Subject: [rbridge] trill-adj Section 3.3 comments

From: Donald Eastlake <[email-masked]>
Date: Thu, 27 Jan 2011 21:52:11 -0500

Response to some comments by Les Ginsberg:

> Section 3.3
> -------------

> Text says that for hellos received on a VLAN Other than the D-VLAN

> "any TRILL Neighbor TLV in such a Hello is ignored..."

> I assume this means that it is an implementation choice as to
> whether to include the neighbor TLV in such hellos? A clear
> statement of this would be helpful.

To avoid the posibility of temporary confusion if there is a change in
the Designated VLAN, the TRILL Neighbor TLV sent on a VLAN should
reflect the neighbors seen on that VLAN. Since an implementation
conformant to this draft is only assured of having per VLAN neighbor
information for the Deisgnated VLAN, I think something like the
following should be added in Section 7.2:

"The TRILL Neighbor TLV sent on a VLAN MUST show the neighbor
information, as sensed by the transmitting RBridge, on that
VLAN. Since implementations conformant to this document maintain such
information on a per VLAN basis only for the Designated VLAN, such
implementations only send the TRILL Neighbor TLV in TRILL Hellos on
the Deisgnated VLAN."

You could imagine an implementation that kept more state and had
neighbor information for multiple VLANs but it doesn't seem worth going
into that.

Thanks,
Donald
=============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 155 Beaver Street
 Milford, MA 01757 USA
 [email-masked]

_______________________________________________
rbridge mailing list
[email-masked]
http://mailman.postel.org/mailman/listinfo/rbridge

---

From: "Les Ginsberg (ginsberg)" <[email-masked]>
Date: Mon, 31 Jan 2011 02:19:51 -0800

Donald -

Thanx for the response.
Please include the IS-IS WG on all emails associated with trill-adj review comments.

Inline.

> -----Original Message-----
> From: Donald Eastlake [mailto:[email-masked]]
> Sent: Thursday, January 27, 2011 6:52 PM
> To: Les Ginsberg (ginsberg); [email-masked]
> Subject: trill-adj Section 3.3 comments
> 

Yes - I agree.

Section 3.2 states:

      o  Two Hello holding timers, each consisting of an 16-bit unsigned
         integer number of seconds: a Designated VLAN holding timer and
         a non-Designated VLAN holding timer.

This text indicates that adjacencies are NOT per VLAN - but that a timer is kept indicating the reception of hellos on a VLAN other than the D-VLAN. Which raises the question as to whether this timer simply tracks reception of a hello on all VLANs other than the D-VLAN (which is what I thought) or is meant to be a separate timer for each VLAN other than the D-VLAN.

Your response indicates that if an implementation were to send neighbor information in a hello sent on a VLAN other than the D-VLAN that it MUST reflect only those neighbors seen on that VLAN - which makes sense to me - but would require that the implementation have a VLAN specific timer. 

I think your suggested text helps a lot and is definitely needed.

   Les