[Xorp-users] Change in RP vs change in next-hop for RP

[Vikram KAUL]

Hi,

  Just wanted to verify the current implementation in XORP regarding 
events that might occur when a group G is active and data is being 
forwarded for that group. The (*,G) and (*,*,RP) state will exist in the 
router.

  When the next-hop to the RP changes, the Upstream (*,*,RP) Join/Prune 
state machine which keeps the last RPF Neighbor towards that same RP, is 
triggered into sending a new Join(*,*,RP) to the new upstream neighbor and 
a Prune(*,*,RP) to the old upstream neighbor.

This I can see in  pim_mre_rpf.cc
PimMre::recompute_nbr_mrib_next_hop_rp_rp_changed()

  However, I was not able to find what happenes when the RP itself changes 
when the group is active. The specs talk aboutthe "RP changed" impacting 
only the  "Per-(S,G) register state machine at the DR". (Look at the 
tabular form, last column, Section 4.4.1). The register tunnels get 
updated via an "update register channel" procedure when the state is Join.

  Specifically, where are the conditions addressed when the RP itself 
changes for the (*,G) and (*,*,RP) state. Not the next hop changes, but 
the RP changes when the group is active. Is the protocol designed to 
handle this ?

  Any pointers to the XORP code and/or the specs will be appreciated

regards..
Vikram