Hi Paul,
Very good talk ! Thank you.
1.
Your clarification made that AP is just a normal router is perfectly
valid one. Your VA proposal does two things which may not be very
obvious ...
- under the same routing infrastructure (no new investment needed)
allows to reduce FIB size on the edge routers.
- In the event where your current routers or subset of them can not
keep all entries in FIB - instead of fork lift upgrade and just by
simple configuration divide the address space into chunks and continue
to operate fine.
2.
Observation made by Yakov that within the POP edge would tunnel to AP
then it would go back to the same POP can be easily resolved. The proper
design of such customer POP would be that "local" routes received from
customers within the POP are present in the FIBs of all edge routers of
this POP. Only intra-POP routes (Internet routes) would be subject to
fib aggregation.
3.
As to the point of setting next hop on the Internet ASBRs to self ...
- pro for doing this is not to have additional entires in the IGP - true
- cons for doing this is that you have no _fast_ sub second IGP based
notification about your peer ASBR or link to peer's ASBR failures to be
propagated through your IGP domain triggering path switchovers well
ahead of time of BGP machinery movement. I think if we add another
benefit of not setting next hop self on ASBRs operators would accept
this. Besides this is just a local config. I want to point out that the
VA functionality is not something mandatory :) If operator is willing to
save $$$ by minor network reconfiguration why not provide him with such
tool kit ?
If they are willing to regularly keep upgrading their routers they are
free to spend money after all ....
Cheers,
R.
Gang,
I think there was some confusion about VA during the talk today, and I
wanted to clear some things up:
1. VA does not require any new hardware. An "Aggregation Point Router"
is a normal router that just happens to be an aggregation point for one or
more virtual prefixes.
>
2. No router FIB need carry the entire DFZ. In our tier-1 ISP study, ALL
routers saw 10x FIB reduction or more, NO routers saw more than a few
percent load increase.
The basic trade-off that VA offers to an ISP is whether to change out
hardware or to increase the amount of config it has to do. I wouldn't
want to presuppose that no ISP would prefer to increase config over change
out hardware.
PF
_______________________________________________
GROW mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/grow
