From: Adrian Liu (adrianliu324@hotmail.com)
Date: Tue Jun 24 2003 - 01:37:42 EDT
We have an interesting situation with a V5.1 cluster, a cluster alias
We have a client application that attempts to communicate with a service
running on a member of the cluster via a UDP port. The service receives a
client request and sends a response to the client.
When monitoring the traffic between the client and server using tcpdump we
see that the initial request from the client comes in and is targetted for
the cluster alias (which is correct). The response however looks to come
from the specific member node rather than the cluster alias (which is
incorrect).
NOTE: This only occurs for clients that are not in the same subnet as the
server. For those clients that are in the same subnet as the server, the
response (reported by tcpdump) comes from the cluster alias, which is
correct.
The following tcpdump output shows the situation from client (s-underdale29)
to cluster alias (mfgprotest), with the member node being pha301. The
response is coming from the member node which is incorrect:
16:47:53.724736 s-underdale29.faulding.com.au.1140 > mfgprotest.5162: udp 62
16:47:53.737431 pha301.5162 > s-underdale29.faulding.com.au.1140: udp 119
(DF)
S-underdale29 is 10.25.250.23
Mfgprotest is 10.3.231.233
Pha301 is 10.3.231.235
The following tcpdump output shows the situation from a DHCP client (on the
same subnet) to cluster alias (mfgprotest). The response is coming from the
cluster alias which is correct:
16:55:11.548381 10.3.230.112.4168 > mfgprotest.5162: udp 62
16:55:11.633340 mfgprotest.5162 > 10.3.230.112.4168: udp 119 (DF)
Does anyone know how I can test this type of UDP conversation with standard
Unix? Ie. Remove the application from the picture, incase the application is
at fault?
Any other suggestions?
Thanks,
Adrian
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