As for routing table size, no router which can handle 10s of Gbps is
at all bothered by the size of the global table,
... as long as it isn't something like a Cisco Catalyst 6509 with SUP720
and doesn't have a PFC3BXL helping out ...
... or if we conveniently don't classify a Catalyst 65xx as a router
because it was primarily intended as a switch, despite how ISP's commonly
use them ...
so only edge devices
or stub networks are in danger of needing to filter /24s. And both of
those can (should?) have something called a "default route", making it
completely irrelevant whether they hear the /24s anyway.
A more accurate statement is probably that "any router that can handle
10s of Gbps is likely to be available in a configuration that is not at
all bothered by the current size of the global table, most likely at some
substantial additional cost."
Good point! I should have said "10s of Gbps and tables associated with default-free networks".
Or are there lots of people using 6500s without 3BXLs in the DFZ? I admit I have not audited every router in the DFZ, so perhaps someone with factual info can help out here.
If not, then we're back to where we started. The DFZ isn't worried about table size this cycle, and the edges can (should?) have default. I'm sure that will change in a couple years, but everything always does.
Oh, and before anyone jumps all over me, I am NOT implying you should deaggregate and blow up the table. Just that 300K prefixes is the DFZ is not a reason to start filtering /24s. Today.
Oh, and before anyone jumps all over me, I am NOT implying you should
deaggregate and blow up the table. Just that 300K prefixes is the DFZ is
not a reason to start filtering /24s. Today.
given
o ipv4 bits not scaling to internet growth
o increase in multi-homing
o internet growth
nats, siit/nat-pt and ipv4/ipv4 nat will increase
combined, this very well may create pressure to globally route longer ipv4 prefixes.
Since this old thread recently became alive (momentarily), and I read
through the posts, (perhaps, again!) ...
Patrick, I would like to understand why you said that routers handling 10G
traffic in DFZ are not bothered (much) by a few extra prefixes? Isn't this
counter-intuitive? For example, for the worst case packet size of 40 bytes,
a router has only 32ns to completely
process a packet (including lookup!) in order to support 10Gb/s line rates.
The higher rates leave with even smaller time, which makes me think that
it's the "slow running" routers that should not be bothered *much* by a
small increase in the number of prefixes. Or, were you referring to 10G
routers "slow running" by comparing them with 100G routers? I do not except
anyone to have such a long memory, so you may want to skim through the
following
