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Transcript
IPv4/6 Nirmala Shenoy Information Technology Department Rochester Institute of Technology Internet Protocol • Scope – – – – – – IPv4 Purpose / Limitations IPv4 features IPv6 features MobileIP Integrated services in IP Differentiated services in IP Internet Protocol • Purpose – To connect different types of local networks – To provide universal communications • Unique addresses – – – – To hide underlying NW technology/SW Robust system – failures and congestion Best effort delivery – data networks No support for timely – reliable delivery Internet Protocol • Purpose – No support for wireless networks – Data forwarding protocols, with network ids – No error control / flow control • ICMP – Connectionless datagram forwarding Internet Protocol • Layers – Comprises Layer 3 functions • Forwarding • Routing decisions • Uses routing algorithms Internet Protocol • PDU (4-bit) (4-bit) Version IHL (8-bit) Type of Service (16-bit) Identification (16-bit) Total Length (in bytes) (3-bit) Flags (8-bit) TTL (8-bit) Protocol (13-bit) Fragment Offset (16-bit) Header Checksum (32-bit) Source Address (32-bit) Destination Address Padding IP Options DATA Internet Protocol • PDU – VERS: version of the IP that created the datagram - current version is 4 – IHL : Internet header length in 32 bit words – due to IP options – TOTAL LENGTH: length of datagram in octets Internet Protocol • PDU – TYPE OF SERVICE – Precedence : (importance of the datagram) – type of transportation • • • • • D- low delay T – high throughput R- high reliability C- minimize cost All bits 0 -normal service – D, T, R and C help in route selection Internet Protocol • PDU – IDENTIFICATION: unique id for each datagram – FLAGS • D – datagram may be / may not be fragmented • M – 0 last fragment, 1 more to come – FRAGMMENT OFFSET Internet Protocol • Fragmentation and reassembly Host B Host A Net 3 Net 1 MTU=1500 MTU=1500 Net 2 G1 MTU=620 G2 Internet Protocol • PDU – Time to Live – PROTOCOL: • Specifies which high level protocol was used to create the message, - UDP, TCP – IP OPTIONS: • Not required in every datagram Internet Protocol • PDU – 8 possible options: 0. 1. end of options list No operation – used for aligning octets between options 2. Security and handling restrictions 3. Loose source routing 4. Record time-stamp along a route 5. Stream identifier (obsolete) 6. Strict source routing 7. Record route Internet Protocol • Routing in Internet Internet Host2 Hosts Physical net Gateway Host1 Internet Protocol • Routing in Internet 20.0.0.5 30.0.0.6 Network Network 10.0.0.0 Dest 10.0.0.0 20.0.0.0 30.0.0.0 40.0.0.0 F 10.0.0.5 Routing Table Next Hop 20.0.0.5 deliver direct deliver direct 30.0.0.7 20.0.0.0 G 40.0.0.7 30.0.0.0 20.0.0.6 Network Network H 30.0.0.7 40.0.0.0 Internet Protocol –v6 • Why IPv6? – IPv4 address extension using CIDR – Real time support – Mobility support – Flexible and efficient Internet Protocol –v6 • Aims of IPv6 – support huge amount of addresses – Reduce size of routing tables – Simplify protocol – router to process packets faster – Better security – authentication and privacy – Handle type of service – real-time data – Aid in multi-castings – Mobility of host – Protocol should be upgradable – Allow for old and new protocols to co-exist Internet Protocol –v6 • Features of IPv6 – addressing capabilities • Address size increased from 32 to 128 bits • More levels of address hierarchy • Support new ‘anycast address’ – Quality of Service Capability • Label packets for special handling during flow Internet Protocol –v6 • Features of IPv6 – Header Format Simplification • Number of fields in header is reduced • Header is of fixed length • Fragmentation not allowed at routers – Only source can fragment Internet Protocol –v6 • Features of IPv6 – Improved Support for options • Encoding of the options changed • Router does not examine options (except hop-by-hop options) • More efficient forwarding • Less stringent limits on the length • Greater flexibility for new options Internet Protocol –v6 • Features of IPv6 – Security • IP level security • Authentication and privacy supported Internet Protocol –v6 • PDU of IPv6 4 Ver Traffic class 12 Payload Length 16 Flow Label Next Hdr Source Address Destination Address 24 31 Hop Limit 40 bytes 0 Internet Protocol –v6 • PDU of IPv6 – Priority – Traffic class • Route choosing • Interactive class – low delay • Real- time – path with less than 100ms delay Internet Protocol –v6 • PDU of IPv6 – Flow Label • Performance guarantees • Path establishment – id provided • id to be used in all packets Internet Protocol –v6 • PDU of IPv6 – Next Header – 8 bits • Id for the header following the IPv6 header • could identify the additional (optional) extension headers if any Internet Protocol –v6 • PDU of IPv6 – Next Header – 0 or more 40 octets IPv6 Extension Extension Header Header Header Transport-level PDU Header format 0 16 8 Next Header Hdr Ext Length (variable length) Options Example IPv6 header Hop-by-hop options header Routing header TCP header Application data Internet Protocol –v6 • PDU of IPv6 – Next header • Exists in IPv6 header and the Extension Header • Used to identify the next header • Extension headers are not processed by any node along the packet’s route (except the hop-by-hop options header) Internet Protocol –v6 • PDU of IPv6 – Destination options – Fragmentation options – Authentication – Payload security – Hop- by hop options – Extended routing Internet Protocol –v6 • Addressing in IPv6 – Unicast – an id for a single interface – Anycast – An id for a set of interfaces – Multicast- an id for a set of interfaces Internet Protocol –v6 • Addressing in IPv6 – Address Representation – hex notation • X: X: X: X: X: X: X: X – Eg:FEDC:BA57:9874:C87B:98AC:7654:A B56:56AB – 1080:0:0:0:800:200C:6:417A ( leading zeros can be omitted) – 1080::800:200C:6:417A Mobile Internet Protocol • MobileIP – Use of portable computers on the Internet – Internet connection on migration – Issues • IP addressing depends on connection to a network Mobile Internet Protocol Ex: 160.80.40.20 – 160.80 – IP address class B network number 8272 – 40.20 is the host number 10260 – Routing tables carry network id – packets routed based on the network id – Machine moves to a different network • IP address changes Mobile Internet Protocol MobileIP Features - ietf – Mobile host must to use its home IP address anywhere – No Software changes to fixed hosts – No Changes to router software and tables – Most packets for mobile hosts should not make detours on the way – No overheads while Mobile host is at home Mobile Internet Protocol Routing to Mobile Hosts – Locate Host – Forward packet to host at current location Mobile Internet Protocol Routing to Mobile Hosts – Locate Host Wireless Cell Home agent Foreign agent MSC Mobile Host Home LAN Foreign agent Foreign LAN WAN MAN Mobile Internet Protocol Routing to Mobile Hosts – Locate Host • Identify areas – LAN, wireless networks • Each area has a Foreign Agent, Home Agent • Home Agent – Responsible for roaming host – Has the details of its current position – Will forward messages to roaming host Mobile Internet Protocol Routing to Mobile Hosts – Locate Host • Foreign Agent – – – – Responsible for foreign host in its territory Roaming Host reports to Foreign Agent Foreign Agent communicates to Home Agent Foreign Agent is the c/o for messages to Mobile Host – Broadcasts itself Mobile Internet Protocol Routing to Mobile Hosts – Locate Host • Foreign Agent – Roaming user registers – giving its home address – Current data link layer address – Security information – FA authenticates from HA – Gives its address as c/o for the mobile node Mobile Internet Protocol Routing to Mobile Hosts – Forwarding packets • Packets addressed to Mobile host intercepted by HA • HA encapsulates packet into a new IP packet with FA as destination and itself as Source and sends to FA – tunnelling • FA removes encapsulation and forwards on layer 2 to roaming mobile Mobile Internet Protocol Routing to Mobile Hosts – Forwarding packets • OR • HA gives FA address to sender of messages and forwards only the first message • Subsequent messages are tunneled to FA from Sender directly bypassing home network Mobile Internet Protocol Routing to Mobile Hosts – Forwarding packets Wireless Cell Packet is tunneled to foreign agent Home agent MSC Mobile Host Foreign LAN Home LAN Foreign agent WAN Subsequent packets are tunneled to foreign agent Packet is sent to Mobile Host’s Home address Sender is given foreign agent’ senderaddress MAN Integrated Service in Internet Proposed Services – Guaranteed services • For intolerant applications • Faithful playback – circuit emulation • Eg: critical control appln Integrated Service in Internet Proposed Services – Predicted services • Tolerant to Qos loss • Predict behavior and requirement from recent past • Flow regulation required – Best effort services • Elastic Applications Integrated Service in Internet Proposed Services – Achieved through • Controlled link sharing • Resource reservation • Admission control Integrated Service in Internet Internet proposed solutions – Stateful Solutions • • • • • Fair queuing under congestion Protection to well behaved traffic Better utilisation and quality assurance Integrated Services support - IntServ per flow quality guarantees Integrated Service in Internet Internet proposed solutions – Stateless Solutions • • • • • Packet dropping on congestion Identify packets into flow aggregates Service offered on aggregated traffic Scalable and Robust Differentiated Services - diffserv Integrated Service in Internet Intserv support – Qos Specifications • • • • • Intserv unaware hops Available path bandwidth Maximum path latency Maximum Packet size QoS service spec – token bucket based Integrated Service in Internet Intserv support - Router features Routing Agent Reservation Setup Agent Management Agent Admission Control [Routing database] [Traffic control database] Classifier Packet scheduler Input driver Internet forwarder Reference model for routers Output driver Integrated Service in Internet Intserv support - Router features – Admission Control – Classifier – Packet Scheduler – Reservation set up protocols Integrated Service in Internet Intserv support - Router features – Reservation set up protocols • Helps provide sat up facilities for specific flow demands • Message carries application requirements and goes though each and every router to the end node • If successful in providing resources – Call accepted • All routers enroute should handle Integrated Service in Internet Intserv support - Router features – Reservation set up protocols • Routing agents decide on the routes when such messages come by • Passed to Reservation set up agent • Communicates with the admission control • Who check if the call can be supported • If so – reservation agents makes bookings Integrated Service in Internet Intserv support - Router features – Classifier • Classifies incoming packets into proper queues for appropriate handling • Classes can be one flow, multiple flows • All packets belonging to one class are handled identically by the scheduler Integrated Service in Internet Intserv support - Router features – Packet scheduler • • • • • • Schedules based on each flow requirement Uses queues and timers Priority only Weighted fair queuing Packet dropping under congestion Sets congestion control mechanisms Integrated Service in Internet Intserv support - Router features Estimator Measures actual outgoing traffic Useful for the admission control Policing Classifying flows Destination address, source address, ports Flow-id – IPv6 Differentiated Service in Internet – Packet are classified into traffic aggregates – Service provided to traffic aggregates – Complexity only at boundary nodes • Classification • Conditioning • Shaping – Interior nodes – no states Differentiated Service in Internet – Interior nodes – no states • Per hop behavior (PHB) defined for each traffic class • TOS field used as DS field – diffserv field • Decouples service from applications • Decouples traffic conditioning and service provisioning from forwarding • Scalable • Robust Differentiated Service in Internet – DS domain • Nodes operating within a common service provisioning • Across domains – Service Level Agreements Differentiated Service in Internet – Diffserv routers • Packet classifier – Classfies – Forwards to appropriate traffic conditioner • Traffic conditioning – Metering, shaping, policing, remarking based on subsequent domains Differentiated Service in Internet – Summary • • • • • • • • High popularity Limited capability Backward compatibility Retro-fit? Will IPng be the solution? Real –time support? Wireless support? High bit rate applications?