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BGP Traffic Tuning

Hi All,

This is my first post, sorry if it is covered somewhere else but I could not get the answer that I am looking for.

I am currently looking at BGP traffic tuning/engineering.

I am looking to create route maps with different values for different senarios.

I have been able to achieve this with Local Pref as i have set conditions based on the AS path.

I was wondering if it was possible to do something similar ot this with MED or AS Path Predending.

All of this configuration is in a theoretical network as I am working with this as part of my BSc project.

Must admit all configuration is currently implimented using Opnet but I am looking to move on to Cisco devices to simulate it working in the near future.

Any help would be GREAT





MED and AS Path are BGP Path Attributes such as Local Pref. If it has a meaning, you should be able to set the same conditions/actions with MED and AS path as with Local Pref. What do you target to do exactly?




You Query is not clear. Please elaborate. I can definitely help you.



generally: Local preference might be used within your AS to modify the way the traffic is sent out from your AS to your neighbors.

MED and AS path prepend are usually used to change the way your neighbors are sending the traffic to you.

But it's not clear to me what are you trying to achieve?



Thanks for the quick response, I am looking to impliment a simple form a load balancing accross links, I have found the maxium route functionality but I am also looking to impliment this with traffic engineering/tuning.

I have been able to do it with local pref as I have used match information to specify a value to be added depending on the AS path. So for exmaple if the AS path contains ASN XXX then apply value X.

I have tried this with MED and AS Path Predending to control the traffic leaving the AS but it does not appear that this functionality is support by the other methods. Is there any way that I can apply different values depending on the given route. I understand that MED is not passed beyond the neighbour. An example of the topoolgy that I am using is shown below.

All ASs have a ASN and i am looking to have the left side of the network send traffic over the left link and the right over the right link. I understand that this is a very simplified secerio for BGP but I am looking at the thoery at this stage.

As I have previuosly stated I have acheived this for outbound traffic with the use of Local Pref but I am struggling to achieve outbout.

Thanks again for you help


I have also began to research communities and I have found that many ISPs will have comunity values that you can aply in order to control the traffic leaving their network, I have started to look at this but do not fully understand, does any one know of a good place to get an example lab to achieve this. An example of this would be applying a community value that in turns applies a local pref setting to the neighbour ASs link