Day 20.2 frame relay
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The document provides an overview of frame relay technology, detailing its features, operation, and essential terminology. It outlines the configuration of serial frame relay connections, the significance of local access rates, virtual circuits, and issues related to routing updates in non-broadcast multi-access (NBMA) environments. The summary highlights the importance of LMI signaling standards and the mapping of DLCIs for proper communication between devices.
Day 20.2 frame relay
- 1. © 2002, Cisco Systems, Inc. All rights reserved.
- 2. © 2002, Cisco Systems, Inc. All rights reserved. 2 Establishing Frame Relay Connections Module 8
- 3. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-3 Objectives Upon completing this module, you will be able to: • Use Cisco IOS commands to configure an operational serial Frame Relay connection and Frame Relay subinterfaces, given a functioning router • Use show commands to identify anomalies in an operational serial Frame Relay connection and Frame Relay subinterfaces, given a functioning router • Use debug commands to identify events and anomalies in an operational serial Frame Relay connection and Frame Relay subinterfaces, given a functioning router and an operational serial Frame Relay connection
- 4. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-4© 2002, Cisco Systems, Inc. All rights reserved. 4 Frame Relay Overview
- 5. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-5 Objectives Upon completing this lesson, you will be able to: • Describe the features and operation of a Frame Relay network • Define important Frame Relay terms including local access rate, virtual circuit, PVC, SVC, DLCI, CIR, InARP, LMI, FECN, and BECN
- 6. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-6 Frame Relay Overview • Connections made by virtual circuits • Connection-oriented service
- 7. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-7 Frame Relay Stack OSI Reference Model Frame Relay Physical Presentation Session Transport Network Data-Link Application EIA/TIA-232, EIA/TIA-449, V.35, X.21, EIA/TIA-530 Frame Relay IP/IPX/AppleTalk, etc.
- 8. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-8 Frame Relay Terminology
- 9. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-9 • Frame Relay default: nonbroadcast, multiaccess (NBMA) Selecting a Frame Relay Topology
- 10. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-10 Reachability Issues with Routing Updates Problem: • Broadcast traffic must be replicated for each active connection. • Split-horizon rule prevents routing updates received on one interface from being forwarded out the same interface.
- 11. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-11 Resolving Reachability Issues • Split horizon can cause problems in NBMA environments. • Subinterfaces can resolve split horizon issues. • Solution: A single physical interface simulates multiple logical interfaces.
- 12. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-12 Frame Relay Address Mapping • Use LMI to get locally significant DLCI from the Frame Relay switch. • Use Inverse ARP to map the local DLCI to the remote router’s network layer address.
- 13. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-13 Frame Relay Signaling • Cisco supports three LMI standards: – Cisco – ANSI T1.617 Annex D – ITU-T Q.933 Annex A
- 14. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-14 Frame Relay Inverse ARP and LMI Signaling
- 15. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-15 Stages of Inverse ARP and LMI Operation
- 16. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-16 How Service Providers Map Frame Relay DLCIs: Service Provider View
- 17. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-17 How Service Providers Map Frame Relay DLCIs: Enterprise View
- 18. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-18 Service Provider Frame Relay-to-ATM Interworking
- 19. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-19 FRF.8 Service Interworking
- 20. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-20 Summary • Frame Relay is an ITU-T and ANSI standard that defines the process for sending data over a public data network. • The core aspects of Frame Relay function at the lower two layers of the OSI reference model. • Knowing the terms that are used frequently when discussing Frame Relay is important to understanding the operation and configuration of Frame Relay services. • Frame Relay allows you to interconnect your remote sites in a variety of topologies including star, full mesh, and partial mesh. • A Frame Relay NBMA topology may cause routing update reachability issues, which are solved by using subinterfaces.
- 21. © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0—8-21 Summary (Cont.) • A Frame Relay connection requires that, on a VC, the local DLCI be mapped to a destination network layer address such as an IP address. • LMI is a signaling standard between the router and the Frame Relay switch that is responsible for managing the connection and maintaining status between the devices. • Service providers map Frame Relay DLCIs so that DLCIs with local significance appear at each end of a Frame Relay connection. • FRF.5 provides network interworking functionality that allows Frame Relay end users to communicate over an intermediate ATM network that supports FRF.5. FRF.8 provides service interworking functionality that allows a Frame Relay end user to communicate with an ATM end user.