3Com 4007, Implementation Manual, Page: 485 / 684

OSPF Memory Partition 485
OSPF Memory
Partition
There are three choices for OSPF memory allocation:
■
Have the system intelligently determine the maximum OSPF memory
partition size (partition size =
1
). This is the default.
■
Have OSPF be part of system memory, growing as needed and without
limit (partition size =
0
).
■
Configure the maximum OSPF memory partition size manually
(partition size =
4096
- <
maximum available memory>
).
You use the
ip ospf partition modify
option to control memory
allocation, as described in the
Command Reference Guide
.
Default Memory
Allocation
You typically do not have to modify the OSPF memory allocation. By
default, the system manages memory by partitioning the total memory
available for applications among the various protocols. This functionality
ensures that the router has enough memory for to perform all of its
functions and enable most features. Under this option, OSPF always has a
partition of memory available for its use.
Under the default OSPF memory allocation scheme, two values have
meaning:
■
Current partition maximum size
■
Allocated memory size
Current Partition Maximum Size
The current partition maximum size is the maximum amount of memory
that OSPF can allocate. It is calculated at system startup as a function of
the maximum routing table size and available memory by the following
formula:
( ( ( externalLSAsize * maxRoutingTab 100000 ) / 100000 ) + 1 ) * 100000
Because most of the routes are going to be external to OSPF, the formula
bases the OSPF memory partition maximum size on the amount of
memory that is required to store an external link state advertisement
(LSA), 80 bytes, times an estimate of the maximum number of routing
table entries that the system can hold (maxRoutingTableSize). It then
rounds to the nearest 100000 bytes and adds an additional 100000 bytes
as a buffer.