SatSig topic:

iDirect 5000 series Satellite Modem/Router

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May 23^rd, 2007 at 8:53am

Hi All,

Pls i need information on this series of iDirect satellite modem/router, particularly on the issue of the number of links that this equipment can carry.

Thanks.

May 23^rd, 2007 at 4:24pm

What do you mean by "number of links"? Do you mean how many PCs can it support? Hundreds - depending on what they are doing.

Do you mean, how many VoIP lines can it support? Probably around 18 depending on the codec used and the amount and type of other data traffic.

Pat

May 24^th, 2007 at 10:29am

I mean supposing it has enough power, can it be used as a hub for other satellite links connected to it?

Secondly what layer 2 protocol does it support?

May 24^th, 2007 at 3:20pm

No. It's not a hub - it's a terminal.

It supports a single VSAT link. It can be configured to run as a remote terminal on an iDirect shared network with services originating from a Hub at a teleport or corporate data center.

It can also be configured to run a single point-to-point iSCPC circuit (IP over SCPC).

It can't do both at the same time.

The protocol used over the VSAT link is an iDirect proprietary protocol designed to optimize efficiency and throughput.

Pat

May 24^th, 2007 at 3:39pm

Thanks Pat but do u know what the proprietary protocol is called?

May 24^th, 2007 at 4:40pm

I'm sorry to say, I don't know what it's called. I have a very old document that traces the life of a packet through the iDirect link, which I obtained back when I worked for iDirect some 4 or 5 years ago when they first got started. I pulled it out, but it doesn't have any protocol identification name. It would probably be some cute name like iLA or iDirect Link Architecture or something like that. In looking at it, I can see that it's HDLC'ish in nature, once all the overhead is stripped off and then represented with a few select bits for reassembly on the other side.

It doesn't really matter what it's called because it's only going to work with another iDirect Hub or modem in iSCPC mode.

May 27^th, 2007 at 1:25pm

The protocol is very similiar to Slotted Aloha, but has some significant differences.

In iDirect proprietary, the payload of each upstream timeslot varies by type of FEC. For example: at .793 the payload of a timeslot is 392 bytes. You still have all the TDMA overhead (Unique Word) in the header and trailers and you can also add additional bytes to the Inroute Protocol Structure if you use things such as SAR, PAD, etc.

As for your original question: You have a remote (terminal). Not a hub. It is capable of locking onto a downstream carrier and can freq hop in mulitple D-TDMA upstreams to get back to the hub. For instance, you can lock onto a large downstream carrier (say 6MB downstream carrier) and you might have return channels aka (inbounds/upstreams) configed as 3ea 2048k channels (TDMA, Freq hop) to get you back to the HUB (hence, return channels). Heck, nothing says they have to be 2048k each. They could be larger, say 2ea 3MB channels? The config of your upstreams are dependent on the capability of your terminal and buying the right amount of MHz to support your requirement.