Re: [DNA] Re: RS/RA Exchange

[Greg Daley <greg.daley@eng.monash.edu.au>]

Hi Brian,

Brian Haberman wrote:
> 
> 
> Erik Nordmark wrote:
> 
>>> I'd guess that the ordering and selection issue is a generic one.
>>> It would be good if we didn't re-invent solutions.
>>
>>
>>
>> There are protocols, like MLD and routing protocols, which elect some
>> form of designated node (querier for MLD) but those protocols don't 
>> produce
>> a full sorted list of all the routers on the link.
>> I wonder if there is something here which could be reused.
> 
> 
> So, I can dust off some "historic" code for this.  DVMRP has a HELLO
> message like many other routing protocols.  But, DVMRP uses them to
> announce reachability and discovery.  That is, peer routers on a link
> look in the other routers' HELLO messages for their own addresses.
> This allows them to determine when they have been "discovered" by
> their peers.

This sounds interesting as allows bidirectional checks that the
router believes in the presence of the peer.

This means that at least the discovery mechanism is assured.
If we can do this based on existing message exchanges or
mechanisms (or code :) that would be good though.

> Could we mimic this and have some type of announcement message that
> a router would send out with all the other routers' addresses that
> it has heard from?

I thought that there was some work going on on
a routing protocol agnostic 'hello' mechanism.

If there is it may make sense to re-use
this, since the identifiers and priorities exchanged
for routing would already have to be configured for
routing protocol use.

I'd guess that this would be possible in the further
future, but security mappings between routers
may be difficult to achieve unless under single
administration.

Greg