3750G V12.1(14r)EA1a

[wgranada1]

Quick question is there any sort of debug I can run to check for connectivity on a switch? I have a Linux server that is trying to run a NFS mout on it but it doesn't work. I was trying to see if I can see anything. I can ping and traceroute to the server but when NFS mount is run it does nothing. Thank you in advance!!

[Collin Clark · Accepted solution]

Have them run wireshark on the servers. There isn't anything you can do on the switch.

[Davidamoore · Accepted solution]

This is the best advice. Run wireshark or sniffer your ports. The switch wont be able to help much

[Mark Yeates · Accepted solution]

I don't know of a debug on the switch to go into that kind of detail. I would think that spanning a port and running a sniffer and sniff the port of the server. Then attempt to generate some connections to the server and see if anything out of the ordinary comes up.

HTH,

Mark

[wgranada1]

Ok thanks guys will do that then I thought there was something on the switch we can use

but thanks for the info!!!!

[Jon Marshall]

Warren

You could span the NFS server port on the switch and see if it is receiving NFS traffic but the easier thing to do would be to run a sniffer on the NFS server itself.

What type of NFS server is it, have you checked the NFS logs on that server, are you absolutely sure traffic is not getting to the NFS server.

Jon

[wgranada1]

The NFS server is a Linux box and I had the admin on the box when we tried doing the NFS mount from a iseries. We can see traffic leaving the iseries and the router but the Linux guy says that he isn't seeing anything.

Thus the question about running some sort of debugs on the switch.

[Jon Marshall]

Linux server should have tcpdump if you can't load up wireshark.

When he says he isn't seeing anything - how is he checking that ?

Jon

[wgranada1]

not sure I would have to ask, I believe he was doing something like a tcpdump. When we where doing the NFS mount he said he didn't see an attempt for a connection but when we did a ping or traceroute he saw it. From what I'm told is that the sort of NFS mount uses a UDP port...sorry forgot which one

[Jon Marshall]

NFS usually uses UDP/2049 altho it doesn't have to. If he was running tcpdump not a lot of point in running wireshark on server.

Is your linux guy sure the client is using the correct port to contact the NFS server. When the NFS request goes from the client does he see any traffic on the NFS server.

Also worth checking if you have any access-lists in the traffic path that may be blocking the NFS traffic.

Jon

[wgranada1]

Hi Jon;

I have no access-list along the path we do have one firewall between the source and destination but the firewall guy assures that

NFS is allow as well as UDP. When we initiate he can see traffic leaving but not coming back. I see the same on the router which believes me to think it is on that Linux box but the admin says he doesn't see an attempt when we try a NFS mount.

[Collin Clark]

Can the client see the server other than with NFS? ie Can they ping each other?

[wgranada1]

Yes I we ping back and forth no problem and traceroute back and forth. The way it is connected is:

source => firewall => router => switch => destination

We asked the firewall guy when we attempt a NFS mount if he sees it and he confirms that he sees the UDP packet and the port number leaving but nothing is coming back.

[Collin Clark]

Like Jon stated, take a look at the router and see if traffic is returning from the destination. Make sure you see it go both ways. If you don't see it return, its time to take a further look at the (destination) server.

[Jon Marshall]

Warren

Is your router closer to the NFS server than the firewall ?

Without going into full NFS details, NFS can make use of something called the port-mapper on linux but it doesn't have to.

What is the firewall guy saying is going to the NFS server. I would be concentrating on the firewall if the router is between the client and the firewall.

Jon