Re: ipv6 - NAT-PT

From: Bob Sinclair (bsin@cox.net)
Date: Mon Apr 25 2005 - 12:30:15 GMT-3


Hi Tim,

Per my experience, the ipv6 nat prefix does not necessarily match any portion
of the interface addresses. I suspect the example assumes one would carve
one's /96 nat prefix from one's assigned /64 space. You are certainly on the
right track re the necessity to advertise the /96 nat prefix to other routers.
Have you seen the Regi Desmeules IPV6 book from Cisco Press? Definitely a
must have, IMHO.

HTH,

Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net

  ----- Original Message -----
  From: ccie2be
  To: Group Study
  Sent: Monday, April 25, 2005 10:55 AM
  Subject: ipv6 - NAT-PT

  Hi guys,

  I've been going over the Cisco doc's on this

  http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/ipv
6
  _c/sa_natpt.htm

  and it seems to me there are a lot of conceptual blanks that need to be
  filled in.

  I'm hoping with the help of GS to be able to fill-in those blanks.

  If you look at page 338 from the above link, you'll see that a portion of
  the ipv6 address assigned to the interface matches the ipv6 nat prefix
  defined in step 3.

  My guess is that is required but the doc doesn't say so. Is that required?
  Also, notice that only the first 8 hex digits of the ipv6 address match the
  ipv6 nat prefix.

  Why only the first 8 hex digits?

  Also, I assume that some IGP must be used to advertise the ipv6 nat prefix
  although none of the examples show this. My reasoning is this: If the
  other ipv6 routers don't know where the nat-pt router is, they can't send
  packets to it. I also assume that the reason the interface has an ipv6
  address that partially matches the ipv6 nat prefix is so that when an IGP
is
  configured on that interface, then the other ipv6 routers will know how to
  reach the nat-pt router.

  Is that assumption correct?

  I'm doing my best to try to fill-in the blanks but I'm completely guessing
  about all these things.

  Can someone explain what's really going on with this and if I'm on the
right
  track?

  TIA, Tim

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