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New Member

T1 line bandwidth question Please Help

Does a full point to point T1 line transfer at 1.5 MBPS full duplex transmit and receive simultaneosly?

So in other words can you transmit 1.5 MBps of traffic while you are receiving 1.5 Mbps at the same time on a T1.

This guy at this service provider has told me that a T1 is 1.5mbps shared between transmit and receive. He said if I am sending 1000kbps of data upsteam , i can only receive 500kbps of data downstream at the same time. Is this true of T1 tecnology?


Re: T1 line bandwidth question Please Help

A T1 is full-duplex so you can transmit and receive at 1.5M at the same time.

The dude from the service provider is trying to pull a fast one on you.

Pls do remember to rate posts.


New Member

Re: T1 line bandwidth question Please Help

If a T1 is full-duplex and there are only 24 channels (assuming channelized) at 64k per channel, that only equals 1.536Mbps with 8k framing overhead equalling 1.544Mbps. So does that mean there are really 48 channels? I know there are 2 pair of wire for send and receive, but any Cisco T1 WICs/VWICs says they support up to 24 Channels?



Re: T1 line bandwidth question Please Help

Each channel is bi-directional, so 24 channels x 64k (each direction) = bidirectional 1536k


Re: T1 line bandwidth question Please Help

Each "channel" is really just a TDM timeslot ... I suppose you could say that there's really 48 channels ... but that's just not the convention.

1.5 meg full duplex implies 1.5 meg concurrently in each direction ... just like 100Meg full duplex Fast Ethernet is still a 100 meg pipe, regardless of what the marketing weenies try to get you to believe.

A T1 WIC will handle the full T1, full duplex.

As far as the 1.536 versus 1.544 thing, each number has it's place. If you're talking payload (like at a Frame-Relay to ATM handoff) then you need to use the 1.536 number.

If you're talking about raw bandwidth, then you'd use the 1.544M number.

For the OP, the representitive from your service provider is wrong, if he was speaking abot a true T1 circuit. Get the rep to show you what documentation the are using to back up their (incorrect) information.

Good Luck


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