RS/960 upgrade ... status report

Fri May 1 04:30:06 UTC 1992

Bill,
  I agree, and we have debated both whether our recovery from
this is correct according to the spec, and (more importantly in
my view) whether the spec is reasonable in this case. I believe
the BGP RFC says that it is ok to close the connection, but
I would prefer that it just log this problem and pretend that
it did not hear this bogus route. That way the NOC and site
people can take a look at the problem after the fact when
it is noticed that packets are not getting to or from
a particular net, but they will not be forced to look at
the problem right away with the whole AS being disconnected.
We are working on this and will eventually have some
modifications to rcp_routed to deploy.
	Mark


> From:    bmanning at is.rice.edu (William Manning)
> To:      regional-techs at merit.edu
> CC:      mak at merit.edu

> 
> 
> 
> Mark said:
> observed during RS/960 testing. The problem involved some aberrant
> behavior of rcp_routed when a misconfigured regional peer router would
> advertise a route via BGP to an ENSS whose next hop was the ENSS
> itself. The old rcp_routed could go into a loop sending multiple
> redirect packets out on to the subnet. The new rcp_routed will close
> the BGP session if it receives an announcement of such a route.  The
> new rcp_routed software also has support for externally administered
> inter-AS metrics, an auto-restart capability, and bug fixes for BGP
> overruns with peer routers.
> 
>         This deployment caused a few problems. One is that this
> new feature of rcp_routed pointed out a misconfigured peer router
> at Rice University in Houston. This caused the BGP connection to
> open and close rapidly which caused further problems on the peer
> router. Eventually the peer was reconfigured to remove the
> bad route, which fixed the problem. Another problem was on the
> Argonne ENSS. This node crashed in such a way that it was
> 
> 		----------------------------------
> 
> What he did not say:
> 
> 	The new rcp_routed will (virtually) immeadiately after the close,
> reopen a BGP session and pump all known routes at the BGP peer. If the
> peer is already  working on processing the old ones, this adds an unneeded
> burden on the regional peer.  I have not reviewed the spec in detail,
> but there should be something in place to prevent a constant cycle of
> close, open, slam 5k routes, close, open, slam 5k routes, close...
> well, you get the picture. This points out a configuration problem with 
> BGP in the ANS T3 routers, in addition to the less than optimal configuration
> that we had in our ciscos.  
> 
> Just my two cents from the other side of the fence.
> -- 
> Regards,
> Bill Manning         bmanning at rice.edu        PO Box 1892
>  713-285-5415         713-527-6099	       Houston, Texas
>    R.U. (o-kome)       			        77251-1892