CCNA: Frame Relay

2 minute read

Rules:

  1. Set encapsulation
  2. Set LMI type (optional)
  3. Configure static/dynamic address mapping
  4. Address protocol-specific problems

Configuring Frame-Relay client side (using sub-interfaces):

R1#config t
R1(config)#int s0/0/0
R1(config-if)#no ip address
R1(config-if)#encapsulation frame-relay
R1(config-if)#exit
R1(config)#int s0/0/0.302 point-to-point
R1(config-if)#ip address 10.1.1.10 255.255.255.252
R1(config-if)#frame-relay interface-dlci 302 # local dlci that connects to 203
R1(config-if)#int s0/0/0.301 point-to-point
R1(config-if)#ip address 10.1.1.13 255.255.255.252
R1(config-if)#frame-relay interface-dlci 301 # local dlci that connects to 103
R1(config-if)#end
R1#config t
R1(config)#int s0/0/0
R1(config-if)#no shut # wait until you are done configuring sub-interfaces before bringing this online
R1(config-if)#end
R1#copy run start

R2#config t
R2(config)#int s0/0/0
R2(config-if)#no ip address
R2(config-if)#encapsulation frame-relay
R2(config-if)#exit
R2(config)#int s0/0/0.203 point-to-point
R2(config-if)#ip address 10.1.1.10 255.255.255.252
R2(config-if)#frame-relay interface-dlci 203 # local dlci that connects to 302 on R1
R2(config-if)#end
R2#config t
R2(config)#int s0/0/0
R2(config-if)#no shut # wait until you are done configuring sub-interfaces before bringing this online
R2(config-if)#end
R2#copy run start

R3#config t
R3(config)#int s0/0/0
R3(config-if)#no ip address
R3(config-if)#encapsulation frame-relay
R3(config-if)#exit
R3(config)#int s0/0/0.103 point-to-point
R3(config-if)#ip address 10.1.1.10 255.255.255.252
R3(config-if)#frame-relay interface-dlci 103 # local dlci that connects to 301 on R1
R3(config-if)#end
R3#config t
R3(config)#int s0/0/0
R3(config-if)#no shut # wait until you are done configuring sub-interfaces before bringing this online
R3(config-if)#end
R3#copy run start

Frame Relay Switch:

NOTE: You don’t have to know this for the exam, but it’s good to know anyway!

Router#conf t
Router(config)#frame-relay switching
Router(config)#int s0
Router(config-if)#clock rate 64000
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay intf-type dce
Router(config-if)#frame-relay route 121 interface s1 112
Router(config-if)#frame-relay route 121 interface s2 111
Router(config-if)#no shut
Router(config-if)#int s1
Router(config-if)#clock rate 64000
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay intf-type dce
Router(config-if)#frame-relay route 112 interface s0 121
Router(config-if)#frame-relay route 112 interface s2 111
Router(config-if)#int s2
Router(config-if)#clock rate 64000
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay intf-type dce
Router(config-if)#frame-relay route 111 interface s0 121
Router(config-if)#frame-relay route 111 interface s1 112
Router(config-if)#no shut
Router#show frame-relay route

Show Commands:

show frame-relay map #after a connection is established
show frame-relay route
show frame-relay pvc
debug frame-relay pvc
debug frame-relay lmi # you want it to report status 0x2 , which is an active link

Main Notes:

“clock rate” commands are usually only issued on the DCE side, not DTE. The DCE sets the clock and the client adjusts to match it.
Packet Switched Networks: X.25, Frame Relay, ATM, MPLS – The concepts of Frame Relay is why it is important.
PVC – Permanent Virtual Circuit. Similar to VPNs.
CIR – Commited inforamtion rate – Lowest bandwidth provided.
Local Access Rate – How fast can it physically go. CIR is minimmum and Access Rate is maximum.
DLCI – Data link connection identifier – Addresses the ISP uses. DLCIs are locally significant. If you leave 105 to go to 501 then you arrive coming FROM 501!
LMI – Local Managment interface – Language between ISP and your router – Cisco, ANSI, and Q.933A
PVC Designs – Partial mesh, full mesh, and hub/spoke.
Multipoint: All on same subnet, multiple DLCIs mapped to interface, causes problems with split horizon. Multipoint should be used for full mesh. In partial and hub/spoke, use point to point.
MPLS is an ISP type technology – Any to Any with tagging.
PVC – permanent virtual connections.
DE bits tell us how many frames are being dropped because traffic that exceeds CIE.
FECN – Forward explicit congestion notification.
DECN – Same but backwards.

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