Dear All,
I strongly recommend
that there should be some transition mechanism between old DR and new DR.
The reason is that even though
the lately booted DR keep the GMP join group membership and already learned source,
The new DR still need time
to reestablish SPT or RPT tree depending whether the group is SM or SSM. Considering
generally deployed PIM scenario, there will be two last-hop routers connecting the
clouds of hosts or layer2 switches. If the link between DR and backup DR is unstable,
there will be data loss and vibration of PIM state maintained on all the routers.
You may say that static group
join may be configured at last-hop DR. But it take some time for new DR to updated
all the downstreams if there are more than 10K level of groups.
So I strongly recommend that
transition mechanism should be considered on the new PIM draft.
One of my suggestions is that,
a new timer DR switch delay timer should be introduced. Before this timer expires,
Old DR won’t give up
the DR responsibility. To avoid the duplicated data, a unique forwarder is elected
between Old DR and New DR
by using assert mechanism.
Request for your comments
Best regards
Su Haiyang
From:
Neeraj Prasad [mailto:neeraj.prasad at gmail.com]
Sent: Tuesday, April 24, 2007 4:50
AM
To: pim at ietf.org
Subject: [pim] Re: pim Digest, Vol
36, Issue 2
1. Interesting
host information is stored in all routers whether DR or non-DR. So at any if a
router becomes DR it will send the Join Information towards RP and the tree
will be maintained. So packets will come to host irrespective who the DR is.
2. It may retain the information or delete it, that is implementation
dependent. The router up the tree will timeout the state, if they do not
receive any JOIN information without taking any action.
Regards,
Neeraj.
On 4/22/07, pim-request at ietf.org
<pim-request at ietf.org > wrote:
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Today's Topics:
1. pim-sm router transitions from DR to non-DR (Binu TN)
----------------------------------------------------------------------
Message: 1
Date: Sat, 21 Apr 2007 09:07:46 -0700 (PDT)
From: Binu TN <tnbinu at yahoo.co.in>
Subject: [pim] pim-sm router transitions from DR to non-DR
To: pim at ietf.org
Message-ID: <223775.16676.qm at web8804.mail.in.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I have a basic doubt in the pim-sm router transition from DR to
non-DR. Let's assume a scenario where a sm router (e.g., RT1) is DR in a LAN
and it has multicast route entry and it is trigerring Join messages to RP (it
is in some other network) as it has some interesting hosts. If another sm
router ( e.g.RT2) with higher IP address comes into the LAN of RT1, as per my
understanding RT2 will become DR and RT1 will become non-DR to that LAN. My
doubts are,
1) whether the multicast route entries that are present in RT1 before entry
of RT2 will be removed?
2) Will RT1 stops trigerring Join messages to RP? Or RT1 will be trigerring
Join messages for existing entries and RT2 will be trigerring for any new
entries?
Please clear my doubts.
Thank you in advance.
Regards,
Binu.
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Thanks and Regards,
Neeraj Prasad
