[Xorp-hackers] PIM-SM4: Cand-RP and Cand-BSR Inconsistency

[Pavlin Radoslavov]

> > I'm playing around with pimsm4 and found a strange behavior that seems to be a bug.
> > 
> > To reproduce it, first add a cand-rp for any group-prefix and commit. Then, add a cand-bsr for the same group-prefix. When trying to commit I got the following error:
> > 
> > 102 Command failed Cannot add configure BSR with vif eth0 address 10.1.3.11 for zone 224.0.0.0/4(non-scoped): already have scope zone 224.0.0.0/4(non-scoped)
> > 
> > =================================================
> > samuellucas at erdinger# set protocols pimsm4 bootstrap cand-rp group-prefix 224.0.0.0/4 cand-rp-by-vif-name eth0
> > [edit]
> > samuellucas at erdinger# commit
> > OK
> > [edit]
> > samuellucas at erdinger# set protocols pimsm4 bootstrap cand-bsr scope-zone 224.0.0.0/4 cand-bsr-by-vif-name eth0
> > [edit]
> > samuellucas at erdinger# commit
> > Commit Failed
> > 102 Command failed Cannot add configure BSR with vif eth0 address 10.1.3.11 for zone 224.0.0.0/4(non-scoped): already have scope zone 224.0.0.0/4(non-scoped)[edit]
> > samuellucas at erdinger# 
> > ==================================================

================
> I need to double-check with the PIM BSR spec, but I think that
> 224.0.0.0/4 has special meaning (it is the "global" zone) and cannot
> be configured as a scoped zone.
> Hence, the behavior is correct, though the error could be more user
> friendly.
================

Please ignore my statement above, because it is complete nonsense
(I was in a hurry and overlooked a number of things).

Yes, I think what you see is a bug.

> > In the code I found that PimNode::add_config_cand_rp adds a BSR zone when adding the RP and add_config_cand_bsr fails when finds this added zone. Also, this zone is not visible in the configuration tree (otherwise xorpsh/rtrmgr would have handled this as a modification in a existing cand-bsr, which works fine).
> > 
> > I'm wondering what would be the best way to handle this. 
> > There are a few options: We can replace the automatically created zone with the user provided one, we can report the zone to rtrmgr/xorpsh or we can reuse the created zone and merge the changes, if possible.

The second one is not really an option, because we never propagate
state back to the rtrmgr/xorpsh.
I think the correct behavior is the third one: reuse the created
zone and merge the changes (if possible).
The first one (replace the automatically created zone with the user
provided one) might result in losing the Cand-RP state, which we
definitely want to avoid.

> > What do you recommend?
> > 
> > 
> > BTW, after writing a patch how do I submit it? Just mail it to this list?

Please open a Bugzilla entry about the issue and add te patch to
that entry.

Thanks,
Pavlin