TCP/IP Family of Protocols - Universität Bremen · What is TCP/IP? TCP/IP stands for Transmission...

TCP/IP Family of Protocols

www.comnets.uni-bremen.de IP - 1

IP: (Internet Protocol)

What is TCP/IP?

� A suite of protocols

� Rules for sending

and receiving data across networks

� Addressing

� Management


� Management

What is TCP/IP?

TCP/IP stands for Transmission Control Protocol/Internet Protocol.

TCP/IP is a collection of protocols, or rules, that govern the way data travels from one machine to


govern the way data travels from one machine to another across networks.

The Internet is based on TCP/IP.

What is TCP/IP?

TCP/IP has two major components: TCP and IP

IP:

� envelopes and addresses the data


� envelopes and addresses the data

� enables the network to read the envelope and forward the data to its destination (routing)

� defines how much data can fit in a single "envelope" (a packet)

What is IP?

The relationship between data, IP, and networks is often compared to the relationship between a letter, its addressed envelope, and the postal system.


What is TCP?

TCP:

� breaks data up into packets that the network can handle efficiently (e.g. letter with 10 pages, only one page per envelope)

� verifies that all the packets arrive at their


� verifies that all the packets arrive at their destination

� "reassembles" the data

TCP can be compared to reliable postal services e.g., registered mail (Einschreiben), where the sender receives an answer on delivery.

What is TCP/IP?

In Summary:

TCP/IP is a suite, or family, of protocols that govern the way data is transmitted across networks.


TCP/IP protocols work together to break the data into small pieces that can be efficiently handled by the network, communicate the destination of the data to the network, verify the receipt of the data on the other end of the transmission, and reconstruct the data in its original form.

TCP/IP Protocol Stack

� UDP

User Datagram Protocol is a rapid transmission protocol that uses IP packets to deliver data with no reliability features

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to deliver data with no reliability features like connections and ACKs. The strength of UDP is speed, not reliability. It is used e.g. in RTP, NFS or TFTP.

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TCP / UDP

IP

LAN

email www phone...

SMTP HTTP RTP...

TCP UDP...

IP + mcast

+ Qos +...

email www phone...

SMTP HTTP RTP...

TCP UDP...

IP

The Hour Glass


+ Qos +...

ethernet PPP...

CSMA async sonet...

copper fiber radio

ethernet PPP...

CSMA async sonet...

copper fiber radio

[Source: Steve Deering - Cisco: 51st IETF; London, England, Aug. 5-10, 2001]

Application Layer Protocols

� FTP File Transfer Protocol allows the transfer of copies of files between one node and another. FTP is not hardware-dependent so its services can function just about anywhere. Using this utility to copy data is typically referred to as "FTPing" a file. FTP usually uses TCP as a transport protocol.

� NFS Network Filing System was developed by Sun Microsystems Inc. It provides shared access to files in a very transparent and integrated way. NFS uses UDP as a transport protocol.


very transparent and integrated way. NFS uses UDP as a transport protocol.

� TELNET Remote Terminal Emulation allows users to communicate with diverse hosts. The TELNET application provides terminal-type access from one network computer to another.

� SMTP Simple Mail Transfer Protocol is the middle-man that uses TCP to move data around from one internetwork host to another. Applications run on both hosts using SMTP.

TCP/IP Protocol Stack


Other Protocols

� ICMP Internet Control Message Protocol offers flow control and error-detection to the unreliable delivery method of IP. It provides a facility for routers and gateways on the network to communicate with a source if there is a problem. It also provides a mechanism for determining if a destination cannot be reached. (IP layer)

� ARP & RARP Address Resolution Protocol & Reverse Address Resolution Protocol are special protocols to allow TCP/IP to interact in environments such as Ethernet. ARP


Address Resolution Protocol are special protocols to allow TCP/IP to interact in environments such as Ethernet. ARP maps TCP/IP addresses to Ethernet Data Link layer addresses. RARP maps the Ethernet Data Link layer address to the TCP/IP address. (IP layer)

IP Frame (Version 4: IPv4)

VersionInternet Header Length

Service Type Total Length

ID Flags Fragment Offset

Time to Live Protocol Header Checksum

32 bits


Source Address

Destination Address

Options Padding

DATA

IP-PDU� Version (4 bit): IP-Version, 4� Internet Header Length (4 bit):

total header length in multiples of 32 bit, e.g. 5 means the header consists of 5 x 32 bit = 160 bit or 20 byte (min. length)

� Type of Service (8 bit): can be used to set priorities for packets, see RFC 3168 (Sept. 2001): Bits 0-5: DSCP (Differentiated Services Code Point), Bits 6-7: ECN (Explicit Congestion Notification / IP Flow Control)


Bits 6-7: ECN (Explicit Congestion Notification / IP Flow Control)� Total Length (16 bit): total length of packet

incl. header in byte (max. length: 65536 byte (64 kB)).� ID (16 bit): ID and the following 2 fields (Flags and Fragment

Offset) control the reassembly of fragmented IP-Packets. Unique ID of a datagram. This together with the 'Source Address‚ is used to identify fragments for reassembly.

� Flags (3 bit): � Bit 0: reserved, must be 0� Bit 1: 0/1 may/may not be fragmented � Bit 2: 0/1 last fragment/more fragments to follow

IP-PDU

� Fragment Offset (13 bit): a number specifying the position of the fragment, offset is given in steps of 64 bit/ 8 byte (first fragment has value 0)

� Time to Live (8 bit): specifies the time to live of a packet. A value of zero means the packet will be deleted. Every router on the path decrements the counter by one. This is used to avoid packets circulating in the network. The standard of 1981 defined it as the time in seconds that a packet spent at a station with a min. of one. Today it is used as a hop-count.


station with a min. of one. Today it is used as a hop-count.

� Protocol (8 bit): specifies the contained protocol, e.g. for a TCP packet: 0x06, for a UDP packet: 0x11 (defined by IANA).

� Header Checksum (16 bit): checks the header

� Source Address (32 bit): IP Address

� Destination Address (32 bit): IP Address

� Options

� Padding (to achieve multiples of 32 bit)

� DATA

What is an IP Address?

� A way to identify machines on the Internet (more precisely: network interfaces)

� A number

� Unique

� Global


� Global

� Standardized


If you want to connect to another computer, transfer files to or from another computer, or send an e-mail message, you first need to know where the other computer is - you need the computer's "address."

An IP (Internet Protocol) address is an identifier for


An IP (Internet Protocol) address is an identifier for a particular machine on a particular network; it is part of a scheme to identify computers on the Internet.

IP addresses are also referred to as IP numbers or Internet addresses.


An IP address consists of four sections separated by periods.

Each section contains a number ranging from 0 to 255.


ranging from 0 to 255.

Example = 198.41.0.52

How many bits does an IP address have?


These four sections represent both the machine itself, or host, and the network that the host is on.

IP address blocks with a fixed network portion of the IP addresses are allocated to Internet Service Providers (ISPs) by the regional Internet registries


the IP addresses are allocated to Internet Service Providers (ISPs) by the regional Internet registries (RIRs), who receive the address blocks from the Internet Assigned Numbers Authority (IANA).

ISPs then assign the host portion of the IP address to the machines on the networks that they operate.


Which sections of the IP address represent the network and which sections represent the machine will depend on what "class" of IP address is assigned to a network.

There are 5 classes of IP addresses:


There are 5 classes of IP addresses: Class A, Class B, Class C, Class D, and Class F.

Classes correspond either to the size of the network (the number of hosts that the network can support) or are reserved for specific purposes, such as multicasting and experimentation.


The diagram below compares Class A, Class B and Class C IP addresses. The blue numbers represent the network and the red numbers represent hosts on the network. Therefore, a Class A network can support many more hosts than a Class C network.



� IP addresses are unique.

� No two machines can have the same IP number.

� IP addresses are global and standardized.

� All machines connected to the Internet agree to


� All machines connected to the Internet agree to use the same scheme for establishing an address.

Classes IP Address Formats


Class A network examplesAddress Block Registry - Purpose Date

--------------- --------------------------------------- ------

000/8 IANA – Reserved (Self-Identification) Sep 81

001/8 Allocated to APNIC Jan 10

002/8 Allocated to RIPE NCC Sep 09

003/8 General Electric Company May 94

004/8 Level 3 Communications, Inc. Dec 92

005/8 Allocated to RIPE NCC Nov 10

006/8 Army Information Systems Center Feb 94

007/8 Administered by ARIN (Allocated to DoD) Apr 95

008/8 Level 3 Communications, Inc. Dec 92

009/8 IBM Aug 92


009/8 IBM Aug 92

010/8 IANA - Private Use Jun 95

011/8 DoD Intel Information Systems May 93

012/8 AT&T Bell Laboratories Jun 95

013/8 Xerox Corporation Sep 91

014/8 IANA - Public Data Network Jun 91 – Feb 08

Allocated to APNIC Apr 10

015/8 Hewlett-Packard Company Jul 94

016/8 Digital Equipment Corporation Nov 94

017/8 Apple Computer Inc. Jul 92

018/8 MIT Jan 94

019/8 Ford Motor Company May 95

020/8 Computer Sciences Corporation Oct 94

...

IP Sub-Networking

� Network mask extensionThe way sub-networking operates is to borrow one or more of the available host bits and then make interfaces locally interpret these borrowed bits as part of the network bits. So to divide a network number into two sub-networks, we would borrow one host bit by setting the appropriate bit in the network mask of the first (normal) host bit to '1'.

Subnet mask is usually specified either by four sections


� Subnet mask is usually specified either by four sections separated by dots, e.g. 255.255.0.0, or by a slash followed by the number of ‘1’-bits in the mask, e.g. /16

� IP address calculations: e.g.: http://library.mobrien.com/net.shtml

� Is 255.247.255.240 a valid subnet mask?

Mobile IPMobility

Management

Subnet 1

Internetwork

HomeAgent

Subnet 2

ForeignAgent

Stationary Node

OriginalPackets

EncapsulatedPackets

Mobile NodeMobile Node

Mobile Node

AdhocNetwork


Mobile Node

BS BS

Mobile Node

Mobile NodeMobile Node

Mobile Node

Mobile IP

� MIP enables roaming

between subnets

� Introduces to IP

Internet

FA

CNEthernet


� Introduces to IP� Home Agent

� Foreign Agent

� Mobile Node

� Integration of heterogeneous network

= problem of routing

� Independent of higher and lower layers

802.11

GSM

RAS

FA

HA

Movement

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 ("IPv4").

� Today's Internet mostly uses IPv4, which was defined in 1981 (RFC 791). IPv4 has been remarkably resilient in spite of its age, but it is beginning to have problems. Most importantly, there is a growing shortage of IPv4 addresses, which are needed by all new machines added to the Internet.


addresses, which are needed by all new machines added to the Internet.

� IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network auto-configuration.

� IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period.

Problems of IPv4

� Some deficiencies unsuitable for fast-growing Internet:

� Limited and inefficient use of address space� two-level address structure (netid and hostid) categorized into 5 classes A, B, C, D and E ((240-248) reserved for future use), F (extension)

cannot accommodate new Internet applications,


� cannot accommodate new Internet applications, such as real-time audio and video transmission� maximum delay and reservation of resources required

� need more complex addressing and routing capabilities

� must accommodate encryption and authentication of data

IPv4 Address Exhaustion

� IANA allocated the last five /8 blocks to the regional registries (AfriNIC, APNIC, ARIN, LACNIC, RIPE NCC) on February 3rd, 2011

� APNIC first regional registry to reach its last /8 block on April 15th, 2011, entering „endgame“ procedures� Each APNIC member can only get one /22 (i.e. 1024 addresses) out of the last /8 block

� RIPE NCC expected to be next regional registry to reach

www.comnets.uni-bremen.de

� RIPE NCC expected to be next regional registry to reachits last /8 block, likely in 2012

� Other regional registries expected to follow in 2013/2014

IP - 30

A new class F is proposed for IPv4 with its six high order bits set to 111110. The new class F address would be placed in the same locations that are used for source and destination IP address in the IP header, but would specify that part of the addressing information is in the options part of the IP header. This is illustrated in the figure below:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Ver. | IHL | TOS | Total Length |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Identification |Flags| Fragment Offset |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|1|1|1|1|1|0| Offset| Reserved | Source IP address part 1 |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Can a new class F solve the problem?


+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

|1|1|1|1|1|0| Offset| Reserved | Destination IP address part 1 |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

: Options :

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

: SADDR Code |Len adr. part 2| Source IP address part 2 :

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

: DADDR Code |Len adr. part 2| Destination IP address part 2 :

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

: Data :

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Can NAT solve the problem?

� NAT : Network Address Translation� Assign private addresses to the internal systems

� Router translates the addresses

Private

Address Space

192.0.0.1203.178.1.1


Global

IP address Space

Address SpaceNAT

Private

Address SpaceNAT

192.0.0.2

192.0.0.1

192.0.0.2133.4.1.5

How does NAT work?

� NAT is often built into routers. It receives each packet from the internal private network and modifies the IP header to match the global IP address of the router, before it is transmitted out into the Internet.

� The router stores the internal IP address, destination IP address and port number in a


destination IP address and port number in a routing table so when a request is returned on the same port, the NAT can match the internal IP address that originated the request, and then modify the IP header to match that of the internal address.

One solution – NAT

�NAT (Network Address Translator)� popular on Dial-ups and VPN networks

� saves IPv4 addresses

� loss of the end-to-end model

� asymmetric identifier/communication model


� asymmetric identifier/communication model

Why not NAT ?

�NAT breaks “end-to-end communication”

� Routers monitor the communication

� Routers change the data

�NAT breaks “Bi-directional communication”

� Hosts with a global address cannot


� Hosts with a global address cannot initiate the communication to the hosts with private addresses.

�Advantages of NAT?

IPv6 Datagram Format� IPv6 datagram format:

mandatory base header followed by payload� 40 bytes, but the header contains less information fields

� payload� optional extension headers

� data from upper layer


IPv4 �� IPv6 header

Ver4Ver4Ver4Ver4 IHLIHLIHLIHL Type of serviceType of serviceType of serviceType of service

Fragmentation OffsetFragmentation OffsetFragmentation OffsetFragmentation Offset

Total LengthTotal LengthTotal LengthTotal Length

IdentificationIdentificationIdentificationIdentification FlagsFlagsFlagsFlags

Time To LiveTime To LiveTime To LiveTime To Live ProtocolProtocolProtocolProtocol Header ChecksumHeader ChecksumHeader ChecksumHeader Checksum

Source AddressSource AddressSource AddressSource Address


Destination AddressDestination AddressDestination AddressDestination Address

OptionsOptionsOptionsOptions

Italics:Italics:Italics:Italics: removed in IPv6removed in IPv6removed in IPv6removed in IPv6

IPv6 header

2128-1 = 340 282 366 920 938 463 463 374 607 431 768 211 455

> 340 * 1036


IPv6� Version - This field is the only field that kept the same meaning

from IPv4 to IPv6. The 4-bit version field contains the number 6. It is the same size as the IPv4 version field, which contains the number 4. However, this field is usually not used to distinguish between IPv4 and IPv6 packets. The protocol type field present in the layer 2 envelope is used for that.

� Priority - The 4-bit priority field allows an application to specify the type of traffic. This allows the network to take advantage of the various queuing and congestion control


advantage of the various queuing and congestion controlmechanisms that may exist within it.

� Flow Label - The 24-bit Flow Label field is used to label a set of packets that belong to the same flow. Similar to the Service Type (Diffserv) field in IPv4, this allows network devices to prioritize, police or shape traffic flows appropriately.

� Payload Length - This 16-bit field is similar to the IPv4 Total Length Field, except that with IPv6 the Payload Length field is the length of the data carried after the header, whereas with IPv4 the Total Length Field included the header.

IPv6� Next Header - This 8-bit field reflects the new organization of

IP packets with IPv6. In IPv4, the IP header is always immediately followed by the transport protocol data. (E.g. UDP or TCP) and defined by the IPv4 Protocol Type field. With IPv6 we can have the same structure and set the next protocol type to be UDP (16) or TCP (6), or we can interleave Extension Headers between the IP and TCP/UDP payload. The next header type will then be set to the type of the first Extension Header.

� Hop Limit - This 8-bit field defines by number a count of the


� Hop Limit - This 8-bit field defines by number a count of the maximum hops that a packet can remain in the network before it is destroyed. With the IPv4 TTL field this was expressed in seconds and was typically a theoretical value and not very easy to estimate and was then practically used as a counter as well.

� Source Address - This 128-bit field contains the Source IPv6 address of the packet.

� Destination Address - This 128-bit field contains the Destination IPv6 address of the packet.

IPv6

� Extension Headers –

The current IPv6 specification defines 6 extension headers� Hop-by-Hop Options Header

� Routing Header

� Fragment Header

� Authentication Header


� Authentication Header

� Encrypted Security Payload

� Destination Options Header

Transition Mechanisms

� (Header Translation)

� RFC 2893 (Transition Toolbox)

� Dual Stack (Dual IP layer) IPv4 & IPv6

� Configured/Automatic


� Configured/AutomaticTunneling of IPv6 over IPv4

� IPv4-compatible IPv6 addresses

(embedded IPv4 addresses)

IPv4 to IPv6 Transitiondual stack router

IPv6 Workstation

IPv6 IPv6


IPv4

dual stack routerIPv6 Server

IPv6 IPv6

Tunneling

�IPv6-over-IPv4 tunneling� IPv6 packets are encapsulated within IPv4

� Overhead?

�Configured Tunneling � Tunnel endpoint address is determined by configuration information on the encapsulating


configuration information on the encapsulating node (point-to-point tunnels)

�Automatic Tunneling � IPv4-compatible IPv6 addresses

(embedded IPv4 addresses)

�Tunnel endpoint address is determined from the embedded IPv4 destination address

IPv4 to IPv6 implications

�DNS: Domain Naming Service� New record types to differentiate type of address

�Tunnels: � Router-to-Router� Host-to-Router� Host-to-Host


� Host-to-Host� Router-to-Host

�Fragmentation� IPv4 layer fragmentation should be avoided� IPv4 path MTU Discovery Protocol

IPv6 packet encapsulation in IPv4

IPv6 Header

Transport Layer Header

Data

IPv6 Transport IPv4


IPv6 Header

Transport Layer Header

DataIPv4 Header

Industry Activities

� IPv6 Forum� Product Presentations

� Product Demonstrations

� IETF Working groups� 6bone

� 6REN

� 6TAP


� 6TAP

� MWIF (Mobile Wireless Internet Forum)

� 3GPP (3rd Generation Partnership Project, UMTS)

� Interoperability Testing � Annually at Connectathon

� Annually at University of New Hampshire

� IPv6 testing at iLabs at Networld+Interop

� IPv6 Forum

TCP/IP Family of Protocols - Universität Bremen · What is TCP/IP? TCP/IP stands for Transmission...

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