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iDirect Series of satellite modem Cum Router

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Ex Member
Ex Member


May 24th, 2007 at 1:39pm  
I am planning to deply the idirect series of modem/router which i think has some financila advantage of having a satellite modem and a router in one box.

However i am curious about the following:

1. what layer 2 protocol does the router support. cisco supports HDLC, PPP, etc.?

2. what other advantages does this series (3000 and 5000 series) have over other brand of satellite modem and or routers like Comtech products?

3. are there other interfaces like serial or any WAN interface (though i haven't seen any in the product data sheet)?

Your contributions on the above issue will be appreciated.

Thank you.

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pgannon
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Posts: 109
Reply #1 - May 24th, 2007 at 4:27pm  
I responded to part of this in another post....

1. The layer 2 protocol over the VSAT link is proprietary.  It would be HDLC-like, but it's going to strip out a lot of IP and Ethernet overhead. It will only work with other iDirect Hubs or modems in iSCPC mode. 

Note that this is normal.  Most vendor's products are proprietary to some extent.  The DVB/RCS standard provides some level of interoperability, but only at the most basic level.  All the value-add features are proprietary to the vendors.

2. In "shared" mode, iDirect's primary advantage is the industry's most efficient inroute (upload) technology.  Other advantages are value-add features such as TCP/HTTP Acceleration, QoS, DNS caching, routing, encryption, mesh support, cRTP header compression, etc.  iDirect was first to offer most of these features and other vendors have worked to add them to their own offerings.  iDirect leapfrogged the competition when they first announced the NetModem and they work hard to maintain their technical and feature advantages over the rest of the field. 

In "dedicated" or iSCPC mode, the primary advantage is cost.  An iDirect 5100 with all the integrated features costs less than a Comtech modem without any of those features - even without their 10/100 IP router module installed.  However the iDirect solution is limited to IP over SCPC only, and does not pass "clear channel" SCPC, which would be supported by other SCPC modems.  (This is of increasingly limited importance as  everything moves to IP).  When you compare the iDirect 5000/7000 series with Comtech's integrated 10/100 IP module you find that iDirect falls far short of Comtech in terms of packet per second forwarding performance.  If you need to support more than about 18 VoIP lines, you will have to move to another solution as iDirect will be out of steam.  However Comtech still does not have an integrated TCP/HTTP Acceleration solution, requiring an external device or server to deliver this critical service for TCP data.

It's important to note that there are applications for both solutions.  iDirect is going to be best in either shared or dedicated mode when you have a mix of data and real-time services such as a handful of VoIP lines.  However for large scale VoIP termination, something like Comtech will be required as the iDirect solution doesn't have the necessary horsepower.

3. You have an additional RX coax port so you can pass through a DTH (direct to home) TV video signal (i.e. the iDirect modem has a built in splitter).  Thus, if the satellite you are pointed to happens to deliver a DTH service, you don't need another dish - you can plug your DTH receiver into the back of the iDirect modem.  There's a serial port that can be used for obtaining GPS coordinates for mobile applications, but it is not designed to be used for serial data applications.  If you need to pass serial data through an iDirect modem/router, you would need a terminal server connected via the Ethernet port.
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