IP routing protocols are dynamic. Dynamic routing calls for routes to be calculated automatically at
regular intervals by software in routing devices. This contrasts with static routing, where routers are
established by the network administrator and do not change until the network administrator changes
them.
An IP routing table, which consists of destination address/next hop pairs, is used to enable dynamic
routing. An entry in this table, for example, would be interpreted as follows: to get to network
172.31.0.0, send the packet out Ethernet interface 0 (E0).
IP routing specifies that IP datagrams travel through internetworks one hop at a time. The entire
route is not known at the onset of the journey, however. Instead, at each stop, the next destination is
calculated by matching the destination address within the datagram with an entry in the current
node’s routing table.
Each node’s involvement in the routing process is limited to forwarding packets based on internal
information. The nodes do not monitor whether the packets get to their final destination, nor does IP
provide for error reporting back to the source when routing anomalies occur. This task is left to
another Internet protocol, the Internet Control-Message Protocol (ICMP), which is discussed in the
regular intervals by software in routing devices. This contrasts with static routing, where routers are
established by the network administrator and do not change until the network administrator changes
them.
An IP routing table, which consists of destination address/next hop pairs, is used to enable dynamic
routing. An entry in this table, for example, would be interpreted as follows: to get to network
172.31.0.0, send the packet out Ethernet interface 0 (E0).
IP routing specifies that IP datagrams travel through internetworks one hop at a time. The entire
route is not known at the onset of the journey, however. Instead, at each stop, the next destination is
calculated by matching the destination address within the datagram with an entry in the current
node’s routing table.
Each node’s involvement in the routing process is limited to forwarding packets based on internal
information. The nodes do not monitor whether the packets get to their final destination, nor does IP
provide for error reporting back to the source when routing anomalies occur. This task is left to
another Internet protocol, the Internet Control-Message Protocol (ICMP), which is discussed in the
following section.
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