Designing Routing and Switching Architectures. Howard C. Berkowitz Chapter 1 Designing Routing and Switching Architectures. Howard C. Berkowitz 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Hierarchical Models Edge of a network is the point at which end hosts connect. Backbone interconnects the edge sites Three tiers: Access edge of network; interact directly with end host Routers, proxies, broadcast and multicast filters. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Distribution Protocol translation Bandwidth management Complex filtering between core and access. Combining data into high speed trunks 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Core Concerned with transferring rather than filtering or traffic management Optimized for effcient transfer Campus networks High end lan atm 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Formulating a Design Methodology Six phase design approach: Step 1. Determine the top management goals, expectations, budget, and i fears. In this step, you define the answer to "What is the problem you are 1 trying to solve?" from the perspective of the people who pay the bills and I ultimately judge success. Step 2. With information technology staff, refine the top management i goals. Identify application users and servers and define the topology among them. Collect information about end hosts. Organize the data by 1 end host name, not address, establishing naming conventions as needed. j Here, you are answering the question "What is the problem you are try- ing to solve?" based on the realities of user applications and end host ! software. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Do not yet focus on specific routing and switching products. Step 3. Design the addressing structure for all relevant layers and then decide on the routing and switching techniques to use. Do not yet focus on specific routing and switching products. Deals with the question "What internal connectivity problem are you trying to solve?" Step 4. Select communications software on end hosts and internetworking devices. Question "What problems is do you want specific software to solve?" 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 5. Select hardware and circuitry, considering tradeoffs between the cost of raw bandwidth and the cost of bandwidth control on internet-working devices. There is likely to be significant back-and-forth analysis between Steps 4 and 5. Question, "What problems need to be solved by which hardware component?" Step 6. Plan deployment. As a sub-step here, you might consider a proof- of-concept demonstration. In many respects, this step poses the question "Have I solved the right problem?" 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 1: Learning Top-Level Requirements Many enterprise network designs fail because the executives involved have no clear-cut definition of success, and the objectives begin to vary, then thrash into chaos, during deployment. As a network architect, your most important job is to articulate the real requirements. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 2: Application Topology and Naming First, of course, you need to identify the endpoints, which are users and servers. Second, as you collect this information, introduce a naming structure to organize what you collect. Should also collect information on the computer- hardware type operating systems networking software type and version Knowing the system and networking software gives you insight into latency 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 3: Addressing, Routing, and Switching Create a working cloud that interconnects your users and meets their needs. The backbone provides connectivity among the user endpoints. Steps 1 and 2, deal with a user-oriented worldview. Inside the network the requirements for efficient and reliable transmission are paramount. Remember your high-level goal is cost-effectiveness. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 4: Software After you have decided on the routing structure and where to use switches to optimize performance, you need to select software functions to enable on the routers and switches. For routers, a major software decision is the mechanism(s) they will use to find paths. Addressing heavily interacts with software selection. If you choose to use unregistered addresses at the edge of the network, but use the global Internet for at least some of your connectivity, you need either to tunnel or translate some of those addresses. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 5: Hardware and Media Speeds and feeds Speeds of media May or may not need switching on all interfaces 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Step 6: Deployment Avoid doing massive cutovers, During times that real users are on the network. In hierarchical networks, it is best to start in one area, then add the core, and then add other areas. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Phase 1: Test network capability Phase 2: Initial trials with live data Phase 3: Just before full cutover Reflect workloads close to real environment Cut back over if necessary Phase 4: Production-level implementation Look for problems under a full load. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Application Requirements Identifying Users and Servers Define how users communicate with servers What do executives think? Flows between users and servers 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Administrative Models Defines responsibility for different aspects of connectivity. Often involves interconnecting separately managed networks. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Administrative Models Intranets:single enterprise-IP arch Proprietary enterprise networks:include IP and non-ip Extranets:Multiple enterprise networks VPN:tunnels across public Internet Global Internet:registered IP, DNS, BGP 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Application Distribution Models Continuing evolving model Mixtures of: Local processing Campus server processing Processing on WAN-connected ent servers Processing using resources in an extranet Processing on Internet-connected hosts 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Network Management Centralized Decentralized Global Internet Single network control center Decentralized Multiple network control centers Inability to control Global Internet Voluntary cooperation 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Successful Network Scalability Availability Usability Users, sites, apps Availability Reliability Threats Load Sharing, backups, mirroring, disaster recovery Usability Ease of network use More secure-less usable 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Successful Network Compatibility Security Manageability Support existing equipment and apps. Security Authorized users Manageability Invisible to users. Configure;expand;troubleshoot 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Addressing, Switching and Routing Design Changes to existing networks tend to be evolutionary rather than revolutionary. Backbone needs to provide the underlying structure. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Layer Fuctions Layer 3: Layer 2: Path determination Packet forwarding Connection-oriented Frame forwarding Connectionless 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Hybrid Label distribution Packet forwarding 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Switching vs Routing Switches Inexpensive speed change VLANs-provide high bandwidth between users and servers on a campus Less configuration Routable and nonroutable protocols 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Routing Get traffic to servers on different subnet 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Application layer gateway isolates the user VLAN broadcast domains as well as a router would. 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

Proxies Firewalls Frequently used data to be kept local Security 9/18/2018 Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing