[rbridge] Consensus Check: Point to Point links
eric.gray at ericsson.com (Eric Gray) Wed, 03 October 2007 15:10 UTC
From: "eric.gray at ericsson.com"
Date: Wed, 03 Oct 2007 10:10:51 -0500
Subject: [rbridge] Consensus Check: Point to Point links
In-Reply-To: <3870C46029D1F945B1472F170D2D9790031840BA@de01exm64.ds.mot.com>
References: <3870C46029D1F945B1472F170D2D9790031840BA@de01exm64.ds.mot.com>
Message-ID: <941D5DCD8C42014FAF70FB7424686DCF01B370EA@eusrcmw721.eamcs.ericsson.se>
Donald, Given that it is not crystal clear what you mean by "point to point link", I am not sure I agree with this, at least as you have worded it here. If you mean that the link is a full-duplex Ethernet link and the two end-points have some definitive mechansim for determining that they are the only entities using the link between them, there may be issues with doing this. For example, if the link is technically an Ethernet link, then it is not unlikely that one or the other devices may have multiple roles - i.e. - it may be both an RBridge for some frames and either a regular bridge or end station (for example, a router) for others. It's arguable that, in this case, the multi-role device is two (or more) separate entities - thus invalidating a "point to point" definition for this case (though only two distinct physical devices are connected via this link). Without a clear agreement between involved entities, this sort of "short-cut" addressing is likely to result in higher-level (slow path) processing of many (if not all) of the frames transiting the link for some implementations. Moreover, without an unambiguous determination of exactly when this would apply, it will not be unambiguously clear when a receiving implementation would have to switch to a "promiscuous listening" mode. I believe omission of the outer VLAN tag suffers from the same ambiguity. For instance, it is possible for two devices to have a "point to point" relationship within a VLAN context that would nto be the case without the VLAN context. Hence it appears we would have to be explicit in what we mean by "point to point" link and how we expect that the entities (RBridges) involved would be able to disambiguate this p2p status for any given link. If we are saying that two devices - using some means out of scope for our specification - are somehow aware of an unambiguous point-to-point relationship between them and can therefore use any MAC DA on transmission, and ignore it on receipt, we could make the same argument for virtually any encapsulation choice we might prefer. But, it would be as valid to observe that we don't need to specify what is - in essence - an out-of-context (mis)behavior between consenting implementations... -- Eric Gray Principal Engineer Ericsson > -----Original Message----- > From: rbridge-bounces at postel.org > [mailto:rbridge-bounces at postel.org] On Behalf Of Eastlake III > Donald-LDE008 > Sent: Tuesday, October 02, 2007 11:27 PM > To: Rbridge at postel.org > Subject: [rbridge] Consensus Check: Point to Point links > > This is a check via the mailing list to confirm or refute an apparent > consensus from the minutes of the Chicago meeting for a change from > protocol draft -05: > > If it is known that a link is a point to point link between two > RBridges, then the outer header, if it is an Ethernet header, can > have any source and/or destination addresses, those addresses will > be ignored on receipt, and the outer VLAN tag can be omitted. > > If no particular controversy arises over this in the next two > weeks, we > will declare it to be the working group consensus. > > Thanks, > Donald & Erik > > _______________________________________________ > rbridge mailing list > rbridge at postel.org > http://mailman.postel.org/mailman/listinfo/rbridge >
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Anoop Ghanwani
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Caitlin Bestler
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Dinesh G Dutt
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Anoop Ghanwani
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Radia Perlman
- [rbridge] Consensus Check: Point to Point links Caitlin Bestler
- [rbridge] Consensus Check: Point to Point links Anoop Ghanwani
- [rbridge] Consensus Check: Point to Point links Eric Gray
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Dinesh G Dutt
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Check: Point to Point links Radia Perlman
- [rbridge] Consensus Check: Point to Point links Caitlin Bestler
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Silvano Gai
- [rbridge] Consensus Check: Point to Point links Anoop Ghanwani
- [rbridge] Consensus Check: Point to Point links Joe Touch
- [rbridge] Consensus Check: Point to Point links Eastlake III Donald-LDE008
- [rbridge] Consensus Withdrawn: Point to Point lin… Eastlake III Donald-LDE008