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The main purpose of this TCS was to familiarize the students with the Frame Relay encapsulation type. They had to learn how it functioned, its advantages over other encapsulations, and how to implement it on to a router. There were also other related learning objectives.

The main learning objectives of the TCS were the following:

1. Describe at what layer of a hierarchical WAN model an ISDN link should be installed.

An ISDN link should be installed at the distribution layer of a hierarchical WAN model. The reason for this is that the ISDN link should be considered part of the backbone between the remote user and the central WAN switch or router. Backbone cabling is by definition located at the distribution.

2. Describe what layers of the OSI model Frame Relay standards address and what are their functions at these layers.

Frame Relay CCITT and American National Standards Institute standard that defines the process for sending data over a public data network (PDN). It is a data-link technology that is streamlined to provide high performance and efficiency. It operates at the Physical and Data Link Layers of the OSI model but it relies on upper layer protocols such as TCP for error correction.

3. Describe what a Permanent Virtual Circuit is.

Permanent Virtual Circuits are the connections that Frame Relay uses to communicate with each other. A PVC is a Virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and tear down in situations where certain virtual circuits must exist all the time.

4. Describe what Discard Eligibility is and what is its function.

The Discard Eligibility Indicator is when the router detects network congestion, the Frame Relay switch will drop packets with the DE bit set first. The DE bit is set on the oversubscribed traffic; that is, the traffic that was received after the CIR was met.

5. How to implement Frame Relay on a router. 

Prompt:		Command:
router-d>		enable
Password:		cisco
router-d#		config t
router-d(config)#		config if s0/0
router-d(config-if)#		encapsulation frame-relay cisco
router-d(config-if)#		frame-relay lmi-type cisco
router-d(config-if)#		bandwidth 56000
router-d(config-if)#		frame-relay inverse-arp ip 1000
router-d(config-if)#		keepalive 12
router-d(config-if)#		frame-relay local-dlci # (# is the dlci number you wish to assign)
router-d(config-if)#		exit
router-d(config)#		exit
router-d#		copy run start

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