Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Attention: The Community will be in read-only mode on 12/14/2017 from 12:00 am pacific to 11:30 am.

During this time you will only be able to see content. Other interactions such as posting, replying to questions, or marking content as helpful will be disabled for few hours.

We apologize for the inconvenience while we perform important updates to the Community.

back to back router using T1


in this type of connection is it necessary that on both router thre should be diffendent clock source command? it means is it like one router sould have command clocksource line and other should have clocksource internal?


and my understanding regarding to it like it soulbe like master clock generated by one and other follow that masterclok which is send with data....i am right or not please clear my fundamental...



Re: back to back router using T1

Hi Devang,

It is absolutely essential that one uses clock source internal and the other clock source line.

Let's consider the alternatives:

1. If you make them both use an internal clock source, you are in essence letting them both free-run. Therefore, if the internal clock source is not very accurate (which is usually the case), you will see clock slips on both sides.

2. If you make them both take clock from the line, this makes even less sense. If both of them are sourcing the clocking signal from the line, who is going to provide the signal in the first palce.

Hope that helps - pls rate the post if it does.



Re: back to back router using T1

thanks Mr. Paresh

ok now one more help if i want to know the hardware detail of T1 card from where i can see like which command will give me that information ....and different card affect the cable length.

and as i told u earlier i am having one SG8 device, it is not having serial card its only having T1 cards so when i am assign ip to t1 interface using interface serial 0/1:0 it run but wht is the exact fundamental for that command and after giveing command show ints s0/1:0 its showing no internetaddress assign??? so what should be possible causes???

and can i have your email id?

thank you



Re: back to back router using T1

Hi Devang,

'sh controller t1 ' will give you more detail on the T1 controller hardware etc.

In order to troubleshoot why you can't assign an IP address to the serial interface, could you post the exact sequence of commands you are entering and the relevant config of the router ?

Hope that helps,


CreatePlease to create content