IP Routing Features

 

Overview of IP Routing

 

IP Route Table

 

The IP route table contains routing paths to IP destinations.

 

 

N o t e

The default gateway, which is configured as part of the IP address configura­

 

tion described in chapter 7, “IP Addressing”, is used only when routing is not

 

enabled on the switch.

 

 

The IP route table can receive the routing paths from the following sources:

A directly-connected destination, which means there are no router hops to the destination

A static IP route, which is a user-configured route

The IP route table contains the best path to a destination. When the software receives paths from more than one of the sources listed above, the software compares the administrative distance of each path and selects the path with the lowest administrative distance. The administrative distance is a protocol- independent value from 1 – 255.

The IP route table is displayed by entering the CLI command show ip route from any context level in the console CLI. Here is an example of an entry in the IP route table:

Destination

Network Mask

Gateway

Type

Sub-Type

Metric

---------------

---------------

+

---------------

---------

----------

-----­

1.1.0.0

255.255.0.0

99.1.1.2

connected

 

1

 

 

 

 

 

 

 

Figure 7-2. Example of IP Route Table Entry

Each IP route table entry contains the destination’s IP address and subnet mask and the IP address of the next-hop router interface to the destination. Each entry also indicates route type. The type indicates how the IP route table received the route.

To configure a static IP route, see “Configuring a Static IP Route” on page 7-18.

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 ProCurve routing 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’s destination.

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