1. 1 IP Addressing: Classful 0 network host 10 network host 110 networkhost 1110 multicast address A B C D class 1.0.0.0 to 127.255.255.255 128.0.0.0 to 191.255.255.255 192.0.0.0 to 223.255.255.255 224.0.0.0 to 239.255.255.255 32 bits 08162431 Dotted-decimal notation 158.108.21.9 Binary form 10011110 01101100 00010101 00001001

2. 2 IP Addresses: Examples Class “A” address:www.mit.edu 18.181.0.31 (18 Class A) Class “B” address:cs.sci.ku.ac.th 158.108.21.9 (128 Class B)

3. 3 Subnetting CLASS “B” e.g. Company 10Net ID Host-ID 214 16 10Net ID Host-ID 214 16 0000 Subnet ID (20) Subnet Host ID (12) 10Net ID Host-ID 214 16 1111 Subnet ID (20) Subnet Host ID (12) 10Net ID Host-ID 214 16 000000 Subnet ID (22) Subnet Host ID (10) 10Net ID Host-ID 214 16 1111011011 Subnet ID (26) Subnet Host ID (6) e.g. Site e.g. Dept

4. 4 Subnet Mask Subnet mask: All 1’s for network suffix and All 0’s for host suffix. (เช่น 255.255.255.192) Used for routing table lookup: IF ((Mask[i] & Destination Addr) = = Destination[i]) Forward to NextHop[i] Mask must have contiguous 1s followed by contiguous zeros. Subnet mask can end on any bit. Internal routers & hosts use subnet mask to identify “subnet ID” and route packets between “subnets” within the “network”. Routers do not support other types of masks.