H3C Technologies H3C S3100 Series Switches - Manual (Page 264)

Operation Manual – Routing Protocol
H3C S3100-52P Ethernet Switch Chapter 1 IP Routing Protocol Overview
1-3
“logical AND” between destination address and network mask, you can get the
address of the network segment where the destination host or router resides. For
example, if the destination address is 129.102.8.10 and the mask is 255.255.0.0,
the address of the network segment where the destination host or router resides is
129.102.0.0. A mask consists of some consecutive 1s, represented either in
dotted decimal notation or by the number of the consecutive 1s in the mask.
z
Output interface: It indicates through which interface IP packets should be
forwarded to reach the destination.
z
Next hop address: It indicates the next router that IP packets will pass through to
reach the destination.
z
Preference of the route added to the IP routing table: There may be multiple routes
with different next hops to the same destination. These routes may be discovered
by different routing protocols, or be manually configured static routes. The one
with the highest preference (the smallest numerical value) will be selected as the
current optimal route.
According to different destinations, routes fall into the following categories:
z
Subnet route: The destination is a subnet.
z
Host route: The destination is a host.
In addition, according to whether the network where the destination resides is directly
connected to the router, routes fall into the following categories:
z
Direct route: The router is directly connected to the network where the destination
resides.
z
Indirect route: The router is not directly connected to the network where the
destination resides.
In order to avoid an oversized routing table, you can set a default route. All the packets
for which the router fails to find a matching entry in the routing table will be forwarded
through this default route.
Figure 1-2 shows a relatively complicated internet environment, the number in each
network cloud indicate the network address and "R" represents a router. The router R8
is connected to three networks, and so it has three IP addresses and three physical
ports. Its routing table is shown in Figure 1-2.