ROUTE Practice. Path Control Scenario

[Jason Norton]

Scenario:

A router is multihomed with one Frame Relay and one MetroE connection. How would you force HTTP traffic from LAN 192.168.100.0 to use just one of the connections? It doesn’t matter which, lets say the MetroE connection. I was thinking an extended access list specifying port 80, and then applied through a route-map command?

[Scott Morris]

That would be true. But then (on the input interface), you would need "ip policy route-map" command in order to make that happen.
It's called Policy-Based Routing.


HTH,
Scott

[Learner]

Hello Jason Norton.. I am also invloved in CCNP studies..

As u mentioned this scenario.. I wanna ask that u assumed this scenario by ur self or u have found such scenario..?

Do u have such scenarios which meet the requirement of production routers.. like the scenarios which happen on production routers? Do u have such scenarios so that i can practise those scenarios on my routers?

[Jason Norton]

Just a scenario I was considering. It goes a little deeper than my book does, and it is not something I could test through GNS3 (Or, I can't figure out how to test that through GNS3, from a host perspective). I think the path control and policy based routing is my weak area.

[Jason Norton]

Okay, so the following configuration alone should accomplish this right? Assuming the next hop of the desired path is 1.1.1.1.

access-list 101 permit tcp 192.168.100.0 0.0.0.255 any eq 80
route-map PBR-HTTP permit 10
match ip address 101
set ip next hop 1.1.1.1

[ErickB]

Hiya.

You would need to apply that config to an interface.


Erick

[Scott Morris]

To expand on that further...

Code: Select all

          (Internet)
              ||
              ||
          (Router A)
              /\
             /  \
            /    \
           /      \
    (RtrB1)        (RTR B2)
  (1.1.1.1)        (2.2.2.1)
      \               /
       \             /
        \           /
  (s0/0) \         / (s0/1)
         (Router C)
             || (fa0/0)
             ||
     (192.168.100.0/24)

So let's assume that you have a default route (static or otherwise) and/or a specific /24 route that prefers S0/1 (towards 2.2.2.1) as the next hop. You want web traffic to traverse S0/0.
You would enter the configuration that you have right there on Router C. And:

int fa0/0
ip policy route-map PBR-HTTP


HTH,
Scott

[Jason Norton]

Thanks Scott and Erick. And alternatively, you could set the outgoing interface as well?

access-list 101 permit tcp 192.168.100.0 0.0.0.255 any eq 80
route-map PBR-HTTP permit 10
match ip address 101
set int s0/0
int fa0/0
ip policy route-map PBR-HTTP

[ErickB]

Yep! You can do that too!

[Learner]

By using the same scenario..

If for example i am using BGP on this scenario. There are two paths two reach RouterA, And we all know that BGP selects path using attributes. Now BGP selects 2.2.2.1 as a best path and I want to make 1.1.1.1 as a best path. Now the following configurations I use on RouterC:-

RouterC(config)# access-list 1 permit 192.168.100.0 0.0.0.255
RouterC(config)# route-map Name permit 10
RouterC(config-route-map)# set local-pref 250
RouterC(config-route-map)# match ip 1

I have conf largest Local pref.. default is 200. 250 will be preffered.

Now by going into BGP conf..

RouterC(config)# router bgp 10
RouterC(config-router)# neighbor 1.1.1.1 route-map Name out

I hope so by using this conf. 1.1.1.1 will be considered as a best path..
Pls correct me if i am wrong.