Multicast - IGMP Filtering

Overview

Receivers notify upstream multicast routers their need to join a multicast group by sending igmp membership report messages to the all routers multicast group 224.0.0.2. The report contains the group address that the receive wishes to receive multicast traffic from. In some instances controlling what groups a receiver can join may be advantageous. In multicast there are two methods to control IGMP membership report joins first is the ip multicast boundary command already discussed in another lab controls IGMP and multicast traffic, and ip igmp access-group [acl] which is the topic of this lab which just controls IGMP membership report messages. You can apply this command either on a global basis or on an interface level. Additionally you can also limit the number of IGMP joins or mstates with the command ip igmp limit [#].

Concepts tested

• Controlling IGMP membership reports
• Configuring PIM SM
• Controlling mstate limits

Topology

Lab Tasks

• Configure PIM SM on all paths from R1 to R5
• Configure R1 as the BSR and RP candidate
• Configure R4 so that it is only allowed to join groups in the range 224.0.0.0 /5
• Also limit the number of mstates that can be created for joins to R4's g2/0 interface to a maximum of 5

GNS3 configuration file, requires IOS v15 for the 7200 router: Link


Solution


R1(config)#ip multicast-routing
R1(config)#int g0/0
R1(config-if)#ip pim sparse-mode
R1(config-if)#exit
R1(config)#int loopback 0
R1(config-if)#ip pim sparse-mode
R1(config-if)#exit
R1(config)#ip pim bsr-candidate loopback 0
R1(config)#ip pim rp-candidate loopback 0

R2(config)#ip multicast-routing

R2(config)#int g0/0

R2(config-if)#ip pim sparse-mode

R2(config-if)#exit

R2(config)#int g1/0

R2(config-if)#ip pim sparse-mode

R2(config-if)#exit

R3(config)#ip multicast-routing

R3(config)#int g0/0

R3(config-if)#ip pim sparse-mode

R3(config-if)#exit

R3(config)#int g1/0

R3(config-if)#ip pim sparse-mode

R3(config-if)#exit

R4(config)#ip multicast-routing

R4(config)#int g0/0

R4(config-if)#ip pim sparse-mode

R4(config-if)#exit

R4(config)#int g1/0

R4(config-if)#ip pim sparse-mode

R4(config-if)#exit

R4(config)#int g2/0

R4(config-if)#ip pim sparse-mode

R4(config-if)#exit

R4(config)#ip access-list standard IGMP_GROUPS

R4(config-std-nacl)#permit 224.0.0.0 7.255.255.255

R4(config-if)#ip igmp access-group IGMP_GROUPS

R4(config-if)#ip igmp limit 5

R5(config)#ip multicast-routing

R5(config)#int g0/0

R5(config-if)#ip pim sparse-mode

R5(config-if)#exit

Verification

Have R5 attempt to join the groups 224.0.10.1 and 232.0.0.1

R4#debug ip igmp 224.0.10.1

*Dec  4 06:23:35.399: IGMP(0): Received v2 Report on GigabitEthernet2/0 from 120.0.45.5 for 224.0.10.1

*Dec  4 06:23:35.403: IGMP(0): Received Group record for group 224.0.10.1, mode 2 from 120.0.45.5 for 0 sources

*Dec  4 06:23:35.407: IGMP(0): Updating EXCLUDE group timer for 224.0.10.1

*Dec  4 06:23:35.407: IGMP(0): MRT Add/Update GigabitEthernet2/0 for (*,224.0.10.1) by 0

R4#sh ip igmp groups 224.0.10.1

IGMP Connected Group Membership

Group Address    Interface                Uptime    Expires   Last Reporter   Group Accounted

224.0.10.1       GigabitEthernet2/0       00:00:14  00:02:45  120.0.45.5      Ac

R4#debug ip igmp 232.0.10.1

*Dec  4 06:27:03.043: IGMP(0): Received v2 Report on GigabitEthernet2/0 from 120.0.45.5 for 232.0.10.1

*Dec  4 06:27:03.047: IGMP(*): Group 232.0.10.1 access denied on GigabitEthernet2/0

R4#sh ip igmp groups 232.0.10.1

IGMP Connected Group Membership

Group Address    Interface                Uptime    Expires   Last Reporter   Group Accounted

R4#

GigabitEthernet2/0 is up, line protocol is up

  Internet address is 120.0.45.4/24

  IGMP is enabled on interface

  Current IGMP host version is 2

  Current IGMP router version is 2

  IGMP query interval is 60 seconds

  IGMP configured query interval is 60 seconds

  IGMP querier timeout is 120 seconds

  IGMP configured querier timeout is 120 seconds

  IGMP max query response time is 10 seconds

  Last member query count is 2

  Last member query response interval is 1000 ms

  Inbound IGMP access group is IGMP_GROUPS

  IGMP activity: 3 joins, 1 leaves

  Interface IGMP State Limit : 2 active out of 5 max

  Multicast routing is enabled on interface

  Multicast TTL threshold is 0

  Multicast designated router (DR) is 120.0.45.5

  IGMP querying router is 120.0.45.4 (this system)

  No multicast groups joined by this system

Now join 224.0.10.2-5 on R5.

*Dec  4 06:32:46.219: %IGMP-6-IGMP_GROUP_LIMIT: IGMP limit exceeded for group (*, 224.0.10.5) on GigabitEthernet2/0 by host 120.0.45.5

R4#sh ip igmp interface g2/0

GigabitEthernet2/0 is up, line protocol is up

  Internet address is 120.0.45.4/24

  IGMP is enabled on interface

  Current IGMP host version is 2

  Current IGMP router version is 2

  IGMP query interval is 60 seconds

  IGMP configured query interval is 60 seconds

  IGMP querier timeout is 120 seconds

  IGMP configured querier timeout is 120 seconds

  IGMP max query response time is 10 seconds

  Last member query count is 2

  Last member query response interval is 1000 ms

  Inbound IGMP access group is IGMP_GROUPS

  IGMP activity: 6 joins, 1 leaves

  Interface IGMP State Limit : 5 active out of 5 max

  Multicast routing is enabled on interface

  Multicast TTL threshold is 0

  Multicast designated router (DR) is 120.0.45.5

  IGMP querying router is 120.0.45.4 (this system)

  No multicast groups joined by this system