OPERATIONAL DEFECT DATABASE
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When IPv4/IPv6 maximum routes are over limit in TCAM, no direct or indirect routes are able to be installed in Hash table. There are two types of memory tables to consider: HASH: A simple memory table (similar to CAM or MAC table) that contains a hashed representation of the entry being programmed to hardware. Any hash entry added to this table must be unique. If there is another entry that results in the same hash, a hash collision occurs and this entry will need to be stored in TCAM instead. This table is binary (it either matched an entry or it did not match that entry) TCAM: (ternary content-addressable memory) is a specialized type of high-speed memory that searches its entire contents in a single clock cycle. The term ?ternary? refers to the memory's ability to store and query data using three different inputs: 0, 1 and X. This type of memory must be used in cases where there can be multiple matches to the same entry, and the resulting Hash for each would not be unique. This table includes a mask or "X" value that allows it to know if it should match or not match this entry. /32 prefixes (either direct connected hosts or indirectly connected host routes) are installed into the Hash table /31 or less prefixes are installed into TCAM table. This bug addresses an issue where TCAM is exhausted, but Hash table still has avaialble room but cannot accept new programming.
IPv4/IPv6 maximum routes are hit in TCAM, no new routes are able to be installed in Hash table.
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NOTE: the first value 16,384 does not mean only Direct routes. It is the value of the Hash table versus the TCAM table. It is important to understand that it is not correct to state Direct = first value 16,384 and Indirect = second value 7168. This is not the case. An indirect route that is a /32 host route will be added to Hash table because the hash computed against the route results in a unique hash and therefore does not cause a hash collision. R38MK21DPTRD04#sh platform hardware fed switch active fwd-asic resource tcam utilization CAM Utilization for ASIC# 0 Table Max Values Used Values -------------------------------------------------------------------------------- Unicast MAC addresses 32768/512 1440/23 Directly or indirectly connected routes 16384/7168 2230/7147 <-- TCAM table is full, HASH table is not CAM Utilization for ASIC# 1
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