RE: [OSPF] Question on flodding scope indraft-ietf-ospf-ospfv3-update-17.txt
"Nitin Kakkar" <nkakkar@force10networks.com> Wed, 10 October 2007 18:01 UTC
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Subject: RE: [OSPF] Question on flodding scope indraft-ietf-ospf-ospfv3-update-17.txt
Date: Wed, 10 Oct 2007 11:02:00 -0700
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From: Nitin Kakkar <nkakkar@force10networks.com>
To: Acee Lindem <acee@redback.com>, Adrian Farrel <adrian@olddog.co.uk>
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Adrian> You are saying that the only router that cause AS scoped flooding is an ASBR. This limit seems to be unnecessary and overly restrictive. Adrian> Can you clarify why a non-ASBR is not allowed to originate an AS-scoped LSA? Acee> This is necessary to enforce the "condition of reachability" for all LSAs. In other words, in order for an LSA to be considered valid, you need to verify that the advertising router is reachable. Hence, a router advertising an AS scoped LSA must advertise itself as ASBR so that Inter-Area-Router-LSAs are advertised into all regular areas. IMHO> It is quite possible in many scenario's that a router originated AS scope LSA's and then changed from ASBR to Non ASBR, leaving older ASE LSA's in domain. 1) If we use implict definition of ASBR (independent of E bit) it will result in incorrect Routes 2) This statement also tries to prevent unnecessary origination of unusable lsa's (If router originate ASE lsa's and does not advertise it self as ASBR, what would be the use of those LSA's? these LSA's will only occupy space in LSDB & result into unnecessary flooding but won't contribute to routing, this is very similar to ) Regards Nitin ________________________________ From: Acee Lindem [mailto:acee@redback.com] Sent: Wednesday, October 10, 2007 8:19 AM To: Adrian Farrel Cc: ospf@ietf.org Subject: Re: [OSPF] Question on flodding scope indraft-ietf-ospf-ospfv3-update-17.txt Hi Adrian, On Oct 10, 2007, at 9:30 AM, Adrian Farrel wrote: Hi, In section 2.3... o AS scope. LSA is flooded throughout the routing domain. Used for AS-external-LSAs. A router that originates AS scoped LSAs is considered an AS Boundary Router (ASBR) and will set its E-bit in Router-LSAs for regular areas. I'm concerned about the impact of this statement for future application of text in 3.4.4 It is expected that new LSAs will be defined that will not be processed during the Shortest Path First (SPF) calculation as described in Section 3.8. For example, OSPFv3 LSAs corresponding to information advertised in OSPFv2 using opaque LSAs [OPAQUE]. But in 3.4.4 it also says To facilitate inter-area reachability validation, any OSPFv3 router originating AS scoped LSAs is considered an AS Boundary Router (ASBR). You are saying that the only router that cause AS scoped flooding is an ASBR. This limit seems to be unnecessary and overly restrictive. Further, this seems to be a change from RFC2740 where section 2.3 had only o AS scope. LSA is flooded throughout the routing domain. Used for AS-external-LSAs. Can you clarify why a non-ASBR is not allowed to originate an AS-scoped LSA? This is necessary to enforce the "condition of reachability" for all LSAs. In other words, in order for an LSA to be considered valid, you need to verify that the advertising router is reachable. Hence, a router advertising an AS scoped LSA must advertise itself as ASBR so that Inter-Area-Router-LSAs are advertised into all regular areas. We are also respinning RFC 2370 (Opaque LSAs) to enforce this. This is draft-ietf-ospf-rfc2370bis-01.txt. Thanks, Acee Thanks, Adrian PS. I think the I-D header should include "Obsoletes RFC2740" _______________________________________________ OSPF mailing list OSPF@ietf.org https://www1.ietf.org/mailman/listinfo/ospf
_______________________________________________ OSPF mailing list OSPF@ietf.org https://www1.ietf.org/mailman/listinfo/ospf
- [OSPF] Question on flodding scope in draft-ietf-o… Adrian Farrel
- RE: [OSPF] Question on flodding scope indraft-iet… Igor Bryskin
- Re: [OSPF] Question on flodding scope in draft-ie… Atanu Ghosh
- Re: [OSPF] Question on flodding scope indraft-iet… Adrian Farrel
- RE: [OSPF] Question on flodding scopeindraft-ietf… Igor Bryskin
- Re: [OSPF] Question on flodding scope in draft-ie… Acee Lindem
- Re: [OSPF] Question on flodding scope indraft-iet… Acee Lindem
- RE: [OSPF] Question on flodding scope indraft-iet… Nitin Kakkar
- Re: [OSPF] Question on flodding scope indraft-iet… Acee Lindem
- RE: [OSPF] Question on flodding scope indraft-iet… Nitin Kakkar