Switch 7700 Configuration Guide, v2

150 CHAPTER 5: ROUTING PROTOCOL OPERATION
■ The if-match mode of at least one node of the Route policy should be the
permit mode. When a Route-policy is used for the routing information
filtering, if a piece of routing information does not pass the filtering of any
node, then it means that the route information does not pass the filtering of
the Route-policy. When all the nodes of the Route-policy are in the deny
mode, then all the routing information cannot pass the filtering of the
Route-policy.
■ The if-match mode of at least one list item of the ip-prefix should be the permit
mode. The list items of the deny mode can be firstly defined to rapidly filter the
routing information not satisfying the requirement, but if all the items are in
the deny mode, any routes will not pass the ip-prefix filtering. You can define
an item of permit 0.0.0.0/0 less-equal 32 after the multiple list items in the
deny mode so as to let all the other routes pass the filtering (If less-equal 32 is
not specified, only the default route will be matched).
Route Capacity In practical networking applications, there is always a large number of routes in
the routing table, especially OSPF routes and BGP routes. The routing information
is usually stored in the memory of the Ethernet switch. When the size of the
routing table increases, the total memory of the Ethernet switch does not change
(unless the hardware is upgraded but upgrading cannot be guaranteed to solve all
problems).
In order to solve such problem, Switch 7700 switches provide a mechanism to
control the size of the routing table. They monitor the free memory in the system
to determine whether to add new routes to the routing table and whether to keep
connection with a routing protocol.
Note: It should be noted that the default value meets the requirements normally.
You should not modify the configuration to avoid reducing the stability and
availability of the system.
Route Capacity
Limitation
As previously mentioned, the huge size of the routing table is caused by BGP
routes and OSPF routes. Therefore, the route capacity limitation of the Switch
7700 is only effective to these two types of routes and has no impact on static
routes and other dynamic routing protocols.
When the free memory of a Switch 7700 reduces to the lower limit value, the
system will disconnect BGP and OSPF and remove corresponding routes from the
routing table so that the memory occupied is released. The system checks the free
memory periodically. When enough free memory is detected to restore the safety
value, BGP and OSPF connection will be restored.
Route Capacity
Configuration
Route capacity configuration includes tasks described in the following sections:
■ Setting the Lower Limit for Switch Memory
■ Setting the Safety Value for Switch Memory
■ Setting the Lower Limit and the Safety Value Simultaneously
■ Disabling the Switch to Recover the Disconnected Routing Protocol
Automatically
■ Enable the Switch to Recover the Disconnected Routing Protocol Automatically