06-Layer 3—IP Services Configuration Guide

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07-Fast forwarding configuration
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07-Fast forwarding configuration 52.79 KB

Configuring fast forwarding

About fast forwarding

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.

Restrictions and guidelines: Fast forwarding configuration

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

Fast forwarding can be implemented by software or hardware. Unless otherwise noted, fast forwarding in this chapter refers to software fast forwarding.

Configuring the aging time for fast forwarding entries

About this task

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.

Procedure

1.     Enter system view.

system-view

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

About this task

Fast forwarding load sharing enables the device to identify a data flow by using the packet information.

If fast forwarding load sharing is disabled, the device identifies a data flow by the packet information and the input interface.

 

Procedure

1.     Enter system view.

system-view

2.     Configure fast forwarding load sharing. Choose one option as needed:

¡     Enable fast forwarding load sharing.

ip fast-forwarding load-sharing

¡     Disable fast forwarding load sharing.

undo ip fast-forwarding load-sharing

By default, fast forwarding load sharing is enabled.

Enabling DSCP-based fast forwarding for GRE and VXLAN packets

About this task

This feature uses the DSCP value in the outer header instead of the source port number among the identification criteria to identify GRE and VXLAN traffic flows.

Procedure

1.     Enter system view.

system-view

2.     Enable DSCP-based fast forwarding for GRE and VXLAN packets.

ip fast-forwarding dscp

By default, DSCP-based fast forwarding for GRE and VXLAN packet is disabled.

3.     (Optional.) Specify the destination UDP port number for identifying VXLAN packets

ip fast-forwarding vxlan-port port-number

By default, the destination UDP port number is 4789.

Display and maintenance commands for fast forwarding

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

 

Task

Command

Display the aging time of fast forwarding entries.

display ip fast-forwarding aging-time

Display fast forwarding entries.

In standalone mode:

display ip fast-forwarding cache [ ip-address ]

In IRF mode:

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

Display fast forwarding entries about fragmented packets.

In standalone mode:

display ip fast-forwarding fragcache [ ip-address ]

In IRF mode:

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

Clear the fast forwarding table.

In standalone mode:

reset ip fast-forwarding cache

In IRF mode:

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