Frame Relay

Frame Relay + Configuration
GROUP MEMBERS:
 TOSEEF HASSAN (BSF1600847)
 MUHAMMAD UMAR (BSF1600824)
 MUHAMMAD ISHFAQ (BSF1604280)
 HAMMAD AHMED (BSF1600830)

Frame Relay + Configuration
TOPICS TO BE COVERED:
 TYPES OF CONNECTIONS
 FRAME RELAY
• Definition
• Access Links
• DTE/DCE
• LMI
• Virtual Circuits
• DLCI
 CONFIGURATION

TYPES OF WAN CONNECTIONS:
To understand the concepts of Frame Relay, first we have to look at
the types of connections of WAN.
There are three basic types of WAN connections:
• Leased Lines
• Packet Switched
• Circuit Switched

LEASED LINES:
In leased lines connection, routers at different locations/sites are
connected through physical lines (cables).
It is also called point-to-point network. Beside the routers and cables,
other networking equipment is also used e.g.
• CPE (Customer Premises Equipment)
• CSU/DSU (Channel Service Unit/Digital Service Unit)
• WAN Switch

LEASED LINES:
CPE refers to the devices that are at the customer site from
the ISP’s perspective. For instance, both the CSU/DSU and
router are CPE devices in the picture below.

PACKET-SWITCHED
 In a packet switched service, physical WAN
connectivity exists, similar to leased lines.
 However, the devices connected to a packet-
switched service can communicate directly with
each other, using a single connection to the
service.
 There are two types of packet-switched service:
• Frame-relay
• ATM (Asynchronous Transfer Mode)

CIRCUIT SWITCHED:
 Circuit switched network is a type of network
where the communication between the end
devices (nodes) must be setup before they can
communicate.
 Once setup, the ‘circuit’ is dedicated to the two
nodes, it connects for the duration of that
connection.
 An example of circuit-switched network is an
analog telephone network.

FRAME RELAY:
 Frame relay is a wide area network (WAN)
connection which used to allow routers at remote
locations to connect to each other without any
physical connection.
OR
 Frame relay is a set of WAN standards that create
a more efficient WAN service as compared to
point-to-point links, while still allowing pairs of
routers to send data directly to each other.

FRAME RELAY:
 ACCESS LINK:
• A leased line is installed between the router and a nearby
frame relay switch; this link is called access link.
• To ensure the link is working, the device outside the
frame relay network called the data terminal equipment
(DTE), exchanges regular messages with the frame relay
switch.
• These keepalive messages with other messages are
defined by the frame relay Local Management Interface
(LMI).

FRAME RELAY:
 DTE/DCE:
• The routers are considered as Data Terminal Equipment
(DTEs), and the frame relay switches are Data
Communications Equipment (DCE).
 VIRTUAL CIRCUIT:
• The logical communication path between each pair of
DTEs is called virtual circuit.
• Virtual circuits have two types:
o PVC (Permanent Virtual Circuit)
o SCV (Switched Virtual Circuit)

FRAME RELAY:
 PVC:
• Pre-defined VCs are called Permanent Virtual Circuits
(PVC).
 SVC:
• A VC that is set up dynamically when needed is called
Switched Virtual Circuit (SVC).

FRAME RELAY:
 DLCI:
• Routers use Data Link Connection Identifier (DLCI) as
the frame relay address, it identifies the VC over which
the frame should travel.
• In the above figure, when R1 needs to forward a packet
to R2, R1 encapsulates the layer 3 packet into a frame
relay header and trailer and then sends the frame.

Frame Relay

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