1. Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Routing Technology CSN11107 Lecture 2: IP Addressing Dr Imed ROMDHANI

2. 2 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Outline  IP Classful Addressing  IP Classless Addressing  Routing Concepts  Routing Protocols

3. 3 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: addressing ClassAddress formatNetmaskBroadcastNetworks A 255.0.0.0 x.255.255.255 126 B 255.255.0.0 x.x.255.25516382 C 255.255.255.0 x.x.x.2552097150 DNo Netmask224.0.0.1 and others - ENo Netmask255.255.255.255- 07 bits24 bits NetworkHost 114 bits16 bits NetworkHost 121 bits8 bits NetworkHost 128 bits Group ID 0 10 110 127 bits Host 1110

4. 4 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IP Address Allocation Strategy Internet Assigned Numbers Authority (IANA) Pool of IP Addresses Management Regional Internet Registries (RIRs) Allocation of Blocks of @ Local IR or Internet Service Provider (ISP) Allocation of small Blocks of @

5. 5 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: addressing ClassAddress RangeReserved Addresses AFrom 1.0.0.0 to 126.0.0.00.x.x.x 127.x.x.x Loopback BFrom 128.1.0.0 to 191.254.0.0128.0.x.x 191.255.x.x CFrom 192.0.1.0 to 253.255.254.0192.0.0.x 223.255.255.x DFrom 224.0.0.0 to 239.255.255.255224.0.0.0 224.0.0.1 and others

6. 6 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Reserved Network Addresses ClassReserved Networks Address Range A110.0.0.0 B16From 172.16.0.0 to 172.31.0.0 C256From 192.168.0.0 to 192.168.255.0 Reserved Network Addresses are defined to avoid conflict between global Internet addressing and private local network addressing First solution: use of Translated Addresses (NAT) Second solution: non routing addresses (RFC 1918)

7. 7 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classful Subnetting Extend network address bits More networks and less hosts inside each network At least the host address should contain 2 bits (1 for the network address and 1 for the broadcast address) ClassNatural NetmaskBits reserved for the network Number of extensible bits A255.0.0.08+1 to 22 bits B255.255.0.016+1 to 14 bits C255.255.255.024+1 to 6 bits

8. 8 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classful Subnetting 128Bit6432 192 224 16 240 8 248 421 252 254 255 Netmasks ExampleReserved bitsRepresentationNetmask 10.0.0.0+210.0.0.0/10255.192.0.0 10.0.0.0+810.0.0.0/16255.255.0.0 175.50.0.0+3175.50.0.0/19255.255.224.0

9. 9 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classful Subnetting 25 host addresses needed Network: 192.168.100.0 2 host addresses needed 20 host addresses needed 2 host addresses needed The full subnetting requirement: at least 5 links and at least 25 hosts 3 subnet bits are required (2 3 – 2 = 6): 5 links are needed 5 host bits are required (2 5 – 2 = 30): the maximum hosts is 25 per subnet The Subnet Mask is: 255.255.255.224

10. 10 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classful Subnetting  Classful Subnetting Limitations  Class C addresses have limited number of hosts  All the created subnets are equal-size (same number of valid host addresses)  Waste of unused addresses (small networks)

11. 11 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classless Subnetting (VLSM) Network: 192.168.50.0/24 50 Host Addresses 100 Host Addresses 2 Host Addresses 15 Host Addresses 5 Host Addresses Challenge: Find how to subnet the network 192.168.50.0 (Class C) to fulfil the requirements of this topology?

12. 12 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 VLSM: Variable-Length Subnet Masking After a network address is subnetted in the standard fashion (using 2 n –n formula), the resulting subnets can themselves be subnetted VLSM is called: Sub-subnetting IPv4: Classless Subnetting (VLSM) 192.168.50.x x x x x x x x 192.168.50.0 x x x x x x x 192.168.50.1 x x x x x x x 192.168.50. 0 000 0000 Net. @ 192.168.50. 0 000 0001 192.168.50. 0 000 0010 ….192.168.50. 0 111 1110 192.168.50. 0 111 1111 Brod. @ 192.168.50. 1 000 0000 Net. @ 192.168.50. 1 000 0001 192.168.50. 1 000 0010 ….192.168.50. 1 111 1110 192.168.50. 1 111 1111 Net. @ By using 1 bit, we obtained 2 subnets 192.168.50.0/25 and 192.168.50.128/25 of 126 hosts each 24 bits8 bits

13. 13 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 The first subnet 192.168.50.0/25 meet the needs of Token Ring subnet The second subnet 192.168.50.128/25 is available and could be used One of the remaining subnets (Ethernet) requires 50 hosts So the mask of 192.168.50.128/25 is expended to 26 bits IPv4: Classless Subnetting (VLSM) 192.168.50.x x x x x x x x 192.168.50.0 x x x x x x x 192.168.50.1 x x x x x x x 25 bits 7 bits Used for the Token Ring 192.168.50. 0/25 (126 hosts) 192.168.50.1 0 x x x x x x 192.168.50.1 1 x x x x x x We obtained 2 Sub-subnets 192.168.50.128/26 and 192.168.50.192/26 of 62 hosts each 192.168.50. 10 00 0000 Net. @ 192.168.50. 10 00 0001 192.168.50. 10 00 0010 ….192.168.50. 10 11 1110 192.168.50. 10 11 1111 Brod. @ 192.168.50. 11 00 0000 Net. @ 192.168.50. 11 00 0001 192.168.50. 11 00 0010 ….192.168.50. 11 11 1110 192.168.50. 11 11 1111 Brod. @

14. 14 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 The first subnet 192.168.50.128/26 is taken for the large Ethernet of 50 hosts The second subnet 192.168.50.192/26 is available and could be used One of the remaining subnets (Ethernet) requires 15 hosts So the mask of 192.168.50.192/26 is expended to 27 bits IPv4: Classless Subnetting (VLSM) 192.168.50.x x x x x x x x 192.168.50.0 x x x x x x x 192.168.50.1 x x x x x x x 26 bits 6 bits Used for the Token Ring 192.168.50.0 /25 (126 hosts) 192.168.50.1 0 x x x x x x 192.168.50.1 1 0 x x x x x Used for the large Ethernet 192.168.50.128 /26 (62 hosts) 192.168.50.1 1 1 x x x x x 27 bits 192.168.50.1 1 x x x x x x 1 2 We obtained 2 “Sub-sub-subnets” 192.168.50.192/27 and 192.168.50.224/27 of 30 hosts each 3

15. 15 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classless Subnetting (VLSM) 192.168.50.x x x x x x x x 192.168.50.0 x x x x x x x 192.168.50.1 x x x x x x x 24 bits 8 bits Used for the Token Ring 192.168.50.0 /25 (126 hosts) 192.168.50.1 0 x x x x x x 192.168.50.1 1 0 x x x x x Used for the large Ethernet 192.168.50.128 /26 (62 hosts) 192.168.50.1 1 1 x x x x x Used for the second Ethernet 192.168.50.192 /27 (30 hosts) 192.168.50.1 1 1 0 x x x x 192.168.50.1 1 1 1 x x x x 192.168.50.224 /27 (30 hosts) is subnetted again by taking 1 more bit : 192.168.50.224 /28 (14 hosts used for the FDDI ) and 192.168.50.240 /28 This subnet is subnetted again by taking 2 bits: 192.168.50.240/30 192.168.50.244/30 (2 hosts) 28 bits

16. 16 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Classless Subnetting (VLSM) Network: 192.168.50.0 50 Hosts 192.168.50.128/26 100 Hosts 192.168.50.0/25 2 Hosts 192.168.50.240/30 2 Hosts 192.168.50.244/30 15 Hosts 192.168.50.192/27 5 Hosts 192.168.50.224/28

17. 17 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Address Aggregation  VLSM: the address mask is extended even more to create subnets within subnets  Subnet Address: may be thought of as a summarisation of a group of sub-subnets  Network Address: may be thought as a summarisation of a group of subnet addresses  Address Aggregation takes summarisation a step further by breaking the class limits of major network addresses (A, B, et C)  An aggregated Address represents a numerically continuous group of network addresses. IPv4: Classless Subnetting (VLSM)

18. 18 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IPv4: Address Aggregation 192.168.16.0/24 192.168.17.0/24 192.168.18.0/24 …. 192.168.30.0/24 192.168.31.0/24 Advertised Route 192.168.16.0/20 11000000 10101000 00010000 00000000 = 192.168.16.0/24 11000000 10101000 00010001 00000000 = 192.168.17.0/24 11000000 10101000 00010010 00000000 = 192.168.18.0/24 …. 11000000 10101000 00011110 00000000 = 192.168.30.0/24 11000000 10101000 00011111 00000000 = 192.168.31.0/24 11000000 10101000 00010000 00000000 = 192.168.16.0/20 R1 R2 The Aggregated Address is made by masking all the common bits of a group of network addresses Routing Table

19. 19 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Network designers face three primary issues when summarising routes:  Summary black holes  Bad combination of summarisation and network design  Add additional links (tunnel) so that routers exchange full routing information between them  Suboptimal routing  Caused by the information hidden in the summary  Solution: provide equal access to routes behind aggregation point or select to not summarise  Managing summary metrics  Make the summary metric constant (creating a loopback interface on the edge router with a fixed metric)  Manually set the summary metric through configuration commands IPv4: Summary issues

20. 20 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IP Protocols: ARP, RARP, ICMP Not Specified ARP, RARP IP ICMPRouting Protocols Not Specified Link Network

21. 21 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 IP Protocols (2)  Internet Protocol (IP)  Provides connectionless, best-effort delivery routing of datagrams  Is not concerned with the content of the datagrams  Internet Control Message Protocol (ICMP)  Provides control and messaging capabilities  Address Resolution Protocol (ARP)  Determines the data link layer address for known IP addresses  Reverse Address Resolution Protocol (RARP)  Determines network addresses when data link layer addresses are known

22. 22 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router A Router performs the routing A Router maintains a Routing Table (Multiple entries for reachable networks) A Router computes its Routing Table based on Routing Algorithms A Routing Protocol is an implementation of Routing Algorithm A Router has several Network Interfaces: Ethernet Interface: E0 (First Interface), E1 (Second Interface), etc. Fast Ethernet: F0 (First Interface), F1 (Second Interface), etc. Serial Interface: S0 (First Interface), S1 (Second Interface), etc. Loopback Interface: Lo0 (First Interface), Lo1 (Second Interface), etc.

23. 23 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router and Routing Table IP router: IP forwarding enabled Host: IP forwarding disabled

24. 24 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router Interfaces S0 (IP Address, Netmask) Router 1 Router 2 Router 3 Ethernet Interface (Ei or Fj) E0 (IP Address, Netmask) E1 (IP Address, Netmask) Serial connection S0 Lo0 (IP Address) Loopback Interface The loopback interface will be used as source-address for all the outgoing IP traffic and as interface to connect to the router. As long as one of the physical interfaces is up, the loopback interface will be reachable.

25. 25 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router: Router Processing Router Processing  IP header validation  Process options in IP header  Parsing the destination IP address  Routing table lookup  Decrement TTL  Perform fragmentation (if necessary)  Calculate checksum  Transmit to next hop  Send ICMP packet (if necessary)

26. 26 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 R1 ICMP (3) ICMP redirect

27. 27 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 ICMP (RFCs 792, 950 and 1256) TypeMessageCodeDescription 3Destination Unreachable 0Network Unreachable 1Host Unreachable 2Protocol Unreachable 3Port Unreachable 4Fragmentation Needed and DF set 5Source Route Failed 11Time Exceeded 0Router receives a packet with TTL=0 1A host does not receive all fragments 12Parameter Problem 0Parameters in the IP header are incorrect 4Source Quench 0Host or Router faces a congestion, it requests from the source to reduce the flow 8Echo Request 0Request a reply from the receiver 0Echo Reply 0Respond an Echo message

28. 28 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 ICMP (RFCs 792, 950 and 1256) TypeMessageCodeDescription 5Redirect 0For the Network: indicates best router to use 1For Host: indicates best host to use 2For the TOS and Network 3For the TOS and Host 13Timestamp 0Elapsed seconds since 00h00 GMT since the message is sent (Evaluate transit time) 14Timestamp Reply 0Elapsed seconds since the Timestamp message is received 15/16Information Request/Reply 0Obsolete (obtain an IP address: Replaced by DHCP) 17Mask Request 0Get an IP mask of the subnet (RFC 950) 9Router Advertisement 0Sent by a router to indicate its IP address. Used for Router discovery (RFC 1265) 10Router Solicitation 0Sent by a Host to request the IP address of the router (RFC 1265)

29. 29 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Classification of Routers Classification (Based on location and functions) Access Router A router that connects directly end hosts It may be mobile of stationary system A mobile access router (Mobile Router) is a router that can be moved from one place to another An MR may be a router in a Bus, Plane, Boat, etc. that provides wired or wireless connectivity to end users Core Router Connects multiple access routers Perform intra-domain routing Edge Router Connects and performs routing between different AS Two types Ingress Router: router from which traffic enters a domain or AS Egress Router: router from which traffic leaves a domain or AS

30. 30 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Classification of Routers

31. 31 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router Discovery A host discovers a router either by: Configuration file at start-up time Listening to router traffic on multicast links Solution: Use ICMP on multicast links A host learns about the TTL from a router Two ICMP messages: Router Advertisement Router Solicitation Serious drawbacks: manual configuration non dynamic track change

32. 32 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Router Discovery Router Advertisement (RA) Sent periodically by a Router from each of its multicast interfaces (From 7 to 10 mn) Sent to all-systems multicast address (224.0.0.1: more preferred if router supports multicast), or to the limited-broadcast address 255.255.255.255 Announces the IP address of each interface Helps hosts to discover the addresses of their neighbouring routers Includes a "preference level" for each advertised router address Includes a "lifetime" field, specifying the validity of the router address (30 minutes) Router Solicitation (RS) Host can request an RA instead of waiting Router can request an RA from its neighbours

33. 33 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Routing Protocols (Overview)

34. 34 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Routing Protocol: Requirements  Any routing protocol relies on the following elements  Routing Algorithm  Data Structures (Routing Table, Database, Cache, etc.)  Timers (For discovery, election, update, failure detection, etc.)  Messages (IP packets for control purposes)  Events (Initialisation, exchange, reboot, etc.)  Network Metrics (Bandwidth, Delay, Link-state, or multiple metrics)  Events and Timers are triggered by specific rules and use specific Messages to update specific Data Structure

35. 35 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Routing Protocol: Complexity  The performance of a Routing Protocol depends on:  Simplicity (Network metrics, Routing Algorithm, etc.)  Complexity (Processes, Data Structures)  Scalability (Suitability to small and large networks, intra-domain, inter- domain)  Reliability (Messages are acknowledged or not)  Security (Authentication)

36. 36 Edinburgh Napier University Imed Romdhani February 2014 Napier University Property Only Module CSN11107 Thanks !! Questions?