05-Layer 3 - IP Services Configuration Guide

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07-Fast forwarding configuration
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07-Fast forwarding configuration 40.84 KB

Configuring fast forwarding

Overview

Fast forwarding reduces route lookup time and improves packet forwarding efficiency by using a high-speed cache and data-flow-based technology. It identifies a data flow by using the following fields: source IP address, source port number, destination IP address, destination port number, and protocol number. After a flow's first packet is forwarded through the routing table, fast forwarding creates an entry and uses the entry to forward subsequent packets of the flow.

Fast forwarding can process fragmented IP packets, but it does not fragment IP packets.

Configuring the aging time for fast forwarding entries

The fast forwarding table uses an aging timer for each forwarding entry. If an entry is not updated before the timer expires, the device deletes the entry. If an entry has a hit within the aging time, the aging timer restarts.

To configure the aging time for fast forwarding entries:

 

Step

Command

Remarks

1.     Enter system view.

system-view

N/A

2.     Configure the aging time for fast forwarding entries.

ip fast-forwarding aging-time aging-time

By default, the aging time is 30 seconds.

 

Configuring fast forwarding load sharing

Fast forwarding load sharing enables the device to load share packets of the same flow. This feature identifies a data flow by using the five-tuple (source IP, source port, destination IP, destination port, and protocol).

If fast forwarding load sharing is disabled, the device identifies a data flow by the five-tuple and the input interface. No load sharing is implemented.

To configure fast forwarding load sharing:

 

Step

Command

Remarks

1.     Enter system view.

system-view

N/A

2.     Enable fast forwarding load sharing.

ip fast-forwarding load-sharing

By default, fast forwarding load sharing is enabled.

 

Displaying and maintaining fast forwarding

Execute display commands in any view and reset commands in user view.

 

Task

Command

(In standalone mode.) Display fast forwarding entries.

display ip fast-forwarding cache [ ip-address ] [ slot slot-number ]

(In IRF mode.) Display fast forwarding entries.

display ip fast-forwarding cache [ ip-address ] [ chassis chassis-number slot slot-number ]

(In standalone mode.) Display fast forwarding entries about fragmented packets.

display ip fast-forwarding fragcache [ ip-address ] [ slot slot-number ]

(In IRF mode.) Display fast forwarding entries for fragmented packets.

display ip fast-forwarding fragcache [ ip-address ] [ chassis chassis-number slot slot-number ]

Display the aging time of fast forwarding entries.

display ip fast-forwarding aging-time

(In standalone mode.) Clear the fast forwarding table.

reset ip fast-forwarding cache [ slot slot-number ]

(In IRF mode.) Clear the fast forwarding table.

reset ip fast-forwarding cache [ chassis chassis-number slot slot-number ]

 

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