Outlines Received due 13 March %

Homework n Review for Midterm (1 March 2000) n Research Paper n Readings [9] “MPLS: Special Delivery” [10] “Diversifying Internet Delivery”

Frame Relay n ANSI Standard covering OSI Layer 2 n Accessed by Routers or FRAD’s n Derived from X.25 Protocol Dumps almost all error checking Requires fiber on the long haul n Uses Permanent Virtual Circuits (PVC’s) VC differs from Datagram Long Term Connection Requires Carrier intervention to change

Frame Relay n Committed Information Rate (CIR) Is a Quality of Service Guarantee ‘Guaranteed’ minimum Bandwidth Should be set > average traffic during appropriate peak period n Port Connection Speed a.k.a. Port Speed or Burst Speed Bandwidth you can burst to provided network capacity exists.

Ex) 1.54 Mbps Leased Lines IXC & Local Carriers dedicate 1.54 Mbps to our use via Circuit Switching & TDM. OKC Detroit NYC IXC Leased Line Network Router Leased Line

Carrier Leased Line Network Leased Line ‘Cloud’ Trunks use TDM & Circuit Switching Cross-Connect Trunks Leased Line

Ex) Frame Relay Local Carriers dedicate 1.54 Mbps to our use. IXC provides random Packet Switched StatMux connectivity via PVC’s. OKC Detroit NYC IXC Frame Relay Network PVC, OKC - Detroit PVC, NYC - OKC Router

Frame Relay Backbone Frame Relay ‘Cloud’ Trunks use StatMux & Packet Switching FR Switch Trunks Leased Line

Ex) Internet Local Carriers dedicate 1.54 Mbps to our use. ISP provides random Packet Switched StatMux connectivity via datagrams. OKC Detroit NYC ISP Network Router

Internet Service Provider Backbone ISP ‘Cloud’ Trunks use StatMux & Packet Switching Router Trunks Leased Line

WAN Design (Link Reduction) n Start with Traffic Matrix n Examine Full Mesh n Consider eliminating lightly used links n Compare costs at each iteration

Circuit Switched connections waste bandwidth for bursty traffic. time traffic NYC to OKC 1.54 Mbps Line Speed 146 Kbps Average Idle Time >> Active Time

Frame Relay n End-to-End Delay Frame Relay > equivalent sized Leased Line Network n Cost Tendency Frame Relay < equivalent sized Leased Line Network

Frame Relay (Inside the Cloud) n Examined a specific case Frame Relay Switch 100 Mbps Trunk ?? 1.54 Mbps Connections P(Access Line is Active) = 10% How many access lines can this switch support?

Bounds on Packet Switch Carrying Capacity 100 Mbps Trunk, 1.54 Mbps Inputs with 154 Kbps average loads LowerUpper 90% % % % Availability Where switch could operate Where switch probably operates

Given 100 Mbps of Bandwidth... n Mbps Circuit Switched TDM Customers n Mbps Packet Switched StatMux Customers with 154 Kbps average load & 99.99% availability More Bursty Data Traffic can be moved with the Packet Switched StatMux network.

Network Cost... n Can be spread over 64 Leased Line customers n Can be spread over 421 Frame Relay customers n Frame Relay & the Internet Are Packet Switched StatMux network Largely hauling bursty data traffic Effectively haul bursty data traffic Inexpensive (compared to a Leased Line)

Switched Network Carrying Capacities 0% Data 100% Data 100% TST 0% TST Offered Load Carrying Capacity Circuit Switch TDM Packet Switch StatMux

Voice Over Frame Relay n Many of same problems as Voice over IP Designed for data One Priority n Quality is worse than Telephone System n Quality is better than Internet Voice CIR guarantees Bandwidth FRAD can prioritize voice n Video over FR products now available

Priorities are a double edged sword... n There is only so much pie to go around Frame Relay Switch 100 Mbps Trunk Hi Priority Voice PVC’s Lo Priority Data PVC’s If voice gets preference, data will suffer!

QoS n DE bit used by FR switches to police network n Traffic > CIR enters switch in a 1 second interval? Marked DE n If you are behaving......and other users exceed their CIR’s......and FR switch becomes congested......then other users’ traffic gets dumped 1st......your traffic is protected. n Helps shelter you from behavior of others

Internet Performance 0% 100% Trunk Offered Load Probability of dropped packets Average Delay for delivered packets

Frame Relay Performance 0% 100% Trunk Offered Load Probability of dropped packets* Average Delay for delivered packets *Dashed: If we are transmitting at > CIR Solid: Provided we are transmitting at < CIR

Worldwide Frame Relay Revenues $0.23B ‘94 $0.65B ‘95 $1.28B ‘96 $3.87B ‘97 $6.25B ‘98 $0.08B ‘93 $9.45B ‘99 Source: Data Communications