logging in or signing up Frame Relay raghav18185 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 1190 Category: Others/ Misc License: All Rights Reserved Like it (1) Dislike it (0) Added: November 02, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: sabbodhillon (1 month(s) ago) can u mail me this presentation please Saving..... Post Reply Close Saving..... Edit Comment Close By: brijesh9831 (14 month(s) ago) i want 2 download FRAME RELAY presentation,which i have 2 give in next week at 12 march,2011;plz allow me 2 download this content Saving..... Post Reply Close Saving..... Edit Comment Close By: swapnali2282 (15 month(s) ago) I want to download this presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: ehsanehsanehsan (17 month(s) ago) gud presentation Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: Frame Relay Slide 2: The E-Lines and X-25 n/w were not meeting the requirements of the users. The user was looking at higher data rates, lower costs, efficient data handling of bursty data transmission and less overheads. Demands on Communication Networks : Demands on Communication Networks Higher data rate at lower cost WAN technology such as leased lines & X-25 offered low data rates. The leased lines provide point – to – point connectivity and creating mesh of these lines is very expensive. FR provides higher data rates at lower cost. Demands on Communication Networks : Demands on Communication Networks Bursty Data The leased lines were designed for fixed – rate need Most of the data networks have bursty data and the capacity of leased lines goes unused. Brusty data requires Band Width on demand Frame Relay accepts bursty data. User is granted an average data rate that can be exceeded during bursty periods. Demands on Communication Networks : Demands on Communication Networks Less overhead due to improved Transmission media The quality of transmission media has improved tremendously, they are reliable and less error prone. There is no need for extensive error checking as was being done in X.25. In X.25 both layer 2 and 3 include flow and error control. The source kept the copy of the frame until it receives a confirmation. Much of the traffic on X.25 network is devoted to error checking and ensuring complete reliability of services. Frame Relay does not provide error checking and does not required acknowledgement in the data link layer. Instead all the error checking is left to protocols in the transport and network layer. Many of data link layer operations are eliminated while others are combined. Slide 6: Frame Relay versus Pure Mesh T-Line Network Slide 7: Fixed-Rate versus Bursty Data Slide 8: X.25 Traffic Slide 9: Frame Relay Traffic Advantages of FR over X.25/ Leased lines : Advantages of FR over X.25/ Leased lines Higher speeds (upto 44.376 Mbps) Operates in Physical and data link layers. It can provide services to protocols that already have network layer protocol e.g TCP/IP. If TCP/IP uses the services of X.25 there is duplication in the network layer functions. X.25 has its own network layer. Allows bursty traffic unlike fixed data rates of X.25 and Leased lines. Frame Relay allows frame size of 9000 bytes which can accommodate all local area network frames. Frame Relay is less expensive. Disadvantages : Disadvantages The data rates of 44.376 Mbps is still not high enough for B-ISDN protocols. Frame Relays allows variable length frames. This may create varying delay for users. Not suitable for sending delay sensitive data such as real time voice or video Frame Relay Operation : Frame Relay Operation Frame Relay connects LANs that do not require real time communications. The bridges, routers and servers can be considered as DTEs which are connected to Frame Relay switches (DCE) through leased lines. Slide 13: Frame Relay Network Virtual Circuits (VC) : Virtual Circuits (VC) Frame Relay is a VC network. It does not use physical addresses to define the DTEs connected to network. Virtual Circuit Identifier (VCI) are used to route the traffic on network VCI are at data link layer unlike X.25 where they are at network layer. VC in Frame Relay is identified by a number called Data Link Connection Identifier (DLCI) When a connection is established a DTE is given DLCI which it can use to access the remote DTE. Slide 15: DLCIs Slide 16: PVC DLCIs SVC : SVC Each time two DTEs want to communicate a new VC should be established This is done by the services of another protocol that has network layer and network layer addresses (such as ISDN or IP) The signaling mechanism of this other protocol makes a connection request using the network layer address. After connection phase the VC is established DTEs can exchange data. Slide 18: SVC Setup and Release Slide 19: SVC DLCIs DLCI Inside the Network : DLCI Inside the Network The DLCI are also assigned between two DCEs (switches) inside the network A switch assigns a DLCI to each VC in an interface which is unique for a particular interface. Slide 21: DLCIs Inside a Network Slide 22: Frame Relay Switch Frame Relay Layers : Frame Relay Layers Has only physical and datalink layer. Frame Relay has 1.5 layers as compared to X.25 which has 3 layer. Frame Relay eliminates all the network layer functions and portion of the conventional data link functions. It therefore save processing time of complete 1.5 layers. Slide 24: Frame Relay Layers Slide 25: Comparing Layers in Frame Relay and X.25 Slide 26: Frame Relay Frame Congestion Control : Congestion Control Occurs if data rate is greater than that allowed by network resources. (limited buffer size) Frame Relay does not use flow control at data link layer and does not have network layer. Frame Relay allows users to transmit bursty traffic and therefore has potential to congest the network. Two approaches are adopted for congestion control one is congestion avoidance and the other is traffic control. Congestion Avoidance : Congestion Avoidance Backward Explicit Congestion Notification (BECN Warns sender of congestion so that it can decrease the data rate for transmission. In full duplex mode response frames from the receiver or predefined connection (DLCI=1023) frame, from switch are used for this specific purpose. Sender’s response to the warning is by reducing the rate. Forward Explicit Congestion Notification (FECN) Warns receiver of congestion in network. Frame Relay assumes that sender and receiver are in communication and are using some kind of flow control at higher level. Discarding If user does not respond to congestion notice the Frame Relay discards frames. Which Frames are discarded are subjected to section called traffic control. Slide 29: BECN Slide 30: FECN Slide 31: Four Cases of Congestion Traffic Control : Traffic Control Traffic Control The user in the Frame Relay is required to negotiate the traffic parameters before data is send on the network. This parameter includes Access Rate, Committed Burst Size, Committed information rate and excess burst size. Access Rate Access rate is defined in bits/sec. Depends on band width of channel connecting user and network. User can never exceed this rate. Slide 33: Committed Burst Size (Bc) Maximum number of bits in a predefined period of time that the network is committed to transfer without discarding any frame or setting DE bit e.g Bc= 400 Kb for a period of 4 sec indicates that user can send 300 Kb in first second and 100 Kb in fourth sec withoput worrying about data loss. Slide 34: Committed Information Rate (CRI) Similar to Bc except it defines average rate in bits per sec. If user follows this rate network is committed to deliver the frames. Since it is an average measurement, a user may send data higher than CRI at times or lower than CRI. As long as average is met frames are delivered. The cumulative bits send during a predefined period should not exceed Bc. CRI=Bc/T bps Slide 35: Excess Burst Rate (Be) Be is the maximum number of bits in excess of Bc that a user can send in predefined period of time. Network is committed to transfer these bits if there is no congestion. There is less commitment than in case of Bc. User Rate If area is less than Bc no discarding If area is b/w Bc and Bc + Be possible discarding if congestion. If area is greater than Bc + Be than discarding of frames at first switch. Slide 36: Relationship between Traffic Control Attributes Slide 37: User Rate in Relation to Bc and Bc + Be Slide 39: Three Address Formats Slide 40: FRAD Slide 41: Leaky Bucket Slide 42: A Switch Controlling the Output Rate Slide 43: Flowchart for Leaky Bucket Algorithm Slide 44: Example of Leaky Bucket Algorithm You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Frame Relay raghav18185 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 1190 Category: Others/ Misc License: All Rights Reserved Like it (1) Dislike it (0) Added: November 02, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: sabbodhillon (1 month(s) ago) can u mail me this presentation please Saving..... Post Reply Close Saving..... Edit Comment Close By: brijesh9831 (14 month(s) ago) i want 2 download FRAME RELAY presentation,which i have 2 give in next week at 12 march,2011;plz allow me 2 download this content Saving..... Post Reply Close Saving..... Edit Comment Close By: swapnali2282 (15 month(s) ago) I want to download this presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: ehsanehsanehsan (17 month(s) ago) gud presentation Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: Frame Relay Slide 2: The E-Lines and X-25 n/w were not meeting the requirements of the users. The user was looking at higher data rates, lower costs, efficient data handling of bursty data transmission and less overheads. Demands on Communication Networks : Demands on Communication Networks Higher data rate at lower cost WAN technology such as leased lines & X-25 offered low data rates. The leased lines provide point – to – point connectivity and creating mesh of these lines is very expensive. FR provides higher data rates at lower cost. Demands on Communication Networks : Demands on Communication Networks Bursty Data The leased lines were designed for fixed – rate need Most of the data networks have bursty data and the capacity of leased lines goes unused. Brusty data requires Band Width on demand Frame Relay accepts bursty data. User is granted an average data rate that can be exceeded during bursty periods. Demands on Communication Networks : Demands on Communication Networks Less overhead due to improved Transmission media The quality of transmission media has improved tremendously, they are reliable and less error prone. There is no need for extensive error checking as was being done in X.25. In X.25 both layer 2 and 3 include flow and error control. The source kept the copy of the frame until it receives a confirmation. Much of the traffic on X.25 network is devoted to error checking and ensuring complete reliability of services. Frame Relay does not provide error checking and does not required acknowledgement in the data link layer. Instead all the error checking is left to protocols in the transport and network layer. Many of data link layer operations are eliminated while others are combined. Slide 6: Frame Relay versus Pure Mesh T-Line Network Slide 7: Fixed-Rate versus Bursty Data Slide 8: X.25 Traffic Slide 9: Frame Relay Traffic Advantages of FR over X.25/ Leased lines : Advantages of FR over X.25/ Leased lines Higher speeds (upto 44.376 Mbps) Operates in Physical and data link layers. It can provide services to protocols that already have network layer protocol e.g TCP/IP. If TCP/IP uses the services of X.25 there is duplication in the network layer functions. X.25 has its own network layer. Allows bursty traffic unlike fixed data rates of X.25 and Leased lines. Frame Relay allows frame size of 9000 bytes which can accommodate all local area network frames. Frame Relay is less expensive. Disadvantages : Disadvantages The data rates of 44.376 Mbps is still not high enough for B-ISDN protocols. Frame Relays allows variable length frames. This may create varying delay for users. Not suitable for sending delay sensitive data such as real time voice or video Frame Relay Operation : Frame Relay Operation Frame Relay connects LANs that do not require real time communications. The bridges, routers and servers can be considered as DTEs which are connected to Frame Relay switches (DCE) through leased lines. Slide 13: Frame Relay Network Virtual Circuits (VC) : Virtual Circuits (VC) Frame Relay is a VC network. It does not use physical addresses to define the DTEs connected to network. Virtual Circuit Identifier (VCI) are used to route the traffic on network VCI are at data link layer unlike X.25 where they are at network layer. VC in Frame Relay is identified by a number called Data Link Connection Identifier (DLCI) When a connection is established a DTE is given DLCI which it can use to access the remote DTE. Slide 15: DLCIs Slide 16: PVC DLCIs SVC : SVC Each time two DTEs want to communicate a new VC should be established This is done by the services of another protocol that has network layer and network layer addresses (such as ISDN or IP) The signaling mechanism of this other protocol makes a connection request using the network layer address. After connection phase the VC is established DTEs can exchange data. Slide 18: SVC Setup and Release Slide 19: SVC DLCIs DLCI Inside the Network : DLCI Inside the Network The DLCI are also assigned between two DCEs (switches) inside the network A switch assigns a DLCI to each VC in an interface which is unique for a particular interface. Slide 21: DLCIs Inside a Network Slide 22: Frame Relay Switch Frame Relay Layers : Frame Relay Layers Has only physical and datalink layer. Frame Relay has 1.5 layers as compared to X.25 which has 3 layer. Frame Relay eliminates all the network layer functions and portion of the conventional data link functions. It therefore save processing time of complete 1.5 layers. Slide 24: Frame Relay Layers Slide 25: Comparing Layers in Frame Relay and X.25 Slide 26: Frame Relay Frame Congestion Control : Congestion Control Occurs if data rate is greater than that allowed by network resources. (limited buffer size) Frame Relay does not use flow control at data link layer and does not have network layer. Frame Relay allows users to transmit bursty traffic and therefore has potential to congest the network. Two approaches are adopted for congestion control one is congestion avoidance and the other is traffic control. Congestion Avoidance : Congestion Avoidance Backward Explicit Congestion Notification (BECN Warns sender of congestion so that it can decrease the data rate for transmission. In full duplex mode response frames from the receiver or predefined connection (DLCI=1023) frame, from switch are used for this specific purpose. Sender’s response to the warning is by reducing the rate. Forward Explicit Congestion Notification (FECN) Warns receiver of congestion in network. Frame Relay assumes that sender and receiver are in communication and are using some kind of flow control at higher level. Discarding If user does not respond to congestion notice the Frame Relay discards frames. Which Frames are discarded are subjected to section called traffic control. Slide 29: BECN Slide 30: FECN Slide 31: Four Cases of Congestion Traffic Control : Traffic Control Traffic Control The user in the Frame Relay is required to negotiate the traffic parameters before data is send on the network. This parameter includes Access Rate, Committed Burst Size, Committed information rate and excess burst size. Access Rate Access rate is defined in bits/sec. Depends on band width of channel connecting user and network. User can never exceed this rate. Slide 33: Committed Burst Size (Bc) Maximum number of bits in a predefined period of time that the network is committed to transfer without discarding any frame or setting DE bit e.g Bc= 400 Kb for a period of 4 sec indicates that user can send 300 Kb in first second and 100 Kb in fourth sec withoput worrying about data loss. Slide 34: Committed Information Rate (CRI) Similar to Bc except it defines average rate in bits per sec. If user follows this rate network is committed to deliver the frames. Since it is an average measurement, a user may send data higher than CRI at times or lower than CRI. As long as average is met frames are delivered. The cumulative bits send during a predefined period should not exceed Bc. CRI=Bc/T bps Slide 35: Excess Burst Rate (Be) Be is the maximum number of bits in excess of Bc that a user can send in predefined period of time. Network is committed to transfer these bits if there is no congestion. There is less commitment than in case of Bc. User Rate If area is less than Bc no discarding If area is b/w Bc and Bc + Be possible discarding if congestion. If area is greater than Bc + Be than discarding of frames at first switch. Slide 36: Relationship between Traffic Control Attributes Slide 37: User Rate in Relation to Bc and Bc + Be Slide 39: Three Address Formats Slide 40: FRAD Slide 41: Leaky Bucket Slide 42: A Switch Controlling the Output Rate Slide 43: Flowchart for Leaky Bucket Algorithm Slide 44: Example of Leaky Bucket Algorithm