Download Frame Relay Switched Virtual Circuits

Understanding Frame Relay
Frame Relay Presentation by Jeff K. Esquibel
Presentation Overview

Frame Relay Benefits
 Frame Relay Components
 Understanding Frame Relay Services
 Competing Technologies
 Frame Relay’s Market Success
 Future Competition
 Frame Relay Vs. ATM
 Frame Relay Vs. IP
 Co-Existence
 Frame Relay’s Continued Success
Benefits of Frame Relay




Savings over Private Lines
– Reduces number of dedicated devices which
reduces equipment costs
– Reduces complexity for network managers
Greater Bandwidth Flexibility than Private Lines
Higher Reliability and Resiliency than Private
Lines
Lower Cost of Ownership and Better Bandwidth
Utilization
– Growth of Branch Office Networks
Benefits of Frame Relay (cont’d)

Consolidation of LAN, SNA, On-net Voice,
and/or Packetized Video
Simplifies Network Architecture
– Reduces Operations and Administrative Costs
– Improves Application Performance and
Network Efficiency
Smooth migration to ATM
– Service and Network Interworking with ATM
(FRF.5 and FRF.8)
–

Frame Relay Basics: Terms And Definitions

User to Network Interface (UNI)
–

Network to Network Interface (NNI)
–

A pre-defined VC
Switched Virtual Circuit (SVC)
–

The connection between two frame relay ports
Permanent Virtual Circuit (PVC)
–

Specifies signaling and management functions between two frame
relay networks
Virtual Circuit (VC)
–

Specifies signaling and management functions between a frame
relay network device and the end user’s device
A VC that is established dynamically
Data Link Connection Identifier (DLCI)
–
Virtual Circuit Identification Number
Differences between PVCs And SVCs

PVCs
– Staticly Defined at
Configuration,
Unless PVC
Parameters Need to
be Modified
– Connection is Always
Configured Whether
There is Information
to Send or Not

SVCs
– Dynamically
Established When
There is Information
to Send (Call-by-Call
Basis)
– Connection is
Released When
There is No More
Information to Send
Benefits Of SVCs



Simplified Network Design, Particularly for
Large and Highly Meshed Networks
– Scalable Network Design
– Provisioning N*(N-1)/2 Connections Not
Required
Easier to Maintain and Manage
Supports Any-to-Any
Connectivity
Benefits Of SVCs


Can Offer a More Cost-Effective Solution
– Pay Based on Usage: Call Length, Bandwidth
Used, Number of Frames Sent, Etc.
– Only Pay When Using the Network
Offers a Migration Path to PVCs
– Locations Already Have Connections
to the Frame Relay Network
– Can Easily Transition to PVCs as Traffic
Volumes Increase
How Does Frame Relay Work?
Frame Relay Structure
Frame Relay Terms And Definitions (cont’d)

Committed Information Rate (CIR)
–

The bandwidth defined for a VC
Bc = Committed Burst
– Maximum number of committed bits to be transmitted over
time interval

Be = Excess Burst
– Number of Excess bits that will be transmitted over time

Tc Time interval
– Time measurement based how much bandwidth is available
for data to burst on to the network
Frame Relay Terms And Definitions (cont’d)

FECN Forward Explicit Congestion Notification
– Bit set by the network node (FR Switch) that is experiencing
congestion
– Sent in the direction of the receiver (destination)

BECN Backward Explicit Congestion Notification
– Bit set by the network node that is experiencing congestion
– Sent in the direction of the sender (source)

DE Discard Eligible bit
– Set by either the DTE (access device FRAD, router etc.) or
the network nodes (switches)
– May be set selectively by some DTE devices
– May be set by network nodes in the event the user has
exceeded CIR and the network is experiencing congestion
Frame Relay Components
NNI
UNI
Frame Relay
Network
DCE
PVC
DTE
DTE
DCE
DCE
SVC
DCE
DTE
Frame Relay
Network
Service Comparison
Private Lines (TDM)
Frame Relay
Engineer Network for Peak
Traffic Needs
Engineer Network for Average
Traffic Needs
CSU/DSU per Leased Line per
remote site
CSU/DSU per Leased Line that
can access many remote sites
Time Division Multiplexing
Statistical Multiplexing and Burst
Capability
Resiliency is Not Inherent
Resiliency is Inherent in Network
Networking for the New Millennium
Frame
Relay
Frame Relay’s Market Success - U.S.
PL Revs:
$9.6B
$10.4B
$10.9B
$11.3B
$11.8B
$7,000
(in $Ms)
$6,000
$5,000
Private Line
X.25
SMDS
Frame
ATM
$4,000
$3,000
$2,000
$1,000
$0
1996
1997
Source: Vertical Systems Group - 1997
1998
1999
2000
Frame Relay’s Market Success
International
PL Revs:
$6,000
$10.3B
$12.2B
$12.6B
$13.1B
$13.5B
(in $Ms)
$5,000
$4,000
Private Line
X.25
SMDS
Frame
ATM
$3,000
$2,000
$1,000
$0
1996
1997
Source: Vertical Systems Group - 1997
1998
1999
2000
Market Forecast by WAN Technology
Leased Lines
$27.7B
$22.6B
Frame Relay
$6.8B
$3.9B
Network Service Market
Worldwide 1997 and 2000
Estimates
X.25
$2.7B $2.6B
ATM
$1.6B
SMDS
$.242B
$.128B $.167B
Sources: Vertical Systems Group 1997 and Data Comm 1998 Forecast
Frame Relay Complements Other Technologies
Application
LAN
LAN & SNA
Data & On-net Voice
Data, On-net Voice
& Packetized Video
Technology
FR, SMDS, ATM
FR, ATM
FR, ATM
FR, ATM
FR or
ATM
FR or
ATM
Dedicated
or Dial FR
Dial Remote Access
or
Dial FR
Speeds
< 1.5 Mbps
FR
1.5 - 45 Mbps
FR, ATM
>45 Mbps
ATM
Interworking
HQ
Regional
Sites
Remote Sites
Mobile Workers &
Telecommuters
Technology
Agreement
FR - ATM
FRF.5 and FRF.8
FR - SMDS
SIP
Technology Comparison
Private
Line
X.25
SMDS
Frame
Relay
ATM
IP
Speed
56K - 622M
9.6K 2.048M
56K - 34M
Dial 45M
1.5M - 622M
Dial - 45M
Traffic Type
Data/Voice/
Video
Data
Data
Data/On Net
Voice and
Video
Data/Voice/
Video
Data
Connection
Oriented
Yes
Yes
No
Yes
Yes
No
Star/Multipoint/MultiDrop
Star
Any-toAny
No
No
No
Typical
Topology
QoS Support
Mesh/Partial Mesh/Partial
Mesh/Star
Mesh/Star
Proprietary
Yes
Any-toAny
No
The Competitive Road Ahead

ATM / Frame Relay Battle Joined By IP
– Deployment of VPDNs (i.e. Intra/Extranets) Power IP
adoption for Businesses

Majority of End Users Migrating Private Line
Networks Will Look to Frame Relay and IP
– Legacy Applications Demanding Frame Relay Performance;
New Applications a Result of IP Features and Benefits

Frame Relay at the Edge, ATM at the Core

Frame Relay Transport for IP Services
High Speed IP Environments

Solutions/Technologies Outside Frame Relays’
Intended Scope are Servicing the Very High
Speed IP Environments and Campus Backbone
– IP Over SONET Offers Users a Simple and
Efficient High Speed Transport Option for IP at
OC-3 and Greater Speeds
– Gigabit Ethernet Delivers the Mass Bandwidth
Many Campus Backbones Operating in a Pure
Data Environment Require
Co-Existence
Frame Relay
ATM
IP
VPN’s, Intranet,
Extranet, etc.

Even as Buying Decisions Move Away from Underlying
Connectivity, Frame Relay will Continue to Play a Major
Role In Service Delivery
Summary
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Frame Relay is Widely Accepted and Deployed,
Building Upon its Own Momentum
Frame Relay’s Longevity and Visibility as a
Technology is Fostered by its Ability to Co-exist
and Complement Legacy as well as Emerging
Technologies
Standards Continue to Evolve to Meet Changing
End User Environments and Requirements
Frame Relay Will Continue to Play an Integral Part
in Layer 2 Connectivity
Accelerated Growth in Frame Relay
Implementations is Expected to Continue
Market Maturity of ATM and IP Still Years Away
Frame Relay Reference Material
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Frame Relay Forum Web page www.frforum.com
Data Communications Magazine
www.datacomm.com
Network World www.nwfusion.com
Internet Week (formerly CommWeek)
www.internetwk.com
Black, Uyless. Frame Relay Networks:
Specifications and Implementations. 2nd ed. New
York: McGraw-Hill, 1996.
Smith, Philip. Frame Relay: Principles and
Applications Wokingham, England: AddisonWesley, 1995.
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