Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 397)

Parameter changes that take effect after disabling and re-enabling
redistribution
The following parameter change takes effect only after you disable and then re-enable redistribution:
• Change the default MED (metric).
Memory considerations
BGP4 can handle a very large number of routes and therefore requires a lot of memory. For example, in
a typical configuration with a single BGP4 neighbor, receiving a full internet route table, a BGP4 device
may need to hold over a million routes. Many configurations, especially those involving more than one
neighbor, can require the device to hold even more routes. Brocade devices provide dynamic memory
allocation for BGP4 data. BGP4 devices automatically allocate memory when needed to support BGP4
neighbors, routes and route attribute entries. Dynamic memory allocation is performed automatically by
the software and does not require a reload.
The following table lists the maximum total amount of system memory (DRAM) BGP4 can use. The
maximum depends on the total amount of system memory on the device.
Maximum memory usage TABLE 90
Platform Maximum memory BGP4 can use
FSX with Management module with 1536 MB 1336 MB
The memory amounts listed in the table are for all BGP4 data, including routes received from neighbors,
BGP route advertisements (routes sent to neighbors), and BGP route attribute entries. The routes sent
to and received from neighbors use the most BGP4 memory. Generally, the actual limit to the number of
neighbors, routes, or route attribute entries the device can accommodate depends on how many routes
the device sends to and receives from the neighbors.
In some cases, where most of the neighbors do not send or receive a full BGP route table (about
80,000 routes), the memory can support a larger number of BGP4 neighbors. However, if most of the
BGP4 neighbors send or receive full BGP route tables, the number of BGP neighbors the memory can
support is less than in configurations where the neighbors send smaller route tables.
Memory configuration options obsoleted by dynamic memory
Devices that support dynamic BGP4 memory allocation do not require or even support static
configuration of memory for BGP4 neighbors, routes, or route attributes. Consequently, the following
CLI commands and equivalent Web management options are not supported on these devices:
• max-neighbors num
• max-routes num
• max-attribute-entries num
If you boot a device that has a startup-config file that contains these commands, the software ignores
the commands and uses dynamic memory allocation for BGP4. The first time you save the device
running configuration (running-config) to the startup-config file, the commands are removed from the
file.
Parameter changes that take effect after disabling and re-enabling redistribution
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 397
53-1003087-04