Wireless Networks Thread, Cisco router "rate-limit" command in Technical; I've got a new Cisco 2851 with 20mb of a T3 going in one end, and two gigabit ethernet ports ...
1st April 2008, 08:06 PM #1
Cisco router "rate-limit" command
I've got a new Cisco 2851 with 20mb of a T3 going in one end, and two gigabit ethernet ports coming out the other. Our student net is currently plugged into one of those ports, and nothing's on the other. Soon we'll move the faculty/staff net over to the unused ethernet port. It's currently on a different router with a different pipe.
Output of "show version" starts with this:
Cisco IOS Software, 2800 Software (C2800NM-SPSERVICESK9-M), Version 12.4(3g), RE
What I want to do is split our 20mb connection to 15/5 between the 2851's two ethernet ports. Our student net would get 15, and our faculty/staff net would get 5. I'm pretty sure I can configure the second port to get the network up, but I'm not confident with limiting the bandwidth usage.
Here's my guess at the rate-limit command:
rate-limit input 15000000 24000 24000 conform-action transmit exceed-action drop
rate-limit output 15000000 24000 24000 conform-action transmit exceed-action drop
Does that sound right? Do I need to provide more info?
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1st April 2008, 10:57 PM #2
Those commands look alright to me......
the one bit of information you might need to provide is how you arrived at the burst size figures.
Also, how are the T3 and gig ethernet interfaces configured at the moment ?i.e any subinterfaces set up.... provide a show run if possible.
1st April 2008, 11:03 PM #3
You going to run the phone system on that? I had a play on 2800 at my friends house. I would recommend the Cisco router field guide for quickly configuring routers.
1st April 2008, 11:18 PM #4
I wouldn't, particularly as it's used to connect to a high speed T3 connection.
Originally Posted by nicholab
Would be advisable to use it purely as the leased line router, and setup CCME and any VoIP gateways on seperate routers.
Having a T3 WIC is pretty cool, you'd never see it a brit school having an E3 even though E3 full rate has a fair bit more bandwidth, or if you did the certainly certainly wouldn't have full control of it as it appears to be the case here.
I'm guessing the T3 pipe is sub-rated.
2nd April 2008, 05:23 PM #5
I used a 20mb example from a Cisco document, and didn't adjust the burst numbers. I planned to just adjust it by testing and guessing. I was actually going to change them before doing it, I was asking about/more concerned with my syntax and strategy than with specific numbers.
We will eventually run the phone system on it. The T3 is from the same company that provides our phone service, and they're dealing with everything phone-related on it.
A normal T3 is good for something like 44mb, IIRC. That leaves 24mb for voice, which is more than we need.
Anyway, something has changed since I posted my question. I may not need to do this at all. We might be keeping our old pipe too, and just have the students alone on the new one and faculty/staff alone on the old one.
3rd April 2008, 02:33 PM #6
In that case the stragety is fine, the CAR feaure on cisco is good for implementing a basic QoS feature for rate limiting based on interface, ip and ACL. You might want to investigate the options for rate-limiting based on ACL rules or look at more advanced QoS mechanisms like traffic shaping.
Originally Posted by ronanian
Will you're service provider be providing a TDM voice service over the T3....i know in the US you can get a channelized line that will allocate 64k channels for tdm voice aswell as data. Is that the setup you plan on having or will they providing a SIP based IP telephony service over the T3 in addition to internet connectivity.
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