[magma] IGMP/MLD-Proxying: broken upstream forwarding rule? (RFC 4605 section 4.2)
Mark Doll <doll@tm.uka.de> Thu, 27 September 2007 16:51 UTC
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Date: Thu, 27 Sep 2007 18:51:23 +0200
From: Mark Doll <doll@tm.uka.de>
Organization: Karlsruhe Institute of Technology
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Subject: [magma] IGMP/MLD-Proxying: broken upstream forwarding rule? (RFC 4605 section 4.2)
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Hi! The IGMP/MLD-Proxying RFC 4605 states in section 4.2. "Forwarding Packets": [...] A proxy device forwards packets received on any downstream interface to the upstream interface, and to each downstream interface other than the incoming interface based upon the downstream interfaces' subscriptions and whether or not this proxy device is the IGMP/MLD Querier on each interface. [...] This seems to suggest an unconditional forwarding in the upstream direction, which will lead to forwarding loops in any non loop-free physical topology (any topology other than a tree). The correct forwarding rule must only forward packets received on interfaces, on which the proxy is the querier. So the above should read: A proxy device forwards packets received on any downstream interface, ON WHICH IT IS THE QUERIER, to the upstream interface, and to each downstream interface other than the incoming interface based upon the downstream interfaces' subscriptions and whether or not this proxy device is the IGMP/MLD Querier on each interface. [...] For an example of a correct forwarding rule specification, cf. BIDIR-PIM's data packet forwarding rules, draft-ietf-pim-bidir-09.txt, section 3.3: On receipt of data to G on interface iif: if( iif == RPF_interface(RPA) || I_am_DF(RPA,iif) ) { oiflist = olist(G) (-) iif forward packet on all interfaces in oiflist } The "I_am_DF(RPA,iif)" (I am Designated Forwarder) in BIDIR-PIM is the equivalent to "I am querier" in IGMP/MLD-Proxying. That's what's IMHO missing in the current spec RFC 4605. Or do I get something completely wrong here? Mark. _______________________________________________ magma mailing list magma@ietf.org https://www1.ietf.org/mailman/listinfo/magma
- [magma] IGMP/MLD-Proxying: broken upstream forwar… Mark Doll
- Re: [magma] IGMP/MLD-Proxying: broken upstream fo… Brian Haberman
- [magma] IGMP/MLD-Proxying: broken upstream forwar… Mark Doll
- Re: [magma] IGMP/MLD-Proxying: broken upstream fo… Mark Doll
- RE: [magma] IGMP/MLD-Proxying: broken upstream fo… Alvaro Fernandez
- Re: [magma] IGMP/MLD-Proxying: broken upstream fo… Mark Doll
- Re: [magma] IGMP/MLD-Proxying: broken upstream fo… Brian Haberman