From: Salau, Yemi (yemi.salau@siemens.com)
Date: Tue Jul 17 2007 - 06:45:56 ART
In response to your question 2, according to the RFC 2236 which
described the IGMPv2 Router State Diagram; the following events can
cause a router to change states between a Querier and Non Querier:
- "query timer expired" occurs when the timer set for query
transmission expires.
- "query received from a router with a lower IP address" occurs when
an IGMP Membership Query is received from a router on the same
network with a lower IP address.
- "other querier present timer expired" occurs when the timer set to
note the presence of another querier with a lower IP address on the
network expires.
There are three actions that may be taken in response to the above
events:
- "start general query timer" for the attached network.
- "start other querier present timer" for the attached network [Other
Querier Present Interval].
- "send general query" on the attached network. The General Query is
sent to the all-systems group (224.0.0.1), and has a Max Response
Time of [Query Response Interval].
So in the light of this, coupled with the fact that there are only 3 ip
igmp query related commands documentated for 12.4, I would say the only
way to get around this will be to:-
1. Either filter off the query messages leaving the Router with lower ip
address, so that the non-Querier will assume the Querier Job, maybe we
could use access-list for this.
2. The other way I'm thinking will be to increase the query-interval on
the lower ip Router to a value of say 12000, and reduce the
query-timeout on the higher ip Router to a value of say 1 second, that
way, the Router with Higher IP address will only wait 1 s before
assuming the post of the Querier, since the Original Querier wouldn't
respond for another 12000 seconds.
Many Thanks
Yemi Salau
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Antonio Soares
Sent: Monday, July 16, 2007 6:27 PM
To: 'Group study'
Subject: Multicast on a segment - PIM DR, IGMP Querying Router, PIM
Forwarder
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
This archive was generated by hypermail 2.1.4 : Sat Aug 18 2007 - 08:17:41 ART