Introduction to frame relay

Introduction to Frame Relay is a high-performance WAN protocol. It runs on the first and second layers of the OSI reference model, that is, the physical layer and the data link layer. Ii. Related Terms 1. local access rate2, virtual circuit3, permanent virtual circuit (PVC) 4. switched virtual circuit (SVC) 5. data-link connection identifier (DLCI) 6. committed information rate (CIR) 7. inverse address resolution protocol (Inverse ARP) 8. local management interface (LM) 9. forward explicit congestion notification (FECN) 10. backward explicity congestion notification (BECN) 3. connection-oriented protocol for Frame Relay, based on upper-layer error correction and Advanced Optical Transmission Technology The error correction mechanism is not provided. Frame Relay is connected to the ISP's Local switching device on the local router, regardless of how the data is transmitted in the ISP cloud. You can also use a serial point-to-point line for the line used by frame relay. The following Serial Standards are supported by cisco router: EIA/TIA-232EIA/TIA-449EIA/TIA-530V.35V.21 4. frame frames for frame frames contain the following parts: 1. opening flag (0x7E) 2. address3, data4, frame check sequence (FCS) 5, closing flags (0x7E) address are composed of 2 bytes, of which 10 bits belong to the dlci part, in addition, 6 bits are used for congestion management, which is also a commonly used DE bit. The data section contains the encapsulated upper-layer protocol content. 5. address mapping has two address ing methods: 1. Dynamic: ll-( Local management interface) and inverse arp technology provide automatic DLCI discovery and binding 2. static: the second method to establish a connection with the peer end is to manually define static map. 6. troubleshooting: show frame-relay mapshow frame-relay. When the display content contains inactive, this indicates a problem occurs on the peer end. Contact your branch office ISP to solve the problem. When the active prompt appears, it indicates that the frame-relay network is normal. If it is deleted, it is a local problem. Check the related configuration. 7. Several words... Hehe invert flipped endorse approve, agree, and sign on .. Subject to make the service and suffering, limitations 8. frame relay configuration instance // left routerint s1 ip ad 1.1.1.1 255.255.255.0 encapsulation frame-relay bandwidth 64 // right routerint s1 ip ad 1.1.1.2 255.255.0 encapsulation frame-relay bandwidth 64 frame- relay lm-type ansi note: 1. According to the above configuration, the problem is that cisco uses cisco by default and has three types of LMS: ansi cisco q933a, the two ends must be consistent before automatic negotiation can be conducted. 2. bandwidth 64: The function here lies in the dynamic routing protocol, the dynamic routing protocols, such as IGRP, OSPF, and OSPF, are included in the corresponding operation mechanism based on the bandwidth value. 3. encapsulation frame-relay: there are two options: cisco ietf, Which Is cisco by default, when devices of different vendors are used, you can select the standard ietf compression option. The above configuration is based on LMS and Inverse ARP. Generally, static frame relay mapint serial 1 ip ad 1.1.1.1 255.255.255.0 encapsulation frame-relay bandwidth 64 frame-relay map ip 1.1.1.2 110 broadcast. Note: Here 110 is the local dlci number, the broadcast option indicates that the broadcast and multicast data frames can be transmitted on this VC, which can be specified for the normal operation of the dynamic routing protocol. If you do not plan to run OSPF or other protocols on the wide area network, we recommend that you remove the broadcast parameter. 9. Detailed description of the point-to-point and multipoint modes of the frame relay subinterface 1. Each point-to-point act like leased line subinterface must have its own subnet CIDR block, the waste of IP addresses applies to hub and spoke star topology 2 and multipoint act like NBMA networks, so it cannot solve the split-horizon problem. All interfaces are in one network segment, example 1 (point-to-point) int s0 no ip address encapsulation frame-relay int s0.110 point-to-point ip address 1.1.1.1 255.255.0 bandwidth 64 frame-relay interface-dlci 1 10 int s0.120 point-to-point ip address 1.1.1.2 255.255.0 bandwidth 64 frame-relay interface-dlci 120 Note: 1. You must manually specify the point-to-point or multipoint, there is no default option here. 2. When it is specified as point-to-point, local dlci must be configured on the sub-interface to distinguish it from the physical interface. Command: frame-relay interface-dlci 110 (local) 3. When multipoint is specified, make sure that inverse arp is enabled. Do not use the static map 4 and frame-relay interface dlci 110 commands on physical interfaces. 5. If you define a point-to-point sub-interface and want to reset it to a multipoint sub-interface, you must restart the router. You can redefine a subinterface number as an alternative. 6. When using a sub-interface, you only need to configure the encapsulation frame-relay command on the physical interface. Example 2: (multipoint) int serial0 no ip address encapsulation frame-relay interface s2.2 multipoint ip address 1.1.1.1 255.255.255.0 bandwidth 64 frame-relay map ip 1.1.1.2 120 broadcast frame-relay map ip 1.1.1.3 130 broadcast frame-relay map ip 1.1.1.4 140 broadcast note: 1. split horizon is disabled by default on the Multi-Point master interface of frame relay, and is enabled on the multi-point interface by default. We must manually disable the split horizon. 10. Verify the configuration and troubleshooting: show frame-relay traffic // display fram relay traffic statistics clear frame-relay-inarp // clear dynamic created fr maps using inarp show int type number // display information about fr dlci and LMIs show frame-relay LR [type number] // display LMIS statistics show frame-relay map // displays current frame-relay map entries show frame-relay pvc/ /displays pvc statisticsshow interface s0 Encapsulation frame-relay LR dlci 1023 LMIS type is a cisco frame relay DTE that displays LMIS type, dlci number, encapsulation frame-relay, DTE. DCE is used when a Cisco router is configured as a frame relay switch. Show frame-relay lbframe relay DTE lbtype = cisco num status enq. sent 113100 num status msgs rcvd 113100 num update status rcvd 0 num status timeouts 0 show frame-relay pvc 100 dlci = 100, dlci usage = local, pvc status = active, interface = s0 also displays the fecn becn traffic show frame-relay map s0 (up): ip 1.1.1.1 dlci 100 (0 × 64, 0 × 1840), dynamic, broadcast, status defined, active: displays the status set up by dynamic LMS. The status is active and normal, for example, inactiv. E indicates a remote error. For example, deleted indicates a local error, or the interface's DLCI number configuration is reversed, or the ISP removes the corresponding DLCI configuration. Clear frame-relay-inarp: clear dynamically established fr mapdebug frame-relay LCM 11. Common fault phenomena and causes. If interface up is found, line protocol down may be due to the following reasons: 1. Cable, hardware, or carrier reasons, solution: replacement method, respectively test the module, cable 2, LMI-TYPE does not match, solution: Determine the configuration type at both ends is consistent (ansi cisco q933a) 3. keepalives not set. The show interface command is used to search for this type of problem. Most of the problems are caused by humans. For example, the examiner may be here during the CCIE test, the default value is keepalives 10 seconds 4. encapsulation mismatch. when connected to a non-Cisco device, you can only use ietf encap. 5. dlci is inactive or has been deleted. Use the show frame-relay pvc command to observe the PVC status and determine whether the status is local or peer. 6. DLCI is defined on the wrong interface, this may also be where the examiner issued trouble. 7. The frame-relay map command is not configured. In this case, enter clear frame-relay-inarp, you can run the show frame-realy map command to check whether a map is deployed on the bundle. If no map is available, it indicates that dynamic LMS and inarp are not used, and you will have to manually configure static map.