Re: [Idr] I-D Action: draft-ietf-idr-rs-bfd-02.txt

"Rajiv Asati (rajiva)" <rajiva@cisco.com> Tue, 14 March 2017 21:08 UTC

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From: "Rajiv Asati (rajiva)" <rajiva@cisco.com>
To: Jeffrey Haas <jhaas@pfrc.org>, Robert Raszuk <robert@raszuk.net>
CC: idr wg <idr@ietf.org>
Thread-Topic: [Idr] I-D Action: draft-ietf-idr-rs-bfd-02.txt
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Date: Tue, 14 Mar 2017 21:08:24 +0000
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Subject: Re: [Idr] I-D Action: draft-ietf-idr-rs-bfd-02.txt
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Jeff, 

Is the assumption here that the client routers have routing view limited to what’s provided by the Route Server? If not, then wouldn’t Client Routers benefit from having to invalidate the path learned from the remote client router as soon as the connectivity check failed?

Of course, Client Routers conveying the lack of NLRI reachability per NH to the Route Server, and expecting Route Server to provide a different NHs of the NLRIs, and expecting it to be functional, while still attracting the traffic for unreachable destinations since the Loc-RIB is still pointing to the unreachable NH for the affected NLRIs.

I wonder whether  https://tools.ietf.org/html/draft-ietf-idr-bgp-bestpath-selection-criteria be useful here.

-- 
Cheers,
Rajiv Asati
Distinguished Engineer, Cisco

-----Original Message-----
From: Idr <idr-bounces@ietf.org>; on behalf of Jeffrey Haas <jhaas@pfrc.org>;
Date: Tuesday, March 14, 2017 at 4:42 PM
To: "robert@raszuk.net"; <robert@raszuk.net>;
Cc: "idr@ietf.org"; <idr@ietf.org>;
Subject: Re: [Idr] I-D Action: draft-ietf-idr-rs-bfd-02.txt

    Robert,
    
    I'll let the other comments in this thread stand on their merit.  However, I
    did want to respond to one specific point here:
    
    On Mon, Mar 13, 2017 at 11:45:25AM +0100, Robert Raszuk wrote:
    > I am afraid you have completely missed my point.
    > 
    > I never said clients must not detect other clients liveness before using it
    > for best path selection and in their local data planes.
    > 
    > I said RS does not need to bothered with that information.
    
    The relevant bit of procedure within this document to run BFD toward an eBGP
    nexthop and use it in the local decision process is of potential value even
    without the RS SAFI part of the protocol.  So, in this respect, I agree.
    
    The authors had previously discussed extracting this procedure from the
    document and are fine with doing so if it makes sense.
    
    The one "common" use case where this may be of benefit outside of a
    route-server environment is BGP "VPNs" that are constructed using IPSEC
    tunnels with the network effectively an NBMA subnet.  
    
    -- Jeff
    
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