Cisco 7600 vs ASR 9000
link at pobox.com
Tue Sep 22 15:41:52 UTC 2009
On Mon, Sep 21, 2009 at 6:22 PM, Nick Colton <networkjedi at geekwhore.net> wrote:
>Cisco has been recommending the Cisco 7600 as our core router. My concern
>is that cisco told us that in the event of an RSP failover the 7600 could take up to
>30 seconds to begin routing packets again, this seems wrong to me since my
>old Extreme Networks BD 6808 can do failovers and rebuild route tables in
>under 5 seconds but??
For NSF/SSO mode the 7600 is claimed to do Sup failover in 0-3 seconds
(which jives pretty well with my experience), but with some caveats. I
think it needs to rebuild its RIB tables, which may take on the order
of 30+ seconds, after a failover and can only keep forwarding traffic
based on the state of the tables at the point of the failover. NSF/SSO
mode has a couple limitations (only BGP, OSPF, and IS-IS supported),
doesn't support IPv6 multicast, etc.
30+ seconds failover time sounds more like RPR/RPR+.
You can find a fairly good overview of this on CCO:
* NSF/SSO: http://www.cisco.com/en/US/docs/routers/7600/ios/12.2SXF/configuration/guide/nsfsso.html
* RPR/RPR+: http://www.cisco.com/en/US/docs/routers/7600/ios/12.2SXF/configuration/guide/redund.html
I run these as essentially switches with very simple LAN routing so I
can't really tell you whether there are any huge honking caveats when
you use them as actual routers (i.e. WAN/SP type applications). I know
there have been some complaints about buggy IOS versions,
unpredictable feature/module support, and the notorious 6500 vs. 7600
platform split (thank you ever so much for that one Cisco, really).
I've been pretty happy with the platform over the years, but while
it's still got plenty of oomph for my applications it is getting to be
a quite old platform. If I were to start looking at building something
new (i.e. no existing platform investment to take into account) I'd
probably be looking at Nexus for datacenter and ASR for anything
router-ish. I think 6500/7600 will still scale further up
(significantly so, iirc) and is more flexible than the ASRs (I view
the ASRs competing/replacing the 7200/7300 rather than 6500/7600), but
if you're looking at anything resembling a clean slate you'll probably
want to evaluate those alternatives.
Anyways, if you're going with Cisco then asking on the cisco-nsp list,
as was suggested elsewhere, is probably not a bad idea.
More information about the NANOG