From: blodwick (blodwick@columbus.rr.com)
Date: Sun Nov 27 2005 - 18:54:23 GMT-3
I have two questions regarding PIM operation. Any help is appreciated.
1. The first question has to do with how PIM sparse-mode, and
bidirectional PIM deal with a joining client within the path between the
DR and the RP. We know initially with sparse-mode there is no issue
because during source registration the packets between the DR and RP are
encapsulated in unicast packets, but we know this does not happen for
long. Once the threshold is hit the RP will initiate an SPT join to the
DR and from then on its multicast. With bidirectional PIM the traffic
starts out as multicast. Therefore if both will be sending multicast
packets up the tree from the DR to the RP we would likely run into an
RPF check issue if clients within the path between the DR and RP had to
join the RP tree.
My suspicion is that somehow PIM tells multicast routers within this
path to only initiate source trees. It must say something like if you
are already receiving multicast traffic from the source, and you receive
a join for that source, do not attempt to create an RP tree.
2. We know that there are two separate instances within PIM sparse-mode
where routers will initiate an SPT.
DR <------- join SPT ------------- RP
We know initially the DR will encapsulate the source multicast packets
in unicast packets before sending them to the RP; then once the RP hits
a threshold it will initiate an SPT back to the DR.
DR <------- join SPT ------------- client servicing / non-RP
We know initially the client servicing / non-RP router will establish an
RPT, but once the incoming traffic hits a threshold it will initiate
an SPT back to the DR.
My question is does the command ip pim spt-threshold establish the
threshold for both situations?
~ Brian L
-- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.362 / Virus Database: 267.13.8/183 - Release Date: 11/25/2005
This archive was generated by hypermail 2.1.4 : Thu Dec 01 2005 - 09:12:08 GMT-3