What is the requirement for two routers to be connected?

[pezhmankh]

Hello

I am studying for CCNA and I was hoping to learn what is the requirement for two routers to be connected?

I know they have to be on the same network using the same protocols, but what is the role of username and password here? Do they have to have the same username and password?

[tobyarnett]

Like devices need a cross over cable, dissimilar devices use a straight through cable. The connecting interfaces need to be on the same subnet, and your speed and duplex settings need to be the same. Your username and password are unique per device, those don't need to be the same to link up


-Toby



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[pezhmankh]

Hello Toby Thank you for your respond.

I was expecting an answer with username and password have to be the same because this was the answer to one of the sample questions I am studying, I'm going to write the configuration to be more clear.

Router 1 Config:

Hostname router 1

username router 2 password cisco

interface serial 0/0

ip address 10.0.8.1 255.255.248.0

encapsulation ppp

ppp authenticantion chap

Router 2 config:

Hostname router 2

username router 1 password cisco1

interface serial 0/0

ip address 10.0.15.2 255.255.248.0

encapsulation ppp

ppp authenticantion chap

And the sample question does also have the answer which is Username/password is incorrectly configured. Are you suggestion the answer is incorrect?

[cadet alain]

Hi,

As you do 2 way PPP CHAP authentication then the passwords must be the same and the username on one router must correspond to the hostname of the router you want to authenticate.

Regards

Alain

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[tobyarnett · Accepted solution]

Sorry your original post did not include anything about using PPP CHAP on the link. So yes in this case as stated above your username on your router must match the *peer* routers hostname, and the passwords should be the same. Note that you do not need PPP CHAP to get your routers to link up, but when you use PPP CHAP you need the same password and you must have a username that matches the *peer* router. So in your reference above you listed Router1 with a username of "router2" but your syntax is incorrect above. Above you have:

Router 1 Config:

Hostname router 1

username router 2 password cisco

interface serial 0/0

ip address 10.0.8.1 255.255.248.0

encapsulation ppp

ppp authenticantion chap

But with the spacing between "router" and "2" this effecively creates a username of "router". So the proper syntax would be:

Router 1 Config:

Hostname router 1

username router2 password cisco

interface serial 0/0

ip address 10.0.8.1 255.255.248.0

encapsulation ppp

ppp authenticantion chap

Router 2 config:

Hostname router 2

username router1 password cisco

interface serial 0/0

ip address 10.0.15.2 255.255.248.0

encapsulation ppp

ppp authenticantion chap

If you notice above the difference between my post and yours is I have removed the spacing in the "username" field after router. This will configure Router 1 to have a username of router2, and Router 2 to have username of router1.

Hope this helps to clarify your issue.

-Toby

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