Addressing of Internet Koji OKAMURA Kyushu University

Quiz An university use /22 for whole campus network and there are three departments in the university; A,B,C. –Department A uses /23 –Department B uses /26 –Department C has about 250 PCs. Which network address should be assigned to Department C? Information Network2

Addressing of Internet Protocol Information Network3 Router

Addressing of Internet Protocol Information Network4 123 Router #1 #2 #3 #4 #5 #6 Internet Address = Network ID (#?) + Host ID (1~3) Network IP address is IP address of which all of host ID’s bit is 0. Broadcast address is IP address of which all of host ID’s bit is 1.

Information Network5 Class A,B,C Class A Class B Class C

Information Network6 Class A Class A Network Address – Host Address –

Information Network7 Class B Class B Network Address – Host Address –

Information Network8 Class C Class C Network Address – Host Address –

Information Network9 Class D(Multicast) Class D Network Address –

Information Network10 クラスレス (Classless Inter-Domain Routing:CIDR) Class C Classless /22

Address Assignment based on Class Class A 2^7 Class A 2^7 Class B 2^14 Class B 2^14 Class C 2^21 Class C 2^21

CIDR:Classless Inter-Domain Routing クラス A 2^7 クラス A 2^7 クラス B 2^14 クラス B 2^14 クラス C 2^21 クラス C 2^21 Prefix = network address + length Many Prefixes 268,500

What’s the problem of many prefixes? Information Network13 ISP University A border BGP router must imports full routing information from all of peering ISP.