Chuong5 2 Chapter 5.2: Network Design

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Logical Network Design  Design a network topology  Design models for addressing and naming  Select switching and routing protocols  Develop network security strategies  Develop network management strategies Hierarchy  Redundancy  Modularity  Welldefined entries and exits  Protected perimeters Reduces workload on network devices  Avoids devices having to communicate with too many other devices (reduces “CPU adjacencies”)  Constrains broadcast domains  Enhances simplicity and understanding  Facilitates changes  Facilitates scaling to a larger size Chapter 5.2: Network Design NGUYỄN CAO ĐẠT E-mail:dat@hcmut.edu.vn Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design Outline  Logical Network Design Design a network topology  Design models for addressing and naming  Select switching and routing protocols  Develop network security strategies  Develop network management strategies  Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design Network Topology Design Themes      Hierarchy Redundancy Modularity Well-defined entries and exits Protected perimeters Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design Why Use a Hierarchical Model?  Reduces workload on network devices      Avoids devices having to communicate with too many other devices (reduces “CPU adjacencies”) Constrains broadcast domains Enhances simplicity and understanding Facilitates changes Facilitates scaling to a larger size Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design Hierarchical Network Design Campus A Enterprise WAN Backbone Core Layer Campus B Campus C Campus C Backbone Distribution Layer Access Layer Building C-1 Hochiminh City University Of Technology Computer Science & Engineering © 2014 Building C-2 Computer Networks Chapter 5: Network Design Cisco’s Hierarchical Design Model    A core layer of high-end routers and switches that are optimized for availability and speed A distribution layer of routers and switches that implement policies and segment traffic An access layer that connects users via hubs, switches, and other devices Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design Star Hierarchical Topology Corporate Headquarters Branch Office Hochiminh City University Of Technology Computer Science & Engineering © 2014 Home Office Branch Office Computer Networks Chapter 5: Network Design Flat Versus Hierarchy Headquarters in Medford Headquarters in Medford Grants Pass Branch Office Klamath Falls Branch Office Ashland Branch Office Flat Loop Topology Hochiminh City University Of Technology Computer Science & Engineering © 2014 Grants Pass Branch Office Klamath Falls Branch Office Ashland Branch Office White City Branch Office Hierarchical Redundant Topology Computer Networks Chapter 5: Network Design Mesh Designs Partial-Mesh Topology Full-Mesh Topology Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design A Partial-Mesh Hierarchical Design Headquarters (Core Layer) Regional Offices (Distribution Layer) Branch Offices (Access Layer) Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 10 Securing Public Servers    Place servers in a DMZ that is protected via firewalls Run a firewall on the server itself Enable DoS protection    Limit the number of connections per timeframe Use reliable operating systems with the latest security patches Maintain modularity  Front-end Web server doesn’t also run other services Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 67 Security Topologies DMZ Enterprise Network Internet Web, File, DNS, Mail Servers Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 68 Security Topologies Internet Firewall DMZ Hochiminh City University Of Technology Computer Science & Engineering © 2014 Web, File, DNS, Mail Servers Enterprise Network Computer Networks Chapter 5: Network Design 69 Securing Remote-Access and Virtual Private Networks       Physical security Firewalls Authentication, authorization, and auditing Encryption One-time passwords Security protocols  CHAP  RADIUS  IPSec Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 70 Securing Network Services   Treat each network device (routers, switches, and so on) as a high-value host and harden it against possible intrusions Require login IDs and passwords for accessing devices    Require extra authorization for risky configuration commands Use SSH rather than Telnet Change the welcome banner to be less welcoming Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 71 Securing Server Farms       Deploy network and host IDSs to monitor server subnets and individual servers Configure filters that limit connectivity from the server in case the server is compromised Fix known security bugs in server operating systems Require authentication and authorization for server access and management Limit root password to a few people Avoid guest accounts Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 72 Securing User Services   Specify which applications are allowed to run on networked PCs in the security policy Require personal firewalls and antivirus software on networked PCs    Implement written procedures that specify how the software is installed and kept current Encourage users to log out when leaving their desks Consider using 802.1X port-based security on switches Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 73 Securing Wireless Networks  Place wireless LANs (WLANs) in their own subnet or VLAN    Simplifies addressing and makes it easier to configure packet filters Require all wireless (and wired) laptops to run personal firewall and antivirus software Disable beacons that broadcast the SSID, and require MAC address authentication  Except in cases where the WLAN is used by visitors Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 74 WLAN Security Options    IEEE 802.11i Wi-Fi Protected Access (WPA) IEEE 802.1X Extensible Authentication Protocol (EAP)    Lightweight EAP or LEAP (Cisco) Protected EAP (PEAP) Virtual Private Networks (VPNs) Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 75 VPN Software on Wireless Clients      Safest way to wireless networking for corporations Wireless client requires VPN software Connects to VPN concentrator at HQ Creates a tunnel for sending all traffic VPN security provides:    User authentication Strong encryption of data Data integrity Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 76 Outline  Logical Network Design Design a network topology  Design models for addressing and naming  Select switching and routing protocols  Develop network security strategies  Develop network management strategies  Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 77 Network Management    Helps an organization achieve availability, performance, and security goals Helps an organization measure how well design goals are being met and adjust network parameters if they are not being met Facilitates scalability  Helps an organization analyze current network behavior, apply upgrades appropriately, and troubleshoot any problems with upgrades Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 78 Network Management Design     Consider scalability, traffic patterns, data formats, cost/benefit tradeoffs Determine which resources should be monitored Determine metrics for measuring performance Determine which and how much data to collect Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 79 Proactive Network Management     Plan to check the health of the network during normal operation, not just when there are problems Recognize potential problems as they develop Optimize performance Plan upgrades appropriately Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 80 Network Management Processes According to the ISO      Fault management Configuration management Accounting management Performance management Security management Hochiminh City University Of Technology Computer Science & Engineering © 2014 Computer Networks Chapter 5: Network Design 81 [...]... Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 26 Private Addressing 10.0.0.0 – 10 .25 5 .25 5 .25 5  1 72. 16.0.0 – 1 72. 31 .25 5 .25 5  1 92. 168.0.0 – 1 92. 168 .25 5 .25 5  Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 27 Criteria for Using Static Vs Dynamic Addressing       The number... Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 28 Designing Networks with Subnets    Determining subnet size Computing subnet mask Computing IP addresses Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 29 More Practice      Network is 1 72. 16.0.0 You have eight LANs, each of... © 20 14 Web, File, DNS, Mail Servers Enterprise Network Computer Networks 2 Chapter 5: Network Design 22 Outline  Logical Network Design Design a network topology  Design models for addressing and naming  Select switching and routing protocols  Develop network security strategies  Develop network management strategies  Hochiminh City University Of Technology Computer Science & Engineering © 20 14... Of Technology Computer Science & Engineering © 20 14 Paris Enterprise NY Option C ISP 2 NY Option D Computer Networks 2 Chapter 5: Network Design 20 Security Topologies DMZ Enterprise Network Internet Web, File, DNS, Mail Servers Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 21 Security Topologies Internet Firewall DMZ Hochiminh... Networks 2 Chapter 5: Network Design 32 Supernetting   Move prefix boundary to the left Branch office advertises 1 72. 16.0.0/14 1 72. 16.0.0 1 72. 17.0.0 1 72. 18.0.0 Branch-Office Router 1 72. 19.0.0 Branch-Office Networks Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Enterprise Core Network Computer Networks 2 Chapter 5: Network Design 33 1 72. 16.0.0/14 Summarization Second Octet... Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 18 HSRP Active Router Enterprise Internetwork Virtual Router Workstation Standby Router Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 19 Multihoming the Internet Connection ISP 1 Enterprise ISP 1 ISP 1 Option A ISP 2 Enterprise Enterprise ISP 1... around Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 12 Cisco’s SAFE Security Reference Architecture Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 13 Campus Topology Design     Use a hierarchical, modular approach Minimize the size of bandwidth... Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 15 VLANs Span Switches VLAN A Station A1 Station A2 VLAN A Station A3 Station A4 Station A5 Switch A Station B1 Station A6 Switch B Station B2 VLAN B Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Station B3 Station B4 Station B5 Station B6 VLAN B Computer Networks 2 Chapter 5: Network Design 16 WLANs and VLANs... 20 14 Computer Networks 2 Chapter 5: Network Design 31 Classless Addressing    Prefix/host boundary can be anywhere Less wasteful Supports route summarization  Also known as  Aggregation  Supernetting  Classless routing  Classless inter-domain routing (CIDR)  Prefix routing Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design. .. 00010010 19 00010011 Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 34 Upgrading to IPv6    Dual stack Tunneling Translation Hochiminh City University Of Technology Computer Science & Engineering © 20 14 Computer Networks 2 Chapter 5: Network Design 35 Guidelines for Assigning Names  Names should be       Short Meaningful
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