Network Overview

Contents Jones network basics and topology Current network technologies LAN and Ethernet Circuit based WAN – ATM and Frame Relay The future – GBN, GTS, etc.

Jones Network History 'The Flat' – LAN, layer 2 based network Layer 2 – Ethernet level switching Limited expandability Single-vendor: Cabletron Also provided management solution, Cabletron Spectrum

LAN/Layer 2 Local Area Networks “Layer 2” of the seven-layer OSI model Computer-to-computer, hardware level Hubs and switches Collision and broadcast domains Controlled by the Spanning Tree Protocol Reconvergence problems Broadcast storms

Jones Campus Network Today Hierarchical Core, Distribution and Access routers Core routers connect all areas Distribution router pairs handle communication and routing Access routers handle port-intensive end-device interfacing Layer 3 based IP Routing Segregates areas, IP routing protocols provide fault tolerance, in combination with hardware redundancy SVAS WADS SVDS SCDS Core CLDS BUDS BRDS CLAS

Layer 3/IP ISO Model, layer 3 Network layer Routing protocols Protocols: IP, IPX, XNS, etc. Higher level addressing and routing functions Provides isolation and routing between LANs IP: Hierarchical addressing, a.b.c.d style Subnetting and Subnet Masks Today: Layer 3=IP Routing protocols BGP, IGRP Provide similar function to STP on the IP level Similar problems, but less widespread

Jones Campus Details Distribution routers in pairs Connect to access switches Closet Distribution Connects to pairs of Closet Access switches Where (most) desktops connect Server Distribution Wide-Area Distribution And WAN ATM Branch Distribution Backup Distribution SOC Distribution An ‘Island’ for the SOC, with SCAS swtich

Jones WAN Technologies Fiber-optic connections to all areas Fiber ring connects all three St. Louis campuses Fiber links to Tempe (now Gigabit Ethernet), UK, Canada Direct from ATM area to cores Used as an access path for other circuits Breaks out into individual links Serial links pass through matrix switches, DSU May go to SNA/Mainframe network directly or to IP WAN IBM 3745, SNA links IP WAN Tier 1: Standard vendor links Tier 2: Jones terminals at remote sites Tier 3: Trusted networks, Boone, Frame-Relay WAH

Circuit-based WAN Protocols PVC concept Permanent Virtual Circuit Divide one connection into many concurrent ones ATM Frame Relay

ATM Asyncronous Transfer Mode The “Network of the Future” - in the ‘90’s Typically used for high-capacity WAN circuits Small packets (cells) of 64 bytes each Provides Quality of Service Time-sensitive data/PVC gets priority Voice, video and data can be carried together Out of style for many duties Ethernet now provides speed and QoS

Frame-Relay ATM’s lower-tech counterpart Used as a sort of layer 2 Internet Each end of a PVC gets an identifying number DLCI - Data Link Connection Identifier Links have two bandwidth numbers CIR - Committed Information Rate Full link rate Commonly used for low-bandwidth connections Point-to-multipoint HQ to branch-style connections To be replaced (maybe) by MPLS Used for vendor, WAH, UK Branch connections

GBN Network Design Large point-to-multipoint network Evolving Design MPLS to varied branch access circuits ADSL, SDSL, T1… Any technology that can be attached to the MPLS cloud Provides one link and redundency at lower cost than Frame Head-end routers St. Louis and Tempe Using DS3 (45mbit serial) for now Branch components Router, local switch, and UPS monitored at this time Final configuration to be determined.

GBN Logical Network Uses MPLS VPN Technology MPLS - Multiprotocol Label Switching “Layer 2.5” add-on tunneling protocol Can be encapsulated and deencapsulated (pushed and popped) multiple times for security or design flexibility Is designed to be more flexible than Frame-Relay with larger packet sizes and less total overhead than ATM VPN (Virtual Private Network) Typically refers to encrypted encapsulation Carries IP traffic (IPSec VPN) or can be used with MPLS Provides secure traffic transmission Allows for use of a cheaper, provider-run ‘insecure’ network