3Com 3C17203 - SuperStack 3 Switch 4400, Implementation Manual

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What is Webcache Support? 95
The redirected TCP port number can be changed through the CLI using
the
feature cacheConfig changePort
command, or via the Web
interface by selecting System > Cache Config > Change TCP Port.
If your Switch is configured to generate SNMP traps, you may see a trap
containing the message
No TCP port specified to be
redirected
when you change the port number. This is normal. When
the Webcache becomes operational, the summary will confirm that the
required port is being redirected.
Cache Health Checks The cache health check is a feature that ensures web traffic is not
redirected to a cache that is not currently operating. The health check
works as follows:
1 The health check requests a factory-defined URL from the Webcache
every eleven seconds and expects to receive a reply to confirm that the
cache is operating normally.
2 If a reply is not received from the Webcache, the Switch will start polling
the Webcache at three second intervals.
3 If the Webcache fails three health check attempts, the Webcache is
deemed to have failed and the Webcache support feature on the Switch
is disabled (that is, it no longer redirects HTTP traffic). From this point on
all HTTP traffic will go directly to the WAN.
4 However, the Webcache support feature, although no longer redirecting
traffic, continues to perform health checks on the Webcache at three
second intervals to determine if the Webcache is operating. If a health
check is successful, redirection of HTTP traffic will start again.