Technical Documentation

Configuring the JUNOS Software to Allocate More Memory for Routing Tables

The jtree memory on all MX Series, all M120, and some M320, M10i, M7i, T640, T1600, and TX router Packet Forwarding Engines has two segments: one segment primarily stores routing tables and related information, and the other segment primarily stores firewall-filter-related information.

Note: For T Series routers only. With JUNOS Release 10.2, enhanced jtree memory allocation is turned OFF by default. For JUNOS Release 9.3 to 10.1, the default routing tables (inet.0 and inet6.0) use both memory segments by default.

The JUNOS Software provides the configuration statement route-memory-enhanced to reallocate the jtree memory. This statement enables you to provide more memory for routing tables over firewall filters on the following routers:

  • M10i and M7i routers with Enhanced CFEB
  • M320 routers with Enhanced III FPC1, Enhanced III FPC2, and Enhanced III FPC3
  • M120 routers
  • MX Series routers
  • T640, T1600, and TX routers with Enhanced Scaling FPC3, and Enhanced Scaling FPC4

This option is useful when you want to support larger routing tables with more routes. For example, you can enable this option, when you want to support a large number of routes for Layer 3 VPNs implemented using MPLS. However, we recommend enabling this option only if you do not have a very large firewall configuration.

To allocate more memory for routing tables, include the route-memory-enhanced statement at the [edit chassis] hierarchy level:

[edit chassis]route-memory-enhanced;

As the allocation of more memory for routing tables might disrupt the forwarding operations of a Packet Forwarding Engine, the JUNOS Software CLI displays a warning to restart all affected FPCs when you commit the route-memory-enhanced configuration. The configuration does not become effective until you restart the FPC or DPC (on MX Series routers).

To restart a single FPC or DPC without rebooting the entire router, issue the request chassis fpc slot slot-number restart command. On an M120 router, issue the request chassis feb slot slot-number restart command.

To view if the configuration is active on an FPC or DPC, issue the show pfe fpc slot-number command.


Published: 2010-04-26