[147938] in North American Network Operators' Group
Re: subnet prefix length > 64 breaks IPv6?
daemon@ATHENA.MIT.EDU (sthaug@nethelp.no)
Wed Dec 28 09:42:06 2011
Date: Wed, 28 Dec 2011 15:41:14 +0100 (CET)
To: glen.kent@gmail.com
From: sthaug@nethelp.no
In-Reply-To: <CAPLq3UNsfjKbadHgyRPDB1mH279Hj9ZvoFMPPu2VVHVPADM1dw@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> Most vendors have a TCAM that by default does IPv6 routing for netmasks <=64.
>
> They have a separate TCAM (which is usually limited in size) that does
> routing for masks >64 and <=128.
Please provide references. I haven't seen any documentation of such an
architecture myself.
> TCAMs are expensive and increase the BOM cost of routers. Storing
> routes with masks > 64 takes up twice the number of TCAM entries as
> the routes with masks <= 64. Since IPv6 is *supposed* to work with /64
> masks, most vendors (usually the not-so-expensive-routers) provide a
> smaller TCAM for > /64 masks.
Ah, but do the "not-so-expensive-routers" use TCAM at all?
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
