06-Layer 3—IP Services Configuration Guide

HomeSupportResource CenterNFVH3C VSRH3C VSRTechnical DocumentsConfigureConfiguration GuidesH3C VSR Series Virtual Services Routers Configuration Guides(V7)-R0621-6W30006-Layer 3—IP Services Configuration Guide
06-IP forwarding basics configuration
Title Size Download
06-IP forwarding basics configuration 78.22 KB

Contents

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

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

Enabling the DSCP setting for packets····························································································· 1

Enabling the VPN peer-based processing························································································· 2

Enabling the FIB-based EXP setting for MPLS packets····································································· 2

Display and maintenance commands for FIB table············································································ 2

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

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

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

Enabling IPv4 bandwidth-based load sharing···················································································· 4

Enabling local-first 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

 

Destination count: 4 FIB entry count: 4

 

Flag:

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

  R:Relay     F:FRR

 

Destination/Mask   Nexthop         Flag     OutInterface/Token       Label

10.2.0.0/16        10.2.1.1        U        GE1/0/1                  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—MPLS Label Switched Path index number.

·     Label—Inner label.

Enabling the DSCP setting for packets

About this task

This feature enables the device to use the DSCP value in the FIB table for packets to be forwarded. The DSCP value in FIB table is set along with the routing information.

This command must be used together with the apply dscp command. For more information about the command, see routing policy commands in Layer 3—IP Routing Command Reference.

Procedure

1.     Enter system view.

system-view

2.     Enable the DSCP setting for packets.

ip forwarding apply dscp enable

By default, the DSCP setting for packets is disabled.

Enabling the VPN peer-based processing

About this task

This feature enables the device to use the VPN peer ID of the routing information in the FIB table to process packets.

This command must be used together with the apply vpn-peer-id command. For more information about the command, see routing policy commands in Layer 3—IP Routing Command Reference.

Procedure

1.     Enter system view.

system-view

2.     Enable the VPN peer-based processing.

ip forwarding apply vpn-peer-id enable

By default, the VPN peer-based processing is disabled.

Enabling the FIB-based EXP setting for MPLS packets

About this task

This feature modifies the EXP field value of MPLS packets based on the EXP value in the FIB entry that matches the packets. It must be used together with the apply mpls-exp command. For more information about the apply mpls-exp command, see routing policy commands in Layer 3—IP Routing Command Reference.

Procedure

1.     Enter system view.

system-view

2.     Enable the FIB-based EXP setting for MPLS packets.

ip forwarding apply mpls-exp enable

By default, the FIB-based EXP setting for MPLS packets is disabled.

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 ] ]


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 load sharing mode

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, destination IP address, source port number, destination port number, IP protocol number, and ingress port.

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.

In standalone mode:

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

In IRF mode:

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

The default setting varies by device model.

Enabling IPv4 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.

Enabling local-first load sharing

About this task

Local-first load sharing distributes traffic preferentially across the output interfaces on the receiving IRF member device if output interfaces for multiple equal-cost routes are on different members. This feature enhances packets forwarding efficiency.

Procedure

1.     Enter system view.

system-view

2.     Enable local-first load sharing.

ip load-sharing local-first enable

The default setting varies by device model.

Loading sharing configuration examples

Example: Configuring load sharing based on source and destination addresses

Network configuration

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

Figure 1 Network diagram

Procedure

# On Switch A, assign GigabitEthernet 1/0 to VLAN 10, and GigabitEthernet 2/0 to VLAN 20.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port gigabitethernet 1/0

[SwitchA-vlan10] quit

[SwitchA] vlan 20

[SwitchA-vlan20] port gigabitethernet 2/0

[SwitchA-vlan20] quit

# On Switch A, configure IP addresses for VLAN-interface 10 and VLAN-interface 20.

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] ip address 10.1.1.1 24

[SwitchA-Vlan-interface10] quit

[SwitchA] interface vlan-interface 20

[SwitchA-Vlan-interface20] ip address 20.1.1.1 24

[SwitchA-Vlan-interface20] quit

# On Switch B, assign GigabitEthernet 1/0 to VLAN 10, and GigabitEthernet 2/0 to VLAN 20.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] port gigabitethernet 1/0

[SwitchB-vlan10] quit

[SwitchB] vlan 20

[SwitchB-vlan20] port gigabitethernet 2/0

[SwitchB-vlan20] quit

# On Switch B, configure IP addresses for VLAN-interface 10 and VLAN-interface 20.

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] ip address 10.1.1.2 24

[SwitchB-Vlan-interface10] quit

[SwitchB] interface vlan-interface 20

[SwitchB-Vlan-interface20] ip address 20.1.1.2 24

[SwitchB-Vlan-interface20] quit

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

<SwitchA> system-view

[SwitchA] ip route-static 1.2.3.4 24 10.1.1.2

[SwitchA] ip route-static 1.2.3.4 24 20.1.1.2

[SwitchA] quit

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

<SwitchA> display fib 1.2.3.4

Destination count: 1 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     Vlan10                   Null

1.2.3.0/24         20.1.1.2        USGR     Vlan20                   Null

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

<SwitchA> system-view

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

Verifying the configuration

# Verify that Switch A implements load sharing.

<SwitchA> display counters outbound interface GigabitEthernet

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

GE1/0                  1045                  0                  0           0

GE2/0                  1044                  0                  0           0