I haven't seen anyone bring up this point yet, but I feel like I'm
missing something...
I receive a full BGP table from several providers. They send me ~490k
*prefixes* each. However, my router shows ~332k *subnets* in the routing
table. As I understand it, the BGP table contains duplicate information
(for example a supernet is announced as well as all subnets within that
supernet) or excess information (prefix is announced as two /17's
instead of a single /16) and can otherwise be summarized to save space
in the RIB.
It appears to me that the weekly CIDR report shows similar numbers:
Recent Table History
Date Prefixes CIDR Agg
30-05-14 502889 283047
31-05-14 502961 283069
01-06-14 502836 283134
02-06-14 502943 283080
03-06-14 502793 283382
04-06-14 503177 282897
05-06-14 503436 283062
06-06-14 503988 282999
In this case, does the 512k limit of the 6500/7600 refer to the RIB or
the FIB? And does it even matter since the BGP prefix table can
automatically be reduced to ~300k routes?
Thanks,
--Blake
Drew Weaver wrote the following on 5/6/2014 10:39 AM:
Hi all,
I am wondering if maybe we should make some kind of concerted effort to remind
folks about the IPv4 routing table inching closer and closer to the 512K route
mark.
We are at about 94/95% right now of 512K.
For most of us, the 512K route mark is arbitrary but for a lot of folks who may
still be running 6500/7600 or other routers which are by default configured to
crash and burn after 512K routes; it may be a valuable public service.
Even if you don't have this scenario in your network today; chances are you
connect to someone who connects to someone who connects to someone (etc...)
that does.
In case anyone wants to check on a 6500, you can run: show platform hardware
capacity pfc and then look under L3 Forwarding Resources.
Just something to think about before it becomes a story the community talks
about for the next decade.
-Drew