Subject: Re: parallel p2p links

From: Liming Wei <[email-masked]>
Date: Wed, 11 Nov 1998 23:45:56 -0800 (PST)

"ravi>" == Ravi Shekhar <[email-masked]> writes:

>>  A host group member will NOT forward packets, and thus will not be
>> competing to win asserts, nor will it send any PIM packets.
    
ravi>>     I understand that part. And thats why "scheduling to prune"
ravi>> is not required on P2P links (or any LAN which has only 2
ravi>> routers) because there wont be any third router to override the
ravi>> prune.

ravi>>     But there is a second side to the problem, which is
ravi>> choosing a router to forward data for LOGAL GROUP MEMBERSHIPS.

ravi>>     Host group members need to recv the data being sent for
ravi>> that group.  The interest in the group would have been conveyed
ravi>> to both the routers using IGMP membership report.

The local member only has a chance to say IGMP reports/leaves.
PIM will treat it as a leaf LAN and will not interact with it
via PIM mechanism.

ravi>>     Which of the two routers will be chosen to forward the data
ravi>> if both send prunes to each other simultaneously? Either both
ravi>> will discard the prunes thinking there is a local group member
ravi>> and thereby sending two copies of the data OR both will prune
ravi>> leaving the host group member without any data.

If you have a local member inside your box on that p2p interface,
you don't prune.

ravi>>     Assert-winner is one way of electing the router which will
ravi>> forward the data for such hosts.

It is a nasty hack of the protocol.

-Liming

---

From: [email-masked] (Ravi Shekhar)
Date: Thu, 12 Nov 1998 12:30:40 -0500 (EST)

>If you have a local member inside your box on that p2p interface, 
    
    So if both the routers have local members, none of them will send a 
    prune to the other router on that P2P oif.

    Which means two copies of data will be put on the wire.

>It is a nasty hack of the protocol. 
    
    No comments. I will let you and Steve decide that .. ;)

    - Ravi Shekhar.