip address 20.141.20.81 255.255.255.252 no ip directed-broadcast (Additional display text is not shown.) 17

Command Reference 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Command Reference This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications. au-3 au-4 tug-3 aug mapping clear counters serial clear interface serial clock source (controller) controller sonet framing (controller) loopback (controller) mode overhead c2 overhead j0 overhead j1 overhead s1s0 report show controllers sonet show interfaces serial sts-1 t1 bert pattern t1 channel-group timeslots t1 clock source t1 fdl ansi t1 framing t1 loopback t3 clock source t3 equipment loopback t3 framing t3 loopback threshold tug-2 e1 bert pattern tug-2 e1 channel-group timeslots tug-2 e1 clock source tug-2 e1 framing tug-2 e1 loopback 18

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers Command Reference tug-2 e1 national bits tug-2 e1 unframed 19

au-3 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers au-3 To enter the AU-3 path configuration mode to configure an AU-3, use the au-3 controller configuration command. To remove the AU-3 configuration, use the no form of this command. au-3 au-3-number no au-3 au-3-number Syntax Description au-3-number A number in the range from 1 to 3. Defaults No default behavior or values. Command Modes Controller configuration Command History Release 12.0(14)S 12.0(17)S Modification This command was introduced. This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines An AUG of an STM-1 can be derived from either AU-3s or an AU-4. In ANSI mapping, the Low Order payloads are aggregated into a VC-3 High Order Path. An AU pointer is added to the VC-3 to create an AU-3 (Administrative Unit type 3). Three such AU-3s are then synchronously multiplexed into an AUG (AU group). The multiplexing scheme is as follows: VC-3 < > AU-3 (x3) < > AUG < > STM-1 To map the AUG to an AU-3, use the aug mapping au-3 controller configuration command. Configuring the au-3 command enters AU-3 configuration mode, and creates a serial interface with the following name format: slot/port.au-3-number/tug-2-number/t1-number:channel-group-number The aug mapping and au-3 commands are available only when SDH framing is configured. Examples In the example that follows, the second AU-3 in port 0 of the Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 4 of a Cisco 12000 series Internet Router is selected for configuration: Router(config)# controller sonet 4/0 Router(config-controller)# framing sdh Router(config-controller)# aug mapping au-3 Router(config-controller)# au-3 2 Router(config-ctrlr-au3)# 20

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers au-3 Related Commands Command Description aug mapping Specify the AUG mapping when SDH framing is selected. 21

au-4 tug-3 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers au-4 tug-3 To configure a TUG-3, use the au-4 tug-3 controller configuration command to enter TUG-3 configuration mode, which is indicated by a change in the command prompt. To remove a TUG-3 configuration, use the no form of this command. au-4 au-4-number tug-3 tug-3-number no au-4 au-4-number tug-3 tug-3-number Syntax Description au-4-number A number in the range from 1 to N, where N is the STM level. (For the Two-port STM-1/OC-3 Channelized E1/T1 line card, N is always 1.) tug-3-number A number in the range from 1 to 3. Defaults No default behavior or values. Command Modes Controller configuration Command History Release 12.0(14)S 12.0(17)S Modification This command was introduced. This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines An AUG of an STM-1 can be derived from either AU-3s or an AU-4. In ETSI mapping, the Low Order payloads are aggregated into a VC-4 High Order Path. An AU pointer is added to the VC-4 to create an AU-4 (Administrative Unit type 4). One AU-4 is multiplexed into an AUG (AU group), which is to say, the AUG is, in fact, equivalent to an AU-4. The multiplexing scheme is as follows: TUG-3 (x3) < > VC-4 < > AU-4 (x1) < > STM-1 To map the AUG to an AU-4, use the aug mapping au-4 controller configuration command. Configuring the au-4 tug-3 command enters TUG-3 configuration mode, and creates a serial interface with the following name format: slot/port.au-4-number/tug-3-number/tug-2-number/e1-number:channel-group-number The aug mapping and au-4 tug-3 commands are available only when SDH framing is configured. 22

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers au-4 tug-3 Examples In the following example, the second TUG-3 of the AU-4 in port 0 of the Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 4 of a Cisco 12000 series Internet Router is selected for configuration: Router(config)# controller sonet 4/0 Router(config-controller)# framing sdh Router(config-controller)# aug mapping au-4 Router(config-controller)# au-4 1 tug-3 2 Router(config-ctrlr-tug3)# Related Commands Command Description aug mapping Specify the AUG mapping when SDH framing is selected. 23

aug mapping 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers aug mapping To specify the AUG mapping when SDH framing is selected, use the aug mapping controller configuration command. To restore the default AUG mapping, use the no form of this command. aug mapping {au-3 au-4} no aug mapping {au-3 au-4} Syntax Description au-3 au-4 Select AU-3 AUG mapping. Select AU-4 AUG mapping. This is the default. Defaults AU-4 mapping Command Modes Controller configuration Command History Release 12.0(14)S 12.0(17)S Modification This command was introduced. This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines In SDH, there are two possible mapping/multiplexing schemes for most payload types: ANSI and ETSI. In ANSI mapping, the Low Order payloads are aggregated into a VC-3 High Order Path. An AU pointer is added to the VC-3 to create an AU-3 (Administrative Unit type 3). Three such AU-3s are then synchronously multiplexed into an AUG (AU group). The multiplexing scheme is as follows: VC-3 < > AU-3 (x3) < > AUG < > STM-1 SDH ANSI mapping is very similar to the SONET frame structure. In ETSI mapping, the Low Order payloads are aggregated into a VC-4 High Order Path. An AU pointer is added to the VC-4 to create an AU-4 (Administrative Unit type 4). One AU-4 is multiplexed into an AUG (AU group), which is to say, the AUG is, in fact, equivalent to an AU-4. The multiplexing scheme is as follows: TUG-3 (x3) < > VC-4 < > AU-4 (x1) < > STM-1 This command is available only when SDH framing is configured. Examples The example that follows selects AU-3 mapping for port 1 of the Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 2 of a Cisco 12000 series Internet Router: Router(config)# controller sonet 2/1 Router(config-controller)# framing sdh Router(config-controller)# aug mapping au-3 24

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers aug mapping Related Commands Command Description framing (controller) Determine whether the port is to be used in SONET mode or SDH mode. 25

clear counters serial 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clear counters serial To clear the counters for a serial interface configured on the Two-port STM-1/OC-3 Channelized E1/T1 line card, use the clear counters serial EXEC command. clear counters serial slot/port.path:channel-group Syntax Description slot port.path :channel-group The chassis slot where the Two-port STM-1/OC-3 Channelized E1/T1 line card is installed. The physical port on the Two-port STM-1/OC-3 Channelized E1/T1 line card. Either 0 or 1. Depends on the interface configuration: When framing is SDH and AUG mapping is AU-4, path takes the form: au-4-number/tug-3-number/tug-2-number/e1-line-number When framing is SDH and AUG mapping is AU-3, path takes the form: au-3-number/tug-2-number/t1-line-number When framing is SONET and the mode is CT3, path takes the form: sts1-number/t1-line-number When framing is SONET and the mode is VT1.5, path takes the form: sts1-number/vtg-number/t1-line-number Channel group identifier: 0 to 30 for an E1 line; 0 to 23 for a T1 line. Defaults No default behavior or values. Command Modes EXEC Command History Release Modification 10.0 This command was introduced. 12.0(17)S This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines The clear counters serial command resets the counters for a serial interface. To reset the interface hardware, use the clear interface serial command. To check the status of the interface, use the show interfaces serial command. Note As long as the serial interface is available, you can enter this command immediately after using the enable command to enter privileged EXEC mode. 26

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clear counters serial Examples The following example clears the counters for serial interface 3/1.1/1/1:1, which is configured in the context of SONET framing in vt-15 mode. The number sequence.1/1/1:1 corresponds to the sts-1-number/vtg-number/t1-line-number:channel-group number sequence. Router# clear counters serial 3/1.1/1/1:1 Clear show interface counters on this interface [confirm] Router# Related Commands Command Description clear interface serial Resets the interface hardware. show interfaces Displays statistics for all interfaces configured on the router or access server. show interfaces serial Displays information about a serial interface. 27

clear interface serial 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clear interface serial To reset the hardware logic for a serial interface configured on the Two-port STM-1/OC-3 Channelized E1/T1 line card, use the clear interface serial EXEC command. clear interface serial slot/port.path:channel-group Syntax Description slot port.path :channel-group The chassis slot where the Two-port STM-1/OC-3 Channelized E1/T1 line card is installed. The physical port on the Two-port STM-1/OC-3 Channelized E1/T1 line card. Either 0 or 1. Depends on the interface configuration: When framing is SDH and AUG mapping is AU-4, path takes the form: au-4-number/tug-3-number/tug-2-number/e1-line-number When framing is SDH and AUG mapping is AU-3, path takes the form: au-3-number/tug-2-number/t1-line-number When framing is SONET and the mode is CT3, path takes the form: sts1-number/t1-line-number When framing is SONET and the mode is VT1.5, path takes the form: sts1-number/vtg-number/t1-line-number Channel group identifier: 0 to 30 for an E1 line; 0 to 23 for a T1 line. Defaults No default behavior or values. Command Modes EXEC Command History Release Modification 10.0 This command was introduced. 12.0(17)S This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines The clear interface serial command resets the interface hardware. To reset the counters for an interface, use the clear counters serial command. To check the status of the interface, use the show interfaces serial command. Note As long as the serial interface is available, you can enter this command immediately after using the enable command to enter privileged EXEC mode. 28

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clear interface serial Examples The following example clears serial interface 3/1.1/1/1:1, which is configured in the context of SONET framing in vt-15 mode. The number sequence.1/1/1/1:1 corresponds to the sts-1-number/vtg-number/t1-line-number:channel-group number sequence. Router# clear interface serial 3/1.1/1/1:1 Router# Related Commands Command Description clear counters serial Clears the interface counters. show interfaces Displays statistics for all interfaces configured on the router or access server. show interfaces serial Displays information about a serial interface. 29

clock source (controller) 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clock source (controller) To specify the clock source for the selected OC-3/STM-1 port on the Two-port STM-1/OC-3 Channelized E1/T1 line card, use the clock source controller configuration command. To reset the clock source to the default, use the no form of this command. clock source {internal line} no clock source {internal line} Syntax Description internal line Internal clock source. Network clock source. This is the default. Defaults Line Command Modes Controller configuration Command History Release Modification 10.3 This command was introduced. 12.0(17)S This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines Typically, an OC-3/STM-1 port on the Two-port STM-1/OC-3 Channelized E1/T1 line card is connected to a SONET or SDH add/drop multiplexer (ADM). In this application, Cisco recommends using the default setting of clock source line, because: The clock source used by the SONET/SDH network is of higher accuracy than the internal clock source on the Two-port STM-1/OC-3 Channelized E1/T1 line card. The SONET/SDH network is designed for optimal operation in synchronous mode, where all clocks used in the network can be traced to a single high-accuracy clock source. Using the internal clock on the Two-port STM-1/OC-3 Channelized E1/T1 line card port introduces an independent clock source into the network, and may cause synchronization-related anomalies to be detected by the SONET/SDH network elements. When configured for line clocking, the Two-port STM-1/OC-3 Channelized E1/T1 line card port will automatically default to internal clocking if the line clock source is considered unusable for any of the following reasons: The port detects a Loss of Signal (SLOS) defect. The port detects a Loss of Frame (LOF) defect. The port detects a Section (RS) Loss of Frame (SLOF) defect. The port detects a Line (MS) Alarm Indication Signal (LAIS) defect. The port receives the Do not use for synchronization code in byte S1 of the Line (MS) overhead. 30

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers clock source (controller) The port has been put into the local loopback mode through the use of the loopback local controller command. When the loopback is cleared, the port reverts to using the line clock source. Note The OC-3/STM-1 port on the Two-port STM-1/OC-3 Channelized E1/T1 line card always sends the Do not use for synchronization code in byte S1 of the Line (MS) overhead toward the directly connected ADM. Examples The following example selects the internal clock source: Router(config)# controller sonet 6/0 Router(config-controller)# clock source internal Router(config-controller)# Related Commands Command Description t1 clock source Set the internal or line (network) clock source for a T1 line on the Two-port STM-1/OC-3 Channelized E1/T1 line card. t3 clock source Set the clock source for the selected T3 link. tug-2 e1 clock source Specify where the clock source is obtained for an E1 line. 31

controller sonet 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers controller sonet To select the physical port to configure on the Two-port STM-1/OC-3 Channelized E1/T1 line card, use the controller sonet global configuration command. To delete the defined controller, use the no form of this command. controller sonet slot/port no controller sonet slot/port Syntax Description slot port The chassis slot where the Two-port STM-1/OC-3 Channelized E1/T1 line card is installed. The physical port on the Two-port STM-1/OC-3 Channelized E1/T1 line card. Either 0 or 1. Defaults No default behavior or values. Command Modes Global configuration Command History Release 12.0(14)S 12.0(17)S Modification This command was introduced. This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines This command is used to select an STM-1/OC-3 physical port so that additional channelization parameters for its associated T3, T1, or E1 links can be configured. Examples The example that follows selects port 1 of the Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 3 of a Cisco 12000 series Internet Router: Router(config)# controller sonet 3/1 Router(config-controller)# Related Commands Command Description show controllers sonet Displays information that is specific to SONET controllers in a Cisco 12000 series Internet Router. 32

2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers framing (controller) framing (controller) To determine whether the port is to be used in SONET mode or SDH mode, use the framing controller configuration command. To reset the framing mode to the default, use the no form of this command. framing {sonet sdh} no framing Syntax Description sonet sdh SONET mode. This is the default. SDH mode. Defaults SONET Command Modes Controller configuration Command History Release 12.0(14)S 12.0(17)S Modification This command was introduced. This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines Normally, both OC-3/STM-1 ports should be configured to the same framing type: either both ports configured for SONET, or both ports configured for SDH. The specific restriction applies to mixing E1 and T1 channels on one line card, which is not supported. If you attempt to violate this restriction, the system will display a warning message. Examples The following example selects SDH framing for port 1 of the Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 3 of a Cisco 12000 series Internet Router: Router(config)# controller sonet 3/1 Router(config-controller)# framing sdh Router(config-controller)# Related Commands Command t1 framing t3 framing tug-2 e1 framing Description Specify the T1 framing format for a T1 line on the Two-port STM-1/OC-3 Channelized E1/T1 line card. Specify the framing type for the T3 link. Specify the E1 framing format for an E1 line on the Two-port STM-1/OC-3 Channelized E1/T1 line card. 33

loopback (controller) 2-port STM-1/OC-3 Channelized E1/T1 Line Card for Cisco 12000 Series Internet Routers loopback (controller) To set a SONET/SDH port loopback on the Two-port STM-1/OC-3 Channelized E1/T1 line card, use the loopback controller configuration command. To remove a loopback, use the no form of this command. loopback [local network] no loopback [local network] Syntax Description local network Local (diagnostic) loopback mode. Network (line) loopback mode. Defaults No loopback is set. Command Modes Controller configuration Command History Release 12.0(17)S Modification This command was modified to support the Two-port STM-1/OC-3 Channelized E1/T1 line card. Usage Guidelines Use the loopback local controller configuration command to diagnose problems with the Two-port STM-1/OC-3 Channelized E1/T1 line card when it is isolated from the network cables. Network loopback loops the entire STM-1/STS-3 frame back toward the network and can be used to diagnose problems with cables. Examples The following example shows how to configure the port for local loopback. The port is port 0 on a Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 6 of the Cisco 12000 series Internet Router: Router(config)# controller sonet 6/0 Router(config-controller)# loopback local Router(config-controller)# The following example shows how to configure the port for network loopback. The port is port 0 on a Two-port STM-1/OC-3 Channelized E1/T1 line card in slot 6 of the Cisco 12000 series Internet Router: Router(config)# controller sonet 6/0 Router(config-controller)# loopback network Router(config-controller)# Related Commands 34