RE: E1 question> E1 is an Telecoms (ITU- previously CCITT) standard of long
standing not of Cisco origin. It
> uses Time Division Multiplexing technology (TDM) with 32 time slots. TS0
is for
> Synchronisation and in a Channel associated E1 TS 16 is the signalling
channel. In a CCS
> link TS1 is often used. The data can be channelised ie each time slot is
a data channel or
> speech channel with mux equipment at the end or one big pipe connecting
to a Router/PABX
> etc. (In this case the channels are all just used by the same source
etc.)In the telecom
> world, 30 speech channels of 64 kb/s are available. In a CCS group of E1's
only the first
> E1 needs a signalling channel so the remaining E1's provide 31 ccts. The
North American
> equivalent is a T1 which has only 24 ccts.
--
To my knowledge, this is not strictly true. E1 timeslot 0 is always used for
framing. Regarding timeslot 16, the signalling scheme chosen does not really
affect E1 in the same way as it does T1 (DS1).
Common Channel Signalling (CCS) in the world of E1 relies on timeslot 16
being used to carry signalling bits for the remaining 30 bearer channels.
Channel-Associated Signalling (CAS) requires the signalling bits to be
carried in timeslot 16 *as well*. T1 bit-robbing takes care of this in North
America, as the signalling bits are "robbed" from the individual bearer
channels. This effectively reduces the bandwidth in data communications
scenarios from 64kbps to 56kbps. However, E1 always uses timeslot 16 for
signalling purposes, regardless of whether you select CCS or CAS. In voice
implementations, this is quite critical. E1 multiframe integrity is
dependent upon the correct signalling bits being sent in each copy of
timeslot 16. The only occasion when timeslot 16 can be used as a bearer
channel is if the E1 service is configured as a "clear channel" service. In
this instance, pure data (i.e. non-voice) environment does not care about
voice signalling bits and can use timeslot 16 for data purposes.
Edward Solomon
CCNA, CCSI
Senior I/T Specialist
Networking Solutions
IBM Canada Ltd. - Learning Services
Tel.: (905) 316-3241 Fax: (905) 316-3101
E-mail: [EMAIL PROTECTED]
Internet: http://www.can.ibm.com/services/learning/net_internet.html
___________________________________
UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
FAQ, list archives, and subscription info: http://www.groupstudy.com
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
