Multiple serial port routers linked together

[cameron.moody]

Hi All,

I have a query from a colleague which I am unsure of the answer and I don't want to risk hardware damage by testing!

They are studying for CCNA and are wanting to do it on the cheap.

The query is, on a model that has two or more serial interfaces, are you able to plug a DTE to DCE cable between the two ports? IE on the same router plugging both serial interfaces to eachother.

Of course on one of the interfaces one would be configured with clocking etc, but would this kind of setup function for this type of learning?

Thanks heaps ! (I really don't want him to test and short circuit the router or anything :P )

[mahmoodmkl]

Hi

For point to point connections u need to have the ip address in the same network.Even if you connect them with the dte -dce cable it will not of use as the router will not allow you to assign the ip address from the same subnet on two interfaces.

Thanks

Mahmood

[Richard Burts]

Mahmood

You are quite right about the behavior of Ethernet interfaces. But if you try it you will find that the behavior of serial interfaces is different and that you can configure two serial interfaces into the same subnet. I am not sure why this behaves in this way different from Ethernet but when I tested it I found that it did work.

Cameron

Connecting two serial interfaces back to back on the same router should not do any harm to the router. I am not clear how much they will learn from doing this, but I do not see that it would do any damage to the router.

HTH

Rick

[mahmoodmkl]

Hi

Rick

Thanks for the information this is new to me,i really appricaite u r contribution to the netpro community.

Thanks

Mahmood

[Richard Burts]

Mahmood

Thank you for the compliment. There are many things like this behavior on serial interfaces that is not obvious until you actually try it on real routers. I am glad to share what I have learned from experience. The forum is a very good place to learn about Cisco equipment and I encourage you to continue to participate in the forum, and also to get as much hands on experience as you can.

HTH

Rick