IPv4/6

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)

Version

(4-bit)

IHL

(8-bit) Type of Service

(16-bit)

Total Length (in bytes)

(16-bit) Identification (3-bit)

Flags

(13-bit)

Fragment Offset

(8-bit)

TTL

(8-bit)

Protocol

(16-bit)

Header Checksum

(32-bit) Source Address

(32-bit) Destination Address

IP Options Padding

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

Net 2

Net 1

G1 MTU=620 G2

Net 3

Host A Host B

MTU=1500 MTU=1500

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. end of options list

1. 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

Hosts

Internet

Host1

Physical net

Gateway

Host2

Internet Protocol

• Routing in Internet

F G Network

10.0.0.0

Network

20.0.0.0 Network

30.0.0.0

Network

40.0.0.0 H

10.0.0.5

20.0.0.5

20.0.0.6

30.0.0.6

30.0.0.7

40.0.0.7

Routing Table Dest Next Hop 10.0.0.0 20.0.0.5 20.0.0.0 deliver direct 30.0.0.0 deliver direct 40.0.0.0 30.0.0.7

Internet Protocol –v6

• Why IPv6?– IPv4 address extension using CIDR– Real time support– Mobility support– Flexible and efficient


• 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


• 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


• 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


• 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


• Features of IPv6– Security

• IP level security• Authentication and privacy supported


• PDU of IPv6

Ver Traffic class Flow Label Payload Length Next Hdr Hop Limit

Source Address

Destination Address

0 4 12 16 24 31

40 b

ytes


• PDU of IPv6– Priority – Traffic class

• Route choosing• Interactive class – low delay• Real- time – path with less than 100ms delay


• PDU of IPv6– Flow Label

• Performance guarantees• Path establishment – id provided• id to be used in all packets


• PDU of IPv6– Next Header – 8 bits

• Id for the header following the IPv6 header • could identify the additional (optional)

extension headers if any


• PDU of IPv6– Next Header –

E x a m p l e

Hop-by-hopoptions header

Routingheader

TCPheader

Applicationdata

IPv6header

0 8 1 6 N e x t

H e a d e r H d r E x t L e n g t h

O p t i o n s

( v a r i a b l e l e n g t h )

I P v 6 H e a d e r

E x t e n s i o n H e a d e r

T r a n s p o r t - l e v e l P D U

4 0 o c t e t s 0 o r m o r e

E x t e n s i o n H e a d e r

H e a d e r f o r m a t


• 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)


• PDU of IPv6– Destination options– Fragmentation options– Authentication– Payload security– Hop- by hop options– Extended routing


• 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


• Addressing in IPv6– Address Representation – hex notation

• X: X: X: X: X: X: X: X

– Eg:FEDC:BA57:9874:C87B:98AC:7654:AB56:56AB

– 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


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


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


Routing to Mobile Hosts– Locate Host– Forward packet to host at current

location


Routing to Mobile Hosts– Locate Host

Foreign agent

Wireless Cell

Mobile Host

Foreign agent

Foreign LAN

WAN

MAN

Home LAN

MSC

Home agent



• 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



• 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



• 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


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



• 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



Packet is tunneled to foreign agent

Subsequent packets are tunneled to foreign agent

Sender is given foreign agent’ address

Packet is sent to Mobile Host’s Home address

sender

Mobile Host Foreign

agent

Foreign LAN

WAN

MAN

Home LAN

Wireless Cell Home

agent MSC

Integrated Service in Internet

Proposed Services– Guaranteed services

• For intolerant applications• Faithful playback – circuit emulation• Eg: critical control appln


Proposed Services– Predicted services

• Tolerant to Qos loss• Predict behavior and requirement from

recent past • Flow regulation required

– Best effort services• Elastic Applications


Proposed Services– Achieved through

• Controlled link sharing• Resource reservation• Admission control


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


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


Intserv support– Qos Specifications

• Intserv unaware hops• Available path bandwidth• Maximum path latency• Maximum Packet size• QoS service spec – token bucket based


Intserv support - Router features

Reference model for routers

Routing Agent

Reservation Setup Agent

Management Agent

Admission Control

[Traffic control database] [Routing database]

Classifier

Input driver

Internet forwarder Output driver

Packet scheduler


Intserv support - Router features– Admission Control– Classifier– Packet Scheduler– Reservation set up protocols


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


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


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


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


Intserv support - Router featuresEstimator

Measures actual outgoing traffic

Useful for the admission control

Policing

Classifying flowsDestination 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


– 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


– DS domain• Nodes operating within a common service

provisioning• Across domains – Service Level

Agreements


– Diffserv routers• Packet classifier

– Classfies– Forwards to appropriate traffic conditioner

• Traffic conditioning– Metering, shaping, policing, remarking based on

subsequent domains


– Summary• High popularity• Limited capability• Backward compatibility• Retro-fit?• Will IPng be the solution?• Real –time support?• Wireless support?• High bit rate applications?

IPv4/6

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