Re: Multiple BFD sessions over one path
Dave Katz <dkatz@juniper.net> Sat, 19 September 2009 06:40 UTC
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From: Dave Katz <dkatz@juniper.net>
To: Mach Chen <mach@huawei.com>
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Subject: Re: Multiple BFD sessions over one path
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Date: Sat, 19 Sep 2009 00:39:58 -0600
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The point of the text in 1hop is that there isn't any use in having more than one session over a "path", and in any case it can't be done because there would be no way to demultiplex the initial packet of multiple sessions on the same "path" (because the first packet carries discriminator 0). But diffserv is essentially a tunnel of sorts; each service level has potentially different forwarding characteristics, so it may be useful to run BFD over more than one level (and the sessions can be demultiplexed because they are contextualized by the diffserv level). Essentially, each diffserv service level is considered to be a separate path, not unlike GRE or IPsec or what have you. Implementors are free to do as they please; the point of the text is to not preclude creative use of BFD where it can be useful. --Dave On Sep 18, 2009, at 9:27 PM, Mach Chen wrote: > Hi, > > After reading the two drafts (draft-ietf-bfd-generic-05 and draft- > ietf-bfd-v4v6-1hop-09), I have some confusion about the session > limitation over a specific network-layer path. > > Section 2 of draft-ietf-bfd-v4v6-1hop-09 says: > "Each BFD session between a pair of systems MUST traverse a separate > network-layer path in both directions..." > > But section 6 of draft-ietf-bfd-generic-05 says: > "...if multiple differentiated services [DIFFSERV] are being > operated over IPv4, an independent BFD session may be run for each > service level...", this implicates that there may be mulitiple BFD > sessions over one network-layer(ipv4) path, but it seems that this > is not allowed in draft-ietf-bfd-v4v6-1hop-09. How to understand > this conflict? or do I miss something? > > Best regards, > Mach Chen > > > >
- Re: Multiple BFD sessions over one path Dave Katz
- Multiple BFD sessions over one path Mach Chen
- Re: Multiple BFD sessions over one path Dave Katz
- Re: Multiple BFD sessions over one path Mach Chen
- Re: Multiple BFD sessions over one path Vishwas Manral
- Re: Multiple BFD sessions over one path Dave Katz