Contents

Basic IP forwarding commands· 1

display fib· 1

ip forwarding· 2

ip global last-hop hold· 3

ipv6 forwarding· 4

Load sharing commands· 5

ip load-sharing mode· 5

 

Basic IP forwarding commands

display fib

Use display fib to display FIB entries.

Syntax

display fib  [ ip-address [ mask | mask-length ] ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

ip-address: Displays the FIB entry that matches the specified destination IP address.

mask: Specifies the mask for the IP address.

mask-length: Specifies the mask length for the IP address. The value range is 0 to 32.

Usage guidelines

If you specify an IP address without a mask or mask length, this command displays the longest matching FIB entry.

If you specify an IP address and a mask or mask length, this command displays the exactly matching FIB entry.

Examples

# Display all FIB entries of the public network.

<Sysname> display fib

Route destination count: 5

Directly-connected host count: 0

 

Flag:

  U:Useable   G:Gateway   H:Host   B:Blackhole   D:Dynamic   S:Static

  R:Relay     F:FRR

 

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

0.0.0.0/32         127.0.0.1       UH       InLoop0                  Null

127.0.0.0/8        127.0.0.1       U        InLoop0                  Null

127.0.0.0/32       127.0.0.1       UH       InLoop0                  Null

127.0.0.1/32       127.0.0.1       UH       InLoop0                  Null

# Display the FIB entries matching the destination IP address 10.2.1.1.

<Sysname> display fib 10.2.1.1

Route destination count: 1

Directly-connected host count: 1

 

Flag:

  U:Useable   G:Gateway   H:Host   B:Blackhole   D:Dynamic   S:Static

  R:Relay     F:FRR

 

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

10.2.1.1/32        127.0.0.1       UH       InLoop0                  Null

Table 1 Command output

Field	Description
Route destination count	Total number of route destination addresses.
Directly-connected host count	Number of directly-connected hosts that are learned through features such as ARP.
Destination/Mask	Destination address and the mask length.
Nexthop	Next hop address.
Flag	Flags of routes: ·     U—Usable route. ·     G—Gateway route. ·     H—Host route. ·     B—Blackhole route. ·     D—Dynamic route. ·     S—Static route. ·     R—Relay route. ·     F—Fast reroute.
OutInterface/Token	Output interface/LSP index number.
Label	Inner label.

 

ip forwarding

Use ip forwarding to enable IPv4 packet forwarding on an interface that has no IPv4 address configured.

Use undo ip forwarding to disable IPv4 packet forwarding on an interface that has no IPv4 address configured.

Syntax

ip forwarding

undo ip forwarding

Default

If an interface has no IPv4 address configured, it cannot forward IPv4 packets.

Views

Interface view

Predefined user roles

network-admin

Usage guidelines

On a device that supports both IPv4 and IPv6, the next hop of an IPv4 packet might be an IPv4 address or an IPv6 address. If the output interface has no IPv4 address configured, the interface cannot forward the IPv4 packet. To resolve this issue, execute this command on the interface. This feature allows the interface to forward IPv4 packets even though the interface has no IPv4 address configured.

Examples

# Enable IPv4 packet forwarding on GigabitEthernet 1/0/1 that has no IPv4 address configured.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] ip forwarding

ip global last-hop hold

Use ip global last-hop hold to enable IPv4 last hop holding globally.

Use undo ip global last-hop hold to disable IPv4 last hop holding globally.

Syntax

ip global last-hop hold

undo ip global last-hop hold

Default

IPv4 last hop holding is disabled globally.

Views

System view

Predefined user roles

network-admin

Usage guidelines

Application scenarios

IPv4 last hop holding implements symmetric routing, ensuring the forward flow and the reverse flow between the local device and a peer device are transmitted over the same path.

Operating mechanism

When the interface enabled with this feature receives the first IP packet of a forward flow, this feature implements the following operations:

·     Obtains the forward flow information and last hop information of the packet.

·     Based on the obtained information, creates a fast forwarding entry for the reverse flow.

When packets of the reverse flow arrive at the device, the device forwards those packets according to the fast forwarding entry.

You can configure IPv4 last hop holding globally by using this command or on a per-interface basis by using the ip last-hop hold command. This feature takes effect on an interface as long as it is enabled globally or on that interface. To disable this feature on an interface, perform the following operations:

·     Disable IPv4 last hop holding globally by using the undo ip global last-hop hold command.

·     Disable IPv4 last hop holding on the interface by using the undo ip last-hop hold command.

Restrictions and guidelines

IPv4 last hop holding relies on fast forwarding entries. If the MAC address of a last hop changes on an Ethernet link, this feature can function correctly only after the fast forwarding entry is updated for the MAC address.

This command is not applicable to MPLS networks.

Examples

# Enable IPv4 last hop holding globally.

<Sysname> system-view

[Sysname] ip global last-hop hold

Related commands

ip last-hop hold

ipv6 forwarding

Use ipv6 forwarding to enable IPv6 packet forwarding on an interface that has no IPv6 address configured.

Use undo ipv6 forwarding to disable IPv6 packet forwarding on an interface that has no IPv6 address configured.

Syntax

ipv6 forwarding

undo ipv6 forwarding

Default

If an interface has no IPv6 address configured, it cannot forward IPv6 packets.

Views

Interface view

Predefined user roles

network-admin

Usage guidelines

On a device that supports both IPv4 and IPv6, the next hop of an IPv6 packet might be an IPv4 address or an IPv6 address. If the output interface has no IPv6 address configured, the interface cannot forward the IPv6 packet. To solve this problem, execute this command on the interface. This feature allows the interface to forward IPv6 packets even though the interface has no IPv6 address configured.

Examples

# Enable IPv6 packet forwarding on GigabitEthernet 1/0/1 that has no IPv6 address configured.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] ipv6 forwarding

 

Load sharing commands

ip load-sharing mode

Use ip load-sharing mode to configure the load sharing mode.

Use undo ip load-sharing mode to restore the default.

Syntax

ip load-sharing mode { per-flow [ dest-ip | dest-port | ip-pro | src-ip | src-port ] * | per-packet } global

undo ip load-sharing mode global

Default

The device performs per-flow load sharing.

Views

System view

Predefined user roles

network-admin

Parameters

per-flow: Implements per-flow load sharing.

dest-ip: Identifies flows by destination IP address.

dest-port: Identifies flows by destination port.

ip-pro: Identifies flows by protocol number.

src-ip: Identifies flows by source IP address.

src-port: Identifies flows by source port.

global: Configures the load sharing mode globally.

per-packet: Implements per-packet load sharing.

Usage guidelines

The per-packet load sharing mode does not take effect in fast forwarding.

Examples

# ‌Configure per-flow load sharing.

<Sysname> system-view

[Sysname] ip load-sharing mode per-flow global