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Re: IPv6 dual stacking and route tables
From: Ryan Rawdon <ryan () u13 net>
Date: Fri, 3 Feb 2012 16:44:33 -0500


On Feb 3, 2012, at 3:25 PM, Philip Dorr wrote:

You should accept the full v6 table, because some IPs may not,
currently, be reachable via one of the carriers.

Definitely agreed here, and this is why we take full v6 tables.  Especially since one of our upstreams does not peer 
with at least one other large network; if we took just a default from them, we would likely be sending them traffic 
which they in turn do not have a route for whereas the other upstream of ours does.


On Fri, Feb 3, 2012 at 2:10 PM, -Hammer- <bhmccie () gmail com> wrote:
So, we are preparing to add IPv6 to our multi-homed (separate routers and
carriers with IBGP) multi-site business. Starting off with a lab of course.
Circuits and hardware are a few months away. I'm doing the initial designs
and having some delivery questions with the carrier(s). One interesting
question came up. There was a thread I found (and have since lost) regarding
what routes to accept. Currently, in IPv4, we accept a default route only
from both carriers at both sites. Works fine. Optimal? No. Significantly
negative impact? No. In IPv6, I have heard some folks say that in a
multi-homed environment it is better to get the full IPv6 table fed into
both of your edge routers. Ok. Fine. Then, The thread I was referring to
said that it is also advisable to have the entire IPv4 table fed in
parallel. Ok. I understand we are talking about completely separate
protocols. So it's not a layer 3 issue. The reasoning was that DNS could
potentially introduce some latency.

"If you have a specific route to a AAAA record but a less specific route to
an A record the potential is for the trip to take longer."

That was the premise of the thread. I swear I googled it for 20 minutes to
link before giving up. Anyway, can anyone who's been thru this provide any
opinions on why or why not it is important to accept the full IPv6 table AND
the full IPv4 table? I have the hardware to handle it I'm just not sure long
term what the reasoning would be for or against. Again, I'm an end customer.
Not a carrier. So my concern is (A) my Internet facing applications and (B)
my users who eventually will surf IPv6.

Any guidance would be appreciated. Thanks.




-Hammer-

"I was a normal American nerd"
-Jack Herer







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