1. 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

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

3. 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

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

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

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

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

16. 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

17. 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.
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

21. 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
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

22. 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
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

26. 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
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

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

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

31. Hybrid Label distribution Packet forwarding
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

34. Routing Get traffic to servers on different subnet
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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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

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Designing Routing and Switching Architectures. Copyright 1999 Macmillan Technical Publishing

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