[OSPF] Re: Comments on draft-berger-ospf-rfc2370bis-00.txt
Lou Berger <lberger@labn.net> Wed, 22 November 2006 21:07 UTC
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Date: Wed, 22 Nov 2006 15:49:54 -0500
To: Acee Lindem <acee@cisco.com>
From: Lou Berger <lberger@labn.net>
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Cc: OSPF List <ospf@ietf.org>
Subject: [OSPF] Re: Comments on draft-berger-ospf-rfc2370bis-00.txt
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Acee, See below. At 06:37 PM 11/20/2006, Acee Lindem wrote: >Hi Lou, >See inline. > > >Lou Berger wrote: >>Acee, >> See responses in-line below. >> >>Should the corrected version go in as draft-berger or draft-ietf? >> >>Lou >> >>At 07:03 PM 11/13/2006, Acee Lindem wrote: >> >>>Hi Lou, >>> >>>My main comment is on section 5 (6 is your draft). The draft adds >>>mandatory reachability checking for AS scoped opaque LSAs. >>>If we add mandatory reachability checking, it should be for all >>>opaque types rather reading like the constraint is unique to AS scoped >>>opaque LSAs (type 11s). >> >>valid point. >> >>>I also think we should put the question as to whether the checking >>>should be madatory or relaxed a bit to allow an application to check >>>less frequently if the opaque data is stale. >> >>What benefit would this have? >This would allow applications that don't require the opaque data to >strictly track the SPF to discontinue using the information less frequently >than the SPF. This would be useful if OSPF and the application using the >opaque data were not tightly coupled. Here is what I put in the OSPFv3 >update draft: > >3.4.4. Future LSA Validation > > 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]. In > general, the new information advertised in future LSAs should not be > used unless the OSPFv3 router originating the LSA is reachable. > However, depending on the application and the data advertised, this > reachability validation MAY be done less frequently than every SPF > calculation. > > To facilitate inter-area reachability validation, any OSPFv3 router > orginating AS scoped LSAs is considered an AS Boundary Router (ASBR). > >On the other hand, there is a school of thought that would consider this an >implementation detail. I, however, think it is better if it is >explicitly stated. >If, for no other reason, to provide guidance to the people testing >the protocols. Consistency between v2 and v3 is goodness where possible, so I'll add a comment (to the end of 3.1) and reference. >>>Detailed comments: >>> >>>Section 2, third paragraph - "aligned" rather than "qaligned". >> >>yes. >> >>>Section 3, "Section 7" rather than "Section 7." >>okay. >> >> >>>Section 3.1 - Type 9 LSA - "keep" rather than "keepk". >> >>yes. Also I added the following to the beginning of the section: >> Section 13 of [OSPF] describes the OSPF flooding procedure. >> Those procedures MUST be followed as defined except where >> modified in this section. >> >>>I believe we >>> should discard a link-local LSA received from >>> a neighbor not >>> on the interface (text similiar to type 11). >> >>okay, updated as follows: >> o If the Opaque LSA is type 9 (the flooding scope is link-local) >> and the interface that the LSA was received on is not the same >> as the target interface (e.g., the interface associated with a >> particular target neighbor), the Opaque LSA SHOULD be discarded >> and not acknowledged, and MUST NOT be flooded out that interface >> (or to that neighbor). An implementation SHOULD keep track of >> the IP interface associated with each Opaque LSA having a >> link-local flooding scope. >I guess I think that if you discard an LSA, it is implied that you won't >reflood it. it does say "and MUST NOT be flooded". I'm open to alternate wording. >>>Section 3.1, Since the area ID is not in the LSA header, the bullet on >>> area flooding is confusing. It should say >>> something to the >>> effect of only flooding type 10 LSAs out >>> interfaces in the >>> LSA's associated area. >> >>okay, updated as follows: >> o If the Opaque LSA is type 10 (the flooding scope is area-local) >> and the area associated with Opaque LSA (as identified during >> origination or from a received LSA's associated OSPF packet >> header) is not the same as the area associated with the target >> interface, the Opaque LSA MUST NOT be flooded out the interface. >> An implementation SHOULD keep track of the OSPF area associated >> with each Opaque LSA having an area-local flooding scope. >I think the action should be same as above. In any case, this can never >happen as the entire Link State Update packet would be discarded. okay, language is a hold-over from 2230. will update to match above. Same fore type 11. >>>I don't care if it said this in RFC 2370 >>> and everyone knew what it implied. >> >>I don't know how to interpret the text otherwise... >RFC 2328 specifically state that packets whose Area ID cannot >be matched to the receiving interfaces are discarded. See section 8.2. I was agreeing with you... [...] >>>5.1 Inter-Area Considerations >>> >>>...... >>> >>> >>>Section 5.1 >>> >>> Type-9 opaque LSAs and type-10 opaque LSAs do not have this problem >>> as a receiving router can detect an a loss of reachability >>> through the intra-area >>> SPF calculation. >>> >>>Section 5.1 >>> >>> To enable OSPF routers in remote areas to check availability of the >>> originator of link-state type 11 opaque LSAs, the orignators of >>> type-11 opaque LSAs are considered Autonomous System Border >>> Routers (ASBRs) and will advertise themselves as such. >> >> >> >>> >>>Section 5.1 - Remove "It is important to note that this solution >>>MUST NOT ..." >>>This is redundant. >> >>which part is redundant, just the sentence you are asking to be >>removed? I agree that it is redundant with 2328, but I thin >>mentioning it is still useful. Will rephrase to remove directive. >This part of the specification doesn't modify stub area behavior. >Here, we are talking about validating AS scoped opaque LSA. >I guess you could say, "Note that AS scoped opaque LSA >validation is not applicable to stub and NSSA areas since LSAs >with AS scope are not flooded into these areas types." However, >I don't see it as necessary. here's what I have now: "It is important to note that per [OSPF] this solution does not apply to OSPF stub areas or NSSAs as neither type-11 LSAs are flooded nor are type-4 LSAs originated into such areas." As you mentioned above, it is worth explicitly stating things sometimes. >>>Remove numbered items (1) and (2), these actions ARE NOT new to >>>opaque LSAs. Make (3) a separate paragraph rather than numbered >>>item. >> >>But inclusion of type-11 originate routers as ASBR is new. Will >>rephrase to make clear that existing ospf requirements apply. >> >>How about: >>The procedures related to inter-area opaque LSAs are as follows: >> >>(1) An OSPF router that is configured to originate AS-scope opaque >> LSAs advertise themselves as ASBRs and MUST follow the related >> requirements related to setting of the Options field E-bit in >> OSPF Hello packets and LSA headers as specified in [OSPF]. >> >>(2) When .... >I don't think these points need to be restated even if they reference >RFC 2328. Opaque LSAs don't modify these conditions. Hence, >I don't see them to be required any more than stating the version field >the OSPF packet header should be set to 2. huh? opaque LSAs aren't present in 2328 and the specification of E-bit setting/handling in 2328 is largely relative to AS-external-LSAs. Thanks again for the comments, Lou _______________________________________________ OSPF mailing list OSPF@ietf.org https://www1.ietf.org/mailman/listinfo/ospf
- [OSPF] Comments on draft-berger-ospf-rfc2370bis-0… Acee Lindem
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Lou Berger
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Acee Lindem
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Lou Berger
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Acee Lindem
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Lou Berger
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Acee Lindem
- Re: [OSPF] Re: Comments on draft-berger-ospf-rfc2… Acee Lindem
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Lou Berger
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Acee Lindem
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Lou Berger
- [OSPF] Re: Comments on draft-berger-ospf-rfc2370b… Acee Lindem