IPv6 dual stacking and route tables

-Hammer- bhmccie at gmail.com
Fri Feb 3 20:10:00 UTC 2012

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.


"I was a normal American nerd"
-Jack Herer

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