I thought it was urban lore until I started digging into data sheets for various DC switches covered in my DC Fabrics webinar (yeah, couldn't resist ;)
All high-speed DC switches use some variant of TCAM-based forwarding. Most of them have shared TCAM for IPv4 and IPv6 with IPv6 table size being 1/2 IPv4 table size. Draw your own conclusions. Juniper EX series is the only exception (AFAIR) with IPv6 table size being 1/4 of the IPv4 table size. Cisco seems to be one of the few vendors with well-documented limitations: Nexus 5500 has 16K shared IPv4+IPv6(probably /64) routes and 128 LPM IPv6 routes. http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/configuration_limits/limits_521/nexus_5000_config_limits_521.html#wp328407 Do I have to go into what happens when a switch runs out of TCAM? Ivan > -----Original Message----- > From: [email protected] [mailto:ipv6- > [email protected]] On Behalf Of Gert > Doering > Sent: Sunday, June 02, 2013 5:00 PM > To: Jeroen Massar > Cc: cb.list6; Arturo Servin; [email protected] > Subject: Re: Point-to-point /64 > > Hi, > > On Sat, Jun 01, 2013 at 01:56:23PM -0700, Jeroen Massar wrote: > > One thing to keep in mind though is that quite some gear is optimized > > upto the first /64 bits, and might use slower paths for longer > > prefixes, > > I keep hearing this statement, but so far, have never heard specifics > about "which gear is that" and "how big is the impact", so I tend to file > this under "urban lore". > > Do you have specifics? Which vendors, which platforms, what impact? > > Gert Doering > -- NetMaster > -- > have you enabled IPv6 on something today...? > > SpaceNet AG Vorstand: Sebastian v. Bomhard > Joseph-Dollinger-Bogen 14 Aufsichtsratsvors.: A. Grundner- > Culemann > D-80807 Muenchen HRB: 136055 (AG Muenchen) > Tel: +49 (89) 32356-444 USt-IdNr.: DE813185279
