2
For example:
<Sysname> display ip routing-table
Routing Tables: Public
Destinations : 7 Routes : 7
Destination/Mask Proto Pre Cost NextHop Interface
1.1.1.0/24 Direct 0 0 1.1.1.1 Vlan11
2.2.2.0/24 Static 60 0 12.2.2.2 Vlan12
…(Part of the output information is omitted)
A route entry includes the following key items:
•
Destination—Destination IP address or destination network
•
Mask—The network mask specifies, in company with the destination address, the address of 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
129.102.8.10 and the mask 255.255.0.0, the address of the destination network is 129.102.0.0. A
network mask is made up of a certain number of consecutive 1s. It can be expressed in dotted
decimal format or by the number of the 1s.
•
Pre—Preference of the route. Among routes to the same destination, the one with the highest
preference is optimal.
•
Cost—When multiple routes to a destination have the same preference, the one with the smallest
cost becomes the optimal route.
•
NextHop—Specifies the IP address of the next hop
•
Interface—Specifies the interface through which a matching IP packet is to be forwarded
Routing preference
Different routing protocols can find different routes to the same destination. However, not all of those
routes are optimal. For route selection, direct routes, and static routes are assigned different preferences.
The route with the highest preference is preferred.
The preference of a direct route is always 0 and cannot be changed. You can manually configure
preferences for any other route type. Each static route can be configured with a different preference. The
following table lists the types of routes and the default preferences. The smaller the preference value, the
higher the preference.
Routing approach
Preference
Direct route
0
Static route
60
Route backup
Route backup can help improve network reliability. With route backup, you can configure multiple routes
to the same destination, expecting the one with the highest preference to be the main route and all the
rest backup routes.
Under normal circumstances, packets are forwarded through the main route. When the link fails, the
route with the highest preference among the backup routes is selected to forward packets. When the link
