analysis of the osi model vs. tcp/ip model and use- case of ansi c12.22-2008 over ip implementation...

Analysis of the OSI Analysis of the OSI Model Model vs. vs. TCP/IP Model TCP/IP Model and use-case of ANSI and use-case of ANSI C12.22-2008 over IP C12.22-2008 over IP implementationimplementation

Original Source: [email protected]

ANSI C12.22-2008 over IP comments

written by

Avygdor Moise, Ph.D. – Future DOS R&D Inc.Richard D. Tucker P.Eng. – Tucker Engineering Associates

May 20, 2009Some content is Copyright 2008-2009 Future DOS R&D Inc., All Rights Reserved. Reprinted with permission from Future DOS R&D Inc.

IntroductionIntroduction

This presentation would discuss some This presentation would discuss some comparison and contrast between the 2 comparison and contrast between the 2 main reference models which uses the main reference models which uses the concept of protocol layering.concept of protocol layering. Open System Interconnection Model (OSI)Open System Interconnection Model (OSI) Transport Control Protocol /Internet Protocol Transport Control Protocol /Internet Protocol

(TCP/IP)(TCP/IP) And it explains how C12.22-2008 fits on And it explains how C12.22-2008 fits on

top of OSI transport layer (4) or the top of OSI transport layer (4) or the TCP/IP transport layerTCP/IP transport layer

The “stacks”The “stacks”

The topics that we will be The topics that we will be discussing would be based on the discussing would be based on the diagram belowdiagram below

OSI TCP / IP

Application (Layer7)

ApplicationPresentation (Layer6)

Session (Layer 5)

Transport (Layer 4) Transport

Network (Layer 3) Internet

Data Link (Layer 2)Subnet

Physical (Layer 1)

ANSI C12.22-2008 Over IP ANSI C12.22-2008 Over IP StackStack

The ANSI C12.22-2008 Standard is based on the OSI reduced-stack The ANSI C12.22-2008 Standard is based on the OSI reduced-stack reference modelreference model

The ANSI C12.22-2008 does not define OSI Layers 4-1, nor does it The ANSI C12.22-2008 does not define OSI Layers 4-1, nor does it define the TCP/IP transport, internet and subnet layersdefine the TCP/IP transport, internet and subnet layers

OSI / C12.22– Reduced Stack C12.22 over TCP / IP

Application (Layer7)C12.22-2008

Tables (data)+EPSEM (service)ACSE (Association)

Null Transport (Layer 4) Transport

Null Network (Layer 3) Internet

Null Data Link (Layer 2)Subnet

Null Physical (Layer 1)

ApplicationC12.22-2008


C12.22 Communication C12.22 Communication Modules (a side note)Modules (a side note)

The ANSI C12.22-2008 Standard also provide a full stack definition for The ANSI C12.22-2008 Standard also provide a full stack definition for a physical interface to an ANSI C12.22 Communication Modulea physical interface to an ANSI C12.22 Communication Module

The ANSI C12.22-2008 Communication Module is a variation on the The ANSI C12.22-2008 Communication Module is a variation on the implementation, where there is a need to separate physically the implementation, where there is a need to separate physically the metrological element of a C12.19 Device into two parts: The C12.22 metrological element of a C12.19 Device into two parts: The C12.22 Device (provides metrology) and the C12.22 Communication Module Device (provides metrology) and the C12.22 Communication Module (provides an interface to any network)(provides an interface to any network)

C12.22 Device Side Native LAN Side

Transport (Layer 4)

Null Network (Layer 3)

Data Link (Layer 2)

Physical (Layer 1)

Optional Application (Layer7)C12.22-2008


Undefined Application (Layer7)

Undefined Presentation (Layer6)

Undefined Session (Layer 5)

Undefined Transport (Layer 4)

Undefined Network (Layer 3)

Undefined Data Link (Layer 2)

Undefined Physical (Layer 1)

The Confusion in the The Confusion in the IndustryIndustry

ANSI C12.22-2008 defines three ISO reduced stacksANSI C12.22-2008 defines three ISO reduced stacks1.1. Common C12.22-2008 Application Services (Layers 7-5) that can Common C12.22-2008 Application Services (Layers 7-5) that can

interface to any transport layer (any network e.g. TCP/IP or UDP/IP)interface to any transport layer (any network e.g. TCP/IP or UDP/IP)2.2. A C12.18-2006 compatible stack (Layers 7-1) than can interface to a A C12.18-2006 compatible stack (Layers 7-1) than can interface to a

local ANSI Type 2 optical portlocal ANSI Type 2 optical port3.3. A C12.22-Device to C12.22 Communication Module (Layers 7-1) that A C12.22-Device to C12.22 Communication Module (Layers 7-1) that

is used strictly when there is a requirement to physically separate is used strictly when there is a requirement to physically separate the communications from metrology: The C12.22 Device (metrology the communications from metrology: The C12.22 Device (metrology unit) and the C12.22 Communication Module (communication unit)unit) and the C12.22 Communication Module (communication unit)

The role of the C12.22 Communication Module is to act as a gateway to The role of the C12.22 Communication Module is to act as a gateway to the native LAN that it servicesthe native LAN that it services

The interface specification of the LAN side The interface specification of the LAN side is notis not defined by the ANSI defined by the ANSI C12.22-2008 StandardC12.22-2008 Standard

Thus, the vendor may supply C12.22 Communication Modules to Thus, the vendor may supply C12.22 Communication Modules to interface his system to the metrology side of any ANSI C12.22 meter to interface his system to the metrology side of any ANSI C12.22 meter to accomplish interoperabilityaccomplish interoperability

The industry may be confused by the special C12.22 Communication The industry may be confused by the special C12.22 Communication Module specification option (Layers 7-1) with the broader general Module specification option (Layers 7-1) with the broader general purpose ANSI C12.22 Network Application that uses only layers 7-5, purpose ANSI C12.22 Network Application that uses only layers 7-5, which is the relevant choice for ANSI C12.22 over IPwhich is the relevant choice for ANSI C12.22 over IP

The ANSI C12.22 Reduced The ANSI C12.22 Reduced StacksStacks

Application LayerANSI C12.19 Tables (data) + EPSEM (services) + ACSE (wrapper)

Segmentation Sub-layer (scatter/gather)

Application LayerANSI C12.19 Tables (data) + EPSEM (services) + ACSE (wrapper)

Segmentation Sub-layer (scatter/gather)

7-5

C12.22Node

Transport LayerTransport Layer

Data-link LayerData-link Layer

Physical LayerPoint-to-pointPhysical LayerPoint-to-point

4

2

1

C12.22 Device



Physical LayerPoint-to-point

Physical LayerPoint-to-point

2

1

External C12.22 Comm. Module



Physical LayerANSI 2 OpticalPhysical LayerANSI 2 Optical

4

2

1

C12.22 Local Port

1 2 3 - 5 6

Any network (e.g. TCP/IP transport

layer)

Any network (e.g. TCP/IP transport

layer)

Any network (e.g. TCP/IP

transport layer)

Any network (e.g. TCP/IP

transport layer)

1 2 3 - 5 6

4

Copyright 2008 Future DOS R&D Inc., All Rights Reserved.

C12.22 Node

C12.22 Comm. Module Interface

The Upper LayersThe Upper LayersOSI TCP / IP

Application (Layer7)

ApplicationPresentation (Layer6)

Session (Layer 5)

The Session (Layer 5)The Session (Layer 5)

The Session layer The Session layer permits two permits two parties to hold ongoing parties to hold ongoing communications called a session communications called a session across a networkacross a network..

Not found in TCP/IP modelNot found in TCP/IP model In TCP/IP,its In TCP/IP,its characteristicscharacteristics are are

provided by the TCP protocol. provided by the TCP protocol.

(Transport Layer)(Transport Layer)

The Presentation (Layer 6)The Presentation (Layer 6)

The Presentation Layer handles data The Presentation Layer handles data format information for networked format information for networked communications. This is done by communications. This is done by converting data into a generic format converting data into a generic format that could be understood by both sides.that could be understood by both sides.

Not found in TCP/IP modelNot found in TCP/IP model In TCP/IP, this function is provided by In TCP/IP, this function is provided by

the Application Layer. the Application Layer. e.g. e.g. External Data Representation Standard (XDR)External Data Representation Standard (XDR)

Multipurpose Internet Mail ExtensionsMultipurpose Internet Mail Extensions (MIME) (MIME)

The Application (Layer 7)The Application (Layer 7)The Application Layer is the top layer of the reference The Application Layer is the top layer of the reference model. It provides a set of interfaces for applications to model. It provides a set of interfaces for applications to obtain access to networked services as well as access to obtain access to networked services as well as access to the kinds of network services that support applications the kinds of network services that support applications directly.directly.

OSIOSI - FTAM,VT,MHS,DS,CMIP,ANSI C12.22- FTAM,VT,MHS,DS,CMIP,ANSI C12.22TCP/IPTCP/IP - FTP,SMTP,TELNET,DNS,SNMP,- FTP,SMTP,TELNET,DNS,SNMP,

C1222-ACSE C1222-ACSE

Although the notion of an application process is common Although the notion of an application process is common to both, their approaches to constructing application to both, their approaches to constructing application entities is different.entities is different.

Approaches use in constructing Approaches use in constructing application entitiesapplication entities

The diagram below provides an overall view on The diagram below provides an overall view on the methods use by both the the methods use by both the OSIOSI and and TCP/IP TCP/IP model.model.

ISO ApproachISO Approach Sometime called Sometime called Horizontal ApproachHorizontal Approach OSI asserts that distributed applications OSI asserts that distributed applications

operate over a strict hierarchy of layers and operate over a strict hierarchy of layers and are constructed from a common tool kit of are constructed from a common tool kit of standardized application service elements.standardized application service elements.

In OSI, each distributed application service In OSI, each distributed application service selects functions from a large common selects functions from a large common “toolbox” of application service element “toolbox” of application service element (ASEs) and complements these with (ASEs) and complements these with application service elements (e.g. ACSE) that application service elements (e.g. ACSE) that perform functions specific to given end-user perform functions specific to given end-user service (e.g. EPSEM).service (e.g. EPSEM).

TCP/IP ApproachTCP/IP Approach

Sometime called Sometime called Vertical ApproachVertical Approach In TCP/IP, each application entity is In TCP/IP, each application entity is

composed of whatever set of function it composed of whatever set of function it needs beyond end to end transport to needs beyond end to end transport to support a distributed communications support a distributed communications service.service.

Most of these application processes builds Most of these application processes builds on what it needs and assumes only that an on what it needs and assumes only that an underlying transport mechanism (datagram underlying transport mechanism (datagram or connection) will be provided. or connection) will be provided.


The functionality of the transport layer is to The functionality of the transport layer is to provide “transparent transfer of data from a provide “transparent transfer of data from a source end open system to a destination source end open system to a destination end open system” (ISO / IEC 7498: 1994).end open system” (ISO / IEC 7498: 1994).

ANSI C12.22 does not provide Transport ANSI C12.22 does not provide Transport Layer for non-comm-module Layer for non-comm-module implementationsimplementations

TCP/IP provides for TransportTCP/IP provides for Transport

OSI TCP / IP

Transport (Layer 4) Transport (TCP/UDP)


Transport is responsible for creating and Transport is responsible for creating and maintaining the basic end-to-end connection maintaining the basic end-to-end connection between communicating open systems, between communicating open systems, ensuring that the bits delivered to the ensuring that the bits delivered to the receiver are the same as the bits transmitted receiver are the same as the bits transmitted by the sender; in the same order and without by the sender; in the same order and without modification, loss or duplicationmodification, loss or duplication


OSI Transport LayerOSI Transport Layer It takes the information to be sent and It takes the information to be sent and

breaks it into individual packets that are sent breaks it into individual packets that are sent and reassembled into a complete message and reassembled into a complete message by the Transport Layer at the receiving nodeby the Transport Layer at the receiving node

Also provide a signaling service for the Also provide a signaling service for the remote node so that the sending node is remote node so that the sending node is notified when its data is received notified when its data is received successfully by the receiving nodesuccessfully by the receiving node


OSI Transport LayerOSI Transport Layer

Transport Layer protocols include the Transport Layer protocols include the capability to acknowledge the receipt of capability to acknowledge the receipt of a packet; if no acknowledgement is a packet; if no acknowledgement is received, the Transport Layer protocol received, the Transport Layer protocol can retransmit the packet or time-out can retransmit the packet or time-out the connection and signal an errorthe connection and signal an error


OSI Transport LayerOSI Transport Layer Transport protocols can also mark packets Transport protocols can also mark packets

with sequencing information so that the with sequencing information so that the destination system can properly order the destination system can properly order the packets if they’re received out-of-sequence packets if they’re received out-of-sequence

In addition, Transport protocols provide In addition, Transport protocols provide facilities for insuring the integrity of packets facilities for insuring the integrity of packets and requesting retransmission should the and requesting retransmission should the packet become garbled when routedpacket become garbled when routed

ANSI C12.22 does not provide Transport ANSI C12.22 does not provide Transport Layer for non-comm-module implementationsLayer for non-comm-module implementations

OSI Transport LayerOSI Transport Layer Transport protocols provide the capability for Transport protocols provide the capability for

multiple application processes to access the multiple application processes to access the network by using individual local addresses to network by using individual local addresses to determine the destination process for each data determine the destination process for each data streamstream

ANSI C12.22 does not provide Transport Layer ANSI C12.22 does not provide Transport Layer for non-comm-module implementationsfor non-comm-module implementations

ANSI C12.22 does not provide network addressesANSI C12.22 does not provide network addresses ANSI C12.22 (Application layer) provides ANSI C12.22 (Application layer) provides

Application Titles (ApTitles) and Application Application Titles (ApTitles) and Application Invocation IDs that may be associated with the Invocation IDs that may be associated with the process of each data streamprocess of each data stream

TCP/IP Transport LayerTCP/IP Transport Layer Defines two standard transport protocols: TCP Defines two standard transport protocols: TCP

and UDPand UDP TCP implements a reliable data-stream protocolTCP implements a reliable data-stream protocol

connection orientedconnection oriented UDP implements an unreliable data-stream UDP implements an unreliable data-stream

connectionlessconnectionless ANSI C12.22 provides hints to network manager ANSI C12.22 provides hints to network manager

about its preference for connection-mode or about its preference for connection-mode or connectionless-mode operations via the connectionless-mode operations via the application layer registration serviceapplication layer registration service

The registration service can be delivered The registration service can be delivered interchangeably via either TCP or UDP on port interchangeably via either TCP or UDP on port 11531153

TCP/IP Transport LayerTCP/IP Transport Layer

TCP provides reliable data TCP provides reliable data transmissiontransmission

UDP is useful in many applicationsUDP is useful in many applications e.g. Where data needs to be e.g. Where data needs to be

broadcasted or multicastedbroadcasted or multicasted Primary difference is that UDP does Primary difference is that UDP does

not necessarily provide reliable not necessarily provide reliable data transmissiondata transmission

TCP/IP Transport LayerTCP/IP Transport Layer Many programs will use a separate TCP Many programs will use a separate TCP

connection as well as a UDP connectionconnection as well as a UDP connection ANSI C12.22 uses TCP/IP or UDP/IP or bothANSI C12.22 uses TCP/IP or UDP/IP or both

TCP/IP Transport LayerTCP/IP Transport Layer TCP is responsible for data recoveryTCP is responsible for data recovery

by providing a sequence number with each by providing a sequence number with each packet that it sendspacket that it sends

TCP requires ACK (acknowledgement) to TCP requires ACK (acknowledgement) to ensure correct data is receivedensure correct data is received

Packet can be retransmitted if error Packet can be retransmitted if error detecteddetected


These are internal features of TCP/IP and are These are internal features of TCP/IP and are not visible to the ANSI C12.22 Applicationnot visible to the ANSI C12.22 Application

TCP/IP Transport LayerTCP/IP Transport Layer Use of ACKUse of ACK This is an internal feature of TCP/IP and not visible to ANSI C12.22This is an internal feature of TCP/IP and not visible to ANSI C12.22


Flow control with Flow control with WindowWindow via specifying an acceptable range of via specifying an acceptable range of

sequence numbers sequence numbers This is an internal feature of TCP/IP This is an internal feature of TCP/IP

and not visible to ANSI C12.22and not visible to ANSI C12.22


TCP and UDP introduce the TCP and UDP introduce the concept of concept of portsports

Common ports and the services Common ports and the services that run on them: that run on them:

FTP FTP 21 and 20 21 and 20 telnet telnet 23 23 SMTP SMTP 25 25 http http 80 80 POP3 POP3 110 110 C1222-ACSEC1222-ACSE 11531153

TCP/IP Transport LayerTCP/IP Transport Layer By specifying ports and including port By specifying ports and including port

numbers with TCP/UDP data, numbers with TCP/UDP data, multiplexingmultiplexing is achieved is achieved

Multiplexing allows multiple network Multiplexing allows multiple network connections to take place connections to take place simultaneouslysimultaneously

The port numbers, along with the The port numbers, along with the source and destination addresses for source and destination addresses for the data, determine a the data, determine a socketsocket

ANSI C12.22 has an assigned TCP and ANSI C12.22 has an assigned TCP and UDP port number 1153UDP port number 1153

Services or applications using Services or applications using port: 1153port: 1153

Protocol: Protocol: TCP & UDP TCP & UDP IANA* status:IANA* status: Official Official Range: Range: Registered Registered Traffic: Traffic: inbound, outbound, both inbound, outbound, both Notification: Notification: N/A N/A Related Ports:Related Ports: N/AN/A

*IANA — Internet Assigned Numbers *IANA — Internet Assigned Numbers AuthorityAuthority

Comparing Transport for both Comparing Transport for both ModelsModels

The features of UDP and TCP defined at The features of UDP and TCP defined at TCP/IP Transport Layer correspond to TCP/IP Transport Layer correspond to many of the requirements of the OSI many of the requirements of the OSI Transport Layer. There is a bit of bleed Transport Layer. There is a bit of bleed over for requirements in the session over for requirements in the session layer of OSI since sequence numbers, layer of OSI since sequence numbers, and port values can help to allow the and port values can help to allow the Operating System to keep track of Operating System to keep track of sessions, but most of the TCP and UDP sessions, but most of the TCP and UDP functions and specifications map to the functions and specifications map to the OSI Transport Layer.OSI Transport Layer.

Comparing Transport for both Comparing Transport for both ModelsModels

The TCP/IP and OSI architecture models both employ all The TCP/IP and OSI architecture models both employ all connection and connectionless models at transport layer. connection and connectionless models at transport layer. However, the internet architecture refers to the two models However, the internet architecture refers to the two models in TCP/IP as simply “connections” and “datagrams”. But the in TCP/IP as simply “connections” and “datagrams”. But the OSI reference model, with its penchant for “precise” OSI reference model, with its penchant for “precise” terminology, uses the terms connection-mode and terminology, uses the terms connection-mode and connection-oriented for the connection model and the term connection-oriented for the connection model and the term connectionless-mode for the connectionless model.connectionless-mode for the connectionless model.

In order to maximize interoperability over any network and In order to maximize interoperability over any network and minimize requirements, ANSI C12.22-2008 implements minimize requirements, ANSI C12.22-2008 implements connectionless-mode ACSE so that it does not require a connectionless-mode ACSE so that it does not require a connection for its services (but it does not preclude it)connection for its services (but it does not preclude it)

For the above reasons the ANSI C12.22-2008 maintains For the above reasons the ANSI C12.22-2008 maintains “associations” between “peers” rather than connections“associations” between “peers” rather than connections

Network vs. InternetNetwork vs. Internet

Like all the other OSI Layers, the network layer Like all the other OSI Layers, the network layer provides both connectionless and connection-provides both connectionless and connection-oriented services. As for the TCP/IP architecture, oriented services. As for the TCP/IP architecture, the internet layer is exclusively connectionlessthe internet layer is exclusively connectionless

ANSI C12.22 does not provide a Network LayerANSI C12.22 does not provide a Network Layer ANSI C12.22 Application is designed around a ANSI C12.22 Application is designed around a

connectionless-mode networkconnectionless-mode network

OSI TCP / IP

Network (Layer 3) Internet


X.25 Packet Level Protocol – OSI’s X.25 Packet Level Protocol – OSI’s Connection-oriented Network ProtocolConnection-oriented Network Protocol The CCITT standard for X.25 defines the The CCITT standard for X.25 defines the DTE/DCE interface standard to provide access to DTE/DCE interface standard to provide access to a packet-switched network. It is the network a packet-switched network. It is the network level interface, which specifies a virtual circuit level interface, which specifies a virtual circuit (VC) service. A source host must establish a (VC) service. A source host must establish a connection (a VC) with the destination host connection (a VC) with the destination host before data transfer can take place. The before data transfer can take place. The network attempts to deliver packets flowing network attempts to deliver packets flowing over a VC in sequence.over a VC in sequence.

Network vs. InternetNetwork vs. Internet Connectionless Network ServiceConnectionless Network Service

Both OSI and TCP/IP support a connectionless Both OSI and TCP/IP support a connectionless network service: OSI as an alternative to network network service: OSI as an alternative to network connections and TCP/IP as the only way in use.connections and TCP/IP as the only way in use.

Internetworking ProtocolsInternetworking Protocols OSI’s CLNP (ISO/IEC 8473: 1993) is functionally OSI’s CLNP (ISO/IEC 8473: 1993) is functionally

identical to the Internet’s IP (RPC 791). Both CLNP identical to the Internet’s IP (RPC 791). Both CLNP and IP are best-effort-delivery network protocols. Bit and IP are best-effort-delivery network protocols. Bit niggling aside, they are virtually identical. The major niggling aside, they are virtually identical. The major difference between the two is that CLNP difference between the two is that CLNP accommodates variable-length addresses, whereas accommodates variable-length addresses, whereas IP supports fixed, 32-bit address (IPV4).IP supports fixed, 32-bit address (IPV4).

Also IPV6 is another parallel implementationAlso IPV6 is another parallel implementation

Network vs. InternetNetwork vs. Internet Internet (IP) AddressesInternet (IP) Addresses

The internet network address is more commonly The internet network address is more commonly called the “IP address.” It consists of bits, some of called the “IP address.” It consists of bits, some of which are allocated to a high-order network-numberwhich are allocated to a high-order network-number part and the remainder of which are allocated to a part and the remainder of which are allocated to a low-order host-numberlow-order host-number part.part.

The distribution of bits - how many form the network The distribution of bits - how many form the network number, and how many are therefore left for the number, and how many are therefore left for the host number - can be done in one of three different host number - can be done in one of three different ways, giving three different ways, giving three different classes classes of IP address of IP address

ANSI C12.22 does not provide IP addressesANSI C12.22 does not provide IP addresses ANSI C12.22 considers IP addresses a native ANSI C12.22 considers IP addresses a native

property of the underlying network IP layer property of the underlying network IP layer (“native address”)(“native address”)

Network vs. InternetNetwork vs. Internet OSI Network Layer AddressingOSI Network Layer Addressing

ISO/IEC and CCITT jointly administer the global ISO/IEC and CCITT jointly administer the global network addressing domain. The initial hierarchical network addressing domain. The initial hierarchical decomposition of the NSAP address is defined by decomposition of the NSAP address is defined by (ISO/IEC 8348). The standard specifies the syntax (ISO/IEC 8348). The standard specifies the syntax and the allowable values for the high-order part of and the allowable values for the high-order part of the address - the Initial Domain Part (IDP), which the address - the Initial Domain Part (IDP), which consists of the Authority and Format Identifier (AFI) consists of the Authority and Format Identifier (AFI) and the Initial Domain Identifier (IDI) - but and the Initial Domain Identifier (IDI) - but specifically eschews constraints on or specifically eschews constraints on or recommendations concerning the syntax or recommendations concerning the syntax or semantics of the domain specific part (DSP).semantics of the domain specific part (DSP).

This has nothing to do with object identifiers used to This has nothing to do with object identifiers used to tag ANSI C12.22 Application Titles (ApTitle)tag ANSI C12.22 Application Titles (ApTitle)

Network vs. InternetNetwork vs. Internet OSI Routing ArchitectureOSI Routing Architecture

End systems (ESs) and intermediate systems (ISs) use End systems (ESs) and intermediate systems (ISs) use routing protocols to distribute (“advertise”) some or all of routing protocols to distribute (“advertise”) some or all of the information stored in their locally maintained routing the information stored in their locally maintained routing information base. ESs and ISs send and receive these information base. ESs and ISs send and receive these routing updates and use the information that they contain routing updates and use the information that they contain (and information that may be available from the local (and information that may be available from the local environment, such as information entered manually by an environment, such as information entered manually by an operator) to modify their routing information base. operator) to modify their routing information base.

ANSI C12.22-2008 does not provide routing capability ANSI C12.22-2008 does not provide routing capability within one native network segment, such as the Internet within one native network segment, such as the Internet (i.e. the entire internet appears to ANSI C12.22 as one (i.e. the entire internet appears to ANSI C12.22 as one contiguous network segment)contiguous network segment)

ANSI C12.22-2008 provides relaying capabilities to bridge ANSI C12.22-2008 provides relaying capabilities to bridge between different network segments (e.g. C12.22 over between different network segments (e.g. C12.22 over internet to C12.22 over SMS) when relaying capability is internet to C12.22 over SMS) when relaying capability is not present between the two incompatible native network not present between the two incompatible native network segmentssegments


TCP/IP Routing ArchitectureTCP/IP Routing Architecture The TCP/IP routing architecture looks very much like The TCP/IP routing architecture looks very much like

the OSI routing architecturethe OSI routing architecture Hosts use a discovery protocol to obtain the Hosts use a discovery protocol to obtain the

identification of gateways and other hosts attached to identification of gateways and other hosts attached to the same network (sub-network)the same network (sub-network)

Gateways within autonomous systems (routing Gateways within autonomous systems (routing domains) operate an interior gateway protocol domains) operate an interior gateway protocol (intradomain IS-IS routing protocol), and between (intradomain IS-IS routing protocol), and between autonomous systems, they operate exterior or border autonomous systems, they operate exterior or border gateway protocols (interdomain routing protocols).gateway protocols (interdomain routing protocols).

ANSI C12.22 ANSI C12.22 does notdoes not provider routing services on provider routing services on the internetthe internet

Data link / Physical vs. Data link / Physical vs. SubnetSubnet

Data link layerData link layer The function of the Data Link Layer is “provides for the control of the

physical layer, and detects and possibly corrects errors which may occur” (ISO/IEC 7498:1994). In another words, the Data Link Layer transforms a stream of raw bits (0s and 1s) from the physical into a data frame and provides an error-free transfer from one node to another, allowing the layers above it to assume virtually error-free transmission

ANSI C12.22 does not provide Data link Layer for non-comm-module implementations

OSI TCP / IP

Data Link (Layer 2)Subnet

Physical (Layer 1)


Physical layerPhysical layer The function of the Physical Layer is to provide The function of the Physical Layer is to provide

“mechanical, electrical, functional, and procedural “mechanical, electrical, functional, and procedural means to activate a physical connection for bit means to activate a physical connection for bit transmission” (ISO/IEC 7498:1994). Basically, this transmission” (ISO/IEC 7498:1994). Basically, this means that the typical role of the physical layer is to means that the typical role of the physical layer is to transform bits in a computer system into transform bits in a computer system into electromagnetic (or equivalent) signals for a electromagnetic (or equivalent) signals for a particular transmission medium (wire, fiber, ether, particular transmission medium (wire, fiber, ether, etc.)etc.)

ANSI C12.22 does not provide Physical Layer for non-ANSI C12.22 does not provide Physical Layer for non-comm-module implementationscomm-module implementations

Data link / Physical vs. Data link / Physical vs. Subnet Subnet

Comparing to TCP/IP Comparing to TCP/IP These 2 layers of the OSI correspond directly to the These 2 layers of the OSI correspond directly to the

subnet layer of the TCP/IP modelsubnet layer of the TCP/IP model Majority of the time, the lower layers below the Majority of the time, the lower layers below the

Interface or Network layer of the TCP/IP model are Interface or Network layer of the TCP/IP model are seldom or rarely discussed. seldom or rarely discussed.

The TCP/IP model does nothing but to highlight the The TCP/IP model does nothing but to highlight the fact the host has to connect to the network using fact the host has to connect to the network using some protocol so it can send IP packets over it. some protocol so it can send IP packets over it. Because the protocol used is not defined, it will vary Because the protocol used is not defined, it will vary from host to host and network to networkfrom host to host and network to network

ANSI C12.22 does not provide Physical Layer for non-ANSI C12.22 does not provide Physical Layer for non-comm-module implementationscomm-module implementations


Comparing to TCP/IPComparing to TCP/IP After much deliberation by organizations, it was After much deliberation by organizations, it was

decided that the Network Interface Layer in the decided that the Network Interface Layer in the TCP/IP model corresponds to a combination of the TCP/IP model corresponds to a combination of the OSI Data Link Layer and network specific functions of OSI Data Link Layer and network specific functions of the OSI network layer (e.g. IEEE 203.3)the OSI network layer (e.g. IEEE 203.3)

Since these two layers deal with functions that are so Since these two layers deal with functions that are so inherently specific to each individual networking inherently specific to each individual networking technology, the layering principle of grouping them technology, the layering principle of grouping them together related functions is largely irrelevanttogether related functions is largely irrelevant

For this reason Smart Grid should not specify the For this reason Smart Grid should not specify the physical layerphysical layer

General ComparisonGeneral Comparison

Focus of Reliability ControlFocus of Reliability Control Roles of Host SystemRoles of Host System De-jure vs. De-factoDe-jure vs. De-facto

Focus of Reliability ControlFocus of Reliability Control Implementation of the OSI model places emphasis on Implementation of the OSI model places emphasis on

providing a reliable data transfer service, while the TCP/IP providing a reliable data transfer service, while the TCP/IP model treats reliability as an end-to-end problemmodel treats reliability as an end-to-end problem

Each layer of the OSI model detects and handles errors, all Each layer of the OSI model detects and handles errors, all data transmitted includes checksums. The transport layer data transmitted includes checksums. The transport layer of the OSI model checks source-to-destination reliabilityof the OSI model checks source-to-destination reliability

In the TCP/IP model, reliability control is concentrated at In the TCP/IP model, reliability control is concentrated at the transport layer. The transport layer handles all error the transport layer. The transport layer handles all error detection and recovery. The TCP/IP transport layer uses detection and recovery. The TCP/IP transport layer uses checksums, acknowledgments, and timeouts to control checksums, acknowledgments, and timeouts to control transmissions and provides end-to-end verificationtransmissions and provides end-to-end verification

ANSI C12.22 application delegates all of the above to the ANSI C12.22 application delegates all of the above to the networknetwork

Roles of Host SystemRoles of Host System Hosts on OSI implementations do not Hosts on OSI implementations do not

handle network operations, but TCP/IP handle network operations, but TCP/IP hosts participate in most network hosts participate in most network protocolsprotocols

TCP/IP hosts carry out such functions as TCP/IP hosts carry out such functions as end-to-end verification, routing, and end-to-end verification, routing, and network controlnetwork control

The TCP/IP internet can be viewed as a The TCP/IP internet can be viewed as a data stream delivery system involving data stream delivery system involving intelligent hostsintelligent hosts

For ANSI C12.22 over IP, the content of For ANSI C12.22 over IP, the content of the data stream is an ACSE PDUthe data stream is an ACSE PDU

De-jure vs. De-facto (OSI)De-jure vs. De-facto (OSI) OSIOSI

Standard legislated by official recognized body. (ISO)Standard legislated by official recognized body. (ISO) The OSI reference model was devised The OSI reference model was devised before before the protocols the protocols

were invented. This ordering means that the model was not were invented. This ordering means that the model was not biased toward one particular set of protocols, which made it biased toward one particular set of protocols, which made it quite general. The down side of this ordering is that the quite general. The down side of this ordering is that the designers did not have much experience with the subject and designers did not have much experience with the subject and did not have a good idea of which functionality to put in did not have a good idea of which functionality to put in which layer.which layer.

Being general, the protocols in the OSI model are better Being general, the protocols in the OSI model are better hidden than in the TCP/IP model and can be replaced hidden than in the TCP/IP model and can be replaced relatively easily as the technology changes.relatively easily as the technology changes.

Not so widespread as compared with TCP/IP. (complex , Not so widespread as compared with TCP/IP. (complex , costly)costly)

More commonly used as teaching aidsMore commonly used as teaching aids However ANSI C12.22 is reality not a teaching aidHowever ANSI C12.22 is reality not a teaching aid

De-jure vs. De-facto De-jure vs. De-facto (TCP/IP)(TCP/IP)

TCP/IPTCP/IP Standards adopted due to widespread use. (Internet)Standards adopted due to widespread use. (Internet) The protocols came first, and the model was really just a The protocols came first, and the model was really just a

description of the existing protocols. There was no problem description of the existing protocols. There was no problem with the protocols fitting the model, but it is hardly possible with the protocols fitting the model, but it is hardly possible to be use to describe other modelsto be use to describe other models..

““Get the job done" orientation. Get the job done" orientation. Over the years it has handled most challenges by growing Over the years it has handled most challenges by growing to meet the needs.to meet the needs.

More popular standard for internetworking for several More popular standard for internetworking for several reasons :reasons :

relatively simple and robust compared to alternatives such as OSIrelatively simple and robust compared to alternatives such as OSI available on virtually every hardware and operating system platform available on virtually every hardware and operating system platform

(often free)(often free) the protocol suite on which the Internet depends. the protocol suite on which the Internet depends.

The EndThe End Original OSI Documentation Original OSI Documentation

Project team membersProject team members ANDREW TAN TENG HONG ANDREW TAN TENG HONG MAH CHEE MENGMAH CHEE MENG CHEE YEW WAICHEE YEW WAI TAN YOKE CHUANTAN YOKE CHUAN CHEONG KIM MINGCHEONG KIM MING

Revised to include ANSI C12.22-Revised to include ANSI C12.22-2008 Comments2008 Comments Avygdor MoiseAvygdor Moise Richard D. TuckerRichard D. Tucker

analysis of the osi model vs. tcp/ip model and use- case of ansi c12.22-2008 over ip implementation...

Documents

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application c12

osi transport layer

reduced stack c12

subnet layers osi c12

transport network layer

tcpip transport layer