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Classless Addresses. A 32 bit number, of n bits followed by h bits, n+h=32, and a mask of length n. Example NH N=10001000100010001000 H=xxxxxxxxxxxx If H is entirely 0’s, it’s the network If H is entirely 1’s, it’s the broadcast. “Class is over”.
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Classless Addresses • A 32 bit number, of n bits followed by h bits, n+h=32, and a mask of length n. • Example NH • N=10001000100010001000 • H=xxxxxxxxxxxx • If H is entirely 0’s, it’s the network • If H is entirely 1’s, it’s the broadcast
“Class is over” • We leave behind: RIP, IGRP, and the words and concepts “class A” “class B” “class C” • Be sure and tell the Cisco: • ip classless • ip subnet-zero
Network Addresses • Every network address (route) must have a mask associated with it, so the masks are advertised along with the networks • For the RIP v1 case, there was room to include a mask in the RIP v2 advertisements with only a little change to the overall format
Variable Length Subnet Masks • Every network has a mask, so no need for the mask lengths to have equal length. • 128.186.121.0 /25 • 128.186.121.128 /30 • 128.186.121.132 /30 • 128.186.121.136 /29 • Think in bits!! 128.186.121.132 /29 is an incorrect network. Do the math.
VLSM example • Review Figure 7.4 and table 7.1 in Doyle, pp 289-290. Expect a quiz on a similar network sometime. • Example: You must connect 2 networks in Tallahassee with 2 networks in Jacksonville. The TLH nets need to support 25 hosts each, JAX nets, 5 and 10 hosts • You may use only 128.186.1.0 /24
Software Tools • iperf is on all the sun blades /usr/local/bin • iperf –c 192.168.10.1 –p 9 • Connects to TCP discard port on router r1 • Compare iperf –c 192.168.10.1 –p 9 with • iperf –c 192.168.16.6 –p 9 • Can also run iperf –s to become a server • iperf –u to use udp instead of tcp
Software Tools and RIP lab • Use traceroute, ping, and especially iperf to test performance of RIP lab network