Can someone explain what a clear channel T3 is?

[t.khan]

I am looking at the card NM-1T3/E3 for a 3662 router. This site will have a fractional T3 at 3Mb. Will this card work? What is the difference between clear channel and not?

[mheusinger]

Hello,

The card should work: NM-1T3/E3: "Subrate support in the Cisco T3/E3 Network Module maximizes the utility of these products in service provider environments"

from "Cisco T3/E3 Network Module Data Sheet"

http://www.cisco.com/en/US/products/hw/modules/ps2797/products_data_sheet09186a008010fba2.html

Another excerpt:

Table 1. Cisco T3/E3 Network Module Branch Office Positioning

Supported Platform

Recommended Type of Service

Recommended Branch-Office Size

Cisco 2650 and 2651XM

Subrate T3/E3

Small to medium branch offices

Cisco 2691

Subrate T3/E3

Small to medium branch offices

Cisco 2800

Subrate T3/E3 with concurrent services

Medium to large branch offices

Cisco 3661 and 3662

Sub and full-rate T3/E3 with limited services

Medium and large branch offices

Now about the "line theory" question. A clear channel T3 is like a serial interface with 45 Mbps. Data sent is not structured in OSI Layer 1.

In the multiplexer environment there will be a structure, 28 T1 are transported in a T3. To allow the demultiplexing, there is a certain structure basically to position T1 frames in the bit stream so that the terminating side is able to extract the different T1 separately. In addition there are Bytes used for OAM and failure indication.

Hope this helps! Please use the rating system.

Regards, Martin

[t.khan]

Martin,

Thank you for your response. Ok, so you are saying we won't be able to break up the fractional T3 with a 'clear channel' card? We are just looking for 3-6Mbps total usage for this router (3662). I am not sure I fully understood your answer on 'line theory'. Is there a difference between a clear channel card and a card that doesn't state clear channel?

Again,

Thank you in advance.

[mheusinger]

What I wanted to say: It should work with the hardware you selected according to the product description (from the link in my first posting).

If a card would be ONLY clear channel, then subrate would be an issue. The NM can do both afaik.

Regards, Martin

[t.khan]

Martin,

Vielen Dank! I think that I am still confused. I have looked through cisco's website. It appears that the T3 clear channel doc is underneath the ISDN Voice section. I just want to make sure this card will work in our 3662 for a fractional data t3 situation. I cannot seem to find any more information out there. I do appreciate your help. If you have any further advice, that would be great. If not, thank you anyway.

Does anyone out there have this card NM-T3 in a 3660 that has it working with a fractional T3 for data?

[mheusinger]

Have you read the product sheet for the card following the link given above? It clearly states that the card can be used for subrate - as far as a non native speaker can judge this.

Regards, Martin

[t.khan]

Martin,

I have. Thank you again. I just never understood the answer. The question I was asking originally is what does clear channel mean?

Thanks.

[Richard Burts · Accepted solution]

Tahir

Martin was trying to explain what that means. A T3 can be channelized on can be un-channelized. (un-channelized is the same as clear channel) In a channelized T3 the data being transmitted is organized in a way such that it can be subdivided and separated out (multiplexed and de-multiplexed). So you might have a number of remote sites where each one has its own T1 to HQ, the service provider combines thses individual T1s into a T3, and a channelized T3 at HQ delivering the data from the multiple remote sites and you could defines subinterfaces on the T3 allowing each remote site a subinterface so that its traffic can be received individually. In clear channel (or un-channelized) you just get one data stream and it can not be subdivided or separated.

Perhaps this different approach to explanation may make it easier to understand.

HTH

Rick

[t.khan]

Rick,

That is exactly what I was looking for. Thank you so much. I understand, and appreciate both your help.

[Richard Burts]

Tahir

I am glad that we were able to help.

Thank you for rating our posts and using the check mark to indicate that a solution has been found. It makes the forum more useful when people can read about an issue and know that a solution was found.

I encourage you to continue your participation in the forum.

HTH

Rick

[bbiandov]

hmm just a clarification:

the channalizing is NOT feature of the provider but whatever the user would please. you just need to know the timeslot range when deifing the virtual interfaces

remember how a vi is defined - "timeslot 1-16" etc so the command timelot is what makes a T1 or T3 channelized or not.

you are correct in that the provider is involved in the multiplexing of the other T1s into a T3 but all they have to tell you is the timeslot range for each, no?

~B