Version 9 template records have a limited lifetime and must be periodically refreshed. Templates are retransmitted when either:
Template refresh based on the timeout period is performed on every module. Since each S- and K-Series module handles its own packet transmissions, template refresh based on number of export packets sent is managed by each module independently.
The refresh rate defines the maximum delay a new or restarted NetFlow collector would experience, before it learns the format of the data records being forwarded (from the template referenced by the data records). Refresh rates affect NetFlow collectors during their start up. Collectors must ignore incoming data flow reports until the required template is received.
The default behavior is for the template to be sent after 20 flow report packets are sent. Since data record packets are sent out per flow, a long FTP flow may cause the template timeout timer to expire before the maximum number of packets are sent. In any case a refresh of the template is sent at timeout expiration as well.
Setting the appropriate refresh rate for your S- and K-Series device must be determined, because the default settings of a 20 flow report packet refresh rate and a 30-minute timeout may not be optimal for your environment. For example, a switch processing an extremely slow flow rate of, say, 20 flow report packets per half hour, would refresh the templates only every half hour using the default settings, while a switch sending 300 flow report packets per second would refresh the templates 15 times per second.
Extreme Networks recommends that you configure your S- or K-Series device so it does not refresh templates more often than once per second.
Use the set netflow template to set the NetFlow export template refresh rate and timeout for this system.
Use the clear netflow template to reset the NetFlow export template refresh rate and timeout to the default values.
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