Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapping-01.txt
"Andy Kessler (kessler)" <kessler@cisco.com> Mon, 06 July 2009 05:21 UTC
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Date: Sun, 05 Jul 2009 22:21:26 -0700
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Thread-Topic: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapping-01.txt
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From: "Andy Kessler (kessler)" <kessler@cisco.com>
To: Leonard Giuliano <lenny@juniper.net>
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Subject: Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapping-01.txt
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Lenny, Yes, what you describe is what I was suggesting in my first reply - that BSR applies the hash function to its mapping cache before they are added to the common group-to-rp mapping table. We could go ahead and specify that in this draft and it might be fine. However, these are some of the other issues we should consider: o There are complications with creating hardware forwarding entries with PIM-Bidir maybe PIM-SM if the hash is used o We want to clarify Section 4.7.1 and 4.7.2 of RFC 4601 which describes the steps for group to RP mapping and use of the hash function. We are trying to improve the algorithm to also consider: - the origin of a group-to-rp mapping (e.g. bsr, autorp, static, etc) - Allow for static override - Allow for higher priority of PIM-Bidir over PIM-SM which is described in section 3.3 of RFC 5059 [BSR] Removing the hash from the group-to-rp mapping algorithm makes sense for these reasons. But if we can come up with some language to describe how the hash will be applied for BSR mappings and not in the general case - we may be open to that approach. Andy -----Original Message----- From: Leonard Giuliano [mailto:lenny@juniper.net] Sent: Thursday, July 02, 2009 12:00 PM To: Andy Kessler (kessler) Cc: pim@ietf.org Subject: Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapping-01.txt Andy- to be clear, last year I suggested deprecating BSR, not just the hash, as Static Anycast is a much better approach. However, if you are unwise enough to use BSR, the hash doesn't seem like a terribly offensive way to load balance among multiple RPs. I am not following you on the problem with the hash's applicability to other mechanisms. The hash is just a tiebreaker within the BSR mechanism. I don't see why it needs to be applicable to static or Auto-RP, just as local-pref is only applicable to BGP and means nothing to ISIS/OSPF/Static/etc. What am I missing? On Wed, 1 Jul 2009, Andy Kessler (kessler) wrote: -) -) Hi Lenny, -) -) Routers can learn group to RP mapping information from several sources -) including statically assigned, BSR, AutoRP and embedded RP. The purpose -) of this draft is to develop a deterministic way to select a particular -) mapping when we have a conflict. It doesn't have anything to do with -) advertising those mappings. -) -) The problem with the hash function is that it only applies to BSR. How -) do you apply the hash across static RP or any of the other methods ? We -) debated at one point in saying that the BSR code itself could use the -) hash and then decide which mappings it would present to the common -) group to RP mapping table. Then we thought it would be best just to -) drop it and recommend Anycast RP. We discussed this on the list. -) -) Last year about this time you said that you agreed that Anycast is a -) better method for load balancing than the hashing function. You still -) agree with that, right ? -) -) I personally would never implement a network with the BSR hash. I'd -) want to which RP was responsible for which group - even if there was -) load sharing with Anycast. -) -) Andy -)
- [pim] I-D ACTION:draft-ietf-pim-group-rp-mapping-… Internet-Drafts
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… John Zwiebel
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Stig Venaas
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Leonard Giuliano
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Leonard Giuliano
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… John Zwiebel
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Stig Venaas
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… John Zwiebel
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Stig Venaas
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Andy Kessler (kessler)
- Re: [pim] I-D ACTION:draft-ietf-pim-group-rp-mapp… Stig Venaas