[c-nsp] NPE-G1 support for jumbo frames

Jose lobo at allstream.net
Tue Apr 1 21:02:26 EDT 2008


Lasher, Donn wrote:
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jose
> To: Gerald Krause
> Subject: Re: [c-nsp] NPE-G1 support for jumbo frames
>
> Gerald Krause wrote:
>   
>> Jose schrieb:
>>   
>>     
>>> We have not been able to change the MTU for the PA-FE-TXs to anything
>>>       
>
>   
>>> larger than the standard 1500.  Every time you try and change it, it 
>>> spits back an error about not being allowed on this interface.  This
>>>       
> is 
>   
>>> with the 7206VXR NPE300 running 12.2(15)T.
>>>       
>
>
> One other "oh surprise!!!" is the fact that the NPE-Gx built-in ports
> won't do over MTU of 1500 when their speed is set to anything other than
> 1000.
>
> Huh? Come again?
>
> Yep.. that's right... set the speed to 100, and the max MTU is 1500. Set
> the speed to 1000, and the max MTU is now 9216. Same port, same
> GBIC/copper, same code.
>
> Found this one in regression testing before we upgraded a mess of
> NPE-300's to NPE-G2's. We ended up having to leave the PA-FE-TX's in for
> a couple months, until a planned switch upgrade could be completed ahead
> of schedule. Others might not be so fortunate.
>
>
>
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>   
Donn, what version of code were you using?  This is pretty scary 
considering that one of the factors of going to NPE-G1 is hoping to take 
advantage of jumbo frame or at least 1530 on the three ports.

Jose


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