and received on each interface that is matched by a network command. Because Yosemite will
send and receive only RIP-1 updates, the other two routers need the appropriate interface
subcommands to tell the router to send and receive RIP-1 updates to and from Yosemite. Both
Albuquerque and Seville will continue to send and (hope to) receive RIP-2 updates on all
interfaces.
performance improvement in the brief history of routers has been through improved algorithms;
many times those improved algorithms later have been implemented in hardware to provide
additional latency improvements. Although these improvements have been a great benefit, it is
typically true that any algorithm that searches a list will run more quickly if the list is short,
compared to searching a similar list that is long. Auto summary and route aggregation (also
known as route summarization) are two IOS features that reduce the size of the IP routing table.
subnets in network X will be summarized and advertised as one route. That route will be
for the entire Class A, B, or C network X.
auto summary can be enabled or disabled. As usual, an example makes the concept much
clearer. Consider Figure 6-11, which shows two networks in use: 10.0.0.0 and 172.16.0.0.
Seville has four (connected) routes to subnets of network 10.0.0.0. Example 6-14 lists the
output of a show ip route command on Albuquerque, as well as RIP-2 debug ip rip output.
ip addr 10.1.2.252 255.255.255.0
interface serial 0
ip addr 10.1.4.252 255.255.255.0
interface serial 1
ip address 10.1.5.252 255.255.255.0
ip rip send version 1
ip rip receive version 1
!
router rip
network 10.0.0.0
version 2