Arista Routing Solutions

Thu Apr 28 05:33:18 UTC 2016

On Wed, Apr 27, 2016 at 4:41 PM, Peter Kranz <pkranz at unwiredltd.com> wrote:

>         Curious if you have any thoughts on the longevity of the 7500R and
> 7280R survival's with IPv4 full tables? How full are you seeing the TCAM
> getting today (I'm assuming they are doing some form of selective
> download)? And if we are currently adding 100k/routes a year, how much
> longer will it last?
>

I can't speak for Ryan or Netflix, but we (Arista) are stating our
technique is good for 1M+ prefixes of IPv4+v6 combined.  Internet right now
is at between 575K and 635K IPv4 and between 28K and 35K IPv6 right now and
its taken many many many years to get there, its foreseeable there's many
years of growth there.
Note that we don't do static partitioning between IPv4 and IPv6 and our how
we do it has more headroom in it than we state, so we're confident.  We're
also not doing "selective download", this is every prefix in current table.

What I can share is two different scenarios today:

1. a traditional internet edge router with multiple transit/peer providers,
Internet as of right now, and a cloud customer  that also has hundreds of
thousands of prefixes internally
Ryan's case might be different to others, but here are three scenarios
deployed today: 1. a large hosting provider with full tables and many
internal prefixes, 2. a cloud deployment.

The former is at 854K IPv4 and 35K IPv6 of 'internet' as of a few weeks ago:

7500R# show ip route summary | grep Total
Total Routes                                          575127
7500R# show ipv6 route summary | grep Total
 Total Routes                          35511
7500R# show hardware capacity | grep Routing
Forwarding Resources Usage

Table    Feature    Chip         Used   Used      Free   Committed   Best
Case       High
                              Entries    (%)   Entries     Entries
Max  Watermark

 Entries
-------- ---------- --------- -------- ------ --------- -----------
----------- ---------
Routing  Resource1                  815   39%     1233           0
 2048        817
Routing  Resource2                  469   45%      555           0
 1024        471
Routing  Resource3                14074   42%    18694           0
32768      14098
Routing  V4Routes                696364   88%    89753           0
 786432     697110
Routing  V6Routes                     0    0%    89753           0
 786432          0

The latter is at 854K IPv4 + 45K IPv6:

7500R# show ip route summary | grep Total
Total Routes                                          854393
7500R# show ipv6 route summary | grep Total
 Total Routes                          45678
7500R# show hardware capacity | grep Routing
Forwarding Resources Usage

Table    Feature    Chip         Used   Used      Free   Committed   Best
Case       High
                              Entries    (%)   Entries     Entries
Max  Watermark

 Entries
-------- ---------- --------- -------- ------ --------- -----------
----------- ---------
Routing  Resource1               1319    64%       729           0
 2048       1320
Routing  Resource2                809    79%       215           0
 1024        814
Routing  Resource3              24102    73%      8666           0
32768      24104
Routing  V4Routes              644336    83%    124302           0
 786432     644364
Routing  V6Routes               17792    12%    124302           0
 786432      17795

One could ask Geoff Huston where he thinks combined IPv4+v6 will exceed 1M
entries but I would expect it to be many years away based on
http://bgp.potaroo.net/ and we'd welcome discussions about if it you want
to know our opinion [*] on how we're doing it will scale.  What we're doing
doesn't explode at 1M, there's headroom in it hence why we say "1M+". Again
we're happy to talk about it, just ask your friendly arista person and if
you don't know who to ask, ask me and i'll put you in touch with the right
folks.

cheers,

lincoln.  [*] ltd at arista.com