CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Chabot CollegeChabot College
Frame RelayFrame RelayPart 1Part 1
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay OverviewFrame Relay Overview
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay OperationFrame Relay Operation
Many other WAN technologies (PPP, ATM) can be used inside the FR cloud.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay Uses PVCsFrame Relay Uses PVCs
PVCs have ID numbers called DLCIs.
DLCI - Data Link Control Identifier
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
DLCIs Identify ConnectionsDLCIs Identify Connections
Frame Relay provides a means for statistically multiplexing many logical data conversations (referred to as virtual circuits) by assigning each pair of DTEs connection identifiers.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
DLCIDLCIA number that identifies the logical circuit between the source and destination device. The FR switch maps the DLCIs between each pair of routers to create a PVC.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
DLCIsDLCIs
• Can have “local only” significance.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Local Access RateLocal Access RateThe clock speed (port speed) of the connection (local loop) to the Frame Relay cloud. It is the rate at which data travels into or out of the network.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Local Management InterfaceLocal Management InterfaceA signaling standard between the CPE device and the FR switch that is responsible for managing the connection and maintaining status between the devices.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Possible LMI FunctionsPossible LMI Functions
• keepalive mechanism, which verifies that data is flowing
• a multicast mechanism which can provide the network server with its local DLCI
• multicast addressing
• the ability to give DLCIs global (whole Frame Relay network) significance
• a status mechanism
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Flavors of LMIFlavors of LMI
Different flavors have different features. Currently, ansi is the most common:
ciscocisco—LMI type defined jointly by Cisco, StrataCom, Northern Telecom, and DEC
ansi—Annex D defined by ANSI standard T1.617
q933a—ITU-T Q.933 Annex A
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
LMI ConfigurationLMI Configuration
Remember to configure your router’s interface to use the same LMI type that the FR provider’s equipment is using.
(config-if)#frame-relay lmi-type cisco
(config-if)#frame-relay lmi-type ansi
(config-if)#frame-relay lmi-type q933a
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
CIR - Committed Info RateCIR - Committed Info Rate
The rate, in bits per second, that the Frame Relay switch agrees to transfer data.
Excess Burst—The maximum number of uncommitted bits that the Frame Relay switch will attempt to transfer beyond the CIR.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
DE - Discard EligibilityDE - Discard Eligibility
When the router detects network congestion, the FR switch will drop packets with the DEDE bit set first. The DE bit is set on the oversubscribed traffic; that is, the traffic that was received after the CIR was met.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
FECN and BECNFECN and BECN
Forward explicit congestion notification:Forward explicit congestion notification:
When a Frame Relay switch recognizes congestion in the network, it sends an FECN packet to the destination device indicating that congestion has occurred.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
FECN and BECNFECN and BECN
Backward explicit congestion notification:Backward explicit congestion notification:
When a Frame Relay switch recognizes congestion in the network, it sends a BECNBECN packet to the source router instructing the router to reduce the rate at which it is sending packets.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
FECN and BECNFECN and BECN
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
DLCIsDLCIs
• Can be a number between 16-1007.
illegal
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
LMI - TypesLMI - Types
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay EncapsulationFrame Relay Encapsulation
• The router must be configured to choose which Frame Relay encapsulation will be used.
IETF Encapsulation Type(Most common)
Cisco Encapsulation Type
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
IETF Frame Relay FrameIETF Frame Relay Frame
variable
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Inverse ARPInverse ARP
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Inverse ARPInverse ARP
The Inverse ARPInverse ARP mechanism allows the router to automatically build the Frame Relay map. The router learns the DLCIs that are in use from the switch during the initial LMI exchange. The router then sends an Inverse ARP request to each DLCI for each protocol configured on the interface if the protocol is supported.
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
The Frame Relay MapThe Frame Relay Map
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay OperationFrame Relay Operation
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Frame Relay OperationFrame Relay Operation
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
B.S. - Before SubinterfacesB.S. - Before Subinterfaces
Network 8888
Network 7777
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
SubinterfacesSubinterfaces
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
SubinterfacesSubinterfaces
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Multipoint SubinterfacesMultipoint Subinterfaces
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
Point-to-Point SubinterfacesPoint-to-Point Subinterfaces
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
11.2 + Autodetects LMI type11.2 + Autodetects LMI type
CHABOT COLLEGE CISCO NETWORKING ACADEMYCHABOT COLLEGE CISCO NETWORKING ACADEMY
FR VerificationFR Verification