[c-nsp] C2950G sh arp

[Jon Lewis]

On Thu, 8 Jun 2006, Kenny Sallee wrote:

> Just had that problem today - make sure you have the 'ip 
> default-gateway' set on the 2950's and disable proxy arp.  Proxy arp is 
> enabled by default on Cisco routers and I personally don't think it 
> should be. Just masks routing problems and makes others difficult to 
> troubleshoot. Kenny

I was just looking at a similar "issue" that's not really a problem yet, 
but just looks ugly.  With no default-gateway (in no ip routing mode), a 
3550 will arp in order to reach any address.  With the everpresent 
scanning on the internet and long default arp cache timeout, that results 
in an arp table mess.

Given a L3 capable switch that provides L2 connectivity for several 
routers in one POP with routers in several other POPs, do you:

a) pick 1 local router to be the switch's default-gateway?..knowing that 
if there's an outage of that 1 router, you've lost remote management of 
the switch...though it'd still be reachable from any of the devices 
directly connected to it.

b) pick 1 virtual IP to be the switch's default-gateway and 
use HSRP/VRRP/etc on the "local" routers to provide that virtual IP?

c) turn on ip routing and run your IGP (OSPF) on an SVI, knowing that due 
to the switch's limitations on routing table size and location in your 
network (firmly planted in area 0) you will eventually outgrow its routing 
table capability?  "ah, but we'll upgrade it to something better before 
then...right?"

d) give it a management uplink into an access switch that has redundant 
uplinks, using the access switch as default-gateway?

e) something else?

c would be tempting if not for the routing table size limitation.  d seems 
to be the simplest solution.

----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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