interview question

Aquabat [banned]

so i had an interview today for a network administrator. I had a couple things on my resume like, T1's DS-3s, PRI. So the interviewer asked me a technical question about T1's that kinda stumped me.

He asked that wehn you hook up a T1 into a Wic-T1 card on a cisco router, what are the encapsulation and framing methods?

I told him " well, that would be a cisco default of hdlc, but there is no framing that needs to be changed"

he told me that that's half of the answer, but he said there is something with the framing? But then he said it's default so it's ok if i didn't know.

Any idea what he means?

dtlokee

Linecoding and framing is probably what he was looking at. Typically T-1 use B8ZS and ESF, but there was the older standard of AMI and SF, and HDLC or PPP would be the encapsulation.

R2(config)#controller t1 3/0
R2(config-controller)#?
Controller configuration commands:
  cablelength    Specify the cable length for a DS1 link
  cas-custom     cas group customization configuration
  channel-group  Specify the timeslots to channel-group mapping for an
                 interface
  clock          Specify the clock source for a DS1 link
  crc-threshold  Specify how many CRC errors per second to be treated as
                 severely errored second (SES)
  default        Set a command to its defaults
  description    Controller specific description
  detect         Enable detection of loopback request
  ds0            ds0 commands
  ds0-group      Replacement of cas-group. Configure group of timeslots to a
                 particular signaling type
  exit           Exit from controller configuration mode
  fdl            Specify the FDL standard for a DS1 data link
  framing        Specify the type of Framing on a DS1 link
  guard-timer    Guard timer (0-20) for xcsp calls - timer duration and
                 accept/reject on expiry
  help           Description of the interactive help system
  linecode       Specify the line encoding method for a DS1 link
  loopback       Put the entire T1 line into loopback
  mode           Configure the controller mode
  no             Negate a command or set its defaults
  pri-group      Configure the specified timeslots for PRI 
  shutdown       Shut down a DS1 link (send Blue Alarm)
  tdm-group      Configure DS0 group for TDM

R2(config-controller)#linecode ?
  ami   AMI encoding
  b8zs  B8ZS encoding

R2(config-controller)#linecode 
% Incomplete command.

R2(config-controller)#frame
R2(config-controller)#framing ?
  esf  Extended Superframe
  sf   Superframe

R2(config-controller)#framing 
% Incomplete command.

R2(config-controller)#

mwgood

Here's an example of the first controller of a channelized T1 -

controller T1 0/0/0
framing esf
clock source internal
linecode b8zs
channel-group 0 timeslots 1-18
tdm-group 1 timeslots 19-24