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7507 Output Drops

jphilope
Level 3
Level 3

Hi,

Need some reassurance I'm on the right track.

We just switched our ATM PVCs over to a 7507 using a PA-A3-T3 card and running in a VIP4-80 and dual RSP4 processors. We upgraded the circuit from a full T-1 to a fractional T3 running at 25meg.

We were experiencing a lot of output drops on the 3662 we had the PVCs on before the move and continue to have a lot of output drops on the 7507. These drops occur on our high volume/speed CIR PVCs and do not on our low volume/speed CIR PVCs.

Router is running IOS version 12.3(13)T1.

Now, all the research I've done so far shows I need to enable some form of queueing (we only use FIFO currently) and it seems DWRED Per-VC is the way to go. This way I can utilize the processing capability of the VIP4-80 we have the PA-A3 installed in.

We did not use anything other than FIFo queueing on the 3662.

So, now onto my questions. Is Per VC-DWRED the way to go (I already have the Cisco doc on this, so no link necessary)? What pitfalls should I lookout for (particularly in the configuration of the individual ATM subinterfaces and globally)?

I'm sure someone out there has had similar experiences and what results should I look for?

To sum up the scope of the problem, I've had 603035 output drops on the main interface in 1d16h since last counter reset.

Here's the current interface and subinterface config:

interface ATM0/1/0

description *** AT&T DNAC/80/ATI ***

mtu 1500

bandwidth 25024

no ip address

no atm auto-configuration

no atm ilmi-keepalive

no atm address-registration

no atm ilmi-enable

interface ATM0/1/0.40 point-to-point

description *** PVC to W L, CT ***

ip address 10.222.0.41 255.255.255.252

ipx network 222A400F

ipx type-20-propagation

pvc 2/40

protocol ip 10.222.0.42 broadcast

vbr-nrt 1244 1244

oam-pvc manage

As you can see, we are routing IP and IPX. Is there something I need to look for for IPX as well?

I thank you for your help in advance.

2 Replies 2

jphilope
Level 3
Level 3

Is there no one out there who can offer advise or assistance?

Thank You

Jim

johansens
Level 4
Level 4

As you stated, you think you have to do some queueing/buffering. I'm sure you have followed this link, but I'll post it anyway:

http://www.cisco.com/en/US/tech/tk39/tk48/technologies_tech_note09186a00800c93dc.shtml

DWRED is a good solution to queuing as it does it preemptively and in a 'nice' way.

I don't have any experience in this exact setup, so I can't help you too much..