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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: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 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.
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.
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