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ashish
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full or half Duplex

Wed Oct 03, 2007 9:17 pm

MT wireless is full duplex or half duplex wireless connectivity...????
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DesertG8
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Re: full or half Duplex

Thu Oct 04, 2007 9:22 am

half

I am not sure if you can obtain true full duplex with dual Nstreme though. Anybody know?
 
ericsooter
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Re: full or half Duplex

Fri Oct 05, 2007 6:03 am

Dual nstreme is full duplex. The only way to acheive true full duplex is with two pairs of radios. Also, I saw at one of the MUMS, Butch Evans showed that full duplex can also be achieved with non-nstreme via two pairs of radios by using OSPF and path costs. Looked real interesting, it transmitted through one pair and received through the other; yet it would resort to a half duplex link if one pair of the radio links failed. Pretty sure that Dual Nstreme doesn't do that.

Eric
 
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Re: full or half Duplex

Wed Oct 17, 2007 5:28 am

Dual nstreme is full duplex. The only way to acheive true full duplex is with two pairs of radios. Also, I saw at one of the MUMS, Butch Evans showed that full duplex can also be achieved with non-nstreme via two pairs of radios by using OSPF and path costs. Looked real interesting, it transmitted through one pair and received through the other; yet it would resort to a half duplex link if one pair of the radio links failed. Pretty sure that Dual Nstreme doesn't do that.

Eric
Really interesting
 
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ghmorris
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Re: full or half Duplex

Wed Oct 17, 2007 2:41 pm

If I understand this correctly, all the Linux-based quad-radio systems are "sorta" full duplex.

A true full duplex system puts data down the transmit channel, and gets everything including acks, back over the receive channel.

The Linux-based systems still get their acks back over the transmit channel so both channels are transmitters and receivers, although the DATA flow in one direction only per channel.

This "quasi-full-duplex" has a number of practical impacts.
1. It slows the channel slightly
2. It means that you still care about the receive capabilities of the transmit channel at the transmit end. Noise levels in particular comes into play here.
3. You can't play silly games with EIRP rules, where one end of the link uses a small antenna and low power to transmit legally, but the other end uses a big antenna to receive as no transmission happens at all. Works very well with a 5.3 / 5.8 split in FCC land, Wmux has been doing it for years.

Still a very good tool for many situations, but not the real deal just yet.

George
 
bushy
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Re: full or half Duplex

Wed Oct 17, 2007 10:07 pm

yet it would resort to a half duplex link if one pair of the radio links failed. Pretty sure that Dual Nstreme doesn't do that.

Eric
Failover is easy to do with Dual Nstreme
 
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Re: full or half Duplex

Mon Oct 22, 2007 5:07 pm

Bushy - quoting you:
Failover is easy to do with Dual Nstreme
I'd like to see this! I have not found a way to make dual Nstreme do any kind of failover.....
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Equis
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Re: full or half Duplex

Tue Oct 23, 2007 2:19 am

Bushy - quoting you:
Failover is easy to do with Dual Nstreme
I'd like to see this! I have not found a way to make dual Nstreme do any kind of failover.....

Scripting?
 
galaxynet
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Re: full or half Duplex

Tue Oct 23, 2007 3:11 pm

To do that with a script you'd have to rewrite the wireless interfaces of all four wireless cards (2 on each RB), that's not exactly failover. So no, scripts won't do it.
Thom Lawless
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