North American Network Operators Group

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Re: Scalability issues in the Internet routing system

  • From: Rubens Kuhl Jr.
  • Date: Wed Oct 26 10:12:12 2005
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> likewise, "FIB table growth" isn't yet a problem either - generally that
> just means "put in more SRAM" or "put in more TCAM space".

> IPv6 may change the equations around .. but we'll see ..

IPv6 will someday account for as many IPv4 networks as would exist
then, and IPv6 prefixes are twice as large as IPv4 (64 bits prefix vs
32 bits prefix+address, remainder 64 bits addresses on IPv6 are
strictly local), so despite a 3x cost increase (1 32 bit table for
IPv4, 2 for IPv6) on memory structures and 2x increase on lookup
engine(2 engines would be used for IPv6, one for IPv4), the same
techonology that can run IPv4 can do IPv6 at the same speed. As this
is not a usual demand today, even hardware routers limit the
forwarding table to the sum of IPv4 and IPv6 prefixes, and forward
IPv6 at half the rate of IPv4.