3Com Switch 7700, Configuration Manual

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Route Capacity 183
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, it can consume a significant amount of switch’s memory.
To solve this 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 or not to
keep connection with a routing protocol.
The default value normally meets the network requirements. You should be
careful when modifying the configuration to avoid reducing the stability of the
network.
Limiting Route Capacity The size of the routing table is determined by BGP and OSPF routes. Therefore, the
route capacity limitation of the Switch 7700 is only effective for 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 their routes from the routing
table to release memory. The system checks the free memory periodically. When
enough free memory is detected to restore the safety value, BGP and OSPF
connection is restored.
Configuring Route
Capacity
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
■
Preventing Automatic Recovery of Disconnected Routing Protocols
■
Enabling Automatic Recovery of Disconnected Routing Protocols
■
Displaying and Debugging Route Capacity
Setting the Lower Limit for Switch Memory
When the Ethernet switch memory is equal to or lower than the lower limit, BGP
and OSPF will be disconnected.
Perform the following configurations in system view.
By default, the lower limit of the Ethernet switch memory is 2Mbytes, that is,
when the available memory is less than 2Mbytes, BGP and OSPF will be
disconnected and BGP routes and OSPF routes will be removed from the routing
table.
The lower limit value set for the memory must be smaller than the safety value.
Table 140 Setting the Lower Limit of the Ethernet Switch Memory
Operation Command
Set the lower limit of the Ethernet switch
memory memory limit value