frame Relay bottleneck

Answered Question
Jun 16th, 2009

hello ALL

We have some branches connected with frame relay with 256kbps bandwidth.

sometime we need to use all these bandwidth for file transferring or other purposes. It seems that connection could not be use 100% this can be viewed by monitoring software or router interface (please see below).

does have on frame relay any restriction (knowing that is packet switching) to be like this, or on provider side must be any congestion or configuration that is not permitting to use full bandwidth

thanks in advance

Serial0:1 is up, line protocol is up

Hardware is DSX1

Description: **conn to XXXX**

Internet address is

MTU 1500 bytes, BW 256 Kbit, DLY 20000 usec,

reliability 255/255, txload 100/255, rxload 120/255

Encapsulation FRAME-RELAY, loopback not set

Keepalive set (10 sec)

I have this problem too.
0 votes
Correct Answer by Edison Ortiz about 7 years 5 months ago

Your FRTS configuration is limiting the circuit to 200kbps.

If you want to use the full 256kbps, you need to modify your FRTS config.




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Overall Rating: 5 (3 ratings)
vmiller Tue, 06/16/2009 - 07:26

First thing, what is the Committed Information Rate ?. Its not always the case that B/W = CIR.

next get comfortable with some of the show commands and start looking to see if anything is being discarded (FECNs &BECNS)

or marked discard elegible.

last but not least. examine the tcp workstation settings. Tht is more often than naught the culprit.

adriatikb Tue, 06/16/2009 - 07:42


nothing is discarding

In our case CIR is 256Kbps.

PVC Statistics for interface Serial0:1 (Frame Relay DTE)

Active Inactive Deleted Static

Local 1 0 0 0

Switched 0 0 0 0

Unused 0 0 0 0


input pkts 17549400 output pkts 16789498 in bytes 1988967189

out bytes 1216136232 pkts dropped in 0

pkts dropped out 9346 dropped bytes out 3560646

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 47 out bcast bytes 1598

5 minute input rate 0 bits/sec, 2 packets/sec

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

Shaping adapts to BECN

pvc create time 5w0d, last time pvc status changed 5d20

Edison Ortiz Tue, 06/16/2009 - 07:29

Can you provide us with the whole config?

Are you using any type of QoS (GTS or FRTS)?

On Frame-Relay, you get 2 numbers; 1:Port Speed, 2: CIR.

The CIR is the maximum the provider will allow you to burst to. This amount isn't guaranteed.

The Port speed reflects the guaranteed speed you've purchased and usually is half of the CIR.

So if you have a 256kbps FR circuit, the guaranteed speed is usually half of that - 128kbps.

If you check your show frame pvc and notice a lot of DE packets (Discard Eligible) and BECN packets (Backward explicit congestion notification) then you have an oversubscribed network.




adriatikb Tue, 06/16/2009 - 07:48

Please see below:

interface Serial0:1

description **conn to XXXX**

bandwidth 256

ip address

encapsulation frame-relay

no fair-queue

frame-relay class map1

frame-relay traffic-shaping

frame-relay interface-dlci 53

map-class frame-relay map1

frame-relay cir 200000

frame-relay bc 2000

frame-relay adaptive-shaping becn

Correct Answer
Edison Ortiz Tue, 06/16/2009 - 07:51

Your FRTS configuration is limiting the circuit to 200kbps.

If you want to use the full 256kbps, you need to modify your FRTS config.





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