Fibre Channel (SAN)

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New Contributor
Posts: 2
Registered: ‎02-20-2007

FCIP Via VPN

Hello all,

External Moderator
Posts: 4,813
Registered: ‎02-23-2004

Re: FCIP Via VPN

Lucian,give here any reason to use 1500 ?

TechHelp24
New Contributor
Posts: 2
Registered: ‎02-20-2007

Re: FCIP Via VPN

The reason is that with the 7500s the minimum MTU to establish an FCIP tunnel is 1500 and the packets go out with the DF bit set. The previous generation (7400) could do it via VPN with a lower MTU apparently and it works just fine, but the new one just doesn't.Now, the thing that really really bugs me is that the FC frames can get to 2K, so going to 1500 meand that they are going to get fragmented anyway. Now, the 7500 lets you pick any MTU size between 1500 and 2300something and, as long as both sides of the tunnel have the same settings, it's all peachy. Why didn't someone come up with the idea that it would be great to be able to pick an MTU say 1400 just to avoid problems like these? I say if the frames are going to get fragmented, what does it matter if one fragment is 1500 and one 500 or the firs 1400 and the next 600??? This is what really really bugs me ...

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