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List:       inet-access
Subject:    Re: Packet over SONET cards for cisco
From:       nishal goburdhan <nishal () is ! co ! za>
Date:       2005-05-12 19:13:27
Message-ID: 20050512191327.GF66866 () is ! co ! za
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On Thu, May 12, 2005 at 10:00:31AM -0700, Daniel J. Vance wrote:
> Hi,
 
hi.

> I know there may be a better list for this, but I'm guessing most of the
> people on this list have done a few OC3s with Cisco gear.


what gear are you planning on using?    :)
just 75xx?  since you obviously won't be able to re-use the POS-IP...

 
> I'm looking to connect two routers together via an OC3.  The PA-POS-OC3SMI
> cards are roughly 2500 right now.   I have a source for POSIP-OC3-40-SM
> cards at about $300/each.  Is there really that much difference between the
> cards for doing IP between sites?  Is the POSIP fully supported in the newer
> IOSs?


disclaimer:  i've never used a POSIP-OC3-40-SM.

but iirc, you would probably expect to see less than the performance that you could \
gain on a vip2-50 + corresponding PA. we currently have one OC3 (vip2-50 + \
PA-POS-OC3SMI) that routinely drops packets when it gets to about 50mb/s.   although \
the bandwidth rate is low, we reckon it's the pps rate and VIP cpu load that kills \
the VIP.   of course, since it's on a transit interface, we do packet \
colouring/uRPF/syn-rate-limiting/etc.

right now:
  30 second input rate 39749000 bits/sec, 9527 packets/sec
  30 second output rate 39830000 bits/sec, 18381 packets/sec

and:
VIP-Slot10>sh proc cpu
CPU utilization for five seconds: 78%/78%; one minute: 81%; five minutes: 81%

> (

ymmv.

otoh, ealier this year, we purchased the PA-POS-2OC3-SMI cards.  picking just one of \
those (7200 npe-g1), with:  30 second input rate 100112000 bits/sec, 19732 \
packets/sec  30 second output rate 10479000 bits/sec, 7728 packets/sec
  30 second input rate 10728000 bits/sec, 7732 packets/sec
  30 second output rate 99482000 bits/sec, 19735 packets/sec

cpu load is 
CPU utilization for five seconds: 17%/16%; one minute: 17%; five minutes: 18%


why am i telling you this?  :)
based on our experiences with 75xx i'd not want to even think about running an OC3 at \
close to full rate. you could always get a better VIP, but those are still pretty \
expensive as compared to a VXR chassis. so if you want the capability of moving to a \
different chassis later, well the PA is obviously your better/only option.

again, ymmv.

[aside:  i remember one of the cisco folk at their RTP facility telling me last year \
that when they tested the PA-POS-2OC3-SMI they could get much better performance on \
it, than the earlier PA-POS-OC3SMI.  he wouldn't let me take the test results, but at \
a marginal price cost, it made sense for me at the time to get the dual port.]

--n.

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