[c-nsp] Failover with 3550-SMI

[Marco Matarazzo]

Jeff,

> I'd say option 1 is the best one:
> 1. it costs nothing
> 2. get rid of RIP
>
> You could put all customers in 1 VLAN --> 1 PVLAN per customer  so only
> one instance of HSRP is needed.

But this requires renumbering them... and also, to what I see from Cisco
website, 3550s only support PVLAN Edge, so ports on different switches can
still talk to each other... or am I missing something?

Thanks!
]\/[arco


My .5 cent

Jeff


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Marco Matarazzo
Sent: Thursday, November 25, 2004 3:19 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Failover with 3550-SMI

Hi all,

I manage a colo-like network, quite simple:

Two borders (7206/NPE400/256Mb) each talking eBGP with two upstreams
(double feed each upstream) and iBGP between them.
Those two 7206 trunk each into a different 2950T-24, that are also
connected together. Then finally a couple of 3550-48-SMI, each connected
with both switches, that talk RIPv2 with the borders (they announce the
connected routes, and take the default gw from the borders). All the
ports are layer3 (except the links to the switches that are layer2,
configured for spanning tree).
In this setup I can only see the 3550 as Single Points of Failure.
Now some customers want dual ethernet for failover. I can see three
scenarios:

1) Put them on the two 3550 layer2 ports, and route the vlan directly on
the border, using HSRP on the border for default gateway failover.
2) Upgrade the 3550-SMI to EMI, and run HSRP between the two customers
facing interfaces.
3) Don't upgrade the 3550, add little router to the customer and
advertise the default route to this router via RIP.

Is there something I overlooked? Could I use some other failover method?
Which of the three would you use? I prefer the third solution, as it
keeps the border and the distribution completely separated, and it seems
more manageable. But that's also the most waste of IP space (need two
additionals /30). Number 1 could also be feasible, but if number of
customers wanting dual ethernet rises, I think that 30 or 40 HSRP
istances together with two full BGP feeds and three downstreams,
netflow, RIP and some access-lists could kill the router (transit
traffic is 40Mbps, router is as 25/30% CPU).
Number 2 is expensive (the upgrade to smi to emi), and again, could
theorically a 3550 handle 48 HSRP instances easily?

Thanks!
]\/[arco

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