Route distribution from IBGP Into EBGP and Filtrering issues

Routing & Switching BGP
#1

I have a difficult lab which I have to do where there are three routers each TOP , RIGHT and LEFT having an internal BGP with AS 300 and on the one side OSPF and the other side EIGRP and both have loopbacks etc where routes are disterbuted between OSPF and EIGRP but in the mean time I am running an IPV6 tunnel from the TOP router into another router located in AS 500 which is not an IBGP. The quesion is that all the routes coming to the AS 300 and going from AS 300 should be done through the Router RIGHT , I want to use AS Path or Local Pref with help of route-maps but does not know exactly how I do it and where to put them ?

To be mentioned that the Routes between LEFT and RIGHT should be used as a backup link

Avancerade Routing Bild (1)
Avancerade Routing Bild (1)986×883 87.3 KB
with the help of static routes. The 172.2.0.0 network should be summerized in BGP LEFT and RIGHT.

In the mean time is it so that in the internal BGP we should use update source loopback but not in EBGP ? And what does the network command do in this case ?

Waiting for your kind responce,

#2

Hello Masood

Just to confirm, routers TOP, RIGHT and LEF are all three in AS300 correct? And within AS300, you are running OSPF in one part of the network, and EIGRP in the other. This is fine, BGP will function as long as routing between all iBGP routers is enabled.

Now, you want to be able to influence traffic so that all communication into and out of AS300 takes place through the RIGHT router. Remember that you have full control of your outgoing traffic. You can choose which router will be used for outbound traffic using the Local Preference BGP attribute. You can take a look at this lesson which describes in detail how this should be implemented:

Now for incoming traffic, you can use the AS Path attribute. Details on how to configure this can be found in the following lesson:

You can also use the BGP MED attribute to influence incoming traffic. Take a look at this lesson as well:

Now remember that from the point of view of your own AS, you can influence which path incoming traffic should take, but you do not have ultimate control. You may use ASPathPrepending or MED, but the receiving AS can override this information if they wish. If both AS’es are under your control, then you have no problem, but often such configurations are done at the network edge where you connect to the ISP. In such a case you should talk with your ISP and let them know what you intend to do.

I believe that if you go over these lessons you will get a clear idea of how to implement what it is that you want to achieve. If you run into any difficulties, you know where to find us!

I hope this has been helpful!

Laz