Hi Srini, In OSPFv3 the Options field is present only in the Hellos and the DD packets, hence you cannot set the AT bit in the LS Update packet containing the Grace LSAs. The helping router would know that AT has been negotiated with the restarting router and MUST hence look for the AT block.
Cheers, Manav ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Srinivasan K L Sent: Friday, February 18, 2011 12.21 PM To: 'Acee Lindem'; 'Alan Davey' Cc: [email protected] Subject: Re: [OSPF] Supporting Authentication Trailer for OSPFv3 Hi Acee, I am a little confused here. Quoting from the draft: 2.1. AT-Bit in Options Field A new AT-bit (AT stands for Authentication Trailer) is introduced into the OSPFv3 Options field. OSPFv3 routers MUST set the AT-bit in OSPFv3 Hello and Database Description packets to indicate that the OSPFv3 router will include the authentication trailer in all OSPFv3 packets on the link. For OSPFv3 Hello and Database Description packets, the AT-bit indicates the AT is present. For other OSPFv3 packet types, the OSPFv3 AT bit setting is preserved from the OSPFv3 Hello/Database Description setting. The last line above says that the bit setting must be preserved from the hello/dd. Does this not mean that the bit will be set in the LS Update containing the Grace LSA? I do understand that the restarting router must remember that AT was used or not before and then set/clear it accordingly. Regards, Srini. ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Acee Lindem Sent: Friday, February 18, 2011 12:03 AM To: Alan Davey Cc: [email protected] Subject: Re: [OSPF] Supporting Authentication Trailer for OSPFv3 Hi Alan, On Feb 17, 2011, at 6:50 AM, Alan Davey wrote: Folks I have read draft-ietf-ospf-auth-trailer-ospfv3-02 and have a few minor nits as follows. - After an unplanned graceful restart, a router may send Grace-LSAs in an LS Update packet before any Hello packets. Unless I am missing something, the draft should include such LS Update packets in the list of those that MUST have the AT-bit set. The options are not included in the LS Update packet. However, if the restarting router was using the authentication restart before the restart, it should use it afterwards and the helping neighbor adjacencies should reflect this fact. - In Figure 1, for the packet on the left hand side, the IP Header Length HL = PL + LL (not PL + AL). Right - this will be included in the 03 version. - In section 4.1 Authentication Trailer, in the Auth type bullet, the following wording be clearer; "At present, the only value defined is 1, to denote ..."? Ok - I'll reword this in the 03 version as well. Thanks, Acee Regards Alan Davey Software Engineer, Network Technologies Division Metaswitch Networks [email protected]<mailto:[email protected]> +44 (0) 20 8366 1177 www.metaswitch.com<http://www.metaswitch.com/> _______________________________________________ OSPF mailing list [email protected]<mailto:[email protected]> https://www.ietf.org/mailman/listinfo/ospf
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