1 IP Address Sirak Kaewjamnong

2 Three Level of Address Host name –ratree.psu.ac.th Internet IP address – (32 bits address with “ dot-decimal ” notation) Station address : Hardware address assigned to network interface card, refer to MAC address or Ethernet Address (48 bits) –00:5c:f0:3b:00:4a

3 Converting Host Name to MAC Address cs05.cs.psu.ac.t h :50:ba:49:9d :b9 Resolve IP address by Domain Name System(DNS) Resolve MAC address by Address Resolution Protocol(ARP)

4 IP Address with Router IP address associated with interface (not machine) Each interface has its own IP address Machine with more than one interface called multi-home Router is multi- homed machine Multi-homed not to be router Interne t

5 Addressing Concept Partitions address into 2 fields *network address *node address

6 IP Address NetworkHost 32 bits 8,16,24 bits 8 bits 32 bits

7 IP Address Class 32 bits address length, contain 2 parts Network identifier Host identifier Class A Host IDNetwork ID0 Multicast Address1110 Unused11110 Host IDNetwork ID110 Host IDNetwork ID10Class B Class C Clas s D Clas s E

8 IP Address Class A ,677,214 B ,534 C D E Class Initial bits Bit net Bit host range address spaces usable

9 Special Address Host ID “ all 0s ” is reserved to refer to network number – , , Host ID “ all 1s ” is reserved to broadcast to all hosts on a specific network – , , Address means “ default route ” Address means “ this node ” (local loopback). Message sent to this address will never leave the local host Address is reserve to broadcast to every host on the local network (limited broadcast)

10 Private Address Reserve for Intranet or private network – (1 class A ) – (16 class B) – (256 class C)

11 Problem with Class Assignment Class A takes 50 % range Class B takes 25 % range Class C take 12.5 % range These leads to: address wasteful (specially in class A) running out of IP address Class A Class B C D E

12 How to assigns IP Address (RFC 1466) Class A : no allocations will be made at this time Class B: allocations will be restricted. To apply: –organization presents a subnetting more than32 subnets –organization more than 4096 hosts class C: divided into allocated block to distributed reginal

13 Class C Assignment Assignment is based on the subscriber ‘ s 24 month projection according to the criteria: 1. Requires fewer than 256 addresses : 1 class C network 2. Requires fewer than 512 addresses : 2 contiguous class C networks 3. Requires fewer than 1024 addresses : 4 contiguous class C networks 4. Requires fewer than 2048 addresses : 8 contiguous class C networks 5. Requires fewer than 4096 addresses : 16 contiguous class C networks 6. Requires fewer than 8192 addresses : 32 contiguous class C networks 7. Requires fewer than addresses : 64 contiguous class C networks

14 Problem with Large Network Class B “ Flat Network ” more than 60,000 hosts –How to manage? –Performance ?

15 Problem with Large Network Class B “ subdivided network ” to smaller group with router Router

16 Subnetwork Benefits Increase the network manager ’ s control the address space Easy to allocate the address space Better network performance Hide routing structure from remote routers, thus reducing routes in their routing tables Subdivide on IP network number is an important initial task of network managers

17 How to assign subnet Divide host ID into 2 pieces Class B address such as might use its third byte to identify subnet –subnet X X = host address range from –subnet X Network IDSubnet addressHost address host ID Choose appropr iate size

18 Subnet Mask 32 bit number, tell router to recognize the subnet field, call subnet mask subnet rule: The bit covering the network and subnet part of address are set to 1 Example class B with 24 bits mask subnet mask = * zero bit are used to mask out the host number resulting the network address

19 Subnet Mask Subnet mask for class B tells: network has been partition to 254 subnets X to X logic “ and ” between IP address with mask yields network address and and

20 Subnet Mask Bits Use contiguous subnet mask = = = = = = = = 255

21 Subnet Class B Example ( ) 0 subnet with hosts (default subnet) ( ) 2 subnets with hosts ( ) 62 subnets with 1022 hosts ( ) 254 subnets with 254 hosts ( ) subnets with 2 hosts

22 Subnet Class C Example ( ) 0 subnets with 254 hosts (default subnet) ( ) 2 subnets with 62 hosts ( ) 6 subnets with 30 hosts ( ) 14 subnets with 14 hosts

23 Subnet Interpretation IP AddressSubnet mask Interpretation host 71 on subnet host 3 on subnet host 4 on subnet host 2 on subnet host 15.2 on subnet

24 Class B Subnet with Router Router is used to separate network Picture from Kasetsart University

25 Subnet Routing Traffic is route to a host by looking “ bit wise AND ” results if dest IP addr & subnet mask = = my IP addr & subnet mask send packet on local network { dest IP addr is on the same subnet} else send packet to router {dest IP address is on difference subnet}

26 Type of Subnet Static subnet: all subnets in the subnetted network use the same subnet mask –pros: simply to implement, easy to maintain –cons: wasted address space (consider a network of 4 hosts with wastes 250 IPs) Variable Length Subnet : the subnets may use difference subnet masks –pros: utilize address space –cons: required well managment

27 Variable Length Subnet Mask General idea of VLSM –A small subnet with only a few hosts needs a subnet mask that accommodate only few hosts –A subnet with many hosts need a subnet mask to accomdate the large number of hosts Network Manager ’ s responsibility to design and appropriate VLSM

28 VLSM Sample Case Picture from Kasetsart university

29 CIDR Classless Inter-Domain Routing

30 Address Allocation Problem Exhaustion of the class B network address space The lack of a network class of size which is appropriate for mid-sizes organization –class C, with a max of 254 hosts, too small –While class B, with a max of hosts, too large Allocate block of class C instead and downside is more routes entry in routing table

31 Routing Table Problems Issue multiple block class C addresses (instead single class B address) solves a running out of class B address Introduces problems of routing table –By default, a routing table contains an entry for every network –How large a routing table should be for all class C networks? Growth of routing table in the internet routers beyond the ability of current software and hardware manage

32 Size of the Routing Table at the core of the Internet Source:

33 Prefix Length Distribution Prefix Length Number of Prefixes Source: Geoff Huston, Oct 2001

34 How to solve Topological allocate IP address assignment We divide the world into 8 regions (RFC 1466) Multi regional Europe Others North America Central/South America Pacific Rim Others Others IANA Reserved

35 Classless Interdomain Routing Class C address ’ s concept becomes meaningless on these route between domain, the technique is call Classless Interdomain Routing or CIDR or Supernet Kay concepts is to allocate multiple IP address in the way that allow summarization into a smaller number of routing table (route aggregate) CIDR is supported by BGP4 and based on route aggregation –16 class C addresses can be summarized to a single routing entry (router can hold a single route entry for a main trunks between these areas)

36 Supernetting An organization has been allocate a block of class C address in 2 n with contiguous address space –archive by using bits which belongs to the network address as hosts bits –class C example : altering the default class C subnet mask such that some bit change from 1 to (Super) netmask 4 class C networks appear to network outside as a single network

37 Supernetting Sample An organization with 4 class C , , , mask net net net net Bit wise AND results : This organization ’ s network has changed from 4 net to a single net with 1,022 hosts

38 The longest Match Supernetting Europe has with mask A case of one organization ( mask ) needs different routing entry datagrams matches both Europe ’ s and this organization. How to do? Routing mechanism selects the longest mask ( is longer than ), then route to the organization

39 Summary Routing decisions are now made based on masking operations of the entries 32 bits address, hence the term “ classes ” No existing routes is changed CIDR slows down the growth of routing tables (current 130K entries in core routers) Short term solution to solve routing problem limitation: not all host/router software allows supernet mask

40 IPv6

41 IPv4 ’ s Limitations Two driving factors : addressing and routing Addressing : address depletion concerns –Internet exhaust the IPv4 address space between 2005 and 2011 [RFC1752]. Routing : routing table explosion –Currently ~120K entries in core router More factors... –Opportunity to optimized on many years of deployment experience –New features needed : multimedia, security, mobile, etc..

42 Key Issues The new protocol MUST Support large global internetworks A clear way to transition IPv4 based networks

43 What is IPv6? IPv6 is short for "Internet Protocol Version 6". IPv6 is the "next generation" protocol designed by the IETF to replace the current version Internet Protocol, IP Version 4

44 IPV6 Key Advantages 128 bit fix length IP address Real time support Self-configuration of workstations or auto configuration Security features Support mobile workstations Protocol remains the same principle IPv4 compatibility

45 IPV6 Address Representation Hexadecimal values of the eight 16-bit pieces x:x:x:x:x:x:x:x Example FEDC:BA98:7654:3210:FEDC:BA98:7654 : :0:0:0:8:800:200C:417A Compressed form: "::" indicates multiple groups of 16-bits of zeros. 1080:0:0:0:8:800:200C:417A 1080::8:800:200C:417A FF01:0:0:0:0:0:0:101 FF01::101 0:0:0:0:0:0:0:1 ::1 0:0:0:0:0:0:0:0 ::

46 IPV6 Address Representation(cont) Mixed environment of IPv4 and IPv6 address IPv4-compatible IPv6 address technique for hosts and routers to dynamically tunnel IPv6 packets over IPv4 routing infrastructure 0:0:0:0:0:0: => :: represent the addresses of IPv4-only nodes (those that do not support IPv6) as IPv6 addresses IPv4-only IPv6-compatible addresses are sometimes used/shown for sockets created by an IPv6-enabled daemon, but only binding to an IPv4 address. These addresses are defined with a special prefix of length 96 (a.b.c.d is the IPv4 address): IPv4-mapped IPv6 address 0:0:0:0:0:FFFF: /96 => :: FFFF: /96

47 Format Prefix Format Prefix : –Leading bits indicate specific type of an IPv6 address –The variable-length field –Represented by the notation: IPv6-address/prefix-length 12AB:0000:0000:CD30:0000:0000:0000:0000/60 12AB::CD30:0:0:0:0/60 12AB:0:0:CD30::/60 Example : the 60-bit prefix 12AB CD3

48 Type of Addresses Three type of addresses UNICAST : defines a single interface A packet sent to a unicast address is delivered to the interface identified by that address. ANYCAST : defines a set of interfaces A packet sent to an anycast address is delivered to one of the interfaces MULTICAST : defines a set of interfaces A packet sent to a multicast address is delivered to all interfaces identified by that address

49 Address Types Unspecified address, 0:0:0:0:0:0:0:0 or :: Loopback address, 0:0:0:0:0:0:0:1 of ::1 Global address, 2000::/3 and E000::/3 currently only 2000::/3 is being assigned Link local address, FE80::/64 Site local address, FEC0::/10

50 IPV6 Address Allocation

51 Address Registries Address registries for IPv6 are the same one as for IPv4, ARIN,RIPE and APNIC. Only large network providers will ever obtain addresses directly from the registries, such as UNINET : one such provider in Thailand If a /35 prefix is allocates, the registry internally will reserve a /32. The basic unit of assignment to any organization is a /48 prefix

52 Aggregatable Unicast Address Three level hierarchy: Public Topology : providers and exchanges who provide public Internet transit services (P1, P2, P3, P4, X1, X2, P5 and P6) Site Topology : does not provide public transit service to nodes outside of the site (S1, S2, S3, S4, S5 and S6) Interface Identifier: interfaces on links X1 P1 P2 P3 P4 x2 P5 P6 S1 S2 S3 S4 S5 S6

53 Aggregatable Unicast Address FP TLA ID RES NLA ID SLA ID Interface ID bits Public Topology Site Topology Interface Identifier TLA= Top Level Aggregation RES= Reserved NLA=Next-Level Aggregation SLA=Site-Level Aggregation FP=Format Prefix= 001

54 Header Comparison Removed (6) –ID, Flags, frag offset –TOS, hlen –header checksum Changed: (3) –total length=> payload –protocol => next header –TTL=> hop limit Added: (2) –Traffic class –flow label Expanded –address 32 bits to 128 bits vers hlen TOS total length identification flags frag offset TTL protocol header checksum source address destination address options and padding bytes vers traffic class flow label pay load length next header hop limit source address destination address 40 bytes IPv4 IPv6

55 IPv6 Node Configuration Ethernet address is an IEEE EUI-48 Node address is an IEEE EUI-64 EUI-48 can be converted into an EUI-64 by inserting the bits FF FE between the 3 rd and 4th octets EUI-48EUI-64 00:06:5B:DA:45:AD = 00:06:5B:FF:FE:DA:45:AD

56 Auto configuration “ Plug and play ” feature Stateless mode : via ICMP (no server required) Stateful server mode : via DHCP Prefix 4c00::/80 Link Address 00:A0:C9:1E:A5:B6 IPv6 Address 4c00::A0:C9FF:EF1E:A5B6 Router adv. DHCP request DHCP response 00:A0:C9:1E:A5:B6 4c00::A0:C9FF:FE1E:A5B6 DHCP server

57 Security Authentication/Confidential Authentication: –MD5 based Confidential : –payload encryption –Cipher Block Chaining mode of the Data Encryption Standard (DES-CBC)

58 Support Protocols ICMPv6 [RFC1885] DHCPv6 DNS extensions to support IPv6 [RFC1886] Routing Protocols –RIPv6 [RFC2080] –OSPFv6 –IDRP –IS-IS –Cisco EIGRP

59 Dual Stack Dual stack hosts support both IPv4 and IPv6 Determine stack via DNS IPV6 IPv4 Dual stack host Application TCP IPv6 IPv4 Ethernet

60 Tunneling: automatic tunneling Encapsulate IPv6 packet in IPv4 Rely on IPv4-compatible IPv6 address IPv6 host IPv4/6 host IPv4 Network :: traffic flow label payload len next hops src = :: (IPv4-compatible IPv6 adr) dst = :: (IPv4-compatible IPv6 adr) payload 4 hl TOS len frag id frag ofs TTL prot checksum src: dst: traffic flow label payload len next hops src = :: (IPv4-compatible IPv6 adr) dst = :: (IPv4-compatible IPv6 adr) payload 4 hl TOS len frag id frag ofs TTL prot checksum src: dst: traffic flow label payload len next hops src = :: (IPv4-compatible IPv6 adr) dest = :: (IPv4-compatible IPv6 adr) payload :: R1 R2

61 Tunneling : configured tunneling Encapsulate IPv6 packet in IPv4 Rely on IPv6-only address IPv6 host IPv4 Network ::1:2:3:4 :: 2:3:4:5 6 traffic flow label payload len next hops src = ::1:2:3:4 (IPv6 adr) dst = ::2:3:4:5 (IPv6 adr) payload 4 hl TOS len frag id frag ofs TTL prot checksum src = R1 dst =R2 6 traffic flow label payload len next hops src =::1:2:3:4 (IPv6 adr) dst = ::2:3:4:5 (IPv6 adr) payload ::2:3:4:5 R2 ::2:3:4:5 R1 R2 6 traffic flow label payload len next hops src = ::1:2:3:4 (IPv6 adr) dst = ::2:3:4:5 (IPv6 adr) payload IPv6 address (IPv4-compatible address are unavailable)

62 Header Translation Full IPv6 system need to support few IPv4-only systems rely on IPv4-mapped IPv6 address IPv6 host IPv4 host IPv6 Network ::1:2:3: traffic flow label payload len next hops src = ::1:2:3:4 (IPv6 adr) dst = :: (IPv6 adr) payload 4 hl TOS len frag id frag ofs TTL prot checksum src = R1 dst =R2 payload ::2:3:4:5 :: R1 R2 6 traffic flow label payload len next hops src = ::1:2:3:4 (IPv6 adr) dst = :: (IPv6 adr) payload

63 Migration Steps 1.Upgrade DNS servers to handle IPv6 Address 2.Introduce dual stack systems that support IPv4 and IPv6 3.Rely on tunnels to connect IPv6 networks separated by IPv4 networks 4.Remove support for IPv4 5.Rely on header translation for IPv4-only systems

64 Conclusion IPv6 will provide for future Internet growth and enhancement IPv6 : –solve the Internet scaling problem –support large hierarchical address –provide a flexible transition mechanism –interoperate with IPv4 –provide a platform for new Internet functionality