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Router Config Frame-Relay Question

Posted on 2003-11-30
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Last Modified: 2010-04-17
Looking to learn more about my frame-relay configurations.  I currently have about 30 or so frame circuits pointing to my host port which is a full T1.  The remote sites (the z end) are a mixture or fractional T1 and 56K frame circuits.  I want to configure the routers properly and I know there must be some things I can do to tweek the interfaces... especially those interfaces that are trying to throw data out a full T1 and into a 56K... is there a way to adjust packet size or maybe throttle... (non technical work sorry)..

Essentially I am looking to learn how to better utilize the bandwidth I have... I want to think about priority of traffic as well.. can anyone get me started?  Thank you..

Essentially now I have a host router 3620 which has a serial interface connected to my CSU... on that serial interface I have sub interfaces... basic config is all I have.. just the necessary component on the config.

Thank you so much for your help in advance.
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Question by:NTGuru705
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sheahmed earned 125 total points
ID: 9848333
High speed to low speed circuit mismatches are possible while dealing with FR ...

If a site has a T1 line into the cloud, while the remote site has a lower speed (56 Kbps). In this case, you need to rate-limit the hub site so that it does not exceed the remote side access rate.

and also ...

If hub site has a single T1 line into the cloud, while the remote sites also have a full T1 line into the cloud, connecting to the same hub site. In this case, you need to rate-limit the remote sites so as to not overrun the hub.

note that: Access Rate is the physical line speed of the interface connecting to the Frame Relay. The guaranteed rate is the committed information rate (CIR) the Telco has given for the PVC.

Frame Relay Traffic Shaping enables an interface enables both traffic shaping and per-VC queueing on all the interface's PVCs and SVCs. Traffic shaping enables the router to control the circuit's output rate and react to congestion notification information if also configured

configuration of frame relay traffic shaping isnt quite difficult and you can find it here...

http://www.cisco.com/warp/public/125/traffic_shaping_6151.html#conf

hope u'll find it easy and more interesting ...

Rgrds, Sheeraz Ahmed

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Assisted Solution

by:NicBrey
NicBrey earned 125 total points
ID: 9849200
Agree with everything that Sheeraz said.
The congestion notification messages are called BECNs and FECNs. (backward explicit congestion notification and forward explicit congestion notification) They are key to the configuration of frame relay traffic shaping.

Here is all the commands you will need to shape the traffic across your PVC's.

Router(config)#map-class frame-relay <map class name>
Define the map class

Router(config-map-class)#frame-relay adaptive-shaping becn
Specify that the router should respond to BECN requests for throughput reduction.

Router(config-map-class)#frame-relay cir [in | out] <bits>
The rate in the frame-relay cir command is expressed in bps and should be the rate at which
transmission should be sent in periods with no congestion.

Router(config-map-class)#frame-relay bc [in | out] <bits>
The Bc is the amount to be transmitted per interval in bytes (usually CIR ÷ 8).

Router(config-map-class)#frame-relay be [in | out] <bits>
The Be is the additional amount to be sent in the first interval.

Router(config-map-class)#frame-relay mincir [in | out] <bits>
Note that the MinCIR in this command is the CIR that was negotiated with the telco. It is usually one-half the actual CIR.

Then you apply it to your sub interface:
Router(config)#int s 0
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay traffic-shaping
Router(config-if)#interface serial 0.1 point-to-point
Router(config-subif)#ip address <Addres and mask>
Router(config-subif)#frame-relay interface-dlci <your dlci>
Router(config-fr-dlci)#class <map class name>

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by:NTGuru705
ID: 9982223
Just so you know I am still on this topic I have just been side tracked... will get back to it.. thank you for your excellent advice..

THank you
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Author Comment

by:NTGuru705
ID: 10026455
Thinking on this question still..

=================================
Router(config-map-class)#frame-relay cir [in | out] <bits>
The rate in the frame-relay cir command is expressed in bps and should be the rate at which
transmission should be sent in periods with no congestion.
=================================
Is the above speed the port speed of the remote site?  I am confused on this.. If my port is 256 but my cir is 128 should it be 128 or 256?

=================================
Router(config-map-class)#frame-relay bc [in | out] <bits>
The Bc is the amount to be transmitted per interval in bytes (usually CIR ÷ 8).
=================================
What is per interval?

=================================
Router(config-map-class)#frame-relay be [in | out] <bits>
The Be is the additional amount to be sent in the first interval.
=================================
What is the additional amount?

I suppose I simply create multiple map-class for each configuration such as 128 CIR and 256 CIR I will need two map-class right?  Then I apply to the correct interfaces.


Thanks for the help.
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LVL 1

Author Comment

by:NTGuru705
ID: 10028906
I understand what cir is but the post says..

The rate in the frame-relay cir command is expressed in bps and should be the rate at which
transmission should be sent in periods with no congestion.

I see now.. this map-class only happens when BECNs occur.. thus you would not want to burst to port at that time.

Thank you
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