A useful list of SAP commandsBy Robert Parkinson

A handy little list of SAP commands for every Basis Consultant's cookbook.

Command Description

/nxxxx - Terminates current transaction and starts transaction "xxxx"

/n - Terminates current transaction /nend Terminates all separate sessions and logs off

/nex - Terminates all separate sessions and logs off immediately

/oxxxx - Opens a new sessions and starts transaction "xxxx" inn new session

/o - Lists existing sessions and allows deletion or opening of a new session

/h - Switches into debugging mode

/hs - Switches into debugging mode and activates the debugging of system functions

/$SYNC - Buffer Command: Resets all buffers in the system

/$CUA - Buffer Command: Resets the CUA buffer of the application server

/$TAB - Buffer Command: Resets the table buffer of the application server

/$NAM - Buffer Command: Resets the nametab buffer of the application server

/$DYNP - Buffer Command: Resets the screen buffer if the application server

/bdel - Deletes the current batch input transaction

/bend - Terminates batch unput processing and sets the sessions to "Failed"

Some Additional Commands:

%sc - FIND if find is not an option in an SAP screen

%pc - SAVE it to a file on your pc

%pri/%prin - Will print the current screen

%bc1 - Takes you back one screen (Green Arrow)

%bc2 - Cancel (Red X)

%bck - Yellow Arrow

In the past when people were discussing SAP, the conversation very quickly boiled down to modules, for example:

SAP training courses were structured along SAP module lines so that you would attend SAP MM 101, 102 and 103. While at the course you would learn many things about MM, but not much about the rest of the SAP system and how SAP MM fits into it. 

A conversation with a SAP recruiter might go something like this: 

Recruiter … “which SAP Modules do you work with?”          Candidate … “well, I have a lot of purchasing process experience”          Recruiter … “yes, but which SAP Modules do you work with?”          Candidate … “well, it’s purchasing functionality … so that would be, umm, SAP MM, SAP FI and SAP CO mainly”          Recruiter … “great I have just the job for you”          Candidate … “fantastic, is it purchasing?”          Recruiter … “well it says here that they want an MM, FI and CO person and that’s you, right?”

Not necessarily! A MM, FI, CO role might include Inventory Management (MM), Accounts Receivable (FI) and Profitability Analysis (CO) – none of which a purchasing person is guaranteed to have

Many programme teams were organised along SAP module lines, so that you would have a FI/CO, an MM and a HR team, for example. Training courses were (therefore) often prepared and delivered along SAP module lines too. The result of this was that solutions were frequently optimised along SAP module lines, and less often well integrated, and as for users, well, they were pretty much trained up in a SAP module and left to get on with it post go-live. Fortunately those days are mostly passed, and more and more programmes (from design to build to training) are being organised along process lines such as:

Order to Cash (including parts of SD, FI-AR and probably TY as well)Purchase to Pay (including MM-Purchasing and FI-AP)Record to Report (FI-GL etc)

SAP now are moving away from describing their system as a set of SAP Modules, and now are using the term ‘solutions’, which is much better, as follows:

Financials Human Resources

Customer Relationship Management

Supplier Relationship Management

Product Lifecycle Management

Supply Chain Management

Business Intelligence

SAP FI Module - where FI means Financial Accounting – essentially this SAP module delivers your regulatory ‘books of record’, including

General ledger Book close

Tax

Accounts receivable

Accounts payable

Asset Management (SAP AM)

Consolidation

Special ledgers

    

SAP CO Module - The CO stands for Controlling – basically the SAP Module which allows you to manage your internal cost/management accounting, including

Cost elements Cost centres

Profit centres

Internal orders

Activity based costing

Product costing

     Go here for more details on the SAP CO Module, or here for a 4 page SAP CO Tutorial

SAP PS Module - and PS is Project Systems – this SAP Module is where you can manage your projects, large and small, including

Make to order Plant shut downs (as a project)

Third party billing (on the back of a project)

SAP HR Module - ah yes, the HR is for Human Resources ... people are the important part of this SAP module, including

Employment history Payroll

Training

Career management

Succession planning

     Go here for more details on the SAP HR Module

SAP PM Module - where Plant Maintenance is the PM – this SAP module is where you maintain your equipment (e.g. a machine, an oil rig, an aircraft etc), including

Labour Material

Down time and outages

SAP MM Module - one of the most important SAP Modules where MM is Materials Management - underpins the supply chain, including

Requisitions Purchase orders

Goods receipts

Accounts payable

Inventory management

BOM’s

Master raw materials, finished goods etc

     Go here for more details on the SAP MM Module

SAP QM Module - and QM stands for Quality Management in this SAP module – improve the quality of your goods, including

Planning Execution

Inspections

Certificates

SAP PP Module - one of the really big SAP modules is Production Planning – manages your production process, including

Capacity planning Master production scheduling

Material requirements planning

Shop floor

SAP SD Module - another one of the large SAP modules is Sales and Distribution – from order to delivery, including

RFQ Sales orders

Pricing

Picking (and other warehouse processes)

Packing

Shipping

     Go here for more details on the SAP SD Module

SAP BW Module - where BW stands for Business (Data) Warehouse which includes the following main functions:

Data extraction from source systems Some technical and functional transformation of the data

Storage of the data in what are called Infoproviders

Reporting (which uses Infoproviders)

     Go here for more details on the SAP BW Module, or here for a 10 page SAP BW Tutorial

SAP ABAP - is not really a module - it stands for Advanced Business Application Programming and this is the is the structured programming language for custom development including reports. Go here for more details on SAP ABAP, or here for some SAP ABAP Tutorials

Go here to see over 200 pages of our best SAP Tutorials, including one on the SAP FI Module and one on the SAP CO Module. If you need more go here to find over 450 more pages of free SAP Articles. Go here for Online SAP Training, and if you are interested in having your own SAP system available to you 24/7 then check this out SAP Access

Router Commands Overview

In this section you will learn about the router commands, configurations, privileged mode commands, routing protocols, cisco labs and network configurations.

There are hundreds of basic and advance level commands of a router. It is not easy to remember all the commands. But some commands are frequently used and can be remembered with some practice. I have provided a list of the most commonly used commands based on their features and usage.

 You will find here some basic terminology of a router.

Routing: Routing is a process of moving the data (packets) through an inter network. Routing performs the two basic tasks. Define the paths for a packet and then forward the packets on the basis of defined paths. Routing can also be defined as the communication between two or more logically and physical networks and this communication (packet transfer) is brought by a router.

  

First of all you should remember the keyboard shortcuts of a router.

Keyboard ShortcutsCTRL-N - show next commandCTRL-P - show previous commandSHIFT-CTRL-6 – Break

Configuring the Router

You will be able to learn the basic commands for configuring a router.sh running-config - details the running configuration file (RAM)sh startup-config - displays the configuration stored in NVRAMsetup - Will start the the automatic setup; the same as when you first boot the routerconfig t - use to execute configuration commands from the terminalconfig mem - executes configuration commands stored in NVRAM; copies startup-config to running-config

config net - used to retrieve configuration info from a TFTP servercopy running-config startup-config - copies saved config in running config (RAM) to NVRAM or "write memory" for IOS under ver.11copy startup-config running-config - copies from non-volatile (NVRAM) to current running config (RAM)boot system flash <put file filename here> - tells router which IOS file in flash to boot fromboot system tftp - tells router which IOS file on the tftp server to boot fromboot system rom - tell router to boot from ROM at next boot

  

copy flash tftp - Copies flash to tftp servercopy tftp flash - Restores flash from tftp servercopy run tftp - Copies the current running-config to tftp servercopy tftp run - Restores the running-config from tftp server

General Commands

Here is a list of the general commands. These are the basic level commands and most commonly usedno shutdown - (enables the interface)reload - restarts the routersh ver - Cisco IOS version, uptime of router, how the router started, where system was loaded from, the interfaces the POST found, and the configuration registersh clock - shows date and time on routersh history - shows the history of your commandssh debug - shows all debugging that is currently enabledno debug all - turns off all debuggingsh users - shows users connected to routersh protocols - shows which protocols are configuredbanner motd # Your customized message here # - Set/change bannerhostname <give router name> - use to configure the hostname of the routerclear counters - clear interface counters

Privileged Mode commands of a router

Learn how to work in the privileged mode of a router.enable - get to privileged modedisable - get to user modeenable password <give password here> - sets privileged mode passwordenable secret <give password here> - sets encrypted privileged mode passwordSetting Passwords on routerHere you will be able to learn how to set the password on a router.enable secret <give password here> - set encrypted password for privileged accessenable password <give password here> - set password for privileged access (used when there is no enable secret and when using older software)Setting the password for console access:(config)#line console 0(config-line)#login (config-line)#password <put password here>Set password for virtual terminal (telnet) access (password must be set to access router through telnet):(config)#line vty 0 4 (config-line)#login (config-line)#password <put password here> Set password for auxiliary (modem) access:(config)#line aux 0(config-line)#login (config-line)#password <put password here>

Router Processes & Statistics

By these command you can see the statistics and different processes of the router.sh processes - shows active processes running on routersh process cpu - shows cpu statisticssh mem - shows memory statisticssh flash - describes the flash memory and displays the size of files and the amount of free flash memorysh buffers - displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Bufferssh stacks - shows reason for last reboot, monitors the stack use of processes and interrupts routines

IP Commands

Here is a list of the IP CommandsConfigure IP on an interface:int serial 0ip address 157.89.1.3 255.255.0.0int eth 0 ip address 2008.1.1.4 255.255.255.0

Other IP Commands:

sh ip route - view ip routing tableip route <remote_network> <mask> <default_gateway> [administrative_distance] - configure a static IP routeip route 0.0.0.0 0.0.0.0 <put gateway of the last resort here> - sets default gatewayip classless - use with static routing to allow packets destined for unrecognized subnets to use the best possible routesh arp - view arp cache; shows MAC address of connected routersip address 2.2.2.2 255.255.255.0 secondary - configure a 2nd ip address on an interfacesh ip protocol

CDP Commands (Cisco Discovery Protocol uses layer 2 multicast over a SNAP-capable link to send data):

sh cdp neighbor - shows directly connected neighborssh cdp int - shows which interfaces are running CDPsh cdp int eth 0/0 - show CDP info for specific interfacesh cdp entry <cdp neighbor here> - shows CDP neighbor detailcdp timer 120 - change how often CDP info is sent (default cdp timer is 60)cp holdtime 240 - how long to wait before removing a CDP neighbor (default CDP holdtime is 180)sh cdp run - shows if CDP turned onno cdp run - turns off CDP for entire router (global config)no cdp enable - turns off CDP on specific interface

IPX Commands

Enable IPX on router:ipx routingConfigure IPX + IPX-RIP on an int: int ser 0

ipx network 4A

Other Commands:

sh ipx route - shows IPX routing tablesh ipx int e0 - shows ipx address on intsh ipx servers - shows SAP tablesh ipx traffic - view traffic statisticsdebug ipx routing activity - debugs IPS RIP packetsdebug ipx sap - debugs SAP packets

Routing Protocols

RIP, IGPR and OSPF are the routing protocols and here is a list of the commands for the working on the routing protocols.Configure RIP:router ripnetwork 157.89.0.0network 208.1.1.0Other RIP Commands: debug ip rip - view RIP debugging infoConfigure IGRP:router IGRP 200network 157.89.0.0network 208.1.1.0Other IGRP Commands:debug ip igrp events - view IGRP debugging infodebug ip igrp transactions - view IGRP debugging info Access Lists Here is a list of the Access list command of a router.sh ip int ser 0 - use to view which IP access lists are applies to which intsh ipx int ser 0 - use to view which IPX access lists are applies to which intsh appletalk int ser 0 - use to view which AppleTalk access lists are applies to which intView access lists:sh access-listssh ip access-listssh ipx access-listssh appletalk access-listsApply standard IP access list to int eth 0:access-list 1 deny 200.1.1.0 0.0.0.255access-list 1 permit anyint eth 0ip access-group 1 inApply Extended IP access list to int eth 0:access-list 100 deny tcp host 1.1.1.1 host 2.2.2.2 eq 23access-list 100 deny tcp 3.3.3.0 0.0.0.255 any eq 80int eth 0ip access-group 100 outApply Standard IPX access list to int eth 0:

access-list 800 deny 7a 8000access-list 800 permit -1int eth 0ipx access-group 800 outApply Standard IPX access list to int eth 0:access-list 900 deny sap any 3378 -1access-list 900 permit sap any all -1int eth 0ipx access-group 900 out

WAN Configurations Commands

Networking over WAN is the main functionality of a router. The most common use of a router is for the WAN connectivity. Here is a list of the commands for the different methods of the WAN connectivity.

PPP Configuration

Point to point protocol is a method for the WAN connectivity and you will find here some commands of PPP.encapsulation pppppp authentication <chap or pap here>ppp chap hostname <put router name here>ppp pap sent-username <put user name here>sh int ser 0 - use to view encapsulation on the interface

Frame-Relay Configuration

One of the methods for the WAN connectivity is the Frame Relay. Find here some basic commands for the WAN connectivity through Frame Relay.encapsulation frame-relay ietf - use IETF when setting up a frame-relay network between a Ciscorouter and a non-Cisco routerframe-relay lmi-type ansi - LMI types are Cisco, ANSI, Q933A; Cisco is the default; LMI type is auto-sensed in IOS v11.2 and upframe-relay map ip 3.3.3.3 100 broadcast - if inverse ARP won't work, map Other IP to Your DLCI # (local)keep alive 10 - use to set keep alivesh int ser 0 - use to show DLCI, LMI, and encapsulation infosh frame-relay pvc - shows the configured DLCI's; shows PVC traffic statssh frame-relay map - shows route mapssh frame-relay lmi - shows LMI info

Miscellaneous Commands

In the last but not least here is a list of the some miscellaneous and useful commandssh controller t1 - shows status of T1 linessh controller serial 1 - use to determine if DCE or DTE device(config-if)#clock rate 6400 - set clock on DCE (bits per second)(config-if)#bandwidth 64 - set bandwidth (kilobits)

P Addressing

Here you will learn about ip address network introduction and general overview of routing, subnet mask, subnetting, data communication. IP address is an identifier for a computer or device on a TCP/IP network and Internet. Networks that use the TCP/IP protocols route traffic based on the IP address of the destination computer or network device. The format of the IP address is 32 bits 4 octets 4 bytes such as 100.100.10.1, 210.100.22.30, 1.10.1.2 these are the examples of the IP address. The format is a 32-bit numeric value written as four numbers and separated by periods.Each number in the IP address can be between 0 and 255. In your private network, you can assign unique IP address randomly. However, when you want to connect your private network to the Public network such as Internet then you must need a registered IP address to communicate on the internet and to avoid duplicate address. The four numbers in an IP address are used in different ways to identify a particular network. The general internet registries such as APNIC, RIP, NCC and LACNIC assigns internet or IP addresses from the following 3 classes.

  

1. Class A- IP address from 0-126. It supports 16 million hosts and 126 networks.2. Class B- IP address from 128-191. It supports 65,000 hosts and 16,000 networks.3. Class C-IP address from 192-223. It supports 254 hosts and 2 million networks.The number of unassigned IP address is running out and a new classless scheme called CIDR is replacing the classes based system of the IP address. In this system the A, B and C class is tied to adoption of IPV6.

Every device connected to the Internet must need a unique identifier, which is called an IP address. An IP address is a numeric value separated by periods into four octets. These numbers are usually assigned to the ISPs (internet service providers) within region-based blocks. An IP address can be used to identify a region or a country. An internet user’s geographical location can be determined with the help of an IP address. The number system is generally difficult to remember so the IP address may also assign to a Host name.

The host names are usually easy to remember. In simple words, every website on the internet must bound or mapped with an IP address. At one time ISPs usually issue one IP address to each user. Within each ISP a DHCP (Dynamic host configuration protocol) server is configured, which dynamically assigns IP addresses from a given pool to each user who connects to the ISP. Dynamic IP addresses also limit the ability of a user to host websites, mail servers, ftp server, mail server and web portals.

Understanding IP Addresses Scheme

An IP address is an address that is used to uniquely identify a device or computer on an IP-based network. An IP address is an address used to uniquely identify a device on an IP network. An IP address can be divided into two parts network portion and a host portion. Each IP address is associated with a subnet mask. The 32 bit address is broken into 4 octets and 1 octet=8 bits. Each octet is converted to a decimal and is separated by periods.

For example 0000000000.11111111.00000000.11111111 this is a binary representation of an IP address. Each octet’s decimal value ranges between 0 and 255. The binary octets convert into decimal value. Here you can see that how a binary octet converts into decimal value. The right most bit or least significant bit of an octet will hold a value of 20.The bit left to that bit will hold a value of 21. This process continues until the left most bit or the most

  

significant bit holds the value of 27. If all the binary bits are one the decimal representation will be like this.

1 1 1 1 1 1 1 1128 64 32 16 8 4 2 1 (128+64+32+16+8+4+2+1=255)

Now here is a sample conversion of the octet if not all the bits are set of 1.

0 0 1 0 0 0 0 10 0 32 0 0 0 0 1 (0+64+0+0+0+0+0+1=33)In the following example you can see the IP address representation both in binary and decimal values.

64. 2. 135. 19 (decimal)64+2+135+19=22001001010.00000010.1000111.00010011 (binary)

The octets are broken down to provide a large number of the addressing scheme that can accommodate small and very large networks. There are five different classes of the IP networks. Class A, B, C, D and E. The classes from A to C and mainly in use, D and E are experimental and reserved so they are not commonly in use. Due to the classless inter domain routing (CIDR) these addresses are not practically in use.

Network/Subnet Masks

A network mask helps you which portion of the address identifies the network portion and the host portion of an IP address. The three different classes of the IP addresses have their own default masks as shown below.Class Subnet Mask

Class A: 255.0.0.0Class B: 255.255.0.0Class C: 255.255.255.0

An IP address on a class A network that has not been subnetted would have an address and subnet mask pair such as 10.111.20.1 255.0.0.0. If you want to know in more detail that how a mask help you identify the network and host part of the address simply convert the IP address and subnet mask into the binary numbers.

4.16.15.1= 00000100. 00010000.00001111.00000001255.0.0.0 = 11111111. 00000000.00000000.00000000If you have the address and the subnet mask in the binary forms then identifying the network portion and the host portion is very easy. Any address value that has the corresponding subnet mask binary value set to 1 show the network ID. Any address bit that has corresponding subnet mask value to 0 represents the host ID.

4.16.15.1= 00000100.00010000.00001111.00000001255.0.0.0 = 11111111.00000000.00000000.00000000

Network id | host id If you know your IP address of a computer, you can access the services such as online games, FTP,

Web and Mail servers, and remote access utilities such as Remotely Anywhere, PCToGo, PCAnywhere, Remote control etc. How do I change my IP address?There are a number of methods by which you can change the IP address of your computer.

What is a Proxy Server?

A proxy server is a computer that offers network and internet access services to the client computers in a network. A client computer connects to the proxy server, requests a connection, services, files and other resources on the other servers. In some cases, the proxy may alter the client’s request and the server’s response for various reasons. By using the proxy server you can hide, conceal and make your network id anonymous by hiding your IP address. To get the anonymous status on the network or Internet, strong intermediate methods are employed like cryptography etc. Examples are remailers, P2P systems etc.

There is a large number of the software available that allows you to hide your IP address with the help of the proxy servers. The well known software for this purpose is Hide IP, Stealth surf, Netconceal, Anonymous surfing, Proxify and Ghost surf.

An IP address is a unique identification number for communication between computer networks, network devices such as computers, fax machines, printers and servers. It is like the number of an apartment or a phone number. IP addresses are of two types Static and Dynamic. Internet service providers’ use dynamic IP addresses and servers usually use static IP address.The class A of the IP address constitutes almost 50% of all the IP addresses. This class is meant for large networks like the big multinational companies. Class B networks are medium sized like used in the colleges, Universities and other educational and training institutes. Class C IP addresses are usually used for the small companies.

The Regional Internet Registry (RIP) provides the IP addresses based on the geographical distribution. RIP also offers protection against the hackers that try to access the confidential data. All the personal information recorded by the ISP is kept in confidentiality.

 

 

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About Huawei > Publications > Communicate > 2005- Issue 18 > 

Communicate 

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   The development trends and application policies of ASONIssue18 (Topic on ASON)Download( 949 KB)  Author: Liu Tao holds the posts of associate dean of Beijing 

Posts and Telecommunications Design Institute, as well as being commissioner of the Science & Technology Standing Committee of Ministry of Information Industry (MII). 

Since his graduation from Beijing University of Posts and Telecommunications in August, 1982, Liu Tao has been working on the design of optical fiber communication engineering at Beijing Posts & Telecommunications Design Institute, which falls under the authority of MII. He was the person in charge of the technical design for the first Chinese-made fiber-optic cable trunk, 2.56Gbit/s SDH trunk (HaikouSanya), and the 82.56Gbit/s DWDM trunk (Jinan-Qingdao), which was the leading cadre of design groups for capacity expansion of Beijing-Tianjin-Shanghai, Beijing-Taiyuan-Xiˇan, and Chengdu-chongqing WDM trunks. Previously, he was the general designer of the 11th Asian Games. He was also the general commander of fiber-optic cable design for Beijing-Jinan-Nanning, Beijin-Taiyuan-Xiˇan, and Beijing-Jiujiang-Guangzhou trunks. In addition, he was previously the chief engineer and chief officer of the No.1 Design Bureau, as well as an associate chief engineer of the institute. 

Development trends of telecom users and telecom service income 

As information technology continues to develop and mature, and society continues its long march down the road of progress, likewise, the growth of telecom users and telecom service income is making it possible for the mobile communications business to take on such features, so that now, it is quickly surpassing fixed communications. Furthermore, broadband service is now superceding narrowband, and data services are surpassing voice services. 

Recent statistics show that the number of broadband users around the world has grown, from 62 million at the end of 2002, to 100.8 million at the end of 2003, which amounts to an increase of 62.8%. During the same period, the number of Chinese broadband users grew, from 3.925 million, to 12.09 million, amounting to an increase of 208%. 

Up to year 2007, all network data traffic between enterprises and consumers, along with 70% of network data traffic between enterprises, will be supported by the Internet. Yankee Group, an American market research institution, indicates that the number of broadband users around the world will increase to 325 million by 2008. 

According to statistics published by MII, during the first four months of this year, mobile communication was still the main contributor of telecom income for China. Proportionally speaking, it now accounts for 44.3% of all total revenues, with and increase rate of 12.3%, which assures a steady increase of income for the telecom business. Data communication remains one of the fastest growing fields, with an increase in income of 25.4% in 2004, which is 2.8 times greater than that reported for telecomˇs main business. The proportion of income for fixed local telephone and long-distance operation in 2004 was 1.36% and 0.63%, respectively. This is lower than what was reported for the same period in 2003. However, in 2004 the proportion of income for mobile and data communication increased by 1.26% and 0.88%, respectively. 

Obviously, mobile communication surpassing fixed communication, broadband surpassing narrowband, and data communication surpassing voice communication, will continue to represent the development trend for telecom users and for telecom service income in the future. In association with this trend optical transport networks will be confronted with a host of new challenges, largely stemming from network development and varied types of 

services.

The development trend of the IP-centric network 

IP technology is at the core of next generation telecom network development, thanks to its non-connection-oriented work mode, which simplifies signaling, avoids the complexity that is commonly associated with node equipment, and its ability to synchronize with developments occurring in transport network technology. The current mainstream viewpoint is that the next generation telecom network will be centered in digital communication technology, which is based on statistical multiplexing and packet switching. To be more exact, it is based on the IP packet. All of these will invariably lead to the creation of new standards for optical transport network technology. 

Changes in transport service 

As society and the economy continues to develop, simple point-to-point fixed voice communication will become less appealing and unsatisfactory. Requirements for communication are more and more likely to be concerned with such features as, diversified business types and the uncertain direction of business. 

In the coming months and years, one of the first things to be encountered will be the changes occurring in the client groupˇs requirements. Currently, optical transport network clients can be divided into three main groups. The first group is the public client. They take on the features of diversification and individualization, and are more inclined to be in fashion and generally are looking for ways to be entertained. In most instances, they have converted their singular way of phone communication, to individual intercommunication, which offers more options and modes. The second group is comprised of enterprises, industries and government personnel. Some of the requirements they impose on service features would include large-scale, high speed, security, and transparency of service quality. Their concrete demands have been converted, from simple communication, to more interactive aspects of information exchange, which also includes the rapid flow of inner information and information security, and backup. The third group constitutes operators like, ISP and ICP. They require high quality, broad coverage and manageability. Their original requirement of simple line leasing, has now been replaced by demands for virtual network resources, which also includes bandwidth resources and the allocation and controlling ability of leased resources, especially leased network resources. 

Besides traditional communication services, other services are now competing for a Lion"s share of the optical transport network market. These mainly include the Optical Virtual Private Network (OVPN), Bandwidth on Demand (BOD), Service Level Agreement (SLA), and Triple-Play. 

Firstly, OVPN is an extension of VPN technology in the optical field. It provides part of the optical network resources for the exclusive use of VIP customers, such as, a private network for multinational companies, government and service providers. With this service, users can directly manage network resources and services allotted by operators, as well as adjust the bandwidth in use, as needed. 

Secondly, BOD represents a real-time change of user traffic, especially in terms of Internet 

traffic flow, which requires that the network bandwidth changes according to the variation of time. BOD, with its dynamic grooming ability, brought about by network intelligence, now helps operators to realize a dynamic, undamaged adjustment of bandwidth, according to the requirement of the service. It further allows operators to efficaciously deal with any unpredictable, high-burst service requirement. Users can significantly cut costs and operators can effectively use network resources, thus promoting operation efficiency. 

Thirdly, SLA service is an agreement between the operator and user to ensure that the operator guarantees specific service performance and reliability if the user pays for them. The amount of the expense is an important factor that decides which class of service quality the operator provides. The SLA provides a general explanation for service quality, priority, responsivity, and so on. It covers many aspects of the relationship between the user and operator. A complete SLA service is equivalent to a legal contract that clearly defines the responsibilities of both parties, all applications and services that shall be provided by the operator, measures of punishment for violating any of the clauses in the agreement, standards for fees and quality of service, as well as any revisions and reports (including the period it takes for a report to come into effect and details of the report) in reference to the clauses and the responsibilities of both parties.  Additionally, it outlines the operatorˇs requirement for the client in aspects of workload and resource use. Included in SLA service are also some objective and measurable parameters that the operator must guarantee the user. In order to prove to the client that service providers are obliged to keep their promises, operators should inform clients of these parameters. 

Lastly, Triple-Play integrates data, voice and video, thus offering a three-in-one service. With IP data traffic flow as its primary means of transport, the IP data traffic flow is composed of various kinds of services that impose different requirements on time delay, jitter, packet loss ratio, and redundancy, which are some of the negative features associated with unpredictable high-burst surges. This service possesses immense market potential and can effectively increase an operatorˇs income, largely because the income derived from data and video services is several times greater than that of voice services. Recent statistics show that 17% of users have expectations that one service packet should be able to provide all the telecom and entertainment services, which would include voice, video, high speed Internet access and wireless services. Another 14% expect that one service packet should be able to provide voice, video, and high speed Internet access services. 

If these expectations are to be fulfilled then it would require optical transport networks to convert, from supporting predominately voice services, to data services; narrowband-centric service, to broadband-centric service; and singular service, to various services. Moreover, this also allows transmission bandwidth to become more operable. In future market competition, those who are able to provide rapid service according to user demands, especially those which are based on the SLA, will be the winners. As a result, optical transport networks should be structured in the following manner: they should be able to provide all kinds of interfaces, segment the bandwidth and QoS, rapidly complete circuit configuration and adjustment, and be able to perform end-to-end monitoring. The key point is that optical transport networks should be able to support multi-service transport effectively, and the network should be intelligent. Therefore, besides being able to effectively enhance the capability of SDH technology in data service transport, networks also need to employ ASON technology. 

Development trends in ASON 

Since its appearance in the 1990s, ASON has made marvelous progress in the eyes of its peers in the industry and has now been put into operation by telecom networks in many countries. Development trends in ASON technology mainly lie in the following four aspects: 1) Adopting mesh network architecture Compared with the ring network, the mesh network has several advantages: It supports many schemes of protection and restoration; It provides transport service according to the SLA; It highly utilizes network resources; Node bottlenecks and multiple invalidation problems do not affect the mesh network; It features high survivability; Its excellent scalability makes it possible to increase nodes according to the requirement of service; Upgrade and expansion is flexible, thus, allowing expansion by segments; It easily realizes end-to-end adjustment and protection of circuits, and efficiently provides various operations; The time delay before protection restoration, and after protection restoration changes little, which is very important for data service. 2) Actively developing the control plane Optimizing the connection control interface (CCI) between the transport plane and control plane

Interface implementation is comprised of external and built-in modes. The built-in mode is where a board is embedded into the equipment. The external mode is where the control unit is not embedded into the equipment, but instead, the board server is used and installed, along with the sub-rack, into the cabinet. In terms of differences between these two implementation modes, the built-in mode has certain advantages in regards to equipment integrity. However, it occupies the slots offered by the equipment sub-rack. Namely, the active/standby mode occupies two slots. The external mode has stronger processing capabilities and is more suitable for ASON networks. 

Implementing distributed intelligence 

Compared with centralized intelligence, distributed intelligence eliminates the communication bottlenecks. Multiple network elements calculate the services at the same time, thus effectively reducing restoration time. The most important advantage derived from having distributed intelligence is that the network becomes safer, and thus more reliable, because problems occurring on a control plane, and on any one node, are prevented from having a deleterious effect on the whole network.

Researching and developing control protocol 

Here, the research focus changes from intra-domain to inter-domain, from the protocol type itself, to some extended protocols, with special attention being focused on inter-domain protection restoration technology. 

         Enhancing the performance of the control plane 

The capability of supporting service discovery and resources discovery should be improved. The most important aspect of control plane performance is the network and service restoration time. Besides restoration time, the most important factor lies in the conditions relating to restoration time like, fault type, the number of service, the signaling transfer mode, the number of nodes and other conditions. In addition, the system restoration speed is of vital importance in the event that any of the following three conditions occur: mesh connection topology with a complex network structure, large amounts of service workload, and simultaneous failure of multiple end-to-end links.

Ensuring intelligence controllability 

The operation, administration and maintenance (OAM) departments should always be able to manage and maintain the functions and performance of the whole network.

3) Enhancing the performance of the administrative plane

Besides management (configuration, fault, performance, security, and charging) of the transport plane, the administrative plane also focuses on management of the control plane. The purpose to the administrative plane is to mainly solve the following problems: Firstly, how best to query and modify the link connection, the link attribute, and link parameter related to the control plane flexibly, accurately and quickly; Secondly, how best to create a customized and usable maintenance circuit report mechanism; Thirdly, how best to combine the actual routing algorithm of ASON node equipment, network planning, optimization tool, and current network state, thus, forming a good simulated environment for the functions, performance, and survivability of the whole network; Lastly, how best to manage value-added services, especially services like, OVPN, BOD, and SLA.

4) Improving the performance of the transport plane

In order to realize high survivability and scalability, flexibility, and intelligence in ASON networks, the ASON transport plane is designed to be different from traditional SDH equipment in networking, hardware, and software capability. ASON must have the functions of digital cross-connect equipment (DXC), as well as the multiple add/drop multiplexer (MADM). Specifically, ASON should have the following functions: Firstly, It should be able to support different network topologies, which would include the mesh network, multiple crossed rings, the ring network, and link network. Secondly, it should support VC-4, and VC-12 service convergence. Thirdly, support LCAS, VCAT, GFP, Layer2 switching, MPLS VPN, and built-in RPR. Fourthly, support multiple ports, thus ensuring large enough node connectivity. Fifthly, provide multi-level QoS services, like, top-level service, with protection and restoration. Finally, provide protected service, restoration service, non-protected service, and extra service, thus, implementing flexible applications of transmission bandwidths.

In addition, it should have a higher order matrix, which needs to be over 160 G. Thus, when capacity is added abruptly, matrix capacity needs no replacement, and no block occurs. The cross-connection should provide such functions as space division cross-connection, add/drop multiplexing, wavelength conversion, and signal regeneration at different levels (fiber, wavelength group and wavelength). The involved technology is the large-capacity optical cross-connection matrix, which is based on optical cross-connection, or electrical cross-connection and optical interconnection. The mechanical switch, waveguide switch, liquid crystal switch, and micro-electronics mechanical switch (MEMS) are currently in use. Generally speaking, the cross-connection scale is usually lower than 32x32. A few manufacturers once produced a switch matrix with a scale that was over 1000x1000. However, this switch matrix is no longer in commercial use, the main factor lies in price, but of course, sub-rate convergence is also an important factor.

To realize ASON functions, the transport plane must have the following capabilities: it needs to work with the control plane in order to complete automatic service discovery and neighbor discovery; provide link and NE state notification; signal monitoring and fault detection; provide optical layer failure protection and restoration; provide dynamic trail configuration

and removal.

The operator provides users with SLA-based services, which include multi-priority circuits and circuit parameters. Therefore, being able to implement end-to-end service grooming and quality monitoring is vitally important. At present, the difficulty for implementing quality monitoring of end-to-end service lies in the optical layer. To solve this problem, two methods were adopted in the past. One used low-frequency amplitude modulation that was transferred in the DWDM channel, which could be measured at the network node. The other added a ¨monitor wavelength〃 in the data transmission channel.

However, the disadvantage of both methods lies primarily in that they cannot provide information about a specific channel. Moreover, utilizing either of these methods may create a noise source. Recently, people have been using an optical performance monitor (OPM), which can implement online monitoring of optical performance. The OPM extracts a small quantity of optical power and inputs signals to each single channel, depending on the wavelength. Namely, the OPM demultiplexes the transmission signals and measures optical power, wavelength, and the signal-to-noise ratio (SNR) of each channel. Then the OPM follows the test result and decides on which parameters will be used, which could include channel wavelength drift, ASE noise, the gain and gain tilt of amplifier, and the Q-value of the channel signal. Demultiplexing can be implemented by using the Fabry-Parot interferometer, the optical spectrum analyzer, which is based on diffraction grating, or the O/E photo-detector.

Difficulties that face ASON

With the high-speed development of ASON, the following problems have yet to be solved.

1) Working with the current optical network and equipment, implementing end-to-end circuit configuration and test

One solution put forward is to use the ¨intelligent agent〃 policy. For example, customer equipment, or existing optical network equipment, is able to connect with the UNI-C through a simple interface. Once this is accomplished, then the UNI-C connects to ASON through a standard UNI-N interface. However, the present state of UNI standard maturity limits the feasibility of this solution. The other solution is to integrate the existing optical network and ASON. By developing the management system, end-to-end management can be realized without changing existing optical network equipment. This solution requires that existing optical network equipment and ASON equipment should be supplied by the same vendor. 

2)  Ensuring network stability and security

3) Standardizing the networks and equipments

ASON standards are accomplished through the efforts of multiple standardization organizations; therefore, it is more important for intra-standard communication and coordination. It is hoped that the standardization process will be hastened in the coming months. The standard maturity of ASONˇs ITU-T is at present only 70%, with the remaining 30% of its contents still awaiting confirmation.

4) Testing equipments

The progress of research and development test equipment lags behind that of equipment which is in the development stage or has already been developed. The ASON/GMPLS tester presently has a few functions, which provide a necessary means for testing ASON. However, its functions and stability still need improvement. For instance, the test equipment still cannot validate the efficiency and consistency of each protocol, stably and reliably. 

Various performance awaits verification 

The efficiency of each function, especially traffic engineering, protection/restoration and support for new services, is waiting verification in an actual network. The main reason for this is that the assessment index architecture of the ASON network has not been set up, so running reliability and long-time stability checks are very difficult. 

Interworking of ASON

A recent OIF interworking test has raised the expectations and confidence level of operators and users. However, complete interworking of ASON has not yet been achieved. The principal difficulty lies in routing, especially hierarchical routing, and the logical information topology abstract.

Application policies for ASON 

Support for various services 

ASON provides support for OVPN services through the control plane and the administrative plane. By way of incorporating such technologies as, virtual concatenation, LCAS, GFP and ASON, optical transport networks can efficiently support BOD services at different rate levels. Switch connection (SC) and software permanent connection (SPC) also provide alternative means for the implementation of BOD services. The means by which BOD services are implemented can be numerous, not just one, because the means by which SC and SPC service connections are initiated are also different. The client can initiate the creation and adjustment of BOD services by way of the SC connection mode. Likewise, the management system which implements the BOD services can also initiate the creation and adjustment of BOD services.

In terms of SLA services, ASON prioritizes circuits with service classes in accordance with usersˇ needs. In ASON networks, service classes are related to different restoration modes, protection options and connection priorities. For example, some of these might include a creation priority, holding priority (whether a system can be freed), restoration priority, and so on. Creation priority refers to the response time for service creation, which could be in a day, an hour, or some minutes, respectively. Holding priority refers to whether or not a system is freed to bear more important services in case other systems are faulty. Because service connection itself is not guarded, restoration priority accounts for restoration time and restoration level (such as the percentage of services restored) when a fault has occurred on a system. ASON networks implement SLA services through quick fault detection and localization, restoration algorithm, restoration route level1 protection, restoration policy

selection, where the restoration algorithm includes a centralized algorithm and distributed algorithm. 

Network development policies 

The industry has been discussing the merits and demerits of the current policy of developing ASON networks. The opinions which have been expressed can best be summarized in two questions: Which network should ASON be applied to first, the backbone network or the metropolitan network? However, these two questions have one thing in common, which is, that ASON technology should be used appropriately in local conditions, depending upon on how ASON is developed and what the service requirements are. Considering that the development of ASON technology requires a mature process in which functions need to be improved gradually, this holds especially true when contemplating the addition of other functions of ASON in the actual application, which should be done in accordance with the requirements of service development and network construction. Operators can adopt different control planes and routing algorithms to meet the requirements of different areas and situations. For example, operators could use a fixed connection between areas, and then introduce a routing mechanism once inter-area routing protocol has matured.

However, there are some risks involved when choosing to adopt this scheme, which is, that equipment from all vendors must guarantee that their E-NNIs can be upgraded to a standard-compliant interface. Once this has been accomplished then network interconnectivity and interoperability can be achieved. 

Coordination with data networks 

In regards to the IP data network, if the network provides telecommunications services, any defects that may appear in terms of security and QoS would need to be amended or corrected. More importantly, a data network and an optical transport network need to be coordinated appropriately in aspects covering protection/restoration and function coordination.

An IP router and optical network both have protection and restoration functions. The problem principally lies in how to use these functions. For instance, if protection and restoration occurs in IP layer only, then network usage is compromised, and thereby reduced. This is because maintaining sufficient bandwidth is the prerequisite for protection and restoration at the carrier-class in an IP network. To ensure that all services remain at the existing QoS level in case of a fault, sufficient network bandwidth redundancy must be ensured. In the existing single-layer protection and restoration mechanism in an IP network, there should be at least 50% of network-wide bandwidth redundancy, otherwise, the QoS level of low level services will be sacrificed.

To ensure the availability of network services, currently leading operatorsˇ networks have an excess amount of network bandwidth that they can draw upon in case of an emergency. As a result, the workload of IP network is lessened. The link bandwidth utilization of a backbone network usually ranges from only 10%-30%, which reflects a considerable waste of network capacity. In contrast, utilization of link bandwidth resources can be increased through the optical transport network, which provides protection and restoration for links in the IP network. Hence, overall construction costs of an IP network and an optical network are decreased. The usability of nodes in an IP network is higher than that of links, and link failure is a weak item which affects network security. Therefore, if a link is capable of protection

and restoration, then the security of the entire network will be greatly improved.

As statistics show, by using the protection and restoration function of an optical transport network, the usability of protected high level services in an IP network show an increase, from 99% to 99.99%, while that of unprotected low level services show an increase, from 54% to 98.5%. This not only enables high level services to be close to the 99.999% index of a public switched telephone network (PSTN), but also makes use of unprotected low level services to provide a virtual private network (VPN) service for small or medium sized enterprises, which maximize the benefits of network resources. Therefore, for networks where basic online services do not require a strict QoS, there is no need to consider extra bandwidth needed for failure restoration, which requires maintaining a high bandwidth utilization level. Basically, all that needs to be done is to use the route protocol of an IP network as the primary protection measure, along with the protection and restoration mechanism. At the same time, operators need to design and optimize the physical network topology of the IP network appropriately, and ensure the incorrelation of the physical route of links between routers in the network, in order to prevent a single physical layer failure such as, a fiber break, which can cause more link failures in the IP network, thus, causing severe route oscillation. If SLA services with QoS assurance are borne, the protection and restoration function offered by an optical transport network will increase the utilization of circuit or line resources, hence, effectively saving overall network construction costs. Currently, as much as 40% of costs can be saved in a network with a bandwidth of VC-4 (155Mbit/s).

In terms of fault restoration speed, the protection and restoration mechanism of an optical network is better than an IP network, especially in scenarios where there are point-to-point and a large volume of services. This kind of mechanism responds to faults such as, a fiber break, almost instantaneously (less than 50ms), without involving high-level protocols and signaling. However, the protection and restoration mechanism at the optical layer cannot handle faults such as, an OXC node breakdown, which must be protected by the protection and restoration mechanism at the IP layer. Therefore, in a large-scale mesh IP optical network with numerous nodes, it is necessary to use a combination of a protection and restoration mechanism of an optical and IP network. According to the first-found-first-handled principle, a more feasible method would be to start protection from the optical network layer first, and then restore from the IP layer, if restoration cannot be carried out in a defined period of time.

An optical transport network and an IP router are similar in functions. Like IP router, the optical transport network also has Layer1 and Layer2 functions. However, the cost of a core router is five times higher than the optical cross-connect equipment with the same capacity. Furthermore, since the IP network is overlapped and has multiple hops, about 60% of transit services are transmitted in Layer3, which is far more expensive in terms of cost. Currently, software and hardware costs are increased by network levels, but not all services need to be transmitted in Layer 3, or if necessary, not every node has to process all IP packets. Therefore, transportation of end-to-end data in Layer1 or Layer2 can greatly reduce operation and maintenance costs, as well as network hardware costs. At the same time, fewer network levels will greatly decrease network delay time, thus increasing network reliability.

Peroration

As the telecom market continues to open up more and more, fiercer competition will ensue,

and this will force telecom operators to improve their service quality, in order to maintain their positions in the market, which in turn, will provide a more prosperous environment for the development of ASON technology.  

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