IPv4 REVIEW AND IPv6 ETI 2506 TELECOMMUNICATION SYSTEMS Monday, - PowerPoint PPT Presentation

IPv4 REVIEW AND IPv6 ETI 2506 – TELECOMMUNICATION SYSTEMS Monday, 07 NOVEMBER 2016

TELECOMMUNICATION SYLLABUS Principles of Telecom (IP Telephony and IP TV) - Key Issues to remember 1. IPv4 Header and how it is used for routing packets 2. Subneting 3. CIDR 4. NAT 5. IPv6 Header and its use for routing packets 2

WHAT IS IPV4? 1. IPv4 is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). 2. It operates on a best effort delivery model, i.e a) It does not guarantee delivery, b) It does it assure proper sequencing, c) It does not avoid duplicate delivery of packets. 3. These aspects, including data integrity, are addressed by an upper layer transport protocol , such as the Transmission Control Protocol (TCP).

IPV4 HEADER • The IPv4 packet header consists of 14 fields, of which 13 are required. • The 14th field (labelled Options) is optional.

Header Length (HL) Version Type of Service The number of 32-bit words in Four-bit field (DiffServ) header. 0100 indicates version 4 (IPv4) Carries QoS 5 ≤ HL ≤ 15 0110 indicates version 6 (IPv6). information, i.e precedence, throughput, delay, reliability, and monetary cost Identifier Total Length Identifies fragments of The entire datagram an original IP datagram size, including header and data, in bytes Flags Used to control or identify fragments. Fragment offset Bit 0: Reserved; must be zero. Specifies the offset of a Bit 1: Don’t Fragment (DF) particular fragment relative to Bit 2: More Fragments (MF) the beginning of the original unfragmented IP datagram.

Protocol Time to Live Defines the protocol used in the Maximum time the datagram is allowed to data portion of the IP datagram, e.g remain in the internet system. TCP, UDP, etc. Zero means the datagram must be destroyed Header checksum 16-bit checksum field is used for error-checking. Destination Address Source Address specifies a custom IP address Specifies the IP address to be used to be used as destination. as source IP address in sent May be changed in transit by packets. a network address translator. Can be used illegitimately for Options spoofing Additional header fields that may follow the destination address. Value included in Total Length (TL) Not commonly used.

TYPE OF SERVICE (DIFFSERV) TOS allows the selection of a delivery service in terms of precedence, throughput, delay, reliability, and monetary cost.

REVIEW – IPV4 • The IP was first standardized in Sep 1981 as IPv4. • Each host attached to the IP based Internet had to be assigned a unique 32-bit address • The 32-bit IP addressing scheme involves a two level addressing hierarchy: Network Number/Prefix Host Number

IPv4 REVIEW – CLASSFUL ADDRESSING 1. In classful addressing, each IP address is divided into 5 classes 2. Class A 8 bits N/W id and 24 bits host id and so on B,C. 3. There was wastage of IP addresses by assigning blocks of addresses which fall along octet boundaries

TECHNIQUES USED TO REDUCE ADDRESS SHORTAGE IN IPV4 Three techniques are used to increase IPv4 address space, i.e 1. Subnetting 2. Classless Inter Domain Routing (CIDR) 3. Network Address Translation (NAT)

SUBNETTING 1. Subnetting uses three-level hierarchy, i.e network, subnet, and host. 2. The network-prefix is extended to accommodate classful network- prefix and the subnet-number 3. The extended-network-prefix is identified by the subnet mask Network-Prefix Subnet-Number Host-Number

ILLUSTRATION OF SUBNETTING 128.10.1.1 128.10.1.2 H1 H2 Sub-network 128.10.1.0 Internet G All traffic to 128.10.0.0 128.10.2.1 128.10.2.2 H3 H4 Net mask 255.255.0.0 Sub-network 128.10.2.0 Subnet mask 255.255.255.0

CLASSLESS INTER-DOMAIN ROUTING (CIDR) - 1 1. Eliminates traditional classful IP routing. 2. Supports the deployment of arbitrarily sized networks 3. Routing information is advertised with a bit mask/prefix length. 4. The mask/prefix length specifies the number of leftmost contiguous bits in the network portion of each routing table entry 5. Example: 192.168.0.0/21

CLASSLESS INTER-DOMAIN ROUTING (CIDR) - 2 • Extract the destination IP address. • Boolean AND the IP address with the subnet mask for each entry in the routing table. • The answer you get after ANDing is checked with the base address entry corresponding to the subnet mask entry with which the destination entry was Boolean ANDed. • If a match is obtained the packet is forwarded to the router with the corresponding base address

NETWORK ADDRESS TRANSLATION (NAT) • Each organization has single IP address • Within organization, each host (workstation) also has IP unique to the organization from reserved address ranges. Reserved ranges for NAT • 10.0.0.0 – 10.255.255.255 (16,777,216 hosts) • 172.16.0.0 – 172.31.255.255/12 (1,048,576 hosts) • 192.168.0.0 – 192.168.255.255/16 (65,536 hosts)

NETWORK ADRESS TRANSLATION (NAT) ILLUTRATION 10.0.0.4 C B Source Source NAT Router's Source NAT Router's 10.0.0.1 Computer's Computer's Assigned Computer IP Address IP Address Port Port Number A 10.0.0.1 400 24.2.249.4 1 B 10.0.0.2 50 24.2.249.4 2 C 10.0.0.3 3750 24.2.249.4 3 D 10.0.0.4 206 24.2.249.4 4

FEATURES OF IPV6 • Introduced in 1995 • Has larger Address Space • Uses aggregation-based address hierarchy – Efficient backbone routing • Uses efficient and Extensible IP datagram • Provides stateless Address Autoconfiguration • Has enhanced security (IPsec mandatory) • Supports for Mobility

128 BIT IPV6 ADDRESS 3FFE:085B:1F1F:0000:0000:0000:00A9:1234 8 groups of 16-bit hexadecimal numbers separated by “ : ”

IPV6 HEADER Version Traffic Class Flow Label • • 4-bit Version number of Internet 8-bit traffic class field. • 20-bit field • Protocol = 6. Sets different classes or different • Labels packets for which the source priorities of IPv6 packets requests special handling by the IPv6 routers. • For example, a source can request non- default quality of service or real-time service.

Next Header Hop Limit 8-bit selector. Identifies the 8-bit unsigned integer. Decremented by type of header that one by each node that forwards the Payload Length immediately follows the IPv6 packet. 16-bit unsigned integer header. The packet is discarded if Hop Limit is Length of the ret of the decremented to zero. packet that follows the IPv6 header, in octets. Source Address Destination Address 128 bits. The address of 128 bits. The address of the intended the initial sender of the recipient of the packet. packet.

COMPARISON OF IPv4 AND IPv6 HEADERS 15 16 31 0 1. Removed (6 ) vers hlen TOS total length • ID, flags, flag offset identification flags flag-offset • TOS, hlen TTL protocol header checksum 20 bytes • header checksum source address destination address 2. Changed (3) options and padding • total length => payload IPv4 • protocol => next header • TTL => hop limit vers traffic class flow-label 3. Added (2) payload length next header hop limit • Traffic class 40 • Flow label source address bytes 4. Expanded destination address • address 32 to 128 bits IPv6

MAJOR IMPROVEMENTS OF IPV6 HEADER 1. No option field: Replaced by extension header. Result in a fixed length, 40-byte IP header. 2. No header checksum: Result in fast processing. 3. No fragmentation at intermediate nodes: Result in fast IP forwarding.

EXTENSION HEADERS 1. Routing – Extended routing, like IPv4 loose list of routers to visit 2. Fragmentation – Fragmentation and reassembly 3. Authentication – Integrity and authentication, security 4. Encapsulation – Confidentiality 5. Hop-by-Hop Option – Special options that require hop-by-hop processing 6. Destination Options – Optional information to be examined by the destination node