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Quick Reference Guide

ManualsBrandsDell ManualsComputer equipmentPowerConnect B-TI24x
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568 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
Overview
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Each IP route table entry contains the destination IP address and subnet mask and the IP address
of the next-hop router interface to the destination. Each entry also indicates the port attached to
the destination or the next-hop to the destination, the route IP metric (cost), and the type. The type
indicates how the IP route table received the route.
To display the IP route table, refer to “Displaying the IP route table” on page 632 (Layer 3 Switch
only)
To configure a static IP route, refer to “Configuring static routes” on page 596 (Layer 3 Switch only)
To clear a route from the IP route table, refer to “Clearing IP routes” on page 634 (Layer 3 Switch
only)
To increase the size of the IP route table for learned and static routes, refer to the section
“Displaying and modifying system parameter default settings” on page 184:
• For learned routes, modify the ip-route parameter.
• For static routes, modify the ip-static-route parameter.
IP forwarding cache
The IP forwarding cache provides a fast-path mechanism for forwarding IP packets. The cache
contains entries for IP destinations. When a Layer 3 Switch has completed processing and
addressing for a packet and is ready to forward the packet, the device checks the IP forwarding
cache for an entry to the packet destination:
• If the cache contains an entry with the destination IP address, the device uses the information
in the entry to forward the packet out the ports listed in the entry. The destination IP address
is the address of the packet final destination. The port numbers are the ports through which
the destination can be reached.
• If the cache does not contain an entry and the traffic does not qualify for an entry in the
session table instead, the software can create an entry in the forwarding cache.
Each entry in the IP forwarding cache has an age timer. If the entry remains unused for ten
minutes, the software removes the entry. The age timer is not configurable.
Here is an example of an entry in the IP forwarding cache.
Each IP forwarding cache entry contains the IP address of the destination, and the IP address and
MAC address of the next-hop router interface to the destination. If the destination is actually an
interface configured on the Layer 3 Switch itself, as shown here, then next-hop information
indicates this. The port through which the destination is reached is also listed, as well as the VLAN
and Layer 4 QoS priority associated with the destination if applicable.
To display the IP forwarding cache, refer to “Displaying the forwarding cache” on page 631.
NOTE
You cannot add static entries to the IP forwarding cache, although you can increase the number of
entries the cache can contain. Refer to the section “Displaying and modifying system parameter
default settings” on page 184.