What is the simplest solution for doing static routing ?

[christoph.ehret]

Hi,

I have to work with a Cisco 800 Series and give some routing parameters to each Interface. I was reading the following page on static routing : http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca765.html

It seems to have so many solution, I do not really know wich one to choose.

So my question : what is actually the simplest way for doing static routing, and for example to say that if you want to join this IP, you have to choose this interface, etc. I would be glad to have a simple example or a link where I can find some examples.

Thanks for your answers.

Chris

[dgahm]

A router knows how to route packets to all connected interfaces with no static routes. Where static (or dynamic)routing comes into play is when the router has a packet that needs to be sent to a network that connects to another router. The simplest static route is a default route:

ip route 0.0.0.0 0.0.0.0 10.1.1.1

This will tell the router to send packets to router 10.1.1.1 (example next hop address) if there is not an explicit route in the routing table. To see the routing table:

show ip route

Many times this single static route is all you will need. If you don't know the next hop address, you can use this variation to send packets out an interface:

ip route 0.0.0.0 0.0.0.0 s0

This depends on the neighbor router doing proxy arp, but if you are connecting to the Internet it usually works.

[Richard Burts]

I have a minor technical correction to the answer provided by David: if the outbound interface is s0 there is not any dependency on proxy ARP. If the outbound interface were Ethernet 0 there would be a dependency on proxy ARP.

And I believe that many ISPs are becoming less willing to enable proxy ARP on the routers that face customer routers. So I think that it is especially important to get the static route with next hop address for default routes pointing to ISP next hops.

HTH

Rick

[dgahm]

Rick, Right you are, no ARP broadcasts on serial links. Can't get away with any mistakes around here ;-)

Dave

[christoph.ehret]

Hi,

Thanks a lot for your answers. Your solution seems to be the simplest one for static routing.

What do you think of using policy routing ?

[Richard Burts]

Policy Based Routing can be very useful and effective if you have a need for this kind of technique.

Normal routing decisions are based on finding the path based only on where is the destination address located. Policy Based Routing can make routing decisions based on what is the source address or on what kind of traffic is it (web browser might be routed one way and EMail traffic might be routed a different way even though they might have the same destination address). So if you have a need to base routing decisions on source address or on traffic type then Policy Based Routing is very effective.

HTH

Rick

[christoph.ehret]

I really thank you for your answer. Now it see a bit more clearer what I have to use as choice for my problem.

Thanks.

Chris