Several people wrote to suggest I send ifconfig/arp/netstat output.
I've gathered that from:
        Server1 - talks to server2->server8
        Server4 - talks to everyone except server8
        Server8 - talks to server1->server3, not to server4->server7
I'm including it here. Details are as below - server1 and server4 send
traffic correctly out "-app2" interface - 192.168.95.192/26 - server8
receives traffic from problematic nodes through "-app2" interface
(192.168.95.192/26) but then tries to send it out "front end" -
192.168.91.0/24 - interface.
=====================================================================
server1 - alpha-s18 - reaches everyone, including server4 and server8
=====================================================================
lo0: flags=100c89<UP,LOOPBACK,NOARP,MULTICAST,SIMPLEX,NOCHECKSUM>
     inet 127.0.0.1 netmask ff000000 ipmtu 4096 
tu0: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.95.14 netmask ffffffc0 broadcast 192.168.95.63 ipmtu
1500 
tu1: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.27.78 netmask ffffffc0 broadcast 192.168.27.127 ipmtu
1500 
tu3: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.95.206 netmask ffffffc0 broadcast 192.168.95.255 ipmtu
1500 
alpha-s17-app2 (192.168.95.203) at 08-00-2b-c3-48-6f
alpha-s19-app2 (192.168.95.207) at 00-06-2b-00-2a-8b
alpha-s20-app2 (192.168.95.208) at 00-06-2b-00-30-5c
alpha-s21-app2 (192.168.95.209) at 00-06-2b-00-78-5e
alpha-s22-app2 (192.168.95.210) at 00-06-2b-00-ba-3a
alpha-s23-app2 (192.168.95.211) at 00-06-2b-00-2d-1b
Route Tree for Protocol Family 2:
default          192.168.27.65      UGS         2  4462725  tu1       
127.0.0.1        127.0.0.1          UHL         9 27764691  lo0       
192.168.27.64/26 192.168.27.78      U           3 746352384  tu1       
192.168.27.78    192.168.27.78      UHL        15  6984023  tu1       
192.168.95/26    192.168.95.14      U          21 253696769  tu0       
192.168.95.14    192.168.95.14      UHL         0 39855248  tu0       
192.168.95.192/26 192.168.95.206    U           1  1378255  tu3       
192.168.95.206   192.168.95.206     UHL         0        0  tu3       
===============================================================
server4 - alpha-s20 - reaches everyone except server8
===============================================================
lo0: flags=100c89<UP,LOOPBACK,NOARP,MULTICAST,SIMPLEX,NOCHECKSUM>
     inet 127.0.0.1 netmask ff000000 ipmtu 4096 
tu0: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.95.15 netmask ffffffc0 broadcast 192.168.95.63 ipmtu
1500 
tu1: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.27.79 netmask ffffffc0 broadcast 192.168.27.127 ipmtu
1500 
tu3: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.95.208 netmask ffffffc0 broadcast 192.168.95.255 ipmtu
1500 
alpha-s17-app2 (192.168.95.203) at 08-00-2b-c3-48-6f
alpha-s18-app2 (192.168.95.206) at 00-06-2b-00-2d-7b
alpha-s19-app2 (192.168.95.207) at 00-06-2b-00-2a-8b
alpha-s21-app2 (192.168.95.209) at 00-06-2b-00-78-5e
alpha-s22-app2 (192.168.95.210) at 00-06-2b-00-ba-3a
alpha-s23-app2 (192.168.95.211) at 00-06-2b-00-2d-1b
Route Tree for Protocol Family 2:
default          192.168.27.65      UGS         2  4431631  tu1       
127.0.0.1        127.0.0.1          UHL         5 25940368  lo0       
192.168.27.64/26 192.168.27.79      U           4 472690551  tu1       
192.168.27.79    192.168.27.79      UHL         8  6983291  tu1       
192.168.95/26    192.168.95.15      U          61 1632716853  tu0       
192.168.95.15    192.168.95.15      UHL         0        0  tu0       
192.168.95.192/26 192.168.95.208    U           1  1376443  tu3       
192.168.95.208   192.168.95.208     UHL         0       12  tu3       
========================================================================
====
server8 - alpha-s24 - reaches server1/server2/server3, not
server4->server7
========================================================================
====
lo0: flags=100c89<UP,LOOPBACK,NOARP,MULTICAST,SIMPLEX,NOCHECKSUM>
     inet 127.0.0.1 netmask ff000000 ipmtu 4096 
tu0:
flags=1c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX,OACTIVE>
     inet 192.168.95.6 netmask ffffffc0 broadcast 192.168.95.63 ipmtu
1500 
tu1: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.27.68 netmask ffffffc0 broadcast 192.168.27.127 ipmtu
1500 
tu2: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.91.55 netmask ffffff00 broadcast 192.168.91.255 ipmtu
1500 
tu3: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.27.9 netmask ffffffc0 broadcast 192.168.27.63 ipmtu
1500 
tu4: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 192.168.95.212 netmask ffffffc0 broadcast 192.168.95.255 ipmtu
1500 
alpha-s18-app2 (192.168.95.206) at 00-06-2b-00-2d-7b
alpha-s19-app2 (192.168.95.207) at 00-06-2b-00-2a-8b
alpha-s20-app2 (192.168.95.208) at 00-06-2b-00-30-5c
alpha-s21-app2 (192.168.95.209) at 00-06-2b-00-78-5e
alpha-s22-app2 (192.168.95.210) at 00-06-2b-00-ba-3a
alpha-s23-app2 (192.168.95.211) at 00-06-2b-00-2d-1b
Route Tree for Protocol Family 2:
default          192.168.91.1       UGS        83 60046628  tu2       
127.0.0.1        127.0.0.1          UHL         7   730563  lo0       
192.246.157/24   192.168.27.1       UGS         0   469300  tu3       
192.168.27/26    192.168.27.9       U           1    37352  tu3       
192.168.27.9     192.168.27.9       UHL         0        0  tu3       
192.168.27.64/26 192.168.27.68      U          11 200780825  tu1       
192.168.27.68    192.168.27.68      UHL         9   623779  tu1       
192.168.91/24    192.168.91.55      U           1   531795  tu2       
192.168.91.55    192.168.91.55      UHL         0        0  tu2       
192.168.95/26    192.168.95.6       U          11 243411281  tu0       
192.168.95.6     192.168.95.6       UHL         0   104801  tu0       
192.168.95.192/26 192.168.95.212    U           1     9888  tu4       
192.168.95.212   192.168.95.212     UHL         0        0  tu4       
======================================================================
Judith Reed
jreed_at_navisite.com
Service delivery manager, Syracuse Data Center
315-453-2912 x5835
-----Original Message-----
From: tru64-unix-managers-owner_at_ornl.gov
[mailto:tru64-unix-managers-owner_at_ornl.gov] On Behalf Of Reed, Judith
Sent: Tuesday, March 23, 2004 11:03 AM
To: tru64-unix-managers_at_ornl.gov
Subject: Question about very strange routing problem
We have a set of 8 servers, all running tru64 v5.1a, pk2. They are all
connected to multiple nets, but all share a common net as well:
Server1 server2 server3 server4 server5 server6 server7 server8
    |      |      |        |        |       |      |      |
----------------------------------------------------------------
server1/server2/server3 can all reach server8 and vice-versa.
server4/server5/server6/server7 can *NOT* reach server8, nor can server8
reach them.
server4/server5/server6/server7 can reach server1/server2/server3 and
vice-versa.
server1->server7 all know to go out the shared network to reach server8.
server8 knows to go out the shared network to reach server1->server3,
but tries to go out a different default route to reach server4->server7,
even when responding to pings/ssh/tcpdump packets coming in the shared
common network from the problematic servers.
server8 also knows the correct MAC address of *all* the servers on the
shared common network, and the correct IPs associated with those MAC
addresses. 
There is nothing odd in /etc/routes or "netstat -r" output on *any* of
the servers, either the ones that *can* communicate or those who
*cannot*.
I'm baffled. If this wasn't a prod env. I'd reboot the d*mn server8, but
that's not an option. Anyone have any suggestions/insights??? 
Regards,
Judith Reed
jreed_at_navisite.com
Service delivery manager, Syracuse Data Center
315-453-2912 x5835
Received on Tue Mar 23 2004 - 16:47:48 NZST