What is Frame Relay and How to Configure Dynamic Mapping of Frame Relay

What is Frame Relay 

Frame Relay is a streamlined connection-oriented Data-Link technology that provides efficiency and high performance. It is dependable on digital networks and fiber, and also it relies on upper-layer protocols for error protection.

Frame Relay WAN attached devices fall into the following two categories:

1.     DCE (Data Communication Equipment)

The Switches in a WAN are Frame Relay switches in most cases.

2.     DTE (Data Terminal Equipment)               

Routers, bridges, and Frame Relay Access Devices (FRAD) are an example of DTE devices.

In Frame Relay the following terms are used frequently:

Virtual Circuit (VC)

A logical circuit is created to ensure bidirectional communication from one DTE device to another, and it is uniquely identified by a Data-Link connection identifier (DLCI).

Local Access Rate (LAR)

Regardless of other settings, the rate at which data travels into or out of the network.

Permanent Virtual Circuit (PVC)

PVC provides established connections permanently that are used for consistent and frequent data transfers.

Switched Virtual Circuit (SVC)

SVC provides temporary connections that are used in situations that require only sporadic data transfer across the Frame Relay network between DTE devices.

Data-Link Connection Identifier (DLCI)

DLCI identifies the VC (Virtual Connection) that contains a 10-bit number in the address field of the Frame Relay frame header. The significance of the DLCI has Local because the identifier references the point between the local Frame Relay switch and the local router to which the DLCI is connected. Therefore, opposite ends of the device connection can use different values of DLCI to refer to the same virtual connection.

Committed Information Rate (CIR)

Specify the CIR when subscribing to a Frame Relay service which is the local access rate, For example, T1 or 56 kbps. Typically, for each DLCI you’re also asked to specify CIR. If the information is sent faster than the CIR on a given DLCI, the network flags some frames with a DE (Discard Eligible) bit.

Inverse Address Resolution Protocol (IARP)

A dynamic method is associating the remote router network layer address with a local DLCI.

Local Management Interface (LMI)

LMI is a signaling standard between the local Frame Relay switch (DCE device) and the router (DTE device) that is responsible for maintaining the status and managing the connection between the Frame Relay switch and the router.

Forward Explicit Congestion Notification (FECN)

FECN is a bit in the address field of the Frame Relay frame header. Frame Relay switches (DCE devices) set the frame FECN bit value to 1 to signal downstream router (DTE devices) that flow control might be warranted if the network is congested.

Backward Explicit Congestion Notification (BECN)

BECN is a bit in the address field of the Frame Relay frame header. BECN operates like the FECN bit but in the opposite direction it travels, informing upstream router (DTE devices) that congestion is occurring and that flow control might be warranted.

Dynamic Mapping of Frame Relay

The IP address of devices must be mapped to their DLCIs (Data-Link Connection Identifier) to communicate with each other over a Frame Relay. There are two ways to ensure that this mapping occurs automatic and manual.

The way to automatically map addresses to their DLCIs is by using the IARP (Inverse ARP) function. By default, Inverse ARP is enabled on an interface but automatically it is disabled on a DLCI when the command of the Frame Relay map is used.

Dynamic Mapping of Frame Relay

Note: We will configure a Cloud as a Frame Relay Switch, and we could also use Frame Relay Switch used in GNS3.

How to Configure Dynamic Mapping of Frame Relay

Configuring Host Names of the Routers R1, R2, and R3

Router R1 (HUB)

Router>enable

Router# configure terminal

Enter configuration commands, one per line. End with CNTL / Z.

Router (config) # hostname HUB

HUB (config) #

Router R2 (SPOKE1)

Router>enable

Router# configure terminal

Enter configuration commands, one per line. End with CNTL / Z.

Router (config) # hostname SPOKE1

SPOKE1 (config) #

Router R3 (SPOKE2)

Router>enable

Router# configure terminal

Enter configuration commands, one per line. End with CNTL / Z.

Router (config) # hostname SPOKE2

SPOKE2 (config) #

Configuring the Cloud as a Frame Relay Switch

Changing the Cloud Name

Frame Relay Switch Configuration

Creating DLCIs and Connecting the Routers with Frame 

Relay Switch

Router 1(HUB) to Cloud

Open the Cloud and then click on the config option, and then click on the interface to which the HUB is connected. Configure the DLCIs on the interfaces.

DLCIs Configuration

Router 2 (SPOKE1)

Click on the interface to which Spoke1 is connected on the Cloud.

Spoke DLCIs Configuration

Router 3 (SPOKE2)

 Click on the interface to which Spoke2 is connected on the Cloud.

Spoke DLCIs Configuration

Connecting the Routers (SPOKES) with Frame Relay on 

the Cloud

Connecting Frame Relya to Cloud

Configuring IP Addresses and Dynamic Routing on 

Router Interfaces

Router 1 (HUB)

HUB (config) #interface G0/0

HUB (config-if) #ip add 192.168.1.10 255.255.255.0

HUB (config-if) #no shutdown

Interface Status UP

HUB (config-if) #exit

HUB (config) #router ospf 1

HUB (config-router) #network 192.168.1.0 0.0.0.255 area 1

HUB (config-router) #network 10.0.0.0 0.0.0.3 area 1

HUB (config-router) #network 10.0.1.0 0.0.0.3 area 1

HUB (config-router) #end

HUB#

Router 2 (SPOKE1)

SPOKE1 (config) # interface G0/0

SPOKE1 (config-if) #ip add 192.168.2.10 255.255.255.0

SPOKE1 (config-if) #no shutdown

Interface Status UP

SPOKE1 (config-if) #exit

SPOKE1 (config) # router ospf 1

SPOKE1 (config-router) #network 192.168.2.0 0.0.0.255 area 1

SPOKE1 (config-router) #network 10.0.0.0 0.0.0.3 area 1

SPOKE1 (config-router) #end

SPOKE1#

Router 3 (SPOKE2)

SPOKE2 (config) # interface G0/0

SPOKE2 (config-if) #ip add 192.168.3.10 255.255.255.0

SPOKE2 (config-if) #no sh

Interface Status UP

SPOKE2 (config-if) #exit

SPOKE2 (config) #router ospf 1

SPOKE2 (config-router) #network 192.168.3.0 0.0.0.255 area 1

SPOKE2 (config-router) #network 10.0.1.0 0.0.0.3 area 1

SPOKE2 (config-router) #end

SPOKE2#

Creating DLCIs and Configuring Frame Relay on Router 

Sub-Interfaces

Router 1 (HUB)

HUB# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

HUB (config) #interface S0/3/0

HUB (config-if) #no shutdown

%LINK-5-CHANGED: Interface Serial0/3/0, changed state to up

HUB (config-if) #no ip address

HUB (config-if) #encapsulation?

encapsulation frame-relay

HUB (config-if) #encapsulation frame-relay

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/3/0, changed state to up

HUB (config-if) # frame-relay inverse-arp

HUB (config-if) # frame-relay lmi-type?

frame-relay lmi-type Ansi

HUB (config-if) # frame-relay lmi-type ansi

HUB (config-if) #interface S0/3/0.107 point-to-point

Interface Status UP

HUB (config-subif) #ip address 10.0.0.1 255.255.255.252

HUB (config-subif) #frame-relay interface-dlci 107

HUB (config-subif) #end

HUB# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

HUB (config) #interface S0/3/0.109 point-to-point

Interface Status UP

HUB (config-subif) #frame-relay interface-dlci 109

HUB (config-subif) #ip address 10.0.1.1 255.255.255.252

HUB (config-subif) #no shutdown

HUB (config-subif) #end

%SYS-5-CONFIG_I: Configured from console by console

HUB#

Router 2 (SPOKE1)

SPOKE1# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

SPOKE1 (config) #interface S0/3/0

SPOKE1 (config-if) #no shutdown

%LINK-5-CHANGED: Interface Serial0/3/0, changed state to up

SPOKE1 (config-if) #encapsulation frame-relay

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/3/0, changed state to up

SPOKE1 (config-if) # frame-relay inverse-arp

SPOKE1 (config-if) # frame-relay lmi-type ansi

SPOKE1 (config-if) # no ip address

SPOKE1 (config-if) #int S0/3/0.207 point-to-point

Interface Status UP

SPOKE1 (config-subif) #ip address 10.0.0.2 255.255.255.252

SPOKE1 (config-subif) #no shutdown

SPOKE1 (config-subif) #frame-relay interface-dlci 207

SPOKE1 (config-subif) #end

%SYS-5-CONFIG_I: Configured from console by console

OSPF Neighbor

SPOKE1#

Router 3 (SPOKE2)

SPOKE2# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

SPOKE2 (config) #interface S0/3/0

SPOKE2 (config-if) #no shutdown

%LINK-5-CHANGED: Interface Serial0/3/0, changed state to up

SPOKE2 (config-if) #encapsulation frame-relay

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/3/0, changed state to up

SPOKE2 (config-if) # frame-relay inverse-arp

SPOKE2 (config-if) # frame-relay lmi-type ansi

SPOKE2 (config-if) # no ip address

SPOKE2 (config-if) #int S0/3/0.209 point-to-point

Interface Status UP

SPOKE2 (config-subif) #ip address 10.0.1.2 255.255.255.252

SPOKE2 (config-subif) #no shutdown

SPOKE2 (config-subif) #frame-relay interface-dlci 209

SPOKE2 (config-subif) #end

%SYS-5-CONFIG_I: Configured from console by console

OSPF Neighbor

SPOKE2#

Frame Relay Verification on Routers

Router 1 (HUB)

HUB# show frame-relay map

frame-relay map

HUB#

Router 2 (SPOKE1)

SPOKE1# show frame-relay map

frame-relay map

SPOKE1#

Router 3 (SPOKE2)

SPOKE2# show frame-relay map

frame-relay map

SPOKE2#

Ping Verification

LP1 to DLCI 207 IP Address

PC> ping 10.0.0.2

Successful Ping Status

LP1 to DLCI 209 IP Address

PC> ping 10.0.1.2

Successful Ping Status

LP 1 to LP 3

PC> ping 192.168.2.2

Successful Ping Status

LP 1 to LP 5

PC> ping 192.168.3.2

Successful Ping Status

LP 4 to LP 2

PC> ping 192.168.2.1

Successful Ping Status

Search Tags

1. Configuring Static and Dynamic DLCI to Network Layer
2. What is Frame Relay map?
3. Frame Relay Address Mapping
4. Frame-Relay Configuration with both Inverse-ARP

If you want to Configure Static Mapping of Frame Relay then visit: 👇

How to Configure Frame Relay Static Mapping

Get Packet Tracer Lab