Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved


Chapter 15 Multicast Deployment and Troubleshooting : Troubleshooting EMS Multicast

Troubleshooting EMS Multicast
Multicast deployment issues are often more difficult to resolve than similar unicast issues. Reasons for the additional difficulty include:
Troubleshooting Tips
This section give some troubleshooting tips to help you respond to difficulties you may experience with your multicast deployment.
General Tips
If you are experiencing problems with your deployment, begin with these practices:
The "bottom-up" approach generally seems best. That is, get the lowest layers of the network stack working first.
Connectivity
EMS will detect multicast connectivity issues; it may take up to 64 seconds to detect a connectivity problem. These suggestions can help resolve issues with connectivity:
Ensure that the channel's ttl is large enough for data to cross all of your switches and routers.
Data Loss
These suggestions can help if you are experiencing data loss:
Application and Multicast Daemon Errors and Warnings
You may find these tips useful if you are experiencing errors in the multicast daemon or client application:
Note that multicast events are also logged at the client if client trace is enabled on the server, but that comes at a performance price and can cause other problems. For this reason, we do not recommend using client trace outside of debugging basic connectivity issues or as directed by TIBCO support.
When the multicast daemon detects excessive loss, the multicast connection exception IO Failed is generated in the application. Usually, this means that the server is sending too fast, and maxrate for the channel needs to be decreased. The multicast daemon will report an error, similar to the following:
2007-10-02 16:45:09.551 Multicast error: channel='mcast', Loss Detected, status=IO failed
You will also notice in the multicast statistics that the particular channel's rcv_losses are growing.
If a consumer receives a multicast exception of TIBEMS_TIMEOUT with a message similar to Timeout reached which may indicate a configuration or hardware problem, this indicates a lack of multicast connectivity. While unicast connectivity exists between the client and server and the multicast channel was set up, multicast data cannot get from the server to the local multicast daemon. Note that this may take more than a minute to detect.
Start a subscriber listening to $sys.monitor.multicast.stats monitoring messages to receive multicast-related statistics.
Server Errors
In General, server errors are self-descriptive. It is important to note that client errors may be returned to the server to be logged, providing a centralized place to look for multicast errors. However, these errors do not include minor loss on a particular client, or loss of messages from a client failover.

Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved