E1 - Timelost division - CCS/CAS

[Guilherme Gianotto Bratfisch]

Hello

I'm currently studying for ccna collab and it is not clear how a E1/T1 circuit are configured to user CCS style or CAS.

I have a sample of configuration and just wonder, why timeslot 16 is not configured, is it used for signaling ?!

 framing NO-CRC4
 ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani
 cas-custom 0
  category 2
  answer-signal group-b 1

[Manish Gogna · Accepted solution]

Hi Guilherme,

E1 time slot 16 (the D channel) is used for signaling, you can read more about this here

http://www.cisco.com/c/en/us/td/docs/ios/12_2/dial/configuration/guide/fdial_c/dafchant.pdf

Manish

- Do rate helpful posts -

[Guilherme Gianotto Bratfisch]

What I dont understand is if I'am using CAS signaling why it needs a D channel for signalings ?

[Manish Gogna · Accepted solution]

CAS is the transmission of signaling information within the information band, or in-band signaling. This means that voice signals travel on the same circuits as line status, address, and alerting signals. As there are twenty-four channels on a full T1 line, CAS interleaves signaling packets within voice packets. Therefore, there are a full twenty-four channels to use for voice.

You may use the following as a reference to configure T1 CAS where full 1-24 timeslots are used

http://www.cisco.com/c/en/us/support/docs/voice/digital-cas/24642-cas-config.html

Manish