[OpenAFS] OpenAFS, Cisco VPN and MAC OS and mtu

[Kim Kimball]

Douglas E. Engert wrote:
>
>
> Kim Kimball wrote:
>> Have you tried setting MTU on the fileserver command line instead?
>
> No, and I don't want to. Our problem is with just a few clients using 
> VPNs
> I don't want to slow everyone else down.
>
Didn't for us, couldn't be measured to any significance.

YMMV

>>
>> That's what we've done, for the same reason.  It has worked, and we 
>> don't have to fiddle with each client.  The negotiation between AFS 
>> client and fileserver for MTU size is "fileserver wins."
>
>
> I got a mod working over the weekend, on Ubuntu (openafs 1.4.7) and
> MacOS 10.4 with OpenAFS 1.4.10, that adds a -rxmaxmtu option to afsd.
> I am putting final touches on it today.
>
>
And we'll use it to good advantage, as it is of course a better solution 
for non VPN users, as you note.


>>
>> Kim Kimball
>>
>> Douglas E. Engert wrote:
>>> We are having problems with Mac OS 10.4 and 10.5  using Cisco VPN
>>> AFS can become unusable.  Mac 10.4 is running OpenAFS 1.4.8 for sure.
>>> I think the Mac 10.5 is running OpenAFS 1.5.59.
>>>
>>> Using rxdebug and looking at the natMTU parameter, on most Unix systems
>>> this is 1444,(1500 - 56) as expected. On Windows systems this is 
>>> usually
>>> 1260.  And on MAC it is 1444.
>>>
>>> Even if I set the interface mtu 1244, and reboot the MAC, rxdebug shows
>>> the interface is using 1244 but rxdebug continues to show a natMTU = 
>>> 1444.
>>> as though it still assumed the mtu was 1500.
>>>
>>> So it looks like the MAC client is not getting the existingMTU
>>> from the OS in util/netutils.c
>>>
>>> The AFS client on Windows has the RxMaxMTU (1244 appears to be the best
>>> setting). Is there any equivelent option for the MAC?
>>>
>>> Any thoughts on this?
>>>
>>
>>
>>
>