Re: Arps and grat arps was (RE: tsv-dir review ofdraft-ietf-vrrp-unified-spec-02.txt)

I don't understand how the ARP type matters as long as the
response doesn't use the VR MAC address in the MAC header.
-don
  -----Original Message-----
  From: [email protected] [mailto:[email protected]]On Behalf Of Mark Handley
  Sent: Tuesday, November 04, 2008 1:27 PM
  To: don provan
  Cc: Stephen Nadas; TSV Dir; vrrp
  Subject: Re: [VRRP] Arps and grat arps was (RE: tsv-dir review ofdraft-ietf-vrrp-unified-spec-02.txt)


  Sorry - my confusion - the text does say ARP *request*, but I was thinking of ARP responses.  You are of course correct.

   - Mark


  On Tue, Nov 4, 2008 at 9:04 PM, don provan <[email protected]> wrote:

    Do they sniff MAC addresses in ARP packets? I didn't know that
    was legal.

    The source MAC address in the ARP packet's MAC header must always
    be the physical MAC address of the system, of course, never the
    VR MAC address. I've only ever heard of switches learning based
    on the source MAC address *in* the MAC header. Am I about to have
    a learning experience?
    -don
      -----Original Message-----
      From: [email protected] [mailto:[email protected]]On Behalf Of Mark Handley
      Sent: Tuesday, November 04, 2008 12:36 PM
      To: don provan
      Cc: Stephen Nadas; TSV Dir; vrrp
      Subject: Re: [VRRP] Arps and grat arps was (RE: tsv-dir review ofdraft-ietf-vrrp-unified-spec-02.txt)





      On Tue, Nov 4, 2008 at 7:27 PM, don provan <[email protected]> wrote:


        But it doesn't really matter: all routers *can* send gratuitous
        ARP messages for the VR. The VR ARP information is constant: it
        does not change when the VRRP master changes. No black hole would
        be created: all the entries map the VR IP address to the VR MAC
        address. The current master is the node that receives all packets
        sent to the VR MAC address no matter what node actually distributed
        the VR ARP mapping.

      Won't you blackhole the traffic if you do this on a LAN composed of MAC-learning switches?

       - Mark

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