Router and T1 circuit

[sarahr202]

Hi everybody

I got a question about t1 .circuit. Please consider the following example:

R1s0------t1 connection-------R2

R1 has three frames in its hardware queue of s0 waiting to be transmitted to R2.

Lets name these frames as f1,f2 and f3. We know that hardware queue uses FIFO.

   Hardware queue on R1 looks like this:

----------------------------------->

F3,F2,F1

Each frame has 1000 bytes

t1 circuit uses 24 slots. Each slot carries 8 bit.

R1 uses slot1 and transmit 8 bits from frame1. 2nd slot comes now what will R1 do? will R1 transmit 8 more bits from frame1 ?

thanks and have a great weekend.

[visitor68 · Accepted solution]

When you talk of time slots, you're describing a channelized T1, which has its roots in D4-AMI framing circuits for channel banks and for digitized voice. In that case, each DS0 was a voice channel and each channel would get sampled 8,000 times a second (8 bit samples), with framing bits interleaving the stream every 192 bits (1 round of sampling of each of the 24 DS0s).

On the other hand, the T1 for the router is non-channelized and typically uses ESF/B8ZS for faming and coding. It's a stream of bits from one channel, so to speak. It will still frame the data every 192 bits, but thats it. No separate channels. Moreover, frame f1 will be serialized and transmitted first, then f2 and then f3.

[sarahr202]

Thanks .

1)WIC-1DSU-T1 card uses unchannelized  t1.  Does a cisco router have  wic that support channelized  t1?( for example for voip environment. providing connection to pstn)

2)  When we order t1 circuit from a telco, do we have to tell telco we want unchannelized t1 circuit or telco just give t1 circuit and it is upto us how we want to use it? If we want to use t1 circuit as unchannelized we make some configurations and if we want to use t1 circuit as channelized we can do so by making some configurations on our end without teleco's involvement. Just want to clarify that.

3)  if we are using T1 data, do we still need to send signaling information using cas or css?  If yes then why,  Because in vwic t1 card it makes sense because we have all signaling information such as dialed number ,which we send over t1 line either using cas or css method.  But when we are using t1 data , there is no signaling information need to be sent just plain data.

I appreciate your help.

Thanks and have a great weekend.