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New Member

Dual T1's and Frame Relay Traffic Shapping

Heres what I'm looking to accomplish. We currently have 2 T1's with a CIR 1024 per T1. I would like to setup traffic shaping to handle congestion. What would be the best way to go about this? Or, where should I start? We are currently utilizing CEF load balancing (per packet).

Thanks,

joel-metz

  • WAN Routing and Switching
1 ACCEPTED SOLUTION

Accepted Solutions

Re: Dual T1's and Frame Relay Traffic Shapping

By default, the router assumes the Bc to be the cir. This could get you into trouble during periods of congestion as you would oversubscribe the PVC big time.

You need to configure the bc to 48000 assuming you are going to use the CIR of 1536000. There are 32 Tc intervals when the CIR is set to 1536k. If you do the math here, 1536000/32 it comes out to 48000.

To verify your work, do a 'show frame pvc (dlci)' and it should look like something below.

R1#show frame-r pvc 102

PVC Statistics for interface Serial0/0 (Frame Relay DTE)

DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0.1

input pkts 11 output pkts 4188 in bytes 644

out bytes 349129 dropped pkts 0 in pkts dropped 0

out pkts dropped 0 out bytes dropped 0

in FECN pkts 0 in BECN pkts 0 out FECN pkts 0

out BECN pkts 0 in DE pkts 0 out DE pkts 0

out bcast pkts 4112 out bcast bytes 343581

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

pvc create time 05:03:15, last time pvc status changed 05:01:47

cir 1536000 bc 48000 be 0 byte limit 6000 interval 31

mincir 1024000 byte increment 5952 Adaptive Shaping none

pkts 290 bytes 23928 pkts delayed 0 bytes delayed 0

shaping inactive

traffic shaping drops 0

Queueing strategy: fifo

Output queue 0/40, 0 drop, 0 dequeued

Check out the following example on CCO and it should make more sense.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a00800942f8.shtml

Let me know if it helped.

--Sundar

6 REPLIES
Purple

Re: Dual T1's and Frame Relay Traffic Shapping

Hi Joel,

How many DLCIs do you have per T1 ? That, and the CIR for each of them, will determine how you shape your traffic out.

Paresh

New Member

Re: Dual T1's and Frame Relay Traffic Shapping

Thanks Paresh for a quick response!

We have one DLCI per T1 circuit. They both have a CIR of 1024.

HTH

joel-metz

Purple

Re: Dual T1's and Frame Relay Traffic Shapping

Then it's easy...

Here's what you can do:

interface Serial0/0:1

no ip address

encapsulation frame-relay IETF

load-interval 30

no fair-queue

frame-relay traffic-shaping

!

interface Serial0/0:1.16 point-to-point

ip address 10.1.1.1 255.255.255.0

frame-relay interface-dlci 16

frame-relay class Shape1024k

!

map-class frame-relay Shape1024k

frame-relay traffic-rate 1024000 1024000

Do the same for the other T1 and you are done !

Hope that helps - pls rate the post if it does.

Paresh

New Member

Re: Dual T1's and Frame Relay Traffic Shapping

Paresh,

What about handling congestion notifications, throttling back when this occurs? Also, do I need to configure the home end as well?

Thanks,

joel-metz

Purple

Re: Dual T1's and Frame Relay Traffic Shapping

If you are getting BECNs from your provider, you can do the following:

interface Serial0/0:1

no ip address

encapsulation frame-relay IETF

load-interval 30

no fair-queue

frame-relay traffic-shaping

!

interface Serial0/0:1.16 point-to-point

ip address 10.1.1.1 255.255.255.0

frame-relay interface-dlci 16

frame-relay class Shape1024k

!

map-class frame-relay Shape1024k

frame-relay cir 1536000

frame-relay mincir 1024000

frame-relay adaptive-shaping becn

With the above config, your router will attempt to shape out at 1536k, the T1 max rate. If it starts receiving BECNs, it will drop down to a minumum of 1024k.

Yes, you do need to configure both ends.

Paresh

Re: Dual T1's and Frame Relay Traffic Shapping

By default, the router assumes the Bc to be the cir. This could get you into trouble during periods of congestion as you would oversubscribe the PVC big time.

You need to configure the bc to 48000 assuming you are going to use the CIR of 1536000. There are 32 Tc intervals when the CIR is set to 1536k. If you do the math here, 1536000/32 it comes out to 48000.

To verify your work, do a 'show frame pvc (dlci)' and it should look like something below.

R1#show frame-r pvc 102

PVC Statistics for interface Serial0/0 (Frame Relay DTE)

DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0.1

input pkts 11 output pkts 4188 in bytes 644

out bytes 349129 dropped pkts 0 in pkts dropped 0

out pkts dropped 0 out bytes dropped 0

in FECN pkts 0 in BECN pkts 0 out FECN pkts 0

out BECN pkts 0 in DE pkts 0 out DE pkts 0

out bcast pkts 4112 out bcast bytes 343581

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

pvc create time 05:03:15, last time pvc status changed 05:01:47

cir 1536000 bc 48000 be 0 byte limit 6000 interval 31

mincir 1024000 byte increment 5952 Adaptive Shaping none

pkts 290 bytes 23928 pkts delayed 0 bytes delayed 0

shaping inactive

traffic shaping drops 0

Queueing strategy: fifo

Output queue 0/40, 0 drop, 0 dequeued

Check out the following example on CCO and it should make more sense.

http://www.cisco.com/en/US/tech/tk713/tk237/technologies_configuration_example09186a00800942f8.shtml

Let me know if it helped.

--Sundar

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