04-Layer 3-IP Services Configuration Guide

HomeSupportResource CenterConfigure & DeployConfiguration GuidesH3C S12500-X & S12500X-AF Switch Series Configuration Guides(R115x)-6W10204-Layer 3-IP Services Configuration Guide
05-IP forwarding basics configuration
Title Size Download
05-IP forwarding basics configuration 68.66 KB

Contents

Basic IP forwarding on the device················································ 1

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

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

Displaying FIB table entries···································································································· 2

Configuring load sharing··························································· 3

Overview······························································································································ 3

Configuring load sharing········································································································ 3

Displaying the load sharing path selected for a flow·································································· 3

Load sharing configuration example························································································ 4

Network requirements····································································································· 4

Configuration procedure································································································· 4

Verifying the configuration······························································································ 5


Basic IP forwarding on the device

The device uses the destination IP address of a received packet to find a match from the forwarding information base (FIB) table. It then uses the matching entry to forward the packet.

FIB table

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 FIB table entries. 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        M-GE0/0/0                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.

·          OutInterfaceOutput interface.

·          TokenMPLS Label Switched Path index number.

·          Label—Inner label.

Saving the IP forwarding entries to a file

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

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.

To save the IP forwarding entries to a file:

 

Task

Command

Remarks

Specify a file to save the IP forwarding entries.

ip forwarding-table save filename filename

Executing this command triggers one-time saving of the IP forwarding entries.

Execute this command in any view.

 

Displaying FIB table entries

Execute display commands in any view.

 

Task

Command

Display FIB entries.

display fib [ vpn-instance vpn-instance-name ] [ ip-address [ mask | mask-length ] ]

 

 


Configuring load sharing

Overview

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

Load sharing is implemented in the following ways:

·          It a routing protocol finds multiple equal-cost best routes, the device implements per-flow load sharing based on the source IP address, destination IP address, source port, destination port, IP protocol, and ingress port.

·          In a complex network, a single load sharing algorithm cannot meet the requirements of load sharing. You can implement load sharing by specifying different algorithms.

To configure per-flow load sharing:

 

Step

Command

Remarks

1.       Enter system view.

system-view

N/A

1.       Configure per-flow load sharing.

·         In standalone mode:
ip load-sharing mode per-flow [ tunnel { all | inner | outer } | algorithm algorithm-number | [ dest-ip | dest-port | ingress-port | ip-pro | src-ip | src-port ] * ] [ slot slot-number ]

·         In IRF mode:
ip load-sharing mode per-flow [ tunnel { all | inner | outer } | algorithm algorithm-number |
[ dest-ip | dest-port | ingress-port | ip-pro | src-ip | src-port ] * ] [ chassis chassis-number slot slot-number ]

By default, the device performs per-flow load sharing based on the source IP address, destination IP address, source port, destination port, IP protocol, and ingress port.

 

 

NOTE:

If you configure both five-tuple per-flow load sharing and five-tuple link aggregation load sharing, make sure both load sharing methods use the same five-tuple configuration.

The switch supports any combination of options for load sharing.

 

Displaying the load sharing path selected for a flow

Execute the display command in any view.

 

Task

Command

Display the load sharing path selected for a flow.

display ip load-sharing path ingress-port interface-type interface-number packet-format { ipv4oe dest-ip ip-address [ src-ip ip-address ] | ipv6oe dest-ipv6 ipv6-address [ src-ipv6 ipv6-address ] } [ dest-port port-id | ip-pro protocol-id | src-port port-id | vpn-instance vpn-instance-name ] *

 

Load sharing configuration example

Network requirements

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

 

Configuration procedure

# On Switch A, assign FortyGigE 1/0/5 to VLAN 10, and FortyGigE 1/0/6 to VLAN 20.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port fortygige 1/0/5

[SwitchA-vlan10] quit

[SwitchA] vlan 20

[SwitchA-vlan20] port fortygige 1/0/6

[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 FortyGigE 1/0/5 to VLAN 10, and FortyGigE 1/0/6 to VLAN 20.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] port fortygige 1/0/5

[SwitchB-vlan10] quit

[SwitchB] vlan 20

[SwitchB-vlan20] port fortygige 1/0/6

[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.

[SwitchA] quit

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

<SwitchA>dis fib 1.2.3.4

 

Destination count: 1 FIB entry count: 2

 

Flag:

  U:Useable   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

Verifying the configuration

# Verify that Switch A implements load sharing.

[SwitchA] display counters outbound interface fortygige

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

FGE1/0/1                     0                  0                  0           0

FGE1/0/2                     0                  0                  0           0

FGE1/0/3                     0                  0                  0           0

FGE1/0/4                     0                  0                  0           0

FGE1/0/5                  1045                  0                  0           0

FGE1/0/6                  1044                  0                  0           0

 

  • Cloud & AI
  • InterConnect
  • Intelligent Computing
  • Security
  • SMB Products
  • Intelligent Terminal Products
  • Product Support Services
  • Technical Service Solutions
All Services
  • Resource Center
  • Policy
  • Online Help
All Support
  • Become a Partner
  • Partner Resources
  • Partner Business Management
All Partners
  • Profile
  • News & Events
  • Online Exhibition Center
  • Contact Us
All About Us
新华三官网