Frame relay
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Frame Relay is a connection-oriented WAN service based on packet switching technology, offering lower costs compared to leased lines but with lower security and no error recovery mechanism. It operates at the data link layer, using data-link connection identifiers (DLCIs) for logical connections between devices, and is commonly used to interconnect local area networks (LANs). The service can be provided by public carriers or private networks, and utilizes Local Management Interface (LMI) for connection management and status reporting.
Frame relay
- 1. FRAME RELAY 1.Shared technology. 2.Less costly then direct lease lines. 3.Low security. 4.Based on packet switching technology.
- 2. FRAME RELAY Frame Relay is a packet-switched, connection- oriented, WAN service. It operates at the data link layer of the OSI reference model. Frame Relay uses a subset of the high-level data link control (HDLC) protocol called Link Access Procedure for Frame Relay (LAPF). Frames carry data between user devices called data terminal equipment (DTE), and the data communications equipment (DCE) at the edge of the WAN. Frame relay is based on the Packet switching technology. It does not define the way the data is transmitted within the service provider’s Frame Relay cloud. This is ATM in many cases!
- 3. FRAME RELAY Typical speeds range from 56 kbps up to 2 Mbps, although higher speeds are possible. (Up to 45 Mbps) The network providing the Frame Relay service can be either a carrier-provided public network or a privately owned network. Because it was designed to operate on high-quality digital lines, Frame Relay provides no error recovery mechanism. If there is an error in a frame it is discarded without notification.
- 4. FRAME RELAY A Frame Relay network may be privately owned, but it is more commonly provided as a service by a public carrier. Because a private owned network is very costly for any organization. It typically consists of many geographically scattered Frame Relay switches interconnected by trunk lines. which is also shared by many other fame relay links. Frame Relay is often used to interconnect LANs. When this is the case, a router on each LAN will be the DTE. A serial connection, such as a T1/E1 leased line, will connect the router to a Frame Relay switch of the carrier at the nearest point-of-presence for the carrier. (access circuit)
- 5. FRAME RELAY DLCI A data-link connection identifier (DLCI) identifies the logical VC between the CPE(connection provider equipment) and the Frame Relay switch. The Frame Relay switch maps the DLCIs between each pair of routers to create a PVC. DLCIs have local significance, although there some implementations that use global DLCIs. DLCIs 0 to 15 and 1008 to 1023 are reserved for special purposes. Service providers assign DLCIs in the range of 16 to 1007. DLCI 1019, 1020: Multicasts DLCI 1023: Cisco LMI DLCI 0: ANSI LMI
- 6. FRAME RELAY LMI LMI: local management interface is a signaling standard between the DTE and the Frame Relay switch. LMI is responsible for managing the connection and maintaining the status between devices. LMI includes: A keep alive mechanism, which verifies that data is flowing A multicast mechanism, which provides the network server (router) with its local DLCI. The Global addressing, which can give DLCIs global rather than local significance in Frame Relay networks (not common). A status mechanism, which provides an ongoing status on the DLCIs known to the switch
- 7. FRAME RELAY LMI states Frame Relay devices can now listen in on both DLCI 1023 or Cisco LMI and DLCI 0 or ANSI and ITU-T simultaneously. The order is ansi, q933a, cisco and is done in rapid succession to accommodate intelligent switches that can handle multiple formats simultaneously. The Frame Relay switch uses LMI to report the status of configured PVCs. The three possible PVC states are as follows: Active state – Indicates that the connection is active and that routers can exchange data. Inactive state – Indicates that the local connection to the Frame Relay switch is working, but the remote router connection to the Frame Relay switch is not working. Deleted state – Indicates that no LMI is being received from the Frame Relay switch, or that there is no service between the CPE router and Frame Relay switch.
- 8. FRAME RELAY Encapsulation Router(config-if)#encapsulation frame-relay {cisco|ietf} FRAME RELAY LMI Router(config-if)#frame-relay lmi-type {ansi | cisco | q933a}
- 9. FRAME RELAY Configuration Frame Relay Network Headquarters Hub City Satellite Office 1 Spokane 172.16.1.1172.16.1.2 DLCI 101 DLCI 102 HubCity(config)# interface serial 0 HubCity(config-if)# ip address 172.16.1.2 255.255.255.0 HubCity(config-if)# encapsulation frame-relay HubCity(config-if)#frame-relay interface-dlci 100 HubCity(config-if)#frame-relay lmi-type cisco Spokane(config)# interface serial 0 Spokane(config-if)# ip address 172.16.1.1 255.255.255.0 Spokane(config-if)# encapsulation frame-relay Spokane(config-if)# frame-relay interface-dlci 200 Spokane(config-if)# frame-relay lmi-type cisco
- 10. FRAME RELAY cloud configuration Serial0=ldh serial1=chd Dlci=100 dlci=20 Name=ldh name=chd add
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