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IP Address Sirak Kaewjamnong 1 Three Level of Address • Host name – ratree.psu.ac.th • Internet IP address – 192.168.100.3 (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 2 Converting Host Name to MAC Address cs05.cs.psu.ac.th 172.28.80.96 00:50:ba:49:9d:b9 Resolve IP address by Domain Name System(DNS) Resolve MAC address by Address Resolution Protocol(ARP) 3 IP Address with Router IP address associated with 172.28.80.15 172.28.80.16 172.28.85.116 172.28.85.120 interface (not machine) • Each interface has its own IP address 172.28.85.1 • Machine with more than one 172.28.80.1 192.168.99.39 interface called multi-home Internet • Router is multi-homed machine 192.168.98.11 • Multi-homed not to be router 192.168.100.4 192.168.100.3 192.168.100.1 4 Addressing Concept • Partitions address into 2 fields * network address * node address 5 IP Address 32 bits 8,16,24 bits Network Host 32 bits 8 bits 8 bits 8 bits 172 28 80 10101100 00011100 01010000 . . . 8 bits 96 01100000 6 IP Address Class 32 bits address length, contain 2 parts • Network identifier • Host identifier 8 16 Class A 0 Network ID Class B 10 Class C 110 Class D 1110 Class E 11110 24 32 Host ID Network ID Host ID Network ID Host ID Multicast Address Unused 7 IP Address Class Initial Bit Bit Class bits net host A B C D E 0 10 110 1110 11110 7 14 21 28 27 24 16 8 - range address spaces usable 0.0.0.0 -127.255.255.255 224 16,677,214 128.0.0.0 -191.255.255.255 216 65,534 192.0.0.0 -223.255.255.255 28 254 224.0.0.0-239.255.255.255 240.0.0.0-247.255.255.255 8 Special Address • Host ID “all 0s” is reserved to refer to network number – 192.168.100.0, 158.108.0.0, 18.0.0.0 • Host ID “all 1s” is reserved to broadcast to all hosts on a specific network – 192.168.100.255, 158.108.255.255, 18.255.255.255 • Address 0.0.0.0 means “default route” • Address 127.0.0.0 means “this node” (local loopback). Message sent to this address will never leave the local host • Address 255.255.255.255 is reserve to broadcast to every host on the local network (limited broadcast) 9 Private Address Reserve for Intranet or private network • 10.0.0.0 – 10.255.255.255 (1 class A ) • 172.16.0.0 – 172.31.255.255 (16 class B) • 192.168.0.0 – 192.128.255.255 (256 class C) 10 Problem with Class Assignment • Class A takes 50 % range • Class B takes 25 % range • Class C take 12.5 % range Class A Class B These leads to: • address wasteful (specially in class A) • running out of IP address E D C 11 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 12 Class C Assignment • Assignment is based on the subscriber ‘s 24 month projection according to the criteria: 1. 2. 3. 4. 5. 6. 7. Requires fewer than 256 addresses : 1 class C network Requires fewer than 512 addresses : 2 contiguous class C networks Requires fewer than 1024 addresses : 4 contiguous class C networks Requires fewer than 2048 addresses : 8 contiguous class C networks Requires fewer than 4096 addresses : 16 contiguous class C networks Requires fewer than 8192 addresses : 32 contiguous class C networks Requires fewer than 16384 addresses : 64 contiguous class C networks 13 Problem with Large Network • Class B “Flat Network” more than 60,000 hosts – How to manage? – Performance? 150.0.0.1 150.0.0.2 ... 150.0.255.254 14 Problem with Large Network • Class B “subdivided network” to smaller group with router 150.0.1.1 150.0.40.1 150.0.40.2 150.0.1.2 150.0.10.1 150.0.10.2 Router 150.0.200.1 150.0.200.2 15 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 16 How to assign subnet • Divide host ID into 2 pieces host ID Network ID Subnet address Host address Choose appropriate size • Class B address such as 150.0 might use its third byte to identify subnet – subnet1 150.0.1.X X = host address range from 1-254 – subnet2 150.0.200.X 17 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 1111 1111 1111 1111 1111 1111 0000 0000 subnet mask = 255.255.255.0 * zero bit are used to mask out the host number resulting the network address 18 Subnet Mask Subnet mask 255.255.255.0 for class B tells: • network has been partition to 254 subnets 150.10.1.X to 150.10.254.X • logic “and” between IP address with mask yields network address 150.10.1.55 150.10.240.243 and and 255.255.255.0 255.255.255.0 150.10.1.0 150.10.240.0 19 Subnet Mask Bits Use contiguous subnet mask 128 1 1 1 1 1 1 1 1 64 0 1 1 1 1 1 1 1 32 0 0 1 1 1 1 1 1 16 0 0 0 1 1 1 1 1 8 0 0 0 0 1 1 1 1 4 0 0 0 0 0 1 1 1 2 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 1 = 128 = 192 = 224 = 240 = 248 = 252 = 254 = 255 20 Subnet Class B Example • 255.255.0.0 (0000 0000 0000 0000) 0 subnet with 65534 hosts (default subnet) • 255.255.192.0 (1100 0000 0000 0000) 2 subnets with 16382 hosts • 255.255.252.0 (1111 1100 0000 0000) 62 subnets with 1022 hosts • 255.255.255.0 (1111 1111 0000 0000) 254 subnets with 254 hosts • 255.255.255.252 (1111 1111 1111 11000) 16382 subnets with 2 hosts 21 Subnet Class C Example • 255.255.255.0 ( 0000 0000) 0 subnets with 254 hosts (default subnet) • 255.255.255.192 (1100 0000) 2 subnets with 62 hosts • 255.255.255.224 (1110 0000) 6 subnets with 30 hosts • 255.255.255.240 (1111 0000) 14 subnets with 14 hosts 22 Subnet Interpretation IP Address 158.108.2.71 150.10.25.3 130.122.34.132 200.190.155.66 18.20.15.2 Subnet mask 255.255.255.0 255.255.255.192 255.255255.192 255.255.255.192 255.255.0.0 Interpretation host 71 on subnet 158.108.2.0 host 3 on subnet 150.10.25.0 host 4 on subnet 130.122.34.128 host 2 on subnet 200.190.155.64 host 15.2 on subnet 18.20.0.0 23 Class B Subnet with Router Router is used to separate network Picture from Kasetsart University 24 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} 25 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 255.255.255.0 wastes 250 IPs) • Variable Length Subnet : the subnets may use difference subnet masks – pros: utilize address space – cons: required well managment 26 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 27 VLSM Sample Case Picture from Kasetsart university 28 CIDR Classless Inter-Domain Routing 29 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 65534 hosts, too large • Allocate block of class C instead and downside is more routes entry in routing table 30 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 31 Size of the Routing Table at the core of the Internet Number of prefixes 140000 120000 100000 80000 60000 40000 20000 0 Aug-87 May-90 Jan-93 Oct-95 Jul-98 Apr-01 Jan-04 Source: http://www.telstra.net/ops/bgptable.html 32 Prefix Length Distribution 70000 60000 Number of Prefixes 50000 40000 30000 20000 10000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Prefix Length Source: Geoff Huston, Oct 2001 33 How to solve • Topological allocate IP address assignment • We divide the world into 8 regions (RFC 1466) Multi regional 192.0.0.0 - 193.255.255.255 Europe 194.0.0.0 - 195.255.255.255 Others 196.0.0.0 - 197.255.255.255 North America 198.0.0.0 - 199.255.255.255 Central/South America 200.0.0.0 - 201.255.255.255 Pacific Rim 202.0.0.0 - 203.255.255.255 Others 204.0.0.0 - 205.255.255.255 Others 206.0.0.0 - 207.255.255.255 IANA Reserved 208.0.0.0 - 223.255.255.255 34 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) 35 Supernetting • An organization has been allocate a block of class C address in 2n 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 0 (Super) netmask 4 class C networks appear 11111111 11111111 11111100 00000000 to network outside as a single network 255.255.252.0 36 Supernetting Sample • An organization with 4 class C 193.0.32.0 , 193.0.33.0 , 193.0.34.0 , 193.0.35.0 11111111 11111111 11111100 00000000 mask 255.255.252.0 11000001 00000000 00100000 00000000 net 193.0.32.0 11000001 00000000 00100001 00000000 net 193.0.33.0 11000001 00000000 00100010 00000000 net 193.0.34.0 11000001 00000000 00100011 00000000 net 193.0.35.0 Bit wise AND results 193.0.32.0: 11000001 00000000 00100000 00000000 • This organization’s network has changed from 4 net to a single net with 1,022 hosts 37 The longest Match Supernetting • Europe has 194.0.0.0 - 195.255.255.255 with mask 254.0.0.0 • A case of one organization (195.0.16.0 - 195.0.36.0 mask 255.255.254.0) needs different routing entry • datagrams 195.0.20.1 matches both Europe’s and this organization. How to do? • Routing mechanism selects the longest mask (255.255.254.0 is longer than 254.0.0.0), then route to the organization 38 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 39 IPv6 40 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.. 41 Key Issues The new protocol MUST • Support large global internetworks • A clear way to transition IPv4 based networks 42 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 43 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 44 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:BA98:7654:3210 1080:0:0:0:8:800:200C: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 45 0:0:0:0:0:0:0:0 :: 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 0:0:0:0:0:0:13.1.68.3 => :: 13.1.68.3 IPv4-mapped IPv6 address 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): 0:0:0:0:0:FFFF:129.144.52.38/96 => :: FFFF:129.144.52.38/96 http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/x324.html 46 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 Example : the 60-bit prefix 12AB00000000CD3 12AB:0000:0000:CD30:0000:0000:0000:0000/60 12AB::CD30:0:0:0:0/60 12AB:0:0:CD30::/60 47 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 48 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 49 IPV6 Address Allocation Allocation Prefix bit Prefix form at fraction of address apace Reserved 0000 0000 0::/8 1/256 Unassigned 0000 0001 100::/8 1/256 Reserved for NSAP Allocation Reserved for IPX Allocation 0000 001 0000 010 200::/7 400::/7 1/128 1/128 Unassigned 0000 011 600::/7 1/128 Unassigned 0000 1 800::/5 1/32 Unassigned 0001 1000::4 1/16 Aggregatable Global Unicast Addresses 001 2000::/3 1/8 Unassigned 010 4000::/3 1/8 Unassigned 011 6000::/3 1/8 Unassigned 100 8000::/3 1/8 Unassigned 101 A000::/3 1/8 Unassigned 110 C000::/3 1/8 Unassigned 1110 E000::/4 1/16 Unassigned 1111 0 F000::/5 1/32 Unassigned 1111 10 F800::/6 1/64 Unassigned 1111 110 FC00::/7 1/128 Unassigned 1111 1110 0 FE00::/9 1/512 Link-Local Unicast Addresses Site-Local Unicast Addresses Multicast Addresses 1111 1110 10 1111 1110 11 1111 1111 FE80::/10 FEC0::/10 FF00::/8 1/1024 1/1024 1/256 50 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 51 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) • Interface Identifier: interfaces on links x2 X1 P2 S1 • Site Topology : does not provide public transit service to nodes outside of the site (S1, S2, S3, S4, S5 and S6) P3 P1 P4 S2 P5 S4 S5 P6 S3 S6 52 Aggregatable Unicast Address 3 13 8 FP TLA ID RES 24 NLA ID Public Topology FP=Format Prefix= 001 TLA= Top Level Aggregation RES= Reserved NLA=Next-Level Aggregation SLA=Site-Level Aggregation 16 SLA ID 64 bits Interface ID Site Topology Interface Identifier 53 Header Comparison 0 15 16 vers hlen 20 bytes TOS • flags protocol frag offset header checksum source address destination address • options and padding pay load length 40 bytes flow label next header hop limit • source address Added: (2) – Traffic class – flow label destination address IPv6 Changed: (3) – total length=> payload – protocol => next header – TTL=> hop limit IPv4 vers traffic class Removed (6) – ID, Flags, frag offset – TOS, hlen – header checksum total length identification TTL 31 • Expanded – address 32 bits to 128 bits 54 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-48 EUI-64 00:06:5B:DA:45:AD = 00:06:5B:FF:FE:DA:45:AD 55 Auto configuration “Plug and play” feature • Stateless mode :via ICMP (no server required) Prefix 4c00::/80 Link Address 00:A0:C9:1E:A5:B6 IPv6 Address 4c00::A0:C9FF:EF1E:A5B6 Router adv. • Stateful server mode : via DHCP 00:A0:C9:1E:A5:B6 DHCP server DHCP request DHCP response 4c00::A0:C9FF:FE1E:A5B6 56 Security • • Authentication/Confidential Authentication: – MD5 based • Confidential : – payload encryption – Cipher Block Chaining mode of the Data Encryption Standard (DESCBC) 57 Support Protocols • • • • ICMPv6 [RFC1885] DHCPv6 DNS extensions to support IPv6 [RFC1886] Routing Protocols – – – – – RIPv6 [RFC2080] OSPFv6 IDRP IS-IS Cisco EIGRP 58 Dual Stack • • Dual stack hosts support both IPv4 and IPv6 Determine stack via DNS Application TCP IPv6 IPv4 Ethernet IPV6 Dual stack host IPv4 59 Tunneling: automatic tunneling • • Encapsulate IPv6 packet in IPv4 Rely on IPv4-compatible IPv6 address IPv6 host ::1.2.3.4 R1 IPv4 Network 2.3.4.5 ::2.3.4.5 6 traffic flow label payload len next hops src = ::1.2.3.4 (IPv4-compatible IPv6 adr) dst = ::2.3.4.5 (IPv4-compatible IPv6 adr) payload IPv4/6 host 2.3.4.5 R2 2.3.4.5 4 hl TOS len frag id frag ofs TTL prot checksum src: 1.2.3.4 dst: 2.3.4.5 6 traffic flow label 4 hl TOS len frag id frag ofs TTL prot checksum src: 1.2.3.4 dst: 2.3.4.5 6 traffic flow label payload len payload len next hops next hops src = ::1.2.3.4 (IPv4-compatible IPv6 adr) src = ::1.2.3.4 (IPv4-compatible IPv6 adr) dst = ::2.3.4.5 (IPv4-compatible IPv6 adr) dest = ::2.3.4.5 (IPv4-compatible IPv6 adr) payload payload 60 Tunneling : configured tunneling • • Encapsulate IPv6 packet in IPv4 Rely on IPv6-only address IPv6 address (IPv4-compatible address are unavailable) IPv6 host ::1:2:3:4 R1 ::2:3:4:5 6 traffic flow label payload len next src = ::1:2:3:4 (IPv6 adr) dst = ::2:3:4:5 (IPv6 adr) payload hops IPv6 host :: 2:3:4:5 IPv4 Network R2 ::2:3:4:5 R2 4 hl TOS len frag id frag ofs TTL prot checksum src = R1 dst =R2 6 traffic flow label payload len next src =::1:2:3:4 (IPv6 adr) hops 6 traffic flow label payload len next hops src = ::1:2:3:4 (IPv6 adr) dst = ::2:3:4:5 (IPv6 adr) payload dst = ::2:3:4:5 (IPv6 adr) payload 61 Header Translation Full IPv6 system need to support few IPv4-only systems rely on IPv6 host ::1:2:3:4 IPv4-mapped R1 IPv6 address ::2:3:4:5 IPv4 host 2.3.4.5 IPv6 Network R2 2.3.4.5 ::2.3.4.5 6 traffic flow label 6 traffic flow label payload len next payload len next src = ::1:2:3:4 (IPv6 adr) dst = ::2.3.4.5 (IPv6 adr) payload hops src = ::1:2:3:4 (IPv6 adr) dst = ::2.3.4.5 (IPv6 adr) hops 4 hl TOS len frag id frag ofs TTL prot checksum src = R1 dst =R2 payload payload 62 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 63 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 64