Subject: Re: Improved "tunnel is up" features.

From: Bill Fenner <[email-masked]>
Date: Tue, 22 Apr 1997 09:01:23 PDT

Tom,

  |In order to minimize one-way neighbor relationships, a router MUST
  |delay sending poison route reports to a neighbor until the neighbor
  |includes the routers address in its probe messages. On point-to-point
  |interfaces and tunnel pseudo-interfaces, this means that no packets
  |should be forwarded onto these interfaces until two-way neighbor
  |relationships have formed.

This doesn't say anything about whether or not it's OK to pass these
routes along to your neighbors.  If you pass the routes along, but
don't poison-reverse to the originator because it's one-way, then
you're creating a black hole.  This language needs to be expanded to
include MUST NOT pass on the routes to other neighbors.

  Bill

---

From: dave pratt <[email-masked]>
Date: Tue, 22 Apr 1997 17:20:32 +0100 (BST)

Thinking further about the comments so far, at least part of the issue
is with "mrinfo" which shows the tunnel up when it's marked down at
the other end.

If I understand correctly, a one way tunnel will be marked up at one
end, but none of the dvmrp routes being received will end up in its rpf
routing tables. That certainly fits my experiences. I also ought to go
and read the latest dvmrp spec again... 

Cheers
Dave P

On Tue, 22 Apr 1997, Bill Fenner wrote:

->Tom,
->
->  |In order to minimize one-way neighbor relationships, a router MUST
->  |delay sending poison route reports to a neighbor until the neighbor
->  |includes the routers address in its probe messages. On point-to-point
->  |interfaces and tunnel pseudo-interfaces, this means that no packets
->  |should be forwarded onto these interfaces until two-way neighbor
->  |relationships have formed.
->
->This doesn't say anything about whether or not it's OK to pass these
->routes along to your neighbors.  If you pass the routes along, but
->don't poison-reverse to the originator because it's one-way, then
->you're creating a black hole.  This language needs to be expanded to
->include MUST NOT pass on the routes to other neighbors.
->
->  Bill
->