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Table Of Contents
Monitoring and Troubleshooting
Monitoring and Troubleshooting
This chapter presents the following major topics:
Troubleshooting Multicast
Several commands can be used to troubleshoot IP multicast (IPmc) networks:
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mstat
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Note
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00804453e7.htmlmstat
Use this command to see the IPmc path in ASCII graphic format. It traces the path between any two points in the network, shows drops and duplicates, time to live (TTL) thresholds, and delays at each node in the network. It is very useful when you need to locate congestion points in the network, or focus on a router with high drop/duplicate counts. Duplicates are indicated in the output as "negative" drops.
mrinfo
Use this command to see IPmc neighbor router information, router capabilities and code version, IPmc interface information, TTL thresholds, metrics, protocol, and status. It is useful when you need to verify IPmc neighbors, confirm that bidirectional neighbor adjacency exists, and verify that tunnels are up in both directions.
mtrace
Use this command to see the IPmc path from the source to the receive. It traces the path between points in the networks, showing TTL thresholds and delay at each node. When troubleshooting, use this command to find where IPmc traffic flow stops, to verify the path of IPmc traffic, and to identify suboptimal paths.
Show Commands
Show commands are presented for the following categories:
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show ip
The following commands provide useful information about IP routing:
Note
http://www.cisco.com/en/US/products/sw/iosswrel/ps5187/products_command_reference_chapter09186a008017cf20.htmlshow ip igmp groups
Use this command to see which IPmc groups are directly connected to the router, and which are learned by means of Internet Group Management Protocol (IGMP). You can use this command to verify that a source or receiver has actually joined the target group on the router interface. The "Last Reporter" column shows only one IGMP host, which indicates that it has sent either an unsolicited IGMP Join or IGMP Report in response to a IGMP Query from the Protocol Independent Multicast (PIM) router for that particular group. You should only see one "Last Reporter" per Group Address.
show ip igmp interface
Use this command to display IPmc-related information about an interface, and to verify that IGMP is enabled, that the correct version is running, the timers, Time To Live (TTL) threshold value, and that IGMP querier router are properly set. IGMP does not need to be configured on an interface. It is enabled by default when you configure ip pim dense-mode | sparse-mode | sparse-dense-mode.
show ip pim neighbor
Use this command to list the PIM neighbors discovered by the Cisco IOS.
show ip pim interface
Use this command to display information about interfaces configured for PIM. In addition, you can use it to verify that the correct PIM mode (dense or sparse) is configured on the interface, the neighbor count is correct, and the designated router (DR) is correct (which is critical for PIM sparse mode). Multi-access segments (such as Ethernet, Token Ring, FDDI) elect a DR based on highest IP address. Point-to-Point links do not display DR information.
show ip mroute summary
Use this command to display the summarized contents of the IPmc routing table. You can also use it to verify the active IPmc group(s) and which IPmc senders are active by looking at the timers and flags.
show ip mroute
Use this command to display the full contents of the IPmc routing table. When you troubleshoot, use this command to verify the following:
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show ip mroute active
Use this command to display the active traffic sources and groups above the threshold. When you troubleshoot, use it to verify active source groups, the traffic rate for each source, group (S,G) pair [you must have switched to Shortest Path Tree (SPT)], and to check if the target group IPmc traffic is being received. If the traffic is not being received, look for active traffic starting from the source towards the receiver.
show ip rpf
Use this command to display how IPmc routing does Reverse Path Forwarding (RPF). When you troubleshoot, use it to verify that the RPF information is correct. If it is not, check the unicast routing table for the source address. Also use the ping and trace commands on the source address to verify that unicast routing works. You may need to use Distance Vector Multicast Routing Protocol (DVMRP) routes or static mroutes to fix any unicast-multicast inconsistencies.
show ip mroute count
Use this command to verify that IPmc traffic is received, and to check on its flow rates and drops. If no traffic is received, work from the source to the receiver until you find where the traffic stops. You can also use this command to verify that traffic is being forwarded. If it is not, use the show ip mroute command to look for "Null Outgoing interface list" and RPF failures.
show ip pim rp mapping
Use this command to check the RP assignment by IPmc group range, and to verify that the source of RP learning (static or auto-RP) and the mapping are correct. If you find an error, check the local router configuration or auto-RP configuration.
show mls
The following command provides useful information about Multi-Layer Switching (MLS).
show mls rate-limit
Use this command to see an exhaustive list of special-case hardware rate limiters (HWRLs). (See Hardware Rate Limiters.) The following output shows all HWRLs available as of Cisco IOS Release 12.2(18)SXE.
Router# show mls rate-limitLoad for five secs: 1%/0%; one minute: 1%; five minutes: 0%Time source is NTP, 17:57:48.508 PST Mon Mar 28 2005Sharing Codes: S - static, D - dynamicCodes dynamic sharing: H - owner (head) of the group, g - guest of the groupRate Limiter Type Status Packets/s Burst Sharing--------------------- ---------- --------- ----- -------MCAST NON RPF Off - - -MCAST DFLT ADJ On 100000 100 Not sharingMCAST DIRECT CON Off - - -ACL BRIDGED IN Off - - -ACL BRIDGED OUT Off - - -IP FEATURES Off - - -ACL VACL LOG On 2000 1 Not sharingCEF RECEIVE Off - - -CEF GLEAN Off - - -MCAST PARTIAL SC On 100000 100 Not sharingIP RPF FAILURE On 100 10 Group:0 STTL FAILURE Off - - -ICMP UNREAC. NO-ROUTE On 100 10 Group:0 SICMP UNREAC. ACL-DROP On 100 10 Group:0 SICMP REDIRECT Off - - -MTU FAILURE Off - - -MCAST IP OPTION Off - - -UCAST IP OPTION Off - - -LAYER_2 PDU Off - - -LAYER_2 PT Off - - -IP ERRORS On 100 10 Group:0 SCAPTURE PKT Off - - -MCAST IGMP Off - - -MCAST IPv6 DIRECT CON Off - - -MCAST IPv6 ROUTE CNTL Off - - -MCAST IPv6 *G M BRIDG Off - - -MCAST IPv6 SG BRIDGE Off - - -MCAST IPv6 DFLT DROP Off - - -MCAST IPv6 SECOND. DR Off - - -MCAST IPv6 *G BRIDGE Off - - -show mls cef adjacency
show mls statistics
Debug Commands
The following debug commands provide useful information:
Note
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a0080087363.htmldebug ip pim
Use this command to display PIM packets received and sent, and to display PIM-related events.
debug ip mpacket
Use this command to display IP multicast packets received and sent,
debug ip mrouting
Use this command to display changes to the IP multicast routing table.
Viewing HWRL Counters
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Although Cisco IOS does not currently have a summarized CLI output of hardware rate limiter (HWRL) counters, it is possible to monitor some of the more interesting ones through module-specific commands. HWRLs are implemented as a series of special Cisco Express Forwarding (CEF) adjacencies, which can be seen with the show mls cef adjacency special command. The output below has been reduced to the more interesting HWRL adjacencies. Note that the limiter type is shown in parentheses for each index.
Router> show mls cef adjacency specialIndex: 0 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 1format: MULTICAST, flags: 0x2000000C00 (mcast_fib_fail)met2: 0, met3: 0packets: 0, bytes: 0Index: 3 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 0format: MULTICAST, flags: 0x2000000800 (mcast_fib_rpf_fail)met2: 0, met3: 0packets: 0, bytes: 0Index: 5 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 1format: MULTICAST, flags: 0x2000000C00 (mcast_dir_conn)met2: 0, met3: 0packets: 0, bytes: 0HWRL counters for each distributed forwarding card (DFC) can be seen by issuing the show mls cef adjacency entry command for each module. If no module is specified then the counters are shown for the policy feature card (PFC). For example, to see counters for the FIB-Miss HWRL (Index 0 from the above output) in a system that has DFC-based modules in slots 1 and 4, issue the commands as shown below. The first command below (without the module subcommand) shows the counters from the PFC3 on the Sup720. The counters from this command show traffic limited on cards that do not have DFC3 submodules.
Router> show mls cef adjacency entry 0Index: 0 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 1packets: 0, bytes: 0
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Router> show mls cef adjacency entry 0 module 1Index: 0 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 1packets: 656, bytes: 891424Router> show mls cef adjacency entry 0 module 4Index: 0 smac: 0000.0000.0000, dmac: 0000.0000.0000mtu: 9234, vlan: 0, dindex: 0x0, l3rw_vld: 1packets: 5004164, bytes: 6775638056These counters are not currently accessible by means of SNMP.
TTL and MTU failures can be seen in the output of the show mls statistics command, as shown below.
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Router# show mls statistics<---snip--->
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ErrorsMAC/IP length inconsistencies : 0Short IP packets received : 0IP header checksum errors : 0TTL failures : 721386MTU failures : 0<---snip--->
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ErrorsMAC/IP length inconsistencies : 0Short IP packets received : 0IP header checksum errors : 0TTL failures : 0MTU failures : 0Total packets L3 Switched by all Modules: 2733893197353 @ 3651668 pps
Posted: Tue Mar 28 07:45:09 PST 2006
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