Contents

Configuring IP forwarding basic settings························································ 1

About FIB table······························································································································· 1

Saving the IP forwarding entries to a file··························································································· 1

Enabling FIB logging······················································································································· 2

Enabling SNMP notifications for FIB events······················································································ 2

Enabling IP forwarding logging········································································································ 2

Enabling SNMP notifications for IP forwarding events······································································· 3

Display and maintenance commands for FIB table············································································ 3

Configuring load sharing··················································································· 4

About load sharing·························································································································· 4

Configuring per-packet or per-flow load sharing················································································ 4

Enabling bandwidth-based load sharing···························································································· 4

Display and maintenance commands for load sharing······································································· 5

Loading sharing configuration examples··························································································· 5

Example: Configuring load sharing based on source and destination addresses·························· 5

Configuring IP forwarding basic settings

About FIB table

A device uses the FIB table to make packet forwarding decisions.

A device selects optimal routes from the routing table, and puts them into the FIB table. Each FIB entry specifies the next hop IP address and output interface for packets destined for a specific subnet or host.

For more information about the routing table, see Layer 3—IP Routing Configuration Guide.

Use the display fib command to display the FIB table. The following example displays the entire FIB table.

<Sysname> display fib

 

Route destination count: 4

Directly-connected host count: 0

 

Flag:

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

  R:Relay     F:FRR

 

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

10.2.0.0/16        10.2.1.1        U        XGE2/0/0                  Null

10.2.1.1/32        127.0.0.1       UH       InLoop0                  Null

127.0.0.0/8        127.0.0.1       U        InLoop0                  Null

127.0.0.1/32       127.0.0.1       UH       InLoop0                  Null

A FIB entry includes the following items:

·     Destination—Destination IP address.

·     Mask—Network mask. The mask and the destination address identify the destination network. A logical AND operation between the destination address and the network mask yields the address of the destination network. For example, if the destination address is 192.168.1.40 and the mask 255.255.255.0, the address of the destination network is 192.168.1.0. A network mask includes a certain number of consecutive 1s. It can be expressed in dotted decimal format or by the number of the 1s.

·     Nexthop—IP address of the next hop.

·     Flag—Route flag.

·     OutInterface—Output interface.

·     Token—Label Switched Path index number.

·     Label—Inner label.

Saving the IP forwarding entries to a file

Restrictions and guidelines

The feature automatically creates the file if you specify a nonexistent file. If the file already exists, this feature overwrites the file content.

This feature triggers one-time saving of the IP forwarding entries.

To automatically save the IP forwarding entries periodically, configure a schedule for the device to automatically run the ip forwarding-table save command. For information about scheduling a task, see Fundamentals Configuration Guide.

Procedure

To save the IP forwarding entries to a file, execute the following command in any view:

ip forwarding-table save filename filename

Enabling FIB logging

About this task

The logs are sent to the information center of the device. For the logs to be output correctly, you must also configure the information center on the device. For more information about information center configuration, see Network Management and Monitoring Configuration Guide.

To avoid memory consumption caused by log recording, you can use the undo fib log enable command to disable FIB logging.

Procedure

1.     Enter system view.

system-view

2.     Enable FIB logging.

fib log enable

By default, FIB logging is disabled.

Enabling SNMP notifications for FIB events

About this task

This feature enables the FIB module to generate SNMP notifications for critical FIB events, such as the exceeding of the message queue length threshold. The SNMP notifications are sent to the SNMP module. For the SNMP notifications to be sent correctly, you must also configure SNMP. For more information about SNMP configuration, see Network Management and Monitoring Configuration Guide.

Procedure

1.     Enter system view.

system-view

2.     Enable SNMP notifications for FIB events.

snmp-agent trap enable fib

By default, SNMP notifications for FIB events are enabled.

Enabling IP forwarding logging

About this task

The logs are sent to the information center of the device. For the logs to be output correctly, you must also configure the information center on the device. For more information about information center configuration, see Network Management and Monitoring Configuration Guide.

To avoid memory consumption caused by log recording, you can use the undo ip forwarding log enable command to disable IP forwarding logging.

Procedure

1.     Enter system view.

system-view

2.     Enable IP forwarding logging.

ip forwarding log enable

By default, IP forwarding logging is disabled.

Enabling SNMP notifications for IP forwarding events

About this task

This feature enables the IP forwarding module to generate SNMP notifications for critical IP forwarding events. The SNMP notifications are sent to the SNMP module. For the SNMP notifications to be sent correctly, you must also configure SNMP. For more information about SNMP configuration, see Network Management and Monitoring Configuration Guide.

Procedure

1.     Enter system view.

system-view

2.     Enable SNMP notifications for IP forwarding events.

snmp-agent trap enable ip-forwarding

By default, SNMP notifications for IP forwarding events are enabled.

Display and maintenance commands for FIB table

Execute display commands in any view.

 

Task	Command
Display FIB entries.	display fib [ topology topology-name | vpn-instance vpn-instance-name ] [ ip-address [ mask | mask-length ] ] [ slot slot-number ]

 

 

Configuring load sharing

About load sharing

If a routing protocol finds multiple equal-cost best routes to the same destination, the device forwards packets over the equal-cost routes to implement load sharing.

Configuring per-packet or per-flow load sharing

About this task

In the per-flow load sharing mode, the device forwards flows over equal-cost routes. Packets of one flow travel along the same routes. You can configure the device to identify a flow based on the following criteria: source IP address, source MAC address, destination IP address, destination MAC address, source port number, destination port number, IP protocol number, and ingress port. You can also configure per-flow load sharing for IP tunnel packets.

In a complex network, when the criteria cannot distinguish flows, you can use the algorithm keyword to specify an algorithm to identify flows.

In the per-packet load sharing mode, the device forwards packets over equal-cost routes.

Procedure

1.     Enter system view.

system-view

2.     Configure load sharing.

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

By default, the device performs per-flow load sharing.

Enabling bandwidth-based load sharing

About this task

This feature load shares flow traffic among multiple output interfaces based on their load percentages. The device calculates the load percentage for each output interface in terms of the interface expected bandwidth.

Devices that run load sharing protocols, such as Locator/ID Separation Protocol (LISP), implement load sharing based on the ratios defined by these protocols.

Procedure

1.     Enter system view.

system-view

2.     Enable IPv4 bandwidth-based load sharing.

bandwidth-based-sharing

By default, the IPv4 bandwidth-based load sharing is disabled.

3.     (Optional.) Configure the expected bandwidth of the interface.

a.     Enter interface view.

interface interface-type interface-number

b.     Configure the expected bandwidth of the interface.

bandwidth bandwidth

By default, the expected bandwidth is the physical bandwidth of the interface.

Display and maintenance commands for load sharing

Execute display commands in any view.

 

Task	Command
Display the load sharing mode in use.	display ip load-sharing mode slot slot-number

 

Loading sharing configuration examples

Example: Configuring load sharing based on source and destination addresses

Network configuration

As shown in Figure 1, Router A has two equal-cost routes to Router B. Configure load sharing on Router A to forward packets through Router B to the destination IP address 1.2.3.4/24.

Figure 1 Network diagram

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Procedure

# On Router A, assign IP addresses to interfaces.

<RouterA> system-view

[RouterA] interface ten-gigabitethernet 2/0/0

[RouterA-Ten-GigabitEthernet2/0/0] ip address 10.1.1.1 24

[RouterA-Ten-GigabitEthernet2/0/0] quit

[RouterA] interface ten-gigabitethernet 2/0/1

[RouterA-Ten-GigabitEthernet2/0/1] ip address 20.1.1.1 24

[RouterA-Ten-GigabitEthernet2/0/1] quit

# On Router B, assign IP addresses to interfaces.

<RouterB> system-view

[RouterB] interface ten-gigabitethernet 2/0/0

[RouterB-Ten-GigabitEthernet2/0/0] ip address 10.1.1.2 24

[RouterB-Ten-GigabitEthernet2/0/0] quit

[RouterB] interface ten-gigabitethernet 2/0/1

[RouterB-Ten-GigabitEthernet2/0/1] ip address 20.1.1.2 24

[RouterB-Ten-GigabitEthernet2/0/1] quit

# On Router A, configure two static routes to the destination IP address.

[RouterA] ip route-static 1.2.3.4 24 10.1.1.2

[RouterA] ip route-static 1.2.3.4 24 20.1.1.2

[RouterA] quit

# On Router A, display FIB entries matching the destination IP address 1.2.3.4.

<RouterA> display fib 1.2.3.4

 

FIB entry count: 2

Flag:

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

  R:Relay     F:FRR

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

1.2.3.0/24         10.1.1.2        USGR     XGE2/0/0                  Null

1.2.3.0/24         20.1.1.2        USGR     XGE2/0/1                  Null

# On Router A, configure per-flow load sharing based on the source IP address and destination IP address.

<RouterA> system-view

[RouterA] ip load-sharing mode per-flow dest-ip src-ip global

[RouterA] quit

Verifying the configuration

# Verify that Router A implements load sharing.

<RouterA> display counters outbound interface GigabitEthernet

Interface         Total (pkts)   Broadcast (pkts)   Multicast (pkts)  Err (pkts)

XGE2/0/0                  1045                  0                  0           0

XGE2/0/1                  1044                  0                  0           0