Subject: RE: [manet] OLSR: RFC 3626 observations.

From: "Dearlove, Chris (UK)" <[email-masked]>
Date: Tue, 04 Nov 2003 10:30:25 +0000

From: Andreas Tønnesen [mailto:[email-masked]]
> A node must only use its main address as originator address in all
> packages, so one would never register nodes with an address 
> that is not
> the main address of that node.
> So if I didn't missunderstand you, the case you describe should not
> occur.

Here's the scenario which I think has the effect I described

Node A has one interface, A1, node B has one interface B1, node C
has two interfaces, C1 and C0. Node C chooses address C0 as its
main address.

There are symmetric connections between A1 and B1 and between
B1 and C1. These can be established before any MID message from
node C is relevant. (In fact node A can't process a MID message
from node C until they are established, on the assumption this
is the only route from node A to node C.)

Node B will broadcast a HELLO message containing address C1.
The HELLO message will not contain C0 (because it contains C1).

Node A will thus put address C1 into its two hop table because,
there being no entry for node C in the interface association set,
node A thinks the main address corresponding to C1 is C1.

Later node A will receive node C's MID message and put an entry
in its interface association set. Now HELLO messages received
from node B will result in C0 being put in the two hop set. This
leaves the C1 entry unwanted in the two hop set until it expires.

My suggestion is that when the MID message associating C0 with
C1 is received that the C1 entry in the two hop set is replaced
by a matching C0 entry. (This is, in essence, actually not unlike
what used to happen when two hop tuples had interface and main
addresses.)

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From: Andreas Tønnesen <[email-masked]>
Date: Tue, 4 Nov 2003 11:39:11 +0100 (MET)

> The HELLO message will not contain C0 (because it contains C1).

No. Node C will use the address of C0 even tough it is sending on
interface C1. So node B will use the main address of C(C0) in its HELLO
message. The only time the address C1 is mentioned in any control
traffic(OLSR)O is in MID messages. Nodes should _not_ ever use the sender
address from the IP header when processing messages. The originator
address on the OLSR message should be used. And this address is _always_
the senders main address.

So IMO the scenario you describe could not occure.

Andreas Tønnesen
UniK University Graduation Center
University of Oslo
http://heim.ifi.uio.no/~andreto/uolsrd/index.cgi

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From: Andreas Tønnesen <[email-masked]>
Date: Tue, 4 Nov 2003 13:45:20 +0100 (MET)

> what used to happen when two hop tuples had interface and main

My bad. You are absolutly right.

Time to read up on the RFC it seems :)

Andreas Tønnesen