1. Variable Length Subnet Mask(VLSM) 可變長度子網路切割 王振生

2. Variable Length Subnetting ‣ VLSM allows us to use one class C address to design a networking scheme to meet the following requirements: ‣ Taipei60 users ‣ Kaohsiung28 users ‣ Taichung 12 users ‣ Tainan 12 users ‣ WAN links between each router

3. Networking Requirements Taipei 60 users Taichung 12 users Tainan 12 users Kaohsiung 28 users WAN 1 WAN 2 WAN 3 If a /26 was used to provide 60 addresses for LANs. There are no addresses left for WAN links Classful subnetting is very wasteful.

4. VLSM Design Scheme Name/required addresses Subnet address Address rangeBroadcastAddress/subnet Taipei/60192.168.12.0 Kaohsiung/28 Taichung/12 Tainan/12 WAN1/2 WAN2/2 WAN3/2

5. VLSM Design Scheme Name/required addresses Subnet address Address rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28 Taichung/12 Tainan/12 WAN1/2 WAN2/2 WAN3/2

6. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12 Tainan/12 WAN1/2 WAN2/2 WAN3/2

7. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12192.168.12.96.97-.110.111192.168.12.96/28 Tainan/12 WAN1/2 WAN2/2 WAN3/2

8. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12192.168.12.96.97-.110.111192.168.12.96/28 Tainan/12192.168.12.112.113 -.126.127192.168.12.112/28 WAN1/2 WAN2/2 WAN3/2

9. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12192.168.12.96.97-.110.111192.168.12.96/28 Tainan/12192.168.12.112.113 -.126.127192.168.12.112/28 WAN1/2192.168.12.128.129 -.130.131192.168.12.128/30 WAN2/2 WAN3/2

10. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 - 62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12192.168.12.96.97-.110.111192.168.12.96/28 Tainan/12192.168.12.112.113 -.126.127192.168.12.112/28 WAN1/2192.168.12.128.129 -.130.131192.168.12.128/30 WAN2/2192.168.12.132.133 - 134.135192.168.12.132/30 WAN3/2

11. VLSM Design Scheme Name/required addresses Subnet addressAddress rangeBroadcastAddress/subnet Taipei/60192.168.12.0.1 -.62.63192.168.12.0/26 Kaohsiung/28192.168.12.64.65 -.94.95192.168.12.64/27 Taichung/12192.168.12.96.97-.110.111192.168.12.96/28 Tainan/12192.168.12.112.113 -.126.127192.168.12.112/28 WAN1/2192.168.12.128.129 -.130.131192.168.12.128/30 WAN2/2192.168.12.132.133 - 134.135192.168.12.132/30 WAN3/2192.168.12.136.137 -.138.139192.168.12.136/30

12. Networking Scheme Taipei/3620 192.168.12.0/26 Taichung/1721 192.168.12.96/28 Tainan/1721 192.168.12.112/28 Kaohsiung/1721 192.168.12.64/27 WAN 1 192.168.12.128/30 S1/0.129 S1/.130 S1/2.133 S1/1.137 WAN 2 192.168.12.132/30 WAN 3 192.168.12.136/30 S1/.138 F0/.65 F0/.113 F0/.97 E0/0.1 S1/.134