Subject: Re: Note from Mike Evans about "TRS clarification request"

From: [email-masked] (Dave Finnie)
Date: Tue, 19 Dec 1995 11:14:17 +1100

> B starts the first time with an empty database.  Connects to A without the 
> HPR bit, with RSN = 2.  B is then shutdown such that it sends no TDUs about 
> the TG from B->A changing status.  No one else will change that TG (A only
> changes the reverse TG, and their RSNs are unrelated).  So the network
> still has RSN = 2.  B comes back up and A is the first node it connects
> to, so with the internal TG_UPDATE it sets RSN = 2.  During the initial
> exchange, both A and B send TDUs about B->A with RSN=2, same CV47 info.
> If only CV47s are compared, both A and B are satisfied.

Presumably if A doesn't do checks on "unknown" options, then it won't spot
a difference, but wouldn't B notice that its own resource is recorded
incorrectly in the topology database ? It should therefore send out
a new TDU with RSN=3 and fix the problem.

> I seem to remember the node adding 2 to the received RSN and sending a TDU,
> but it makes more sense to set the RSNs equal if the CVs compare the same.
> Saves a little on net traffic.

Yes, you're probably right - adding 2 makes sense (and equal if the same
also makes sense). It's been a while since I looked at that stuff.

Dave