[Asterisk-Users] Is Gigabit Ethernet necessary?

[Gilad Ben-Yossef]

rsenykoff at harrislogic.com wrote:
> 
> For an office that is using VoIP phones to connect to Asterisk, is 
> gigabit ethernet really necessary for the Asterisk box to connect to the 
> switch? I know that I won't even approach the limits of 100 Mbps, but 
> would gigabit help with latency / collisions when several calls are 
> underway? The fact is, anything going outside the office will be over a 
> data T1, so intuition tells me that 100 Mbps should be fine...  The 
> office will have 20 phones, with remote VoIP phones added to the mix 
> later on.

The reason to chose a Gigabit Ethernet card has nothing to do with 
bandwidth - (most of?) these card use some sort of interrupt mitigation 
technique which takes a hell lot of load off of the processor for 
dealing with interrupts.

VoIP traffic, with it's typical many small packets, is very susceptible 
to causing interrupt live lock on servers and routers and interrupt 
mitigation scheme (or even polling, but that's rare) makes a real change 
in performance.

Having said that, there are 100Mb cards that do interrupt mitigation as 
well (for example AFAIK the Intel e100 cards) and there are drivers that 
implement interrupt mitigation at the software level (customized drivers 
for the tulip chip set based cards and the Linux NAPI framework).

However, it is simply much easier to just grab a Giga card then research 
which 100Mb chip and which driver you need to get ;-)

Hope this helps,
Gilad

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