1. Inductive Logic Internet Protocol Fundamentals Gateway to the World By Eric L. Michelsen

2. Inductive Logic 11/9/20002 Topics 4 Internet Protocol Services 4 Where in the Stack Is IP? 4 IP Addressing 4 IP Networks and Hosts 4 IP Network Classes 4 Multi-homed hosts 4 Routing 4 Minimum Host Configuration 4 Point to Point Links 4 Subnetting 4 Classless Inter-Domain Routing (CIDR) 4 Private Addressing 4 DNS 4 UDP 4 TCP: Reliable Delivery 4 IPv6 (IP, the Next Generation)

3. Inductive Logic 11/9/20003 Where in the Stack is IP? 4 IP is a layer 3 protocol (network layer) 4 IP is designed to run over any and all link layers (layer 2) 4 IP folk used to think of a 4-layer stack 76543217654321 Physical Link Network Transport Session Presentation Application 10Base-T, T1, V.34, EIA-232 Ethernet II, IEEE 802.2 IP, IPX, NetBIOS UDP, TCP, Novell SPX Telnet, FTP, email, Netware services OSI Physical Application Network Transport IP 43214321 TCP, UDP

4. Inductive Logic 11/9/20004 Internet Protocol Services 4 IP v4 (RFC-791, and many others) 4 IP provides 3 primary Services: Global addressing Best-effort (not guaranteed) datagram delivery Fragmentation 4 Base protocol on which many others are built 4 Upper layers provide reliability as needed 4 Fragmentation is inefficient, and generally avoided.

5. Inductive Logic 11/9/20005 IP Addressing 4 32-bit (4-octet) address, written in dotted decimal: w.x.y.ze.g.,206.71.190.4 w, x, y, and z are octets, ranging from 0 to 255 4 Each IP address is globally unique except for private addresses 4 An IP network is a group of hosts that can communicate “directly” with each other “directly” means no intervening IP devices 4 All IP packets include the destination and source IP address

6. Inductive Logic 11/9/20006 IP Networks and Hosts 4 A typical IP network might be an Ethernet: Host 206.71.190.4 4 Each host interface has an IP address 4 An IP address includes two parts: the network address, and the host address, e.g. network 206.71.190.4 host 4 All hosts on net have the same network address 4 The network as a whole is referred to as host = 0 206.71.190.0 Host 206.71.190.3 Host 206.71.190.2 Host 206.71.190.1

7. Inductive Logic 11/9/20007 Another Sample IP Network 4 Full-mesh Frame Relay network Any two hosts can communicate “directly” 4 Broadcasts must be duplicated by sender to each VC The whole mesh is network 206.71.190.0 Host 206.71.190.4 Host 206.71.190.3 Host 206.71.190.2 Host 206.71.190.1 PVC Single IP Interface PVC

8. Inductive Logic 11/9/20008 Classical Class 4 Network/host address sizes vary in classes: Class A: N.h.h.h (0.0.0.0 to 127.0.0.0) è 128 networks, 16M hosts per network è Example:10.1.1.1network 10, host.1.1.1 Class B: N.N.h.h (128.0.0.0 to 191.255.0.0) è 16,384 networks, 65k hosts per network è Example:132.10.5.17network 132.10, host.5.17 Class C: N.N.N.h (192.0.0.0 to 223.255.255.0) è 2M networks, 254 hosts per network è Example:206.71.190.13network 206.71.190, host.13 Classes D & E are “special” 4 Host address of all 1s (e.g., 206.71.190.255) means broadcast to an entire IP network (deprecated)

9. Inductive Logic 11/9/20009 Multi-homed Host 4 A host may appear on multiple networks 4 Each network interface has an IP address 199.107.10.12 multi-homed Host 206.71.183.4 206.71.183.0 199.107.10.0 4 A multi-homed host may be used to forward packets between networks (i.e., as a router)

10. Inductive Logic 11/9/200010 Routing 4 Connecting networks into an “internetwork” Host 192.168.1.1 Router 206.71.183.1 206.71.183.0 192.168.20.1 Router 206.71.183.2 192.168.20.0 192.168.1.0 Host

11. Inductive Logic 11/9/200011 Minimum Host Configuration 4 2 configuration items required for full internetwork access: An IP address A default router 4 Host learns new routes from default router with redirects 4 Every host (not just routers) must maintain a routing table 192.168.1.1 Router 206.71.183.1 206.71.183.0 192.168.20.1 Router 206.71.183.2 Host IP 206.71.183.9 Default router 206.71.183.2 1 st packet to 192.168.1.x redirect forwarded 1 st packet subsequent packets 192.168.20.0192.168.1.0

12. Inductive Logic 11/9/200012 Point-to-Point Links 4 Numbered Link: standard IP (wasteful) All hosts must have same network number Wastes a whole network address for 2 hosts 4 Unnumbered Link: efficient No network number Host addresses are completely arbitrary Used almost exclusively on routers, and host PPP links Host 206.71.190.2 206.71.190.0 Host 206.71.190.1 Router 199.107.183.15 unnumbered Router 206.71.190.3

13. Inductive Logic 11/9/200013 Subnet Masks 4 The subnet mask defines which parts of an IP address are the ‘network’ and ‘host’ parts 4 1s in the subnet mask specify network address bits, 0s specify host address bits 4 Standard class subnet masks: Class A: 255.0.0.0 11111111.00000000.00000000.00000000 Class B: 255.255.0.0 11111111.11111111.00000000.00000000 Class C: 255.255.255.0 11111111.11111111.11111111.00000000

14. Inductive Logic 11/9/200014 Subnetting 4 Creates networks smaller than the default for their class (breaks up Class A, B, & C networks) Example: subnet mask 255.255.255.192 = 11111111.11111111.11111111.11000000 creates a subnet of 64 addresses (62 hosts) Can use 255.255.255.0 on an (otherwise) Class B network to create 256 Class-C-size subnets (254 hosts) 4 Network part is always on left end of subnet mask 4 Handy table: 4 Sometimes written as /n, where n is # bits in Network part, e.g., /26 => 255.255.255.192 1281000 0000 2401111 0000 1921100 0000 2481111 1000 2241110 0000 2521111 1100

15. Inductive Logic 11/9/200015 Examples of IP Subnetting 4 192.168.1.0/24 (mask 255.255.255.0) standard Class C 254 hosts:192.168.1.1 - 192.168.1.254 4 192.168.2.0/25 (mask 255.255.255.128) 126 hosts:192.168.2.1 - 192.168.2.126 4 192.168.2.128/26 (mask 255.255.255.192) 62 hosts:192.168.2.129 - 192.168.2.190 4 192.168.2.192/27 (mask 255.255.255.224) 30 hosts:192.168.2.193 - 192.168.2.222 192.168.2.128 192.168.2.128/26 192.168.2.191 192.168.1.0 192.168.1.0/24 192.168.1.255 192.168.2.192/27 192.168.2.0 192.168.2.0/25 192.168.2.127

16. Inductive Logic 11/9/200016 CIDR 4 Classless Inter-Domain Routing 4 Eliminates Class A, B, and C networks. 4 Subnet masks must be specified for everything This is a 3rd piece of configuration now required by an IP host: è IP address è Subnet mask è Default Router 4 Widely used, and growing

17. Inductive Logic 11/9/200017 Private Addresses 4 IETF set aside some addresses for “private” use: 1 Class A network10.0.0.0 16 Class B networks172.16.0.0 - 172.31.0.0 256 Class C networks192.168.*.0 4 Internet routers are configured to discard packets addressed to these addresses 4 These addresses are not visible to the Internet, so multiple sites can use them at will

18. Inductive Logic 11/9/200018 DNS: Domain Name System 4 RFCs 1034, 1035 4 Memorizing IP addresses is difficult 4 DNS is a distributed directory of names, and associated IP addresses, and other info “First DNS server” is a 4th piece of IP host config 4 Hierarchical system of shared authority Right parts are higher authority than left www.enterprise.com InterNIC Administered Enterprise Administered

19. Inductive Logic 11/9/200019 UDP: User Datagram Protocol 4 RFC 768 4 Built above IP (Layer 4, Transport) 4 Best-effort, datagram (packet) delivery (connectionless) 4 Adds an additional addressing layer: port Each UDP datagram includes a 16-bit destination and 16-bit source port There are many “well-known” ports, which essentially act as Server IDs or Protocol IDs for UDP è DNSport 53 è BOOTP/DHCPports 67 (server), 68 (client) è TFTPport 69 è SNMPport 161

20. Inductive Logic 11/9/200020 TCP: Transmission Control Protocol 4 RFC 793, plus many modifications 4 Reliable, error-corrected stream of data 4 Connection oriented (has setup and teardown) 4 Uses a highly efficient, self-adjusting pacing mechanism for high throughput 4 No packetization (or frame) boundaries Packetization of data stream into IP packets is invisible to the application layer 4 Packet boundaries (if needed) must be created by higher layers 4 Like UDP, has ports. Well known ports: è FTP controlport 20 è Telnetport 23 è SMTPport 25

21. Inductive Logic 11/9/200021 IPv6 (IPng) 4 Primarily intended to address the problem of running out of IP addresses 4 Aka Network Engineer Employment Act of 1994 Nearly every IP protocol must change Nearly every IP software application must change 4 Addresses extended to 16 octets (128 bits) Enough for each molecule on the surface of the earth to have its own IP address 4 Part of address is locally assigned 4 Fragmentation confined to endpoints (routers don’t fragment, hosts do)

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