Re: [PCE] Inter-AS PCE Path Sequence Autoexplore

[Mach Chen]

Vijay,   What you said is that an EBGP speaker(ASBR) connect to multiple different EBGP peers which are in different ASes, respectively? If so, in such a scenario, the EBGP speaker SHOULD have the multiple paths advertisement capability which was proposed in draft-bhatia-bgp-multiple-next-hops-01.txt or draft-walton-bgp-add-paths-05.txt. So the EBGP speaker can advertise multiple paths to the PCE according to a specific situation. And in the really network,  an AS wants to "multi-home" to multiple ASes, there will be multiple ASBRs.   As to the policy configuration on the EBGP speaker as you said, in such scenario, I think there may be two possibility: one is that the AS where the EBGP speaker is in doesn't want to forward any traffic throuth the AS where those filtered routes come from, the other is that the EBGP speaker just wants to use a default route, the EBGP speaker can advertise a default route to its IBGP peers(includes PCE, of cause , the PCE can't use the default route to track the PCE sequence). So, if you want to use this method to track PCE sequence, enough route infomation is desirable.   Thanks,   Mach   ----- Original Message ----- From: Vijayanand C - TLS, Chennai. To: Mach Chen Cc: [EMAIL PROTECTED] Sent: Wednesday, October 18, 2006 7:02 PM Subject: RE: [PCE] Inter-AS PCE Path Sequence Autoexplore Mach, A question about the pce sequence autoexplore I-D.   This method seems to rely on BGP to get the next AS en-route to the destination. BGP may not give all the possible ASes, since based on its decision process and policy it may select only one route to pass on. For ex. If an EBGP speaker gets route for the same prefix from different EBGP peers from different ASes, it may select one of them and advertise to its IBGP peers. (The PCE may not have access to all the alternate routes of the EBGP speaker connecting to all the ASes) But we don't know the TE characteristic of the link connecting with the speaker whos' route was chosen( it may not be TE capable ?). Also, the policy configuration on the EBGP speaker itself may block some inbound routes. So some information is lost here.   Regards, Vijay     -----Original Message----- From: Mach Chen [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 17, 2006 7:19 AM To: [EMAIL PROTECTED] Subject: [PCE] Inter-AS PCE Path Sequence Autoexplore   Hi folks,   We have posted a new I-D http://www.ietf.org/internet-drafts/draft-chen-pce-interas-pce-sequence-autoexplore-00.txt which is about how to explore those PCEs and track their sequence which are engaged in computing an end-to-end path spanning multiple ASes.   Any feed-back and comments would be most welcome.   Best regards,   Mach ·         To: i-d-announce at ietf.org ·         Subject: I-D ACTION:draft-chen-pce-interas-pce-sequence-autoexplore-00.txt ·         From: Internet-Drafts at ietf.org ·         Date: Thu, 12 Oct 2006 15:50:02 -0400 ·         Cc: ·         List-archive: <http://www1.ietf.org/pipermail/i-d-announce> ·         List-help: <mailto:[EMAIL PROTECTED]> ·         List-id: i-d-announce.ietf.org ·         List-post: <mailto:i-d-announce@ietf.org> ·         List-subscribe: <https://www1.ietf.org/mailman/listinfo/i-d-announce>, <mailto:[EMAIL PROTECTED]> ·         List-unsubscribe: <https://www1.ietf.org/mailman/listinfo/i-d-announce>, <mailto:[EMAIL PROTECTED]> ·         Reply-to: internet-drafts at ietf.org A New Internet-Draft is available from the on-line Internet-Drafts directories.       Title                : Inter-AS PCE Path Sequence Autoexplore   Author(s)          : M. Chen   Filename : draft-chen-pce-interas-pce-sequence-autoexplore-00.txt   Pages              : 16   Date                : 2006-10-12      In Inter-AS scenario, as usual, multiple Path Computation Elements    (PCEs) will take part in path computation. [PCE-DISCO-OSPF], [PCE-    DISCO-ISIS],PCE-DISCO-BGP] or some other means can be used to    discover all underling PCEs, but there is lack of solutions to find    out those PCEs and their sequence which are engaged in computing an    end-to-end inter-AS TE LSP.  This document proposes a solution to    identify these PCEs and their sequence which can be used to compute a    TE LSP across multiple ASes.        A URL for this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-chen-pce-interas-pce-sequence-autoexplore-00.txt   To remove yourself from the I-D Announcement list, send a message to i-d-announce-request at ietf.org with the word unsubscribe in the body of the message. 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