Contents

Configuring fast forwarding· 1

About fast forwarding· 1

vSystem support for features· 1

Restrictions and guidelines: Fast forwarding configuration· 1

Configuring the aging time for fast forwarding entries· 1

Configuring fast forwarding load sharing· 2

Configuring hardware fast forwarding· 2

Enabling DSCP-based fast forwarding for GRE and VXLAN packets· 3

Enabling the fast forwarding chip to encapsulate the incremental checksum in outgoing packets· 3

Enabling the fast forwarding chip to do packet integrity check· 3

Specifying the action on altered packets· 4

Enabling single-chip hardware forwarding for upstream packets· 4

Configuring packet processing mode for security modeules· 5

Ignoring interface sequence numbers during hardware fast forwarding· 5

Display and maintenance commands for fast forwarding· 6

 

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.

vSystem support for features

Non-default vSystems do not support the following features:

·     Hardware fast forwarding.

·     Enabling/disabling fast forwarding.

For information about the support of non-default vSystems for the commands, see fast forwarding command reference. For information about vSystem, see Virtual Technologies Configuration Guide.

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.

Configuring hardware fast forwarding

About this task

Hardware fast forwarding stores session information during fast forwarding to speed up subsequent traffic forwarding by comparing the traffic with session information.

Disable hardware fast forward when you troubleshoot problems on forwarding chips.

Procedure

1.     Enter system view.

system-view

2.     Configure hardware fast forwarding.

¡     Enable hardware fast forwarding.

In standalone mode:

hardware fast-forwarding enable [ slot slot-number [ cpu cpu-number ] ]

In IRF mode:

hardware fast-forwarding enable [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]

¡     Disable hardware fast forwarding.

In standalone mode:

undo hardware fast-forwarding enable [ slot slot-number [ cpu cpu-number ] ]

In IRF mode:

undo hardware fast-forwarding enable [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]

By default, hardware fast forwarding 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.

Enabling the fast forwarding chip to encapsulate the incremental checksum in outgoing packets

1.     Enter system view.

system-view

2.     Enable the fast forwarding chip to encapsulate the incremental checksum in outgoing packets.

In standalone mode:

hardware fast-forwarding checksum encap incremental [ slot slot-number cpu cpu-number ]

In IRF mode:

hardware fast-forwarding checksum encap incremental [ chassis chassis-number slot slot-number cpu cpu-number ]

By default, the fast forwarding chip encapsulates the incremental checksum in outgoing packets.

Enabling the fast forwarding chip to do packet integrity check

1.     Enter system view.

system-view

2.     Enable the fast forwarding chip to check the integrity of outgoing outgoing packets.

In standalone mode:

hardware fast-forwarding checksum inspect [ l3 | l4 [ tcp | udp ] ] enable [ slot slot-number cpu cpu-number ]

In IRF mode:

hardware fast-forwarding checksum inspect [ l3 | l4 [ tcp | udp ] ] enable [ chassis chassis-number slot slot-number cpu cpu-number ]

By default, the fast forwarding chip checks the integrity of outgoing packets to prevent packet alteration.

Specifying the action on altered packets

1.     Enter system view.

system-view

2.     Specify the action to take on altered packets.

In standalone mode:

hardware fast-forwarding checksum inspect action { drop-err | log } [ slot slot-number cpu cpu-number ]

In IRF mode:

hardware fast-forwarding checksum inspect action { drop-err | log } [ chassis chassis-number slot slot-number cpu cpu-number ]

By default, the device forwards the altered packet and generates a log message.

Enabling single-chip hardware forwarding for upstream packets

About this task

This feature enables a dual-chip module to forward upstream packets by using only one of the chips. It does not apply to downstream packets. The module uses both chips to forward downstream packets.

Restrictions and guidelines

This feature applies only to modules that have more than one hardware forwarding chip.

After you change the hardware forwarding mode for upstream packets, you must restart the module for the change to take effect.

To change the hardware forwarding mode for upstream packets in a security engine group with multiple security engines (multiple modules), perform the following tasks:

·     Execute the hardware fast-forwarding standalone or undo hardware fast-forwarding standalone command on all modules one by one to change their hardware forwarding mode for upstream packets.

·     Restart all modules.

For details about security engine group, see context configuration in Virtual Technologies Configuration Guide.

Procedure

1.     Enter system view.

system-view

2.     Enable single-chip hardware forwarding for upstream packets.

In standalone mode:

hardware fast-forwarding standalone [ slot slot-number [ cpu cpu-number ] ]

In IRF mode:

hardware fast-forwarding standalone [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]

By default, dual-chip hardware forwarding is enabled for upstream packets.

Configuring packet processing mode for security modeules

About this task

When a CPU core on the security module processes too many packets in a short time, the performance of other CPU cores might be degraded. To resolve this issue, perform this task to enable the security module to process packets in attack-resistance mode. The security module will prefer using the fast-forwarding chip for packet processing.

Restrictions and guidelines

This task is applicable only to Blade IV security modules.

Procedure

1.     Enter system view.

system-view

2.     Set the packet processing mode to attack-resistance for security modules.

hardware processing-mode attack-resistance

By default, security modules use the CPU for packet processing.

Ignoring interface sequence numbers during hardware fast forwarding

About this task

On a network that has two equal-cost egresses, the device might receive the return packets of a forward flow on different interfaces. By default, the device determines that the return packets are in different traffic flows, because their incoming interfaces are different. As a result, the device cannot implement hardware fast forwarding for the return packets in a different flow.

To resolve this issue, use this feature to enable the device to ignore interface sequence numbers during hardware fast forwarding. The device can perform hardware fast forwarding for the return packets of a forward flow even if they are received on different interfaces.

Restrictions and guidelines

This feature takes effect only after you enable hardware fast forwarding.

If a forwarding error occurs, you can disable this feature for debugging.

Procedure

1.     Enter system view.

system-view

2.     Ignore interface sequence numbers during hardware fast forwarding.

Standalone mode:

hardware fast-forwarding ifsn match enable [ slot slot-number cpu cpu-number ]

IRF mode:

hardware fast-forwarding ifsn match enable [ chassis chassis-number slot slot-number cpu cpu-number ]

By default, the device does not ignore interface sequence numbers during hardware fast forwarding.

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 ] [ slot slot-number [ cpu cpu-number ] ] In IRF mode: display ip fast-forwarding cache [ ip-address ] [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]
Display fast forwarding entries about fragmented packets.	In standalone mode: display ip fast-forwarding fragcache [ ip-address ] [ slot slot-number [ cpu cpu-number ] ] In IRF mode: display ip fast-forwarding fragcache [ ip-address ] [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]
Clear the fast forwarding table.	In standalone mode: reset ip fast-forwarding cache [ slot slot-number [ cpu cpu-number ] ] In IRF mode: reset ip fast-forwarding cache [ chassis chassis-number slot slot-number [ cpu cpu-number ] ]