Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

What is exactly the Cisco's E1/T1 time slot?

How do I configure them?

share|improve this question
up vote 1 down vote accepted

The time slots are inherent to the (channelised) E1/T1 transmission method. An E1 has 32 time slots. One is used as a clock and is not usable for sending payload (this is, I believe, time slot 0). When used as an ISDN30 link, the E1 also has one time slot (slot 15) dedicated as a control channel (running Q.921 and Q.931 for ISDN signaling), but when used for data transfer, this is normally available for payload.

It is configured in a way similar to this (I shall happily assume that you have a channelised E1 controller in slot 0/0 for the purposes of the example):

controller E1 0/0
 description The E1 controller
 ! you'll need relevant timing and framing to be configured, ask your ISP
 channel-group 0
  timeslots 1-2
 channel-group 1
  timeslots 3-7

interface serial0/0:1
 description This is the interface corresponding to channel-group 1
interface serial0/0:2
 description And this is the interface corresponding to channel-group 2
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.