Limit the bandwitch

[Tauer Drumond]

Hi all,

I have a 2801 router.

I have a 34MB link from ISP plugged at my interface f0/1, but I would like to use only 12MB. Can I restrict the bandwitch on the router?

Thanks

Tauer

[Tauer Drumond]

Hi Joseph,

The main goal to restrit the bandwitch is that my router has many other links coming to him and the fastehternet is becoming full.

My organization bought a 34MB dedicate link, but the router will not support an aditional 34MB, it will only support 12MB.

So...ill try to do what you and the other guys said, to apply a shaper on outside and inside interface as well.

Thank for reply

[paolo bevilacqua]

Oi, I wanted to come back to the fact you believe the 2801 supports only 12 MB, how did you arrived to this conclusion ?

[Tauer Drumond]

Oi, Maybe im wrong but we have 4 link with differents clients: 2x34MB, 1x12MB, 1x8. This is equal 88M, and the router interface is 100MB. so, I have only 12MB to add.

[Joseph W. Doherty]

A bit confusing, unless you have something like a WAN FastEthernet handoff, which actually delivers 100 Mbps capacity, and you're trying to partition the bandwidth between customers.

One issue to consider, even though a 2801 has FastEthernet interfaces, it doesn't really have the performance to sustain FastEthernet line rates. I believe there's a less of a performance requirement to police inbound vs. shape outbound, so this might be an instance where a policer might be better for your needs. Also, if possible, to also minimize performance required on your 2801, it would be best to control inbound traffic on far side device's outbound.

[paolo bevilacqua]

One thing is that it's unlikely you can use 100 mbps interface a wire speed in a 2801.

Seems like you need to clarify better how your network is designed and why you got such a small router for so many fast links.

[Tauer Drumond]

Hi,

sorry about confusing. Check the attachment.

I have 4 link from ISPs. And we bought a new one (34Mbps). If we calculate the result will be 122Mbps and the interface of router is a 100Mbps one.

[Pravin Phadte]

Hi,

Looking at the diagram makes me feel that there would be a bootleneck, conjestion, packet drop and high cpu utilization on the switch and the router.

Would still wait for some experts comments on this.

Regrads,

Pravin

[Tauer Drumond]

Actually, I segment every external network on VLANS (on 2950) and subinterfaces at router. It helps me a little bit and dont have many problems with what you said above.

Anyway, my only trouble is not allow the sub-interface on router flow more than 12Mbps.

Thanks once more

Tauer

[Pravin Phadte]

Hi,

I guess this is for inbound and outbound traffic limit which you are looking for.

It was pointed out well above about the rate limit and i was able to test it and had few latency in ping in rate-limit.

The below link has one more way where you can limit the BW. It says only "outbond".

I was not able to test this. It has one way of adding access-list for the traffic shape.

If you would like to test it not so sure what would be the result but you can apply the access-list for tcp any any and udp any any and apply it on interface with access-group in and out and check if it limits the bandwidth.

http://www.cisco.com/en/US/docs/ios/12_1/qos/configuration/guide/qcdgts.html

I a bit tuff for me to belive that the network is working fine without any errors in the above setup.

Anyways as long as it working fine its good.

Hope this helps.

regards,

Pravin

[paolo bevilacqua]

Hi, what Joseph and I are telling you is that the 2801 will not be able to handle the 100 mbps in full duplex at or near wirespeed, so no matter of shaping or not, you need to upgrade to a bigger router. Your expensive circuits need a faster hardware to be used in full.

See attached document for performance guidelines on routers.

[Tauer Drumond]

Hi, but is the way im thinking wrong?

Cause im just adding the values and getting a result: 34+34+12+8=88Mbps. If I add more 34Mbps, I think I'll have a problem, cause my fastethernet is a 100Mbps only.

Thanks once more.

Tauer

[paolo bevilacqua]

You will have a problem anyway, because router performance is measure in packets per second (PPS).

Once you go above a certain number of PPS to hit the router, when the hardware is not fast enogu (the 2801 is not very fast), the router CPU will go very high, and packets will be dropped and things will work poorly. At that point, either if you shape or rate limit, that will not change anything, because the damage is done already.

You could then rate limit on the switch, but my suggestion is to get a faster router. Else, why did you took so many fast circuits ?

[Pravin Phadte]

Hi,

Experts plz suggest for the best.

I got the above Generic Traffic Shaping (GTS) tested.

Connected 2 routers serial back 2 back.

Rouetr 1 config.

interface Serial0/0

bandwidth 16

ip address 20.1.1.1 255.255.255.0

ip access-group 101 in

ip access-group 101 out

encapsulation ppp

serial restart-delay 0

traffic-shape group 101 9000 1125 1125 1000

access-list 101 permit tcp any any

access-list 101 permit udp any any

access-list 101 permit ip any any

The BW is been set to 9 Kb since i would be testing on extended ping. Bandwidth command is put to check the rx and tx can be ignored.

I tried this also with 8000 since it was min and the results did not go above 8 K. Same i tried by chaing it to 9K and the results did not go above 9k

Attached is the logs.

regards,

Pravin

[paolo bevilacqua]

Hi, you cannot test with pings. You need proper traffic generators on both sides of the circuit. That is not very easy to do, but it is the only way to get valid results.

[Pravin Phadte]

Hi,

Thats some prob i cant use it on my live network unless i have a request for some new. Well yes compared to rate limit there were no ping drops.

I totaly agree that its not the best way to test. Its the only option i had.

Anyone if someone gets it tested would help me.

Regards,

Pravin