[ale] SSH Cisco Networking Issue

[Watson, Keith]

> -----Original Message-----
> From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Omar
> Chanouha
> Sent: Friday, September 17, 2010 12:14
> To: Atlanta Linux Enthusiasts - Yes! We run Linux!
> Subject: Re: [ale] SSH Cisco Networking Issue
> 
> Thanks for that explanation Keith. The server is actually behind a NAT.
> As it turned out the max MTU I could have is 1400, god call. It hangs at
> 1408 or higher.
> 
> The IT wizard is telling me that he thinks this is due to a driver
> issue. Linux, of course, is always to blame. The server is actually a
> virtual machine on top of Vmware on top of an intel NIC.
> 
> Is there any truth to his theory?
> Is the performance hit I am taking significant enough to keep fiddling
> with it?
> Is there a way to fix the NAT/Firewall, or is it just suck like that til
> we get a firmware upgrade? The HW is actually very new. Just purchased
> within 6mo I think.
> 
> Thanks,
> 
> -O

I really doubt it is a problem on your end. You will only see a performance hit when transferring lots of large files. If you are generally using a shell via ssh then it isn't worth the effort to try to get the remote admin to fix it.

If I understand correctly he is using VMware to host the server you are trying to connect to via ssh.

You mention new NAT/Firewall hardware, is this sitting in front of the VMware server?

It is also possible he is using VMware to provide NAT. Is he using VMware Server, ESX or ESXi? I think NAT is implemented natively in VMware Server however with ESX and ESXi you have to create a second virtual switch and use a NAT router virtual machine between the ESX(i) default switch and the second virtual switch where the server resides. This means that the virtual switches and the NAT virtual machine all have to negotiate properly. I haven't tried configuring the virtual switches. In fact I'm not sure you can. The firmware would be for the NAT virtual machine. If he is using a NAT virtual machine, which one is he using?

keith

-- 

Keith R. Watson                        Georgia Institute of Technology
Systems Support Specialist IV          College of Computing
keith.watson at cc.gatech.edu             801 Atlantic Drive NW
(404) 385-7401                         Atlanta, GA 30332-0280