nanog mailing list archives

Re: subnet prefix length > 64 breaks IPv6?


From: sthaug () nethelp no
Date: Sat, 07 Jan 2012 14:24:28 +0100 (CET)

 "Note: An IPv4 route requires only one TCAM entry. Because of the
    hardware compression scheme used for IPv6, an IPv6 route can take
    more than one TCAM entry, reducing the number of entries forwarded
    in hardware. For example, for IPv6 directly connected IP addresses,
    the desktop template might allow less than two thousand entries."


Translated: "The stated numbers for IPv6 routes are twice the real max.
However, prefix compression may give better utilisation under certain
conditions".

Thanks, that's the first *specific* information I've seen of equipment
that might have problems (reduced number of entries) with longer than
64 bit prefixes. Fortunately we're not using 3560/3750 for IPv6 routing
at the moment.

Any other takers?

Steinar Haug, Nethelp consulting, sthaug () nethelp no


Current thread: