2. SUBNET Communication Technologies CIS 505 Prepare by Thanantinee Tantivejakul

3. What is Subnet? n Subnetwork n an identifiably separate part of an organization’s network n the network can be connected to the Internet with a single shared network address

4. Advantage of Subnet n Hide the internal network organization to external routers and thus simplies routing n Shorter routing tables means faster network transfers n Allows address administration to be decentralized

5. What is Subnet addressing? n Class A: 0xxx, or 1-126 decimal. n Class B: 10xx, or 128-191 decimal. n Class C: 110x, or 192-223 decimal. n Class D: 1110, or 224-239 decimal. n Class E: 1111, or 240-254 decimal. Address Class

6. 127 decimal? n 127 decimal or 01111111 reserved for Loopback and for internal testing on a local machine n Class D are reserved for multicasting n Class E are reserved for future use

7. Class determines... n N n N = Network, n = node n Class n Class A -- NNNNNNNN.nnnnnnnn.nnnnnnnn.nnnnnnnn B -- NNNNNNNN.NNNNNNNN.nnnnnnnn.nnnnnnnn C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.nnnnnnnn

8. Subnet Mask n Save the router having to handle the entire 32 bit address n allow to identify the network and node parts of the address

9. 10001100.10110011.11110000.11001000 140.179.240.200 11111111.11111111.00000000.00000000 255.255.000.000 --------------------------------------------------------------------------- 10001100.10110011.00000000.00000000 140.179.000.000 Example of Class B

10. CIDR & Supernetting n CIDR = Supernetting n CIDR: Classless InterDomain Routing n To avoid the address space crisis by eliminate class system

11. Subnet vs. CIDR n Borrow bits from the Host ID portion, which increases the number of bits used for the Network ID portion n Combine multiple Class C networks into blocks rather than dividing them into segments

15. Supernet 4 Class C networks 192.60.128.0: 11000000.00111100.10000000.00000000 192.60.129.0: 11000000.00111100.10000001.00000000 192.60.130.0: 11000000.00111100.10000010.00000000 192.60.131.0: 11000000.00111100.10000011.00000000

16. 192.60.128.0: Supernetted Subnet address 11000000.00111100.10000000.00000000 255.255.252.0: Subnet Mask 11111111.11111111.11111100.00000000 192.60.131.255: Broadcast address 11000000.00111100.10000011.11111111

17. CIDR n Reduced subnet mask notation to a shorthand n From 192.60.128.0 - 192.60.131.255 n 192.60.128.0, Subnet Mask 255.255.252.0 n As 192.60.128.0/22