Contents

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

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

Saving the IP forwarding entries to a file··························································································· 2

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

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

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

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

Destination count: 8 FIB entry count: 8

Flag:

  U:Usable   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

127.255.255.255/32 127.0.0.1       UH       InLoop0                  Null

224.0.0.0/4        0.0.0.0         UB       NULL0                    Null

224.0.0.0/24       0.0.0.0         UB       NULL0                    Null

255.255.255.255/32 127.0.0.1       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—MPLS 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 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.

You can enable specific SNMP notifications for FIB events as needed. If you do not specify any SNMP notification types, the command enables all types of SNMP notifications.

·     With entry-consistency specified, if the FIB software and hardware entries on a module are inconsistent, the device sends an SNMP notification that carries the module number to the SNMP module.

·     With entry-limit specified, when the number of FIB entries exceeds the upper limit, the device sends an SNMP notification that carries the FIB entry module name to the SNMP module.

·     With deliver-failed specified, when FIB entry deployment to the hardware fails, the device sends an SNMP notification that carries the entry VRF, IP address type, IP address, mask, and failure reason 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 [ deliver-failed | entry-consistency | entry-limit ] *

By default, SNMP notifications for FIB events are enabled.

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.

You can enable SNMP notifications for the following IP forwarding events as needed:

·     After you enable SNMP notifications about TTL timeout, the device checks the number of dropped packets at the specified time interval. An SNMP notification is generated and sent to the SNMP module when the number of dropped packets reaches or exceeds the specified threshold.

·     After you enable SNMP notifications about MBUF allocation failures, an SNMP notification is generated and sent to the SNMP module when MBUF allocation fails.

If you do not specify any parameters, the command enables all types of SNMP notifications for IP forwarding events.

After you disable the SNMP notifications for IP forwarding events, the device sends only logs to the device's information center module. In this case, you can configure the log output destinations and output rules to view the log information of the basic IPv6 modules. For more information about configuring the information center, see information center configuration in 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 [ ttl-expired | mbuf-alloc ]

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

Display and maintenance commands for FIB table

Execute display commands in any view.

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