Re: [netext] I-D Action: draft-ietf-netext-logical-interface-support-03.txt

Brian Haley <brian.haley@hp.com> Tue, 06 September 2011 13:34 UTC

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Date: Tue, 06 Sep 2011 09:36:20 -0400
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Subject: Re: [netext] I-D Action: draft-ietf-netext-logical-interface-support-03.txt
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Hi Sri,

On 09/05/2011 12:15 PM, internet-drafts@ietf.org wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Network-Based Mobility Extensions Working Group of the IETF.
> 
> 	Title           : Logical Interface Support for multi-mode IP Hosts
> 	Author(s)       : Telemaco Melia
>                           Sri Gundavelli
> 	Filename        : draft-ietf-netext-logical-interface-support-03.txt
> 	Pages           : 26
> 	Date            : 2011-09-05

I read this draft and had a comment on Section 6.5:

6.5.  ND Considerations for Logical Interface

   The following are the Neighbor Discovery related considerations for
   the logical interface.

   o  Any Neighbor Discovery messages, such as Router Solicitation,
      Neighbor Solicitation messages that the host sends to a multicast
      destination address of link-local scope such as, all-nodes, all-
      routers, solicited-node multicast group addresses, using either an
      unspecified (::) source address, or a link-local address
      configured on the logical interface will be replicated and
      forwarded on each of the sub-interfaces under that logical
      interface.  However, if the destination address is a unicast
      address and if that target is known to exist on a specific sub-
      interface, the message will be forwarded only on that specific
      sub-interface.

I'm not sure about other OSes, but since you mentioned the Linux bonding driver
as an example of a Logical interface I can respond regarding that.  There are
configurations where you do NOT want to replicate a packet and forward it on all
the underlying physical interfaces.  Doing so can cause DAD failures if any of
the other interfaces see those packets sent to the all-nodes multicast address.
 We noticed and fixed that back in 2008.

BTW, I'm not subscribed to net-next, so haven't seen any previous discussion on
the draft.

-Brian