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This document describes the Cisco IOS Inverse Multiplexing over ATM (IMA) feature available with the introduction of Asynchronous Transfer Mode (ATM) IMA T1 port adapters for Cisco 7200 series routers.
This document includes the following sections:
ATM T1 IMA port adapters provide eight T1 ports with inverse multiplexing capability. These modules allow WAN uplinks at speeds ranging from 1.546 Mbps to 12.288 Mbps for T1. (For details, see the "Bandwidth Considerations" section on page 4.)
Cisco's scalable ATM IMA solution means that network designers and managers can deploy only the bandwidth they need, using multiple T1 connections instead of more expensive T3 or OC-3 lines to bridge between LANs and ATM WAN applications. Enterprises and branch offices can aggregate traffic from multiple lower-bandwidth physical transmission media, such as T1 pipes, to transmit voice and data at high-bandwidth connection speeds.
In the transmit direction, IMA takes cells from the ATM layer and sends them in sequential distribution over the individual links that make up a logical link group called an IMA group (links can also be assigned as individuals rather than as group members). The IMA group performance is approximately the sum of the links, although some overhead is required for ATM header and control cells. At the receiving end, the cells are recombined to form the original cell stream and are passed up the ATM layer.
Filler cells are used to ensure a steady stream on the receiving side. IMA Control Protocol (ICP) cells control the operation of the inverse multiplexing function. Using a frame length of 128 cells, one out of every 128 cells on each link is an ICP cell. The inverse multiplexing operation is transparent to the ATM layer protocols, and therefore the ATM layer can operate normally as if only a single physical interface is being used.
Figure 1 illustrates inverse multiplexing and demultiplexing with four bundled links, providing 5.52 Mbps of bandwidth for T1s for packet traffic, after subtracting the overhead of ATM cell headers and ICP cells. The transmitting side, from which cells are distributed across the links, is referred to as Tx, and the receiving side, where cells are recombined, is called Rx.
ATM networks were designed to handle the demanding performance needs of voice, video, and data, at broadband speeds of 34 Mbps and higher. However, the high cost and sporadic availability of long-distance broadband links limits broadband ATM WANs, preventing many organizations from taking advantage of ATM power. In response to these issues, the ATM Forum defined lower-speed ATM interface options for T1 or E1. However, this was not a complete solution, because a single T1 or E1 link often does not provide enough bandwidth to support either traffic among different router and switch locations or heavy end-user demand.
For this reason, many organizations find themselves caught between the bandwidth limitations of a narrowband T1 or E1 line and the much higher costs of moving to broadband links. In response to this dilemma, the ATM Forum defined IMA. Using Cisco 7200 series routers and 7500 series routers to provide ATM access gives branch offices and enterprises an affordable LAN-to-ATM interface.
ATM IMA T1 or E1 support on Cisco 7200 series routers and 7500 series routers includes the following features:
The following are benefits offered by the ATM T1 or E1 IMA features for Cisco 7200 series routers and 7500 series routers:
This section describes general restrictions and ATM aspects that the ATM IMA feature does not support, as well as bandwidth considerations.
The following restrictions apply to the ATM IMA feature on Cisco 7200 series routers and 7500 series routers:
When planning IMA groups and payload bandwidths, consider the overhead required for ATM headers and ICP cells. Table 1 and Table 2 show approximate values for T1 and E1 IMA groups, respectively with a frame length of 128, estimating ATM overhead at about 10 percent. The effective payload bandwidth varies based on packet size because the packets must be divided into an integer number of ATM cells leaving the last cell padded with filler bytes.
| Number of Links in the Group | Total Bandwidth | Payload Bandwidth |
|---|---|---|
1 | 1.536 | 1.38 |
2 | 3.072 | 2.76 |
3 | 4.608 | 4.14 |
4 | 6.144 | 5.52 |
5 | 7.68 | 6.91 |
6 | 9.216 | 8.28 |
7 | 10.752 | 9.66 |
8 | 12.288 | 11.04 |
| Number of Links in the Group | Total Bandwidth | Payload Bandwidth |
|---|---|---|
1 | 1.92 | 1.74 |
2 | 3.84 | 3.47 |
3 | 5.76 | 5.21 |
4 | 7.68 | 6.95 |
5 | 9.60 | 8.69 |
6 | 11.52 | 10.43 |
7 | 13.44 | 12.17 |
8 | 15.36 | 13.90 |
No new or modified RFCs are supported by this feature.
No new or modified RFCs are supported by this feature.
Before you can configure a Cisco 7200 series router or Cisco 7500 series router to provide ATM T1 or E1 IMA service, you must perform the following tasks:
For details about software configuration, see the Cisco IOS Release 12.0 software documents, Wide-Area Networking Configuration Guide and Wide-Area Networking Command Reference. For more information about the physical characteristics of the ATM T1 or E1 IMA port adapters for the Cisco 7200 series, or for instructions on how to install the port adapters, either see the Inverse Multiplexing over ATM (IMA) Port Adapter Installation and Configuration Guide that came with your ATM T1 or E1 IMA port adapter.
This section describes the configuration tasks required to set up ATM IMA groups. You can also configure ATM links individually, but this feature description only includes those individual configuration steps that might pertain to ATM IMA groups. For complete information about ATM configuration, see the Cisco IOS Release 12.0 Wide-Area Networking Configuration Guide and Wide-Area Networking Command Reference.
Perform the following configuration tasks in order to enable ATM inverse multiplexing:
Repeat the steps below to configure each ATM interface for ATM IMA operation. For complete information about ATM interface configuration, see the Cisco IOS Release 12.0 Wide-Area Networking Configuration Guide.
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router# configure terminal | Enter global configuration mode. | ||
| Router(config)# interface atm slot/port (7200 series routers)
Router (config)# interface serial slot/port-adapter/port (Cisco 7500 series | Enters interface configuration mode and specifies the location of the interface.
The Cisco IOS software creates the interfaces automatically when a port adapter is installed. | ||
| Router(config-if)# clock source {line | internal } | Sets the clock source for a link.
| ||
| Router(config-if)# lbo long {gain26 | gain36} {-15db | -22.5db | -7.5db | 0db}
or lbo short {133 | 266 | 399 | 533 | 655} | Sets a cable length longer than 655 feet for a T1 or E1 link.
Sets a cable length 655 feet or shorter for a T1 or E1 link. There is no default for lbo short. The keywords are as follows:
If you do not set the cable length, the system defaults to a setting of lbo long gain260db. | ||
| Router(config-if)# no ip address | Instead of configuring protocol parameters on the physical interface, you can set these up on the IMA group virtual interface. | ||
| Router(config-if)# | Enables the ATM bandwidth manager, which keeps track of bandwidth used by virtual circuits on a per-interface basis. When you specify the no form of the command, a check determines whether the ATM link is already oversubscribed. If it is, the command is rejected. Otherwise, the total bandwidth available on the link is recorded and all future connection setup requests are monitored to ensure that the link is not oversubscribed. | ||
| Router(config-if)# no scrambling cell-payload | Randomizes the ATM cell payload frames to avoid continuous non-variable bit patterns and improve the efficiency of ATM's cell delineation algorithms. Normally the default setting for this command is sufficient, with no specific command required. Helping to ensure reliability, scrambling By default, scrambling is off for T1 or E1 links. | ||
| Router(config-if)# loopback [line | local | payload | remote] | (For testing only) Loops all packets from the ATM interface back to the interface, as well as directs the packets to the network. The default line setting places the interface into external loopback mode at the line.
| ||
| Router(config-if)# fdl {ansi | att} | (Optional) Sets the Facility Data Link (FDL) exchange standard for the CSU controllers. The FDL is a 4-Kbps channel used with the Extended SuperFrame (ESF) framing format to provide out-of-band messaging for error-checking on a T1 or E1 link. Changing the default allows better management in some circumstances, but can cause problems if your setting is not compatible with that of your service provider. | ||
| Router(config-if)# ima-group group-number | Specifies that the link is included in an IMA group. Enter an IMA group number from 0 to 3. You can specify up to four groups per IMA port adapter. IMA groups usually span multiple ports on a port adapter. | ||
| Router(config-if)# no shutdown | Ensures that the link is active at the IMA level. |
Follow the steps below to verify configuration of ATM interfaces.
Step 1 Use the privileged EXEC show interface atm slot/port command to verify configuration of the ATM interface. Important information appears in bold. Note that the total count of configured virtual circuits (VCs) is shown.
router# show interface atm1/1 ATM0/1 is up, line protocol is up
Hardware is ATM T1 Internet address is 10.0.0.0/8 MTU 4470 bytes, sub MTU 4470, BW 1500 Kbit, DLY 20000 usec, reliability 1/255, txload 1/255, rxload 1/255 Encapsulation ATM, loopback not set Keepalive not supported Encapsulation(s): AAL5 256 maximum active VCs, 3 current VCCs VC idle disconnect time: 300 seconds Last input never, output never, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 3 interface resets 0 output buffer failures, 0 output buffers swapped out
Step 2 To get information about the physical link, use the privileged EXEC show controller [atm [slot/port] command.
Router#show controller atm 1/ima0
Interface ATM1/ima0 is up
Hardware is IMA PA - DS1 (1Mbps)
Lane client mac address is 0090.b1f8.e41c
Framer is PMC PM7344, SAR is LSI ATMIZER II
Firmware rev:G102, ATMIZER II rev:3
idb=0x61DE9F10, ds=0x6185C0A0, vc=0x6187D3C0, pa=0x6184AF40
slot 1, unit 9, subunit 0, fci_type 0x00BA, ticks 701720
400 rx buffers:size=512, encap=64, trailer=28, magic=4
Curr Stats:
rx_cell_lost=0, rx_no_buffer=0, rx_crc_10=0
rx_cell_len=0, rx_no_vcd=0, rx_cell_throttle=0, tx_aci_err=0
Rx Free Ring status:
base=0x3CFF0040, size=1024, write=320
Rx Compl Ring status:
base=0x338DCE40, size=2048, read=1275
Tx Ring status:
base=0x3CFE8040, size=8192, write=700
Tx Compl Ring status:
base=0x338E0E80, size=2048, read=344
BFD Cache status:
base=0x61878340, size=5120, read=5107
Rx Cache status:
base=0x61863D80, size=16, write=11
Tx Shadow status:
base=0x618641C0, size=8192, read=687, write=700
Control data:
rx_max_spins=12, max_tx_count=25, tx_count=13
rx_threshold=267, rx_count=11, tx_threshold=3840
tx bfd write indx=0x27, rx_pool_info=0x61863E20
Control data base address:
rx_buf_base = 0x038A15A0 rx_p_base = 0x6185CB40
rx_pak = 0x61863AF0 cmd = 0x6185C320
device_base = 0x3C800000 ima_pa_stats = 0x038E2FA0
sdram_base = 0x3CE00000 pa_cmd_buf = 0x3CFFFC00
vcd_base[0] = 0x3CE3C100 vcd_base[1] = 0x3CE1C000
chip_dump = 0x038E3D7C dpram_base = 0x3CD80000
sar_buf_base[0] = 0x3CE4C000 sar_buf_base[1] = 0x3CF22000
bfd_base[0] = 0x3CFD4000 bfd_base[1] = 0x3CFC0000
acd_base[0] = 0x3CE88360 acd_base[1] = 0x3CE5C200
pci_atm_stats = 0x038E2EC0
ATM1/ima0 is up
hwgrp number = 1
grp tx up reg= 0x5, grp rx up reg= 0x3, rx dcb reg= 0xD4 0x4, tx links grp reg=
0x3, scci reg= 0x3C, ima id reg= 0x0, group status reg= 0xA2, tx timing reg= 0x
20, tx test reg= 0x21, tx test pattern reg= 0x41, rx test pattern reg= 0x42, icp
cell link info reg= 0xFC, icp cell link info reg= 0xFC, icp cell link info r
eg= 0x0, icp cell link info reg= 0x0, icp cell link info reg= 0x0, icp cell li
nk info reg= 0x0, icp cell link info reg= 0x0, icp cell link info reg= 0x0
The ima-group command configures links on an ATM interface as IMA group members. When IMA groups have been set up in this way, you can configure settings for each group.
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router# configure terminal | Enters global configuration mode. | ||
| Router(config)# interface atm slot/ima <group number> (7200 series routers)
Router(config)# interface atmslot/port-adapter/port (Cisco 7500 series)
| Enters interface configuration mode and specify the slot location of the interface and IMA group number.
| ||
| Router(config-if)# ip address ip-address | Sets protocol parameters for the whole group. | ||
| Router(config-if)# pvc vpi vci ilmi | If you are going to use SVCs, create an ATM permanent virtual circuit (PVC) for ILMI management purposes and enter VC configuration mode. To set up communication with the ILMI, use a value of ilmi for ATM adaptation layer encapsulation; the associated vpi and vci values are ordinarily 0 and 16, respectively.1 | ||
| Router | Enables the signaling for setup and tear-down of SVCs by specifying the Q.SAAL (Signaling ATM adaptation layer) encapsulations; the associated vpi and vci values are ordinarily 0 and 5, respectively. Note You can also set up PVCs for sending information. | ||
| Router | To complete configuration of a PVC, exit VC configuration mode. | ||
| Router
| Sets up SVCs for sending ATM information. Once you specify a name for an SVC, you can reenter the interface-ATM-VC configuration mode by simply entering svc name. nsap-address is a 40-digit hexadecimal number. | ||
| Router | Specifies a protocol address for the SVC. Note The default AAL5 layer and SNAP encapsulation is used in this example, so the encapsulation aalencap command is unnecessary. | ||
| Router | Exits VC configuration mode and returns to interface configuration mode. | ||
| Router(config-if)# ima clock-mode {common <port> | independent} | Sets the transmit clock mode for the group. If all the links in the group should share a clock source, use the common keyword. If each link uses a different clock source, use the independent clock source keyword. The port keyword allows you to specify a link to be used for common clocking. The default uses the common clock as the transmit clock source. | ||
| Router(config-if)# ima active-links-minimum number | Specifies how many transmit links must be active in order for the IMA group to be operational, by using this command with a number value from 1 to 8. The setting you choose depends upon your performance requirements as well as the total number of links in the group. If fewer than the preset minimum are active, the group is automatically rendered inactive until the minimum number of links are up again. The default value is 1. | ||
| Router(config-if)# ima differential-delay-maximum msec | Specifies the differential timing delay among the links in an IMA group by entering a milliseconds value from 25 to 250. If a link delay exceeds the specified maximum, the link is dropped; otherwise, the IMA feature adjusts for differences in delays so that all links in a group are aligned. A shorter value provides less resiliency in adjusting for variations than a higher value. However, a higher value might affect overall group performance, because increased differential delay adds more latency to the traffic that is transmitted across the group. | ||
| Router(config-if)# ima test [link port] [pattern pattern-id]
| Troubleshoots or diagnoses physical link connectivity. The IMA feature performs ongoing tests on all links in a group, to verify link connectivity. Use this command to specify a link to use for testing as well as a test pattern. The pattern is sent from the specified link and looped back from the receiving end in the multiplexing-demultiplexing process. A byte in the ICP cell identifies the pattern. |
Step 1 Use the privileged EXEC show ima interface atm [slot] /ima [group-number] [detail] command to get information about IMA group interfaces. First, the group information appears. Then, information about each link in the group (there are two in this example) is displayed under "IMA Detailed Link Information."
Important information is shown in bold.
Router#show ima interface atm 1/ima0 detail
ATM1/ima0 is up
ImaGroupState:NearEnd = operational, FarEnd = operational
ImaGroupFailureStatus = noFailure
IMA Group Current Configuration:
ImaGroupMinNumTxLinks = 2 ImaGroupMinNumRxLinks = 2
ImaGroupDiffDelayMax = 25 ImaGroupNeTxClkMode = common(ctc)
ImaGroupFrameLength = 128 ImaTestProcStatus = disabled
ImaGroupTestLink = 0 ImaGroupTestPattern = 0xFF
IMA MIB Information:
ImaGroupSymmetry = symmetricOperation
ImaGroupFeTxClkMode = common(ctc)
ImaGroupRxFrameLength = 128
ImaGroupTxTimingRefLink = 0 ImaGroupRxTimingRefLink = 0
ImaGroupTxImaId = 0 ImaGroupRxImaId = 0
ImaGroupNumTxCfgLinks = 2 ImaGroupNumRxCfgLinks = 2
ImaGroupNumTxActLinks = 2 ImaGroupNumRxActLinks = 2
ImaGroupLeastDelayLink = 1 ImaGroupDiffDelayMaxObs = 0
IMA group counters:
ImaGroupNeNumFailures = 78 ImaGroupFeNumFailures = 68
ImaGroupUnAvailSecs = 441453 ImaGroupRunningSecs =
445036
IMA Detailed Link Information:
ATM1/0 is up
ImaLinkRowStatus = LinkRowStatusUnknown
ImaLinkIfIndex = 0 ImaLinkGroupIndex = 0
ImaLinkState:
NeTx = active
NeRx = active
FeTx = active
FeRx = active
ImaLinkFailureStatus:
NeRx = noFailure
FeRx = noFailure
ImaLinkTxLid = 0 ImaLinkRxLid = 0
ImaLinkRxTestPattern = 65 ImaLinkTestProcStatus = disabled
ImaLinkRelDelay = 0
IMA Link counters :
ImaLinkImaViolations = 1
ImaLinkNeSevErroredSec = 41 ImaLinkFeSevErroredSec = 34
ImaLinkNeUnavailSec = 441505 ImaLinkFeUnAvailSec = 28
ImaLinkNeTxUnusableSec = 2 ImaLinkNeRxUnUsableSec = 441542
ImaLinkFeTxUnusableSec = 74 ImaLinkFeRxUnusableSec = 57
ImaLinkNeTxNumFailures = 0 ImaLinkNeRxNumFailures = 15
ImaLinkFeTxNumFailures = 4 ImaLinkFeRxNumFailures = 3
ATM1/1 is up
ImaLinkRowStatus = LinkRowStatusUnknown
ImaLinkIfIndex = 1 ImaLinkGroupIndex = 0
ImaLinkState:
NeTx = active
NeRx = active
FeTx = active
FeRx = active
ImaLinkFailureStatus:
NeRx = noFailure
FeRx = noFailure
ImaLinkTxLid = 1 ImaLinkRxLid = 1
ImaLinkRxTestPattern = 65 ImaLinkTestProcStatus = disabled
ImaLinkRelDelay = 0
IMA Link counters :
ImaLinkImaViolations = 1
ImaLinkNeSevErroredSec = 40 ImaLinkFeSevErroredSec = 42
ImaLinkNeUnavailSec = 441389 ImaLinkFeUnAvailSec = 38
ImaLinkNeTxUnusableSec = 2 ImaLinkNeRxUnUsableSec = 441427
ImaLinkFeTxUnusableSec = 99 ImaLinkFeRxUnusableSec = 99
ImaLinkNeTxNumFailures = 0 ImaLinkNeRxNumFailures = 16
ImaLinkFeTxNumFailures = 4 ImaLinkFeRxNumFailures = 4
Step 2 Use the privileged EXEC show atm vc command to see how SVCs and PVCs are set up.
VCD / Peak Avg/Min Burst Interface Name VPI VCI Type Encaps SC Kbps Kbps Cells Sts 1 1 0 50 PVC SNAP UBR 1000 INAC IMA3 2 0 5 PVC SAAL UBR 4000 UP IMA3 3 0 16 PVC ILMI UBR 4000 UP IMA3 first 1 13 PVC MUX VBR 640 320 80 UP IMA3 4 0 34 SVC SNAP VBR-RT 768 768 UP
To troubleshoot ATM configuration and IMA group configuration, use the ping EXEC (user) or privileged EXEC command that checks host reachability and network connectivity. This command can confirm basic network connectivity on AppleTalk, International Organization for Standardization (ISO), Connectionless Network Service (CLNS), IP, Novell, Apollo, Virtual Integrated Network Service (VINES), DECnet, or Xerox Network SystemsXNS networks.
For IP, the ping command sends Internet Control Message Protocol (ICMP) Echo messages. If a station receives an ICMP Echo message, it sends an ICMP Echo Reply message back to the source.
The extended command mode of the ping command permits you to specify the supported IP header options. This allows the router to perform a more extensive range of test options. To enter ping extended command mode, enter yes at the extended commands prompt of the ping command.
For detailed information on using the ping and extended ping commands, refer to the Cisco IOS Release 12.0 Configuration Fundamentals Command Reference.
If a ping command fails, check the following possible reasons for the connectivity problem:
 | Tips |
It is a good idea to use the ping command when the network is functioning properly to see how the command works under normal conditions and so that you can compare the results when troubleshooting.
If a communication session is closing when it should not be, an end-to-end connection problem can be the cause. The debug ip packet command is useful for analyzing the messages traveling between the local and remote hosts. IP debugging information includes packets received, generated, and forwarded. Because the debug ip packet command generates a significant amount of output, use it only when traffic on the IP network is low, so other activity on the system is not adversely affected.
| Command | Purpose |
|---|---|
Router# show ima interface atm [slot]/ima[group-number] [detail] | Displays general or detailed information about IMA groups and the links in those groups. |
Router# show controllers [atm slot/imagroup-number] | Displays information about current settings and performance at the physical level. |
This section shows one sample configuration for a router that is set up for ATM T1 or E1 IMA.
The following configuration example shows the setup of ATM interfaces, IMA groups, PVCs, and SVCs for T1 IMA.
version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption no service dhcp ! hostname router ! ! ! ! ! ! ip subnet-zero ! ! ! ! !
There are four links in IMA group 3. ATM interface 0/1 has a PVC configured on it, set to the default AAL5 SNAP encapsulation. The no scrambling cell-payload command is actually unnecessary, as this is the default for T1 links. Because the T1 default binary-eight zero substitution (B8ZS) line encoding is normally sufficient for proper cell delineation, this is the usual setting for T1 links, The scrambling setting must match the far-end.
interface ATM0/0 no ip address no ip directed-broadcast loopback line no atm ilmi-keepalive ima-group 3 no scrambling cell-payload no fair-queue ! interface ATM0/1 ip address 21.1.1.2 255.0.0.0 no ip directed-broadcast no atm ilmi-keepalive pvc 0/50 protocol ip 21.1.1.1 broadcast ! ima-group 3 no scrambling-payload no fair-queue ! interface ATM1/2 no ip address no ip directed-broadcast no atm ilmi-keepalive ima-group 3 no scrambling-payload no fair-queue ! interface ATM0/3 no ip address no ip directed-broadcast no atm ilmi-keepalive ima-group 3 no scrambling-payload no fair-queue ! !
IMA group 3 has PVCs that are set up for SVC management and signaling. Two SVCs and a communications PVC are also set up on the group interface.
interface ATM0/IMA3 no ip address no ip directed-broadcast no atm ilmi-keepalive pvc 0/16 ilmi ! pvc 0/5 qsaal ! ! pvc first 1/13 vbr-nrt 640 320 80 encapsulation aal5mux ip ! ! svc nsap 47.0091810000000002F26D4901.444444444444.01 !
The group commands below specify that three links must be active for the group to be operational. The common clock source is the first link, ATM 0/0, and ATM 0/1 is the test link. The differential delay maximum is set to 50 milliseconds (ms).
ima active-links-minimum 3 ima clock-mode common 0 ima differential-delay-maximum 50 ima test link 1 ! interface Ethernet1/0 no ip address no ip directed-broadcast shutdown ! interface Ethernet1/1 no ip address no ip directed-broadcast shutdown ! ip classless no ip http server ! ! ! line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 login ! ! end
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.
To enable a BERT test pattern on a T1 or E1 line, use the bert controller configuration command. To disable a BERT test pattern, use the no form of this command.
bert pattern {2^23 | 2^20 | QRSS | 2^15 | 2^11 | 1s | 0s |alt-0-1} interval time
pattern {2^23 | 2^20 | QRSS | 2^15 | 2^11 | 1s | 0s |alt-0-1} | Specifies the length of the repeating BERT test pattern. Values are: · 2^23---Pseudo-random 0.151 test pattern that is 8,388,607 bits in length. · 2^20---Pseudo-random O.153 test pattern that is 1,048,575 bits in length. · QRSS---Pseudo-random QRSS 0.151 test pattern that is 1,048,575 bits in length. · 2^15---Pseudo-random O.151 test pattern that is 32,768 bits in length. · 2^11---Pseudo-random test pattern that is 2,048 bits in length. · 1s---Repeating pattern of ones (...111...). · 0s---Repeating pattern of zeros (...000...). · alt-0-1---Repeating alternating pattern of zeros and ones (...01010...). |
interval time | Specifies the duration of the BERT test. The interval can be a value from |
Disabled
Controller configuration
| Release | Modification |
|---|---|
12.0(5)XE | The command was introduced. |
This command first appeared in Cisco IOS Release 11.1 CC.
Bit error rate testing (BERT) is supported on each of the T1 or E1 links. The BER testing is done only over a framed T1 or E1 signal and can be run only on one port at a time.
To view the BERT results, use the show controller e1 or show controller t1 EXEC command. The BERT results include the following information:
When the T1 or E1 line has a BER test running, the line state is DOWN. Also, when the BER test is running and the Status field is Not Sync, the information in the Bit Errors field is not valid. When the BER test is done, the Status field is not relevant.
The bert pattern command is not written to NVRAM because it is only used for testing the T1 or E1 line for a short predefined interval and to avoid accidentally saving the command, which could cause the interface not to come up the next time the router reboots.
In the following example on a Cisco 7200 series router, a BER test pattern of all zeros is run for 30 minutes on T1 line 0 on the port adapter in slot 9:
Router# controller t1 9/0 Router(config-controll)# bert pattern 0s interval 30
show controllers e1
show controllers t1
Use the framing controller configuration command to select the frame type for the T1 or E1 data line.
framing {sfadm | esfadm} (for T1 lines)
sfadm | Specifies Super Frame as the T1 channel. |
esfadm | Specifies Extended Super Frame as the T1 channel. |
crc4adm | Specifies CRC4 frame as the E1 channel. |
pcm30adm | Specifies CRC4 disabled framing mode the E1 channel. |
clear e1 | Specifies clear-e1 framing mode for E1 channel. |
Extended Super frame (ESF) (for a T1 line)
CRC4 frame (for an E1 line)
Controller configuration
| Release | Modification |
|---|---|
11.3 | This command was first introduced. |
12.0(5)XE | The command was enhanced as an ATM interface configuration command. |
Use this command in configurations where the router or access server is intended to communicate with T1 or E1 fractional data line. The service provided determines which framing type, either sf, esf, or crc4, is required for your T1 or E1 circuit.
The following example selects extended super frame as the T1 frame type:
framing esf
cablelength
linecode
To set the minimum number of links that must be operational in order for an ATM IMA group to remain in service, execute the IMA interface configuration command ima active-links-minimum. The no form of the command removes the current configuration and sets the value to the default.
ima active-links-minimum number
number | Enter a value from 1 to 8. |
One link.
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
The minimum number of links that should be active for continued group operation depends upon the applications you are using and the speeds they require. ATM frame size and the number of links in a group affect the overhead required by ATM.
When planning, you should assume that only the bandwidth supplied by the minimal number of links will be available. If you decrease the value set in this command, make sure that virtual circuits of a higher bandwidth than the minimum supported by the command are torn down as necessary.
On a Cisco 7200 or 7500 series router, the following example specifies that two links in IMA group 2 must be operational for the group to remain in service:
interface atm 2/ima2 ima active-links-minimum 2
To set the transmit clock mode for an ATM IMA group, execute the ima clock-mode IMA interface configuration command. If all the links in the group share a clock source, use the common keyword. If all the links use different clock sources, use the independent clock source keyword. The no form of the command removes the current configuration.
ima clock-mode {common [<link_number>] | independent}
common | Specifies that transmit clocks for all the links in the group are derived from the same source. |
link_number | When you choose a common clock source, you should also specify the link number that is to provide clocking for the IMA group, called the common link. If the common link fails, the system automatically chooses one of the remaining active links to provide clocking. |
independent | Specifies that the transmit clock source for at least one link in the IMA group is different from the clock source used by the other links. |
The default value is common. If no port is specified, the system automatically chooses an active link to provide clocking.
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
This command controls the clock for the IMA group as a whole. When the independent keyword is set, the clock source ATM interface configuration command is used under each interface to determine clocking individually. When the common keyword is set, the clock source ATM interface configuration command for the common link determines clocking for all the links in the group.
Because the system automatically chooses a replacement for the common link when it fails, any link in an IMA group potentially can provide the recovered transmit clock. For this reason, even when the common keyword is set with a specific link stipulated by the port value, it is a good idea to make sure that the clock source is configured correctly on each interface in the IMA group, using the ATM interface configuration clock-source command.
On a Cisco 7200 or 7500 series router, the following example specifies that the links in IMA group 2 use a common clock source on link 0:
interface atm 1/ima2 ima clock-mode common 0
| Command | Description |
clock-source {line | internal} | This ATM interface configuration command sets the clock source for a link. line specifies that the link uses the recovered clock from the link and is the default setting. internal specifies that the DS-1 link uses the internal clock. |
show ima interface atm [slot] /ima[group-number] [detail] | This command shows clock source information about an IMA group as a whole and about the links included in it. |
To specify a maximum differential timing delay among the links in an IMA group, use the ima differential-delay-maximum IMA interface configuration command. If a link delay exceeds the specified maximum, the link is dropped; otherwise, the IMA feature, while multiplexing and demultiplexing, adjusts for differences in delays so that all links in a group are aligned. The no form of the command restores the default setting.
ima differential-delay-maximum msec
no ima differential-delay-maximum msec
msec | Specify a value from 25 to 250, to define the differential delay in milliseconds. |
25 milliseconds
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
This command controls latency in an IMA group by setting a limit on how much latency a slow link can introduce when links are aligned. Setting a high value allows a slow link to continue operating as part of the group, although such a setting means there is more potential for latency when a link is slow. A low setting provides better guaranteed bandwidth on active links and more resiliency than a high setting, although it can mean that the system takes a slow link out of operation.
When a link has been removed from service, it is automatically placed back in service when it meets the delay differential standard.
On a Cisco 7200 or 7500 series router, the following example specifies that the links in IMA group 2 have a maximum differential delay of 50 ms:
interface atm 1/ima2 ima differential-delay-maximum 50
show ima interface atm [slot] /ima[group-number] [detail] | This command shows differential delay information about an IMA group. |
To specify the number of cells in IMA frames, use the ima frame-length command. IMA frames are numbered sequentially and each contains an IMA Control Protocol (ICP) cell at a specific position. The no form of the command removes the current setting and restores the default value.
ima frame-length {32 | 64 | 128 | 256}
no ima frame-length {32 | 64 | 128 | 256}
32 | Specify a value of 32 cells. |
64 | Specify a value of 64 cells. |
128 | Specify a value of 128 cells. |
256 | Specify a value of 256 cells. |
The default value is 128 cells in a frame.
Interface configuration
| Release | Modification |
|---|---|
12.0(5)XE | This command was introduced. |
Frame length can affect performance, because the greater the total number of frames required to communicate a given number of cells, the greater the overhead for header and other control cells. In addition, shorter frame lengths might diminish performance when translated ATM-Frame Relay interworking occurs.
On a Cisco 7200 or 7500 series router, the following example specifies that the links in IMA group 2 have a frame length of 64 cells:
interface atm 1/ima2 ima frame-length 64
To define physical links as IMA group members, execute the ima-group configuration command for each group member. When you first perform the configuration or when you change the group number, the interface is automatically disabled, moved to the new group, and then enabled. The no form of the command removes the port from the group.
ima-group group-number
group-number | Enter an IMA group number from 0 to 3. IMA groups can span multiple ports on a port adapter but cannot span port adapters. |
Enable
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
On a Cisco 7200 or 7500 series router, the following example makes interface 1 on the ATM port adapter in slot 1 a member of IMA group 1:
interface atm 1/1 ima-group 1
| Command | Description |
interface atm slot/port | Configures physical links for ATM on Cisco 7200 series routers and 7500 series routers. |
interface atm slot/ima group-number | Configures an ATM IMA group. You set the various interface parameters for the group as a whole. |
show ima interface atm [slot] /ima[group-number] [detail] | This command shows the links that are included in an IMA group---use the detail keyword. |
shutdown | Disables or enables (no form) the interface without deleting the configuration. |
To specify an interface and a test pattern, execute the ima test IMA configuration command. To verify link connectivity, the pattern is sent from the specified link and looped back from the receiving end in the multiplexing-demultiplexing process. This can help troubleshoot physical link connectivity or configuration problems at the remote end. All links in the group are tested, and testing is continuous. An ICP cell in each frame identifies the pattern. The no form of the command returns to default settings.
ima test [link port] [pattern pattern-id]
no ima test [link port] [pattern pattern-id]
port | (Optional) The identifier for the interface (as in slot/port) where the physical link is located. |
pattern-id | (Optional) A value from 0 to 255, identifying a pattern to be sent to the far end of the link. |
There is no default for the port value. The default value for pattern-id is 0x6A (106).
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
When a link is not transmitting or receiving a pattern correctly, the command reports the link number where the problem exists.
On a Cisco 7200 or 7500 series router, the following example configures link 4 to send test pattern 56.
interface atm 1/ima 2 ima test link 4 pattern 56
| Command | Description |
show ima interface atm [slot] /ima[group-number] [detail] | This command shows the currently configured test link and test pattern for an IMA group. |
To configure an ATM IMA group and enter interface configuration mode, use the interface atm ima global configuration command. If the group does not exist when the command is issued, the command automatically creates the group.
interface atm slot/ima<group-number>
slot | This setting specifies the slot location of the ATM IMA port adapter. The values range from 1 to 5 depending upon the router. |
group-number | Enter an IMA group number from 0 to 3. You can create up to four groups. |
By default there are no IMA groups, only individual ATM links.
Global configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
When a port is configured for IMA functionality, it no longer operates as an individual ATM link.
Specifying ATM links as members of a group using the ima group interface command does not enable the group. You must use the interface atm slot/ima<group-number> command to create the group.
On a Cisco 7200 or 7500 series router, the following example configures IMA group 0 on the port adapter in Slot 1:
interface atm 1/ima0
ip address 255.255.255.0
| Command | Description |
ima-group group-number | Configures the physical links as IMA group members; execute this interface configuration command for each physical link that you include in an IMA group. |
interface atm slot//port | Configures physical links for ATM. |
show ima interface atm [slot] /ima[group-number] [detail] | This command displays general and detailed information about IMA groups and the links they include. |
shutdown | Disables or enables (no form) the interface without deleting the configuration. |
To set a cable length longer than 655 feet for a DS-1 link, use the lbo long interface configuration command on the interface for a T1 link. The no form of this command deletes the lbo long value.
lbo {long {gain26 | gain36} {-15db | -22.5db | -7.5db | 0db} | short {133 | 266 | 399 | 533 | 655}}
gain26 | Specifies the decibel pulse gain at 26. This is the default pulse gain. |
gain36 | Specifies the decibel pulse gain at 36. |
-15db | Specifies the decibel pulse rate at -15 decibels. |
-22.5db | Specifies the decibel pulse rate at -22.5 decibels. |
-7.5db | Specifies the decibel pulse rate at -7.5 decibels. |
0db | Specifies the decibel pulse rate at 0 decibels. This is the default. |
133 | Specifies a cable length from 0 to 133 feet. |
266 | Specifies a cable length from 133 to 266 feet. |
399 | Specifies a cable length from 266 to 399 feet. |
533 | Specifies a cable length from 399 to 533 feet. |
655 | Specifies a cable length from 533 to 655 feet. |
Gain 26 and 0db
Interface configuration
| Release | Modification |
|---|---|
11.3 MA | This command was introduced as a Cisco MC3810 controller configuration command. |
12.0(5)XE | The command was introduced as an ATM interface command. |
This command is supported on T1 long-haul links only.
Each T1 port can operate in long haul or short haul mode. In long haul mode the user must specify the gain and the line build out. In short haul mode, the user must specify the cable length in feet.
The transmit attenuation value is best obtained by experimentation. If the signal received by the far-end equipment is too strong, reduce the transmit level by entering additional attenuation.
On a Cisco 7200 or 7500 series router, the following example specifies a pulse gain of 36 and a decibel pulse rate of -7.5 decibels:
interface atm 1/2 lbo long gain36 -7.5db
To loop packets back to the interface for testing, enter the loopback interface configuration command with or without an optional keyword. The no form of the command removes the loopback.
loopback {diagnostic | local {payload | line} | remote {iboc | esf {payload | line}}}diagnostic | Loops the outgoing transmit signal back to the receive signal |
line | Places the interface into external loopback mode at the line. |
local | Places the interface into local loopback mode. |
payload | Places the interface into external loopback mode at the payload level. |
remote | Keeps the local end of the connection in remote loopback mode. |
iboc | Sends an in band bit oriented code to the far-end to cause it to go into line loopback. |
esf | Specifies extended super frame as the T1 or E1 frame type. |
No loopback.
Interface configuration
| Release | Modification |
|---|---|
11.1 | This command was introduced as a controller configuration command for the Cisco MC3810. |
12.0(5)XE | The command was introduced as an ATM interface configuration command for the Cisco 7200 and 7500 series. |
You can use a loopback test on lines to detect and distinguish equipment malfunctions caused either by line and Channel Service Unit/Digital Service Unit (CSU/DSU) or by the interface. If correct data transmission is not possible when an interface is in loopback mode, the interface is the source of the problem.
The local loopback does not generate any packets automatically. Instead, the ping command is used.
On a Cisco 7200 or 7500 series router, the following example sets up local loopback diagnostics:
interface atm 1/0 loopback local line
To set the E1 national bit, enter the national reserve interface configuration command. To return to the default E1 national bit, use the no form of this command.
national reserve <0-1><0-1><0-1><0-1><0-1><0-1>This command has no arguments or keywords.
111111
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
This command applies only for E1. This command not only sets national reserve bits but also interantional bit as well. The leftmost digit represents the international bit. All six digits must be present for the pattern to be valid.
On a Cisco 7500 series router, the following example sets the national bit on interface 1 on the port adapter in slot 0 to no scrambling:
interface atm1/0 national reserve 011011
Scrambling improves data reliability by randomizing the ATM cell payload frames to avoid continuous non-variable bit patterns and improve the efficiency of ATM's cell delineation algorithms. The no form disables scrambling.
scrambling cell-payloadThis command has no arguments or keywords.
No scrambling .
Interface configuration
| Release | Modification |
12.0(5)XE | This command was first introduced. |
Normally, you do not issue the scrambling-payload command explicitly, because the default value is sufficient. On T1 or E1 links, the default B8ZS line encoding normally assures sufficient reliability.
The scrambling setting must match that of the far end.
On a Cisco 7200 or 7500 series router, the following example sets the link on interface 1 on the port adapter in slot 0 to no scrambling:
interface atm0/1 no scrambling cell-payload
Use the privileged EXEC show controllers command to see information about an IMA group. Important information is shown in bold.
show controllers [atm slot/port-adapter/port] (physical port hardware information) (for the Cisco 7500 series)
slot/port-adapter/port | [Optional] This setting specifies the slot location and port number of the ATM IMA port adapter. The values range from 1 to 5 depending upon the router. |
group-number | Enter an IMA group number from 0 to 3. Do not insert a space between ima and the number. |
No default behavior or values.
Privileged EXEC
| Release | Modification |
12.0(5)XE | This command was first introduced. |
Use this command to monitor and diagnose ATM IMA links and groups.
On a Cisco 7200 or 7500 series router, the following example displays detailed information about IMA group hardware related information. It includes the configuration of IMA hardware and IMA Alarms.
Router#show controller atm 1/ima0
Interface ATM1/ima0 is up
Hardware is IMA PA - DS1 (1Mbps)
Lane client mac address is 0090.b1f8.e41c
Framer is PMC PM7344, SAR is LSI ATMIZER II
Firmware rev:G102, ATMIZER II rev:3
idb=0x61DE9F10, ds=0x6185C0A0, vc=0x6187D3C0, pa=0x6184AF40
slot 1, unit 9, subunit 0, fci_type 0x00BA, ticks 701720
400 rx buffers:size=512, encap=64, trailer=28, magic=4
Curr Stats:
rx_cell_lost=0, rx_no_buffer=0, rx_crc_10=0
rx_cell_len=0, rx_no_vcd=0, rx_cell_throttle=0, tx_aci_err=0
Rx Free Ring status:
base=0x3CFF0040, size=1024, write=320
Rx Compl Ring status:
base=0x338DCE40, size=2048, read=1275
Tx Ring status:
base=0x3CFE8040, size=8192, write=700
Tx Compl Ring status:
base=0x338E0E80, size=2048, read=344
BFD Cache status:
base=0x61878340, size=5120, read=5107
Rx Cache status:
base=0x61863D80, size=16, write=11
Tx Shadow status:
base=0x618641C0, size=8192, read=687, write=700
Control data:
rx_max_spins=12, max_tx_count=25, tx_count=13
rx_threshold=267, rx_count=11, tx_threshold=3840
tx bfd write indx=0x27, rx_pool_info=0x61863E20
Control data base address:
rx_buf_base = 0x038A15A0 rx_p_base = 0x6185CB40
rx_pak = 0x61863AF0 cmd = 0x6185C320
device_base = 0x3C800000 ima_pa_stats = 0x038E2FA0
sdram_base = 0x3CE00000 pa_cmd_buf = 0x3CFFFC00
vcd_base[0] = 0x3CE3C100 vcd_base[1] = 0x3CE1C000
chip_dump = 0x038E3D7C dpram_base = 0x3CD80000
sar_buf_base[0] = 0x3CE4C000 sar_buf_base[1] = 0x3CF22000
bfd_base[0] = 0x3CFD4000 bfd_base[1] = 0x3CFC0000
acd_base[0] = 0x3CE88360 acd_base[1] = 0x3CE5C200
pci_atm_stats = 0x038E2EC0
ATM1/ima0 is up
hwgrp number = 1
grp tx up reg= 0x5, grp rx up reg= 0x3, rx dcb reg= 0xD4 0x4, tx links grp reg=
0x3, scci reg= 0x3C, ima id reg= 0x0, group status reg= 0xA2, tx timing reg= 0x
20, tx test reg= 0x21, tx test pattern reg= 0x41, rx test pattern reg= 0x42, icp
cell link info reg= 0xFC, icp cell link info reg= 0xFC, icp cell link info r
eg= 0x0, icp cell link info reg= 0x0, icp cell link info reg= 0x0, icp cell li
nk info reg= 0x0, icp cell link info reg= 0x0, icp cell link info reg= 0x0,
| Command | Description |
show ima interface atm [slot] /ima[group-number] [detail] | This command displays general and detailed information about IMA groups and the links they include. |
The show ima interface command provides information about all configured IMA groups or a specific group.
show ima interface [atm slot/port-adapter/slot] [detail](for the Cisco 7500 series)
atm slot/port | (Optional) ATM slot number and port number. |
slot/port-adapter/slot | This setting specifies the slot location of the ATM IMA port adapter. The values range from 1 to 5 depending upon the router. |
ima group-number | Enter an IMA group number from 0 to 3. Do not insert a space between ima and the number. |
detail | [Optional] To obtain detailed information, use this keyword. |
No default behavior or values.
Privileged EXEC
| Release | Modification |
12.0(5)XE | This command was first introduced. |
Use this command to monitor the status of IMA group links.
On a Cisco 7200 or 7500 series router, the following example displays detailed information about IMA group 0 on ATM interface 2. If you do not enter the detail keyword, the information beginning with "Detailed group Information:" does not appear.
Router# show ima interface atm 2/ima0 detail
ATM4/1/ima0 is administratively down
Group Index = 1
State: NearEnd = notConfigured, FarEnd = notConfigured
FailureStatus = otherFailure
IMA Group Current Configuration:
MinNumTxLinks = 1 MinNumRxLinks = 1
DiffDelayMax = 25 FrameLength = 128
NeTxClkMode = common(ctc) CTC_Reference_Link = ATM2/0
TestLink = 0 Testpattern = Not Specified
TestProcStatus = disabled GTSM change timestamp =
000000000000
Detailed group Information:
Symmetry = symmetricOperation
FeTxClkMode = common(ctc)
RxFrameLength = 0
TxTimingRefLink = 255 RxTimingRefLink = 255
TxImaId = 0 RxImaId = 255
NumTxCfgLinks = 2 NumRxCfgLinks = 2
NumTxActLinks = 0 NumRxActLinks = 0
LeastDelayLink = 255 DiffDelayMaxObs = 0
Group counters:
NeNumFailures = 0 FeNumFailures = 0
UnAvailSecs = 0 RunningSecs = 0
IMA Detailed Link Information:
ATM4/0 is administratively down
RowStatus = active
IfIndex = 3 GroupIndex = 1
State:
NeTx = notInGroup NeRx = notInGroup
FeTx = notInGroup FeRx = notInGroup
FailureStatus:
NeRx = imaLinkFailure FeRx = imaLinkFailure
TxLid = 0 RxLid = 255
RxTestPattern = 255 TestProcStatus = disabled
RelativeDelay = 255
IMA Link counters :
ImaViolations = 0
NeSevErroredSecs = 0 FeSevErroredSecs = 0
NeUnavailSecs = 0 FeUnAvailSecs = 0
NeTxUnusableSecs = 0 NeRxUnUsableSecs = 0
FeTxUnusableSecs = 0 FeRxUnusableSecs = 0
NeTxNumFailures = 0 NeRxNumFailures = 0
FeTxNumFailures = 0 FeRxNumFailures = 0
ATM4/1 is administratively down
RowStatus = active
IfIndex = 4 GroupIndex = 1
State:
NeTx = notInGroup NeRx = notInGroup
FeTx = notInGroup FeRx = notInGroup
FailureStatus:
NeRx = imaLinkFailure FeRx = imaLinkFailure
TxLid = 1 RxLid = 255
RxTestPattern = 255 TestProcStatus = disabled
RelativeDelay = 255
IMA Link counters :
ImaViolations = 0
NeSevErroredSecs = 0 FeSevErroredSecs = 0
NeUnavailSecs = 0 FeUnAvailSecs = 0
NeTxUnusableSecs = 0 NeRxUnUsableSecs = 0
FeTxUnusableSecs = 0 FeRxUnusableSecs = 0
NeTxNumFailures = 0 NeRxNumFailures = 0
FeTxNumFailures = 0 FeRxNumFailures = 0
| Command | Description |
show controllers [atm slot//ima group-number] | This command displays detailed information about IMA groups and the links they include, as well as about current queues and ATM QoS settings. |
The show ima interface atm command provides information about all configured IMA groups or a specific group.
show ima interface atm [slot] /ima[group-number] [detail]
slot | [Optional] This setting specifies the slot location of the ATM IMA port adapter. The values range from 1 to 5 depending upon the router. |
group-number | Enter an IMA group number from 0 to 3. Do not insert a space between ima and the number. |
detail | [Optional] To obtain detailed information, use this keyword. |
No default behavior or values.
Privileged EXEC
| Release | Modification |
12.0(5)XE | This command was first introduced. |
Use this command to monitor the status of IMA group links.
On a Cisco 7200 or 7500 series router, the following example displays detailed information about IMA group 0 on ATM interface 2. If you do not enter the detail keyword, the information beginning with "Detailed group Information:" does not appear.
Router# show ima interface atm 2/ima0 detail
ATM4/1/ima0 is administratively down
Group Index = 1
State: NearEnd = notConfigured, FarEnd = notConfigured
FailureStatus = otherFailure
IMA Group Current Configuration:
MinNumTxLinks = 1 MinNumRxLinks = 1
DiffDelayMax = 25 FrameLength = 128
NeTxClkMode = common(ctc) CTC_Reference_Link = ATM2/0
TestLink = 0 Testpattern = Not Specified
TestProcStatus = disabled GTSM change timestamp =
000000000000
Detailed group Information:
Symmetry = symmetricOperation
FeTxClkMode = common(ctc)
RxFrameLength = 0
TxTimingRefLink = 255 RxTimingRefLink = 255
TxImaId = 0 RxImaId = 255
NumTxCfgLinks = 2 NumRxCfgLinks = 2
NumTxActLinks = 0 NumRxActLinks = 0
LeastDelayLink = 255 DiffDelayMaxObs = 0
Group counters:
NeNumFailures = 0 FeNumFailures = 0
UnAvailSecs = 0 RunningSecs = 0
IMA Detailed Link Information:
ATM4/0 is administratively down
RowStatus = active
IfIndex = 3 GroupIndex = 1
State:
NeTx = notInGroup NeRx = notInGroup
FeTx = notInGroup FeRx = notInGroup
FailureStatus:
NeRx = imaLinkFailure FeRx = imaLinkFailure
TxLid = 0 RxLid = 255
RxTestPattern = 255 TestProcStatus = disabled
RelativeDelay = 255
IMA Link counters :
ImaViolations = 0
NeSevErroredSecs = 0 FeSevErroredSecs = 0
NeUnavailSecs = 0 FeUnAvailSecs = 0
NeTxUnusableSecs = 0 NeRxUnUsableSecs = 0
FeTxUnusableSecs = 0 FeRxUnusableSecs = 0
NeTxNumFailures = 0 NeRxNumFailures = 0
FeTxNumFailures = 0 FeRxNumFailures = 0
ATM4/1 is administratively down
RowStatus = active
IfIndex = 4 GroupIndex = 1
State:
NeTx = notInGroup NeRx = notInGroup
FeTx = notInGroup FeRx = notInGroup
FailureStatus:
NeRx = imaLinkFailure FeRx = imaLinkFailure
TxLid = 1 RxLid = 255
RxTestPattern = 255 TestProcStatus = disabled
RelativeDelay = 255
IMA Link counters :
ImaViolations = 0
NeSevErroredSecs = 0 FeSevErroredSecs = 0
NeUnavailSecs = 0 FeUnAvailSecs = 0
NeTxUnusableSecs = 0 NeRxUnUsableSecs = 0
FeTxUnusableSecs = 0 FeRxUnusableSecs = 0
NeTxNumFailures = 0 NeRxNumFailures = 0
FeTxNumFailures = 0 FeRxNumFailures = 0
| Command | Description |
show controllers [atm slot//ima group-number] | This command displays detailed information about IMA groups and the links they include, as well as about current queues and ATM QoS settings. |
The yellow command provides information about all configured IMA groups or a specific group. This command is applicable to the T1 IMA port adapter.
yellow {generation | detection}
generation | This setting enables or disables generation of the yellow alarm. |
detection | This setting enables or disables detection of the yellow alarm. |
Yellow alarm generation and detection are disabled.
Configuration mode
| Release | Modification |
12.0(5)XE | This command was first introduced. |
Use this command to generate and detect yellow alarms.
On a Cisco 7500 series router, the following example displays Router(config) # interface atm 3/1/0 Router(config-if)#yellow generation Router(config-if)#yellow detection
| Command | Description |
show controllers [atm slot//ima group-number] | This command displays detailed information about IMA groups and the links they include, as well as about current queues and ATM QoS settings. |
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.
AAL5---ATM adaptation layer 5. One of four AALs recommended by the ITU-T. AAL5 supports connection-oriented VBR services and is used predominantly for the transfer of classical IP over ATM and LANE traffic. AAL5 uses simple and efficient AAL (SEAL) and is the least complex of the current AAL recommendations. It offers low bandwidth overhead and simpler processing requirements in exchange for reduced bandwidth capacity and error-recovery capability.
ABR---available bit rate. QoS class defined by the ATM Forum for ATM networks. ABR is used for connections that do not require timing relationships between source and destination. ABR provides no guarantees in terms of cell loss or delay, providing only best-effort service. Traffic sources adjust their transmission rate in response to information they receive describing the status of the network and its capability to successfully deliver data.
AIS---alarm indication signal. In a T1 transmission, an all-ones signal transmitted in lieu of the normal signal to maintain transmission continuity and to indicate to the receiving terminal that there is a transmission fault that is located either at, or upstream from, the transmitting terminal.
ATM---Asynchronous Transfer Mode. International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media such as E3, SONET, and T3.
B8ZS---binary 8-zero substitution. Line-code type, used on T1 circuits, in which a special code is substituted whenever 8 consecutive zeros are sent over the link. This code is then interpreted at the remote end of the connection. This technique guarantees ones density independent of the data stream.
CPCS---common part convergence sublayer. One of the two sublayers of any AAL. The CPCS is service-independent and is further divided into the CS and the SAR sublayers. The CPCS is responsible for preparing data for transport across the ATM network, including the creation of the 48-byte payload cells that are passed to the ATM layer.
CS---convergence sublayer. One of the two sublayers of the AAL common part convergence sublayer (CPCS), which is responsible for padding and error checking. PDUs passed from the service specific convergence sublayer (SSCS) are appended with an 8-byte trailer (for error checking and other control information) and padded, if necessary, so that the length of the resulting PDU is divisible by 48. These PDUs are then passed to the SAR sublayer of the CPCS for further processing.
ESF---Extended Superframe. Framing type used on T1 circuits that consists of 24 frames of 192 bits each, with the 193rd bit providing timing and other functions. ESF is an enhanced version of SF.
FDL---Facility Data Link. A 4-Kbps channel, provided by the Extended SuperFrame (ESF) T1 framing format. The FDL performs outside the payload capacity and allows a service provider to check error statistics on terminating equipment, without intrusion.
ICP---IMA control protocol
ICMP---Internet Control Message Protocol. Network layer Internet protocol that reports errors and provides other information relevant to IP packet processing. Documented in RFC 792.
ILMI---Interim Local Management Interface. Specification developed by the ATM Forum for incorporating network-management capabilities into the ATM User-Network Interface (UNI).
IMA---Inverse Multiplexing for ATM, a standard protocol defined by the ATM Forum in 1997.
IMA group---Physical links grouped to form a higher-bandwidth logical link whose rate is approximately the sum of the individual link rates.
ISDN---Integrated Services Digital Network. Communication protocol, offered by telephone companies, that permits telephone networks to carry data, voice, and other source traffic.
OAM cell---Operation, Administration, and Maintenance cell. ATM Forum specification for cells used to monitor virtual circuits. OAM cells provide a virtual circuit-level loopback in which a router responds to the cells, demonstrating that the circuit is up, and the router is operational.
PDU---protocol data unit.
POTS---Plain Old Telephone Service. Basic telephone service supplying standard single-line telephones, telephone lines, and access to the public switched telephone network.
PVC---permanent virtual circuit. Virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and tear down in situations where certain virtual circuits must exist all the time. In ATM terminology, called a permanent virtual connection.
QoS---quality of service. Measure of performance for a transmission system that reflects its transmission quality and service availability.
SAR---segmentation and reassembly. One of the two sublayers of the AAL CPCS, responsible for dividing (at the source) and reassembling (at the destination) the PDUs passed from the CS. The SAR sublayer takes the PDUs processed by the CS and, after dividing them into 48-byte pieces of payload data, passes them to the ATM layer for further processing.
SF---Super Frame. Common framing type used on T1 circuits. SF consists of 12 frames of 192 bits each, with the 193rd bit providing error checking and other functions. SF is superseded by ESF, but is still widely used. Also called D4 framing.
SONET---Synchronous Optical Network. High-speed (up to 2.5 Gbps) synchronous network specification developed by Bellcore and designed to run on optical fiber. STS-1 is the basic building block of SONET.
SSCS---service specific convergence sublayer. One of the two sublayers of any AAL. SSCS, which is service dependent, offers assured data transmission. The SSCS can be null as well, in classical IP over ATM or LAN emulation implementations.
SVC---switched virtual circuit. Virtual circuit that is dynamically established on demand and is torn down when transmission is complete. SVCs are used in situations where data transmission is sporadic. Called a switched virtual connection in ATM terminology.
T3---Digital WAN carrier facility. T3 transmits DS-3-formatted data at 44.736 Mbps through the telephone switching network.
UBR---unspecified bit rate. Quality of Service (QoS) class defined by the ATM Forum for ATM networks. UBR allows any amount of data up to a specified maximum to be sent across the network, but there are no guarantees in terms of cell loss rate and delay.
UNI---User-Network Interface. ATM Forum specification that defines an interoperability standard for the interface between ATM-based products (a router or an ATM switch) located in a private network and the ATM switches located within the public carrier networks. Also used to describe similar connections in Frame Relay networks.
VBR---variable bit rate. QoS class defined by the ATM Forum for ATM networks. VBR is subdivided into a real time (RT) class and non-real time (NRT) class. VBR (RT) is used for connections in which there is a fixed timing relationship between samples. VBR (NRT) is used for connections in which there is no fixed timing relationship between samples, but that still need a guaranteed QoS.
VC---virtual circuit. Logical circuit created to ensure reliable communication between two network devices. A virtual circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or switched (SVC). Virtual circuits are used in Frame Relay and X.25. In ATM, a virtual circuit is called a virtual channel.
This document describes the Cisco IOS Inverse Multiplexing for ATM (IMA) features available with the introduction of Multiport T1/E1 ATM port adapters with IMA for the Cisco 7200 series routers and Cisco 7500 series routers.
This document includes the following sections:
The inverse multiplexing over ATM (IMA) port adapter is a single-width port adapter that allows Cisco 7200 series, and Cisco 7500 series routers to support inverse multiplexing over ATM. These port adapters allow WAN uplinks at speeds ranging from 1.544 Mbps to 12.288 Mbps for T1 or E1 connections. (For details, see the "Bandwidth Considerations" section on page 4.)
With Cisco's scalable ATM IMA solution, network designers and managers can deploy only the bandwidth they need, using multiple T1 or E1 connections instead of more expensive T3 or OC-3 lines to bridge LANs and ATM WAN applications. Enterprises and branch offices can aggregate traffic from multiple lower-bandwidth physical transmission media, such as T1 or E1 pipes, to transmit voice and data at high-bandwidth connection speeds.
Posted: Wed May 3 10:39:00 PDT 2000
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