Jing Teng on Thu, 7 Mar 2002 12:28:52 -0500


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[PLUG] Final Answer to IBM Thin Client and Red Hat Linux Networking problem


I called IBM about this problem. After a few days of testing, we finally
found that it was the Ethernet Standard setting on NetVista box. I used
IEEE802.3, which, according to IBM, has problems. After I changed it to
Version 2, it worked very well.

-----Original Message-----
From: plug-admin@lists.phillylinux.org
[mailto:plug-admin@lists.phillylinux.org] On Behalf Of Jing Teng
Sent: Friday, March 01, 2002 2:11 PM
To: plug@lists.phillylinux.org
Subject: RE: [PLUG] IBM Thin Client and Red Hat Linux Networking


Thanks Paul! I think I got it this time.

Tcpdump was the only thing I didn't try. Here are some results: 1. On
w2k(10.1.2.41), arp table is empty, ping RH (10.1.2.58), 
windump -n host 10.1.2.58 captures:
================================================================
13:37:53.736436 arp who-has 10.1.2.58 tell 10.1.2.41 13:37:53.736673 arp
reply 10.1.2.58 is-at 0:8:c7:f3:ba:8 13:37:53.736691 10.1.2.41 >
10.1.2.58: icmp: echo request 13:37:53.736927 10.1.2.58 > 10.1.2.41:
icmp: echo reply 13:37:54.734484 10.1.2.41 > 10.1.2.58: icmp: echo
request 13:37:54.734721 10.1.2.58 > 10.1.2.41: icmp: echo reply
13:37:55.735930 10.1.2.41 > 10.1.2.58: icmp: echo request
13:37:55.736170 10.1.2.58 > 10.1.2.41: icmp: echo reply 13:37:56.747390
10.1.2.41 > 10.1.2.58: icmp: echo request 13:37:56.747629 10.1.2.58 >
10.1.2.41: icmp: echo reply 13:37:58.726564 arp who-has 10.1.2.41 tell
10.1.2.58 13:37:58.726599 arp reply 10.1.2.41 is-at 0:1:2:2e:fa:9b
=================================================================

2. On w2k(10.1.2.41), arp table is empty, ping NetVista (10.1.4.222), 
windump -n host 10.1.4.222 captures:
=================================================================
13:38:28.693243 arp who-has 10.1.4.222 tell 10.1.2.41 13:38:28.693523
10.1.2.41 > 10.1.4.222: icmp: echo request 13:38:29.688486 10.1.2.41 >
10.1.4.222: icmp: echo request 13:38:30.689924 10.1.2.41 > 10.1.4.222:
icmp: echo request 13:38:31.691368 10.1.2.41 > 10.1.4.222: icmp: echo
request
=================================================================

3. On RH(10.1.2.58), arp table is empty. Ping 10.1.2.41, 
tcpdump -n host 10.1.2.41 captures:
================================================================
13:56:37.526721 arp who-has 10.1.2.41 tell 10.1.2.58 13:56:37.526721 arp
reply 10.1.2.41 is-at 0:1:2:2e:fa:9b 13:56:37.526721 10.1.2.58 >
10.1.2.41: icmp: echo request (DF) 13:56:37.526721 10.1.2.41 >
10.1.2.58: icmp: echo reply (DF)
================================================================

4. On RH(10.1.2.58), arp table is empty. Ping 10.1.4.222, 
tcpdump -n host 10.1.4.222 captures:
================================================================
13:57:36.436721 arp who-has 10.1.4.222 tell 10.1.2.58 13:57:37.436721
arp who-has 10.1.4.222 tell 10.1.2.58 13:57:38.436721 arp who-has
10.1.4.222 tell 10.1.2.58

After comparing the results, we can see NetVista doesn't reply to arp
request! This is why RH can't ping NetVista. But why can a W2k box ping
NetVista? I have not figured out. 

Something interesting is that any ping to RH involving two arps, one is
"who is RH?" , the other is "who is pinging me? "from RH. After the
ping, RH will have an entry for the pinger in its arp table.

Jing


-----Original Message-----
From: plug-admin@lists.phillylinux.org
[mailto:plug-admin@lists.phillylinux.org] On Behalf Of Paul
Sent: Thursday, February 28, 2002 9:47 PM
To: plug@lists.phillylinux.org
Subject: Re: [PLUG] IBM Thin Client and Red Hat Linux Networking

Jing,

What does "traceroute" show?  Have you tried running "tcpdump" on the
linux box to see if the ping packets are hitting its interface?  Does
"arp" resolve the IPs to their proper MAC addresses?


______________________________________________________________________
Philadelphia Linux Users Group       -      http://www.phillylinux.org
Announcements-http://lists.phillylinux.org/mail/listinfo/plug-announce
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______________________________________________________________________
Philadelphia Linux Users Group       -      http://www.phillylinux.org
Announcements-http://lists.phillylinux.org/mail/listinfo/plug-announce
General Discussion  -  http://lists.phillylinux.org/mail/listinfo/plug


______________________________________________________________________
Philadelphia Linux Users Group       -      http://www.phillylinux.org
Announcements-http://lists.phillylinux.org/mail/listinfo/plug-announce
General Discussion  -  http://lists.phillylinux.org/mail/listinfo/plug