Multicast on a segment - PIM DR, IGMP Querying Router, PIM

From: Antonio Soares (amsoares@netcabo.pt)
Date: Mon Jul 16 2007 - 14:26:33 ART


Hello group,

1) We know that the PIM router with the HIGHEST IP Address will be elected
the PIM DR on a particular segment (we can change this with the "ip pim
dr-priority" command).

2) We also know that the PIM router with the LOWEST IP Address will be
elected the IGMPv2 Querying Router on a particular segment. Is there any way
to change this default behaviour ?

3) Finally, we know that if the AD and Metric is the same for a particular
(S,G) pair, the Assert mechanism will dictate that the Router with the
HIGHEST IP Address will be the Forwarder on a particular segment. Once
again, is it possible to change this default behaviour ?

Bellow an example of a router which is a DR but not an IGMPv2 Querier.

++++++++++++++++++++
R6#sh ip igmp interface f0/1
FastEthernet0/1 is up, line protocol is up
  Internet address is 100.1.64.6/24
  IGMP is enabled on interface
  Current IGMP host version is 2
  Current IGMP router version is 2
  IGMP query interval is 60 seconds
  IGMP 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 not set
  IGMP activity: 0 joins, 0 leaves
  Multicast routing is enabled on interface
  Multicast TTL threshold is 0
  Multicast designated router (DR) is 100.1.64.6 (this system) <-----
  IGMP querying router is 100.1.64.4 <-----
  No multicast groups joined by this system
R6#
++++++++++++++++++++

Thanks,
Antonio



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