- Table of Contents
- 04-Layer 3-IP Services Configuration Guide
- 01-ARP configuration
- 02-IP addressing configuration
- 03-DHCP configuration
- 04-DNS configuration
- 05-mDNS relay configuration
- 06-IP forwarding basics configuration
- 07-Fast forwarding configuration
- 08-IRDP configuration
- 09-IP performance optimization configuration
- 10-Adjacency table configuration
- 11-UDP helper configuration
- 12-IPv6 basics configuration
- 13-DHCPv6 configuration
- 14-IPv6 fast forwarding configuration
- 15-GRE configuration
- 16-HTTP redirect configuration
- 17-Tunneling configuration
- Related Documents
|06-IP forwarding basics configuration||56.06 KB|
Configuring IP forwarding basic settings························································ 1
About FIB table······························································································································· 1
Saving the IP forwarding entries to a file··························································································· 2
Display and maintenance commands for FIB table············································································ 2
Configuring load sharing··················································································· 3
About load sharing·························································································································· 3
Specifying a shift value for load sharing algorithm result··································································· 3
Enabling local-first load sharing······································································································· 3
Configuring IP forwarding basic settings
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
U:Usable G:Gateway H:Host B:Blackhole D:Dynamic S:Static
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
126.96.36.199/4 0.0.0.0 UB NULL0 Null
188.8.131.52/24 0.0.0.0 UB NULL0 Null
255.255.255.255/32 127.0.0.1 UH InLoop0 Null
· 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.
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.
To save the IP forwarding entries to a file, execute the following command in any view:
ip forwarding-table save filename filename
Execute display commands in any view.
Display FIB entries.
display fib [ vpn-instance vpn-instance-name ] [ ip-address [ mask | mask-length ] ]
Display the FIB table usage.
display fib usage
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.
By default, the device uses the following criteria to identify a flow for per-flow load sharing: source and destination IP addresses, source and destination port numbers, IP protocol number, and ingress port.
About specifying a shift value for load sharing algorithm result
In a complex network, when the traffic is not load shared equally, you can use the shift keyword to improve the load sharing.
1. Enter system view.
2. Specify a shift value for load sharing algorithm result.
By default, the shift value is 0 for the load sharing algorithm result.
About local-first load sharing
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.
1. Enter system view.
2. Enable local-first load sharing.
ip load-sharing local-first enable
By default, local-first load sharing is enabled.