[AusNOG] What is more important? - ipv4 vs. routing table size

[Glen Turner]

[cc trimmed to the list I'm subscribed to]

I think some concern about the forwarding table size is reasonable.

Because of the increased (mis)use of switches for routing there is a
firm limit on the forwarding table size of a lot of ISP hardware due
to each forwarding table entry using a the TCAM entry. Most of the
switches I've seen don't handle a TCAM overflow with grace.

We're about to see the more entries in the forwarding table, from:
MPLS VPNs; more -- but smaller -- IPv4 routes; and an increase in
IPv6 routes.

Combined with some, frankly, stupid TCAM allocation algorithms by
one large manufacturer, it's well possible for some network designs
to run out of forwarding table.  We saw this before when MPLS VPNs
first appeared and another manufacturer's static RAM-based forwarding
tables proved to be too small.

As for the amount of forwarding table growth from IPv4 address recovery,
who knows <shrug>?  My guess is that whatever it is it will be less than
the forwarding table growth from MPLS VPNs and VPLS.

-- 
Glen Turner  <http://www.gdt.id.au/~gdt/>