3Com SUPERSTACK 3 WEBCACHE 3000 User Manual page 57

ICP Caching has two disadvantages against Parent Caching:
ICP Caching does not scale well — if your infrastructure grows and
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more caches are installed, the network bandwidth used by ICP, and
the latency and reliability of the protocol can become an issue. This
does not occur with Parent Caching.
ICP Caching uses a connectionless protocol (UDP/IP) — if your
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network is busy and a packet containing caching information is lost, it
will not be retransmitted. Consequently caching latency may go up as
UDP messages are lost and unnecessary cache misses occur.
3Com recommends that you use Parent Caching in preference to ICP
Caching unless you have an existing network of ICP Caches that you wish
to maintain.
ICP Caching 57