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Variable Length Subnet Mask(VLSM) 可變長度子網路切割. 王振生. Variable Length Subnetting. VLSM allows us to use one class C address to design a networking scheme to meet the following requirements: Taipei 60 users Kaohsiung 28 users Taichung 12 users Tainan 12 users WAN links between each router .
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Variable Length Subnetting • VLSM allows us to use one class C address to design a networking scheme to meet the following requirements: • Taipei60 users • Kaohsiung 28 users • Taichung 12 users • Tainan 12 users • WAN links between each router
Networking Requirements Taipei 60 users WAN 2 WAN 1 WAN 3 Kaohsiung 28 users Tainan 12 users Taichung 12 users • If a /26 was used to provide 60 addresses for LANs. There are no addresses left for WAN links • Classful subnetting is very wasteful.
Networking Scheme Taipei/3620192.168.12.0/26 E0/0 .1 S1/2 .133 S1/0 .129 WAN 2192.168.12.132/30 S1/1 .137 WAN 1192.168.12.128/30 WAN 3192.168.12.136/30 S1/.138 S1/.134 S1/.130 F0/.65 F0/.113 F0/.97 Tainan/1721192.168.12.112/28 Kaohsiung/1721 192.168.12.64/27 Taichung/1721 192.168.12.96/28