Foundry Switch Jumbo Frames Support

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  • Updated 5 months ago
I have some Foundry FESX424F-PREM switches running version 3.1. I see from various places online that jumbo frames are supported.

In the config menu, I do see the jumbo command to enable jumbo frame support switch wide.

In a manual I dug up on version 4.3, I see commands to enable jumbo frame support per-port. I don't see those commands in my CLI, so can I assume that my version doesn't have that ability and I need to upgrade?

Note: In another thread I am asking about the upgrade process.
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Mike Hammett

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Posted 5 months ago

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Ben, Employee

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The old guides used to be a mix of numerous products (XMR, MLX, FES, FESX, etc). It's possibly they aren't for the FESX. Generally speaking, the 'jumbo' command is global only and requires a reload. Which commands were you looking at?
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Mike Hammett

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To change the MTU for interface 1/5 to 1000, enter the following commands:

FastIron(config)#int e 1/5
FastIron(config-if-1/5)#ip mtu 1000
FastIron(config-if-1/5)#write memory
FastIron(config-if-1/5)#end
FastIron#reload

No good indicator around there as to any platform limitations, but I have seen them elsewhere, so I know what you're talking about.

That section seemed to be about layer 3 stuff, but MTU is a layer 2 thing, so maybe I'm not even in the right section. I didn't find any better section, though.
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Ben, Employee

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'Jumbo' command is only going to be global. The 'ip mtu' is only going to be applicable on layer 3 interfaces whether that's routed interfaces like your example or VEs. It won't work on a pure layer 2 port though. 
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Mike Hammett

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So on a pure layer 2, I'd have to issue global?

That's what I took away, but confirmation is key.
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Ben, Employee

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Correct