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Unformatted text preview: outer beyond netb, to gateway, we expect the metric to our subnet
(188.8.131.52) to be 2. We can check this by executing:
sun % ripquery -n gateway
504 bytes from gateway
184.108.40.206, metric 1
10.5 220.127.116.11, metric 2 lots of other lines deleted
the top Ethernet in Figure 10.5
the bottom Ethernet in Figure 10.5 Here the metric for the top Ethernet in Figure 10.5 (18.104.22.168) stays at 1, since that
Ethernet is directly connected to both gateway and netb. Our subnet 22.214.171.124,
however, now has the expected metric of 2.
We'll now watch all the unsolicited RIP updates on an Ethernet and see just what RIP sends
on a regular basis to its neighbors. Figure 10.7 shows the arrangement of many of the
noao.edu networks. We have named the routers Rn for simplicity, where n is the subnet
number, except for the ones we use elsewhere in the text. We show the point-to-point links
with dashed lines and the IP address at each end of these links. file:///D|/Documents%20and%20Settings/bigini/Docu.../homenet2run/tcpip/tcp-ip-illustrated/dynamic.htm (8 of 17) [12/09/2001 14.46.53] Chapter 10. Dynamic Routing Protocols Figure 10.7 Many of the noao.edu 140.252 networks.
We'll run the Solaris 2.x program snoop, which is similar to tcpdump, on the host
solaris. We can run this program without superuser privileges, but only to capture
broadcast packets, multicast packets, or packets sent to the host. Figure 10.8 shows the
packets captured during a 60-second period. We have replaced most of the official hostnames with our notation Rn.
solaris % snoop -P -tr udp port 520
0.00000 R6.tuc.noao.edu -> 126.96.36.199 RIP R (1
4.49708 R4.tuc.noao.edu -> 188.8.131.52 RIP R (1
6.30506 R2.tuc.noao.edu -> 184.108.40.206 RIP R (1
11.68317 R7.tuc.noao.edu -> 220.127.116.11 RIP R (1
16.19790 R8.tuc.noao.edu -> 18.104.22.168 RIP R (1
16.87131 R3.tuc.noao.edu -> 22.214.171.124 RIP R (1
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- Spring '12