
Configuring Bridging Services
3-8 114060 Rev. A
Query caching consumes approximately 100 bytes per entry. Each cache entry
remains in the query cache for a short time (approximately 3 seconds). However,
if the number of NetBIOS stations and applications in your network is large, you
may want to leave the query cache MIB function disabled to enhance router
performance.
Cache Lookup
The source routing bridge uses a table lookup process for name searching, which
uses a fast-string hash and search mechanism. You can use the Hash Entry Count
global parameter to adjust the number of entries in the hash table. (Refer to
“NetBIOS Global Parameter Descriptions” later in this chapter for a description of
this parameter.)
When you increase the number of entries in the hash table, you
• Decrease the likely number of names the router must compare before it finds a
specific cached name.
• Decrease the amount of time it takes the router to find a particular cached
name.
• Increase memory usage.
Note that when you increase the number of entries in the hash table, you do not
increase the number of names that the router can cache. You determine the number
of names using the Max Number Query Cache Entries global parameter. (Refer to
“NetBIOS Global Parameter Descriptions” later in this chapter for a description of
this parameter.)
When you decrease the number of entries in the hash table, this generally
produces an opposite effect on the cache lookup mechanism.
Cache Aging
The router ages name cache and query cache entries to ensure that cached routes
remain consistent with the current network topology. If the cache table lookup
mechanism does not access a cache entry within the interval you set in the
appropriate cache aging time parameter, the router deletes the entry from the
table.
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