EN253206 Broadband Communication WAN...

EN253206Broadband Communication

WAN Infrastructure

Asst. Prof. Nararat Ruangchaijatupon

Electrical Engineering ProgramFaculty of Engineering, KKU

Office: EN04325A, Email: [email protected]

Wide Area Network

2Source: https://www.netprivateer.com/lanwan.html

Wide Area Network

3Source: https://brain4net.com/solutions/solutions-corporate/sd-wan-transport/

What is WANs?A wide area network (WAN) is a telecommunications network that extends over a large geographical area for the primary purpose of computer networking. Wide area networks are often established with leased telecommunication circuits.

Business, as well as education and government entities use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations across the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN.

4Source: https://en.wikipedia.org/wiki/Wide_area_network

What is WANs?• Good Watch

– https://www.youtube.com/watch?v=JlyYNVAGURc (Please Watch!)

– https://www.youtube.com/watch?v=9WkZT0YMZ70 (Please Watch!)

– https://www.youtube.com/watch?v=fCxfp1iUbqw

– https://www.youtube.com/watch?v=GCbBkY7fE5w

– https://www.youtube.com/watch?time_continue=7&v=UL_uh--LuAo&feature=emb_logo

5

What is WANs?• Good Read

– https://www.inc.com/encyclopedia/wide-area-networks-wans.html

– https://en.wikipedia.org/wiki/Wide_area_network

– https://searchnetworking.techtarget.com/definition/WAN-wide-area-network

– https://www.bbc.co.uk/bitesize/guides/z36nb9q/revision/1

6

Write Down Your Own Definition of WANs

7

WAN Topologies

• https://www.youtube.com/watch?v=9WkZT0YMZ70

• Always Up vs. On Demand

• Point-to-point– T1 (Speed=?), Dedicated Leased Line

• Point-to-multipoint– Frame Relay

– ATM (Asynchronous Transfer Mode)

8

Designing of WANsWANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive.

Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, Multiprotocol Label Switching (MPLS), Asynchronous Transfer Mode (ATM) and Frame Relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

9Source: https://en.wikipedia.org/wiki/Wide_area_network

Frame RelayFrame Relay is a standardized wide area network technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Network providers commonly implement Frame Relay for voice (VoFR) and data as an encapsulation technique used between local area networks (LANs) over a wide area network (WAN). Each end-user gets a private line (or leased line) to a Frame Relay node. The Frame Relay network handles the transmission over a frequently changing path transparent to all end-user extensively used WAN protocols. It is less expensive than leased lines and that is one reason for its popularity. The extreme simplicity of configuring user equipment in a Frame Relay network offers another reason for Frame Relay's popularity.

10Source: https://en.wikipedia.org/wiki/Frame_Relay

Frame Relay

11

Source: https://en.wikipedia.org/wiki/Frame_Relay

Source: https://www.orbit-computer-solutions.com/frame-relay-wan-connection-explained/

Frame Relay Data UnitFrame Relay puts data in variable-size units called "frames" and leaves any necessary error-correction (such as retransmission of data) up to the end-points. This speeds upoverall data transmission. For most services, the network provides a permanent virtual circuit (PVC), which means that the customer sees a continuous, dedicated connectionwithout having to pay for a full-time leased line.

12


Frame Relay Protocol Data Unit (1)

• Frame-relay frame structure essentially mirrors almost exactly that defined for LAP-D

• Flag Field indicates the beginning and end of the frame with the unique pattern 01111110.

• Address Field Each address field may occupy either octet 2 to 3, octet 2 to 4, or octet 2 to 5, depending on the range of the address in use. A two-octet address field comprises the EA=ADDRESS FIELD EXTENSION BITS and the C/R=COMMAND/RESPONSE BIT

13


Source: https://www.rfwireless-world.com/Tutorials/Frame-Relay-tutorial.html

Frame Relay Protocol Data Unit (2)

• DLCI (Data Link Connection Identifier Bits) identifies the virtual connection so that the receiving end knows which information connection a frame belongs to. Note that this DLCI has only local significance.– FECN, BECN, DE bits. These bits report congestion:

– FECN=Forward Explicit Congestion Notification bit

– BECN=Backward Explicit Congestion Notification bit

– DE=Discard Eligibility bit

• Information Field - Higher lay PDU. (Maximum of at least 262 octets)

• Frame Check Sequence (FCS) Field for error detection. The error detection mechanism used in Frame Relay uses the cyclic redundancy check (CRC) as its basis.


Frame Relay• Good Watch

– https://www.youtube.com/watch?v=F926ApfBMfQ(Please watch!)

– https://www.youtube.com/watch?v=0cfExF68kQE(Please watch!)

– https://www.youtube.com/watch?v=bWTAykjeRT8(Please watch!)

• Good Read– https://www.orbit-computer-solutions.com/frame-

relay-wan-connection-explained/

– https://www.rfwireless-world.com/Tutorials/Frame-Relay-tutorial.html

15

Frame Relay ComponentsAfter watching 3 videos, explain terminologies

• Frame Relay Switch

• CPE

• Virtual Circuit

• CIR

16

Frame Relay VCsAfter watching 3 videos, explain terminologies

• DTE

• DCE

• Switch Virtual Circuit

• Permanent Virtual Circuit

17

Frame Relay VCsAfter watching 3 videos, explain terminologies

• Fully Mesh

• Partial Mesh

• Access Link

18

Frame Relay’s Congestion Control (1)

• Admission Control - Network decides whether to accept a new connection request, based on the relation of the requested traffic descriptor and the network's residual capacity. The traffic descriptor consists of three elements:

1. Committed Information Rate (CIR). The average rate (in bit/s) at which the network guarantees to transfer information units over a measurement interval T. This T interval is defined as: T = BC/CIR.

2. Committed Burst Size (BC). The maximum number of information units transmittable during the interval T.

3. Excess Burst Size (BE). The maximum number of uncommitted information units (in bits) that the network will attempt to carry during the interval.


Frame Relay’s Congestion Control (2)

• The edge node must monitor the connection's traffic flow to ensure that the actual usage does not exceed.

• Frame Relay allows the network to enforce the end user's information rate and discard information when the subscribed access rate is exceeded.

• Explicit congestion notification is for congestion avoidance. Special congestion control bits have been incorporated into the address field: FECN and BECN bits.

• FECN = 1 indicates that congestion was experienced in the direction of the frame transmission, so it informs the destination that congestion has occurred.

• BECN =1 indicates that congestion was experienced in the network in the direction opposite of the frame transmission.

20

ATM – Asynchronous Transfer Mode

• ATM stands for Asynchronous Transfer Mode. It is a switching technique that uses time division multiplexing (TDM) for data communications.

• ATM networks are connection oriented networks for cell relay that supports voice, video and data communications. It encodes data into small fixed - size cells so that they are suitable for TDM and transmits them over a physical medium.

21Source: https://www.tutorialspoint.com/ATM-Networks

ATM Cell• The size of an ATM cell is 53 bytes: 5 byte

header and 48 byte payload

22

Source: https://www.tutorialspoint.com/ATM-Networks

• There are 2 different cell formats– User-network

interface (UNI)

– Network-network interface (NNI)

Source: http://ecomputernotes.com/computernetworkingnotes/switching/atm-cell-structure

8

12

ATM Cell Format (1)

• GFC (Generic Flow Control) was designed to give the User-Network Interface (UNI) 4 bits in which to negotiate multiplexing and flow control among the cells of various ATM connections

• VPI = Virtual path identifier (8 bits UNI / 12 bits NNI)

• VCI = Virtual channel identifier (16 bits)

23

ATM Cell Format (2)

• PT = Payload type (3 bits) – PT bit 3 (msbit): Network management cell. If 0,

user data cell and the following apply:

– PT bit 2: Explicit forward congestion indication (EFCI); 1 = network congestion experienced

– PT bit 1 (lsbit): ATM user-to-user (AAU) bit. Used by AAL5 to indicate packet boundaries.

• CLP = Cell loss priority (1-bit)

• HEC = Header error control (8-bit CRC, polynomial = X8 + X2 + X + 1)

24

ATM Reference Model• Physical Layer is responsible for synchronizing

transmission and reception by sending and receiving a continuous flow of bits with associated timing information. This layer corresponds to the OSI physical layer.

25Source: http://network-activity.blogspot.com/2019/09/atm-protocol.html

• ATM Layer is responsible for the simultaneous sharing of virtual circuits over the physical link and passing cells through the ATM network. Combined with the ATM adaptation layer, the ATM layer corresponds to the data-link layer of the OSI model.

• ATM adaptation Layer is responsible for isolating higher layer protocols from the ATM process. The AAL prepares data into payloads.

ATM Functional Reference Model

26

Benefits of ATM• Dynamic bandwidth (suitable for bursty traffic)• Data transmission is simple, uniform and predictable (equal-size cell)• Uniform packet size ensures that mixed traffic is handled efficiently• Small sized header reduces packet overload. Hence, effective

bandwidth usage.• ATM networks are scalable both in size and speed.

ATM: Resources• Good Watch

– https://www.youtube.com/watch?v=qZcv-9jS5LA&list=PLcxPetO_cDzu0f-TeH-cTVvreoz3vJdFD&index=11 (Please Watch!)

– https://www.youtube.com/watch?v=0dU1am2u1Jw

• Good Read– http://ecomputernotes.com/computernetworkingn

otes/switching/atm-cell-structure

– https://www.tutorialspoint.com/ATM-Networks

– http://network-activity.blogspot.com/2019/09/atm-protocol.html 27

MPLS

• Multiprotocol Label Switching

• MPLS is a routing technique– routing between label switches

• MPLS can encapsulate packets of various network protocols

• Good Watch– https://www.youtube.com/watch?v=U1w-b9GIt0k

(Please Watch!)

– https://www.youtube.com/watch?v=E5Ud1m9h0yc

28

SD-WAN• Software-Defined networking in a WAN

• It simplifies the management and operation of a WAN by decoupling the networking hardware from its control mechanism

29Source: https://www.techtalkthai.com/3-sd-wan-use-cases-by-silver-peak/

WANs Wrap UpAdvantages

• Covers large geographical area

• Centralized data

• Get updated files and data

• A lot of application to exchange messages

• Sharing of software and resources

• Distribute workload and decrease travel cost

Disadvantages

• Security problems

• Need firewall and antivirus software

• The setup cost is high

• Troubleshooting problems

• Server down and disconnection issue

30Source: http://www.itrelease.com/2018/07/advantages-and-disadvantages-of-wide-area-network-wan/

Recommended Resources• WANs: Good Watch

– https://www.youtube.com/watch?v=BAvQY9_cvp4

• SD-WAN: Good Watch– https://www.youtube.com/watch?time_continu

e=1&v=5Tv-Lf8_3NM&feature=emb_logo

• SD-WAN: Good Read– https://www.silver-peak.com/sd-wan/sd-wan-

explained– https://www.blognone.com/node/92222

– https://www.techtalkthai.com/3-sd-wan-use-cases-by-silver-peak/ 31

Question & DiscussionIn-class Qiuz

AssignmentLet’s the students familiarize themselves

with all terminologies

EN253206 Broadband Communication WAN...

Documents

Transcript of EN253206 Broadband Communication WAN...