Point-to-point /64

[Ivan Pepelnjak]

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: ipv6-ops-bounces+ipepelnjak=gmail.com at lists.cluenet.de [mailto:ipv6-
> ops-bounces+ipepelnjak=gmail.com at lists.cluenet.de] On Behalf Of Gert
> Doering
> Sent: Sunday, June 02, 2013 5:00 PM
> To: Jeroen Massar
> Cc: cb.list6; Arturo Servin; ipv6-ops at lists.cluenet.de
> 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...?
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