From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon Apr 25 2005 - 12:43:55 GMT-3
Hey Bob,
Yes, I have that book and I checked to see if it shed anymore light on these
questions prior to my posting on GS.
Unfortunately, that book didn't have anymore info about this than what was
in the Cisco doc.
But, I fully agree with you about that Cisco Press book - a must read for
all current ccie candidates.
Getting back to this issue of the nat /96 prefix - how is a /96 prefix
"carved" from a /64 bit address?
I could understand how that would work in reserve i.e. carving a /64 prefix
from a /96 prefix.
And, also, if there's no requirement for the interface ipv6 address to be
related to the nat prefix, how would that prefix be advertised?
Thanks for getting back to me.
Tim
_____
From: Bob Sinclair [mailto:bsin@cox.net]
Sent: Monday, April 25, 2005 11:30 AM
To: ccie2be; Group Study
Subject: Re: ipv6 - NAT-PT
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 <mailto:ccie2be@nyc.rr.com>
To: Group Study <mailto:ccielab@groupstudy.com>
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/ipv6
_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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