Riverstone Networks WICT1-12 - Manual (Page 195)

Riverstone Networks RS Switch Router User Guide Release 8.0 11-17
IP Routing Configuration Guide Setting Memory Thresholds
The default memory thresholds are shown in Table 11-1 . You can use the
ip-router global set
memory-threshold
command to change the thresholds.
When a level-1, level-2, or level-3 threshold is reached, the RS may delete routes in the RIB or not add new routes to
the RIB, depending upon the routing protocol. When threshold level-4 is reached (by default, 75% of available memory
used by the RIB), no new routes are added.
Table 11-2 shows what actions the RS takes in updating the RIB when each threshold is reached.
Table 11-1 Default Memory Thresholds
Threshold Level Percentage of Memory
OHYHO 
OHYHO 
OHYHO 
OHYHO 
Table 11-2 RIB Updates When Memory Threshold is Reached
Route
Protocol Threshold Action
OSPF/
IS-IS level-1
level-2
level-3
level-4 Updates are processed as usual.
RIP level-1 • A new RIP route is added only if it is the only RIP route to
the given destination.
• Maximum of 2 routes allowed to a given destination. If there
are more than 2 routes to a given destination, the least
preferred route(s) are deleted.
level-2 • A new RIP route is added only if is an active RIP route to the
given destination.
level-3 • Only one route is allowed to a given destination. If there is
more than one route to a given destination, the least preferred
route is deleted.
level-4 No new routes are added.