Presentation on theme: "Part 2 Logical Network Design"— Presentation transcript:
1Part 2 Logical Network Design Network TopologyAddressing and NamingSwitching and Routing ProtocolsNetwork Security StrategiesManagement Strategies
2Chapter Five Designing a Network Topology Copyright 2010 Cisco Press & Priscilla Oppenheimer
3Network Topology Design Themes Hierarchy (opposite to flat or mesh network)Core layerDistribution layerAccess layersRedundancyModularityWell-defined entries and exitsProtected areas
4Why Use a Hierarchical Model? Reduces workload on network devicesAvoids devices having to communicate with too many other devices (reduces “CPU adjacencies”)Constrains broadcast domainsMinimize costs. Only buy appropriate devices for each layerFacilitates changes easy and cheapGood for modularity and scalability
7Cisco’s Hierarchical Design Model A core layer of high-end routers and switches that are optimized for availability and speedA distribution layer of routers and switches that implement policies and segment trafficAn access layer that connects users via hubs, switches, and other devices
8Access Layer requirements: Utilize the Hierarchical Design Model to Develop a Cost-Effective Network DesignAccess Layer requirements:Connectivity for existing devices and new devicesVLANs to separate voice, security, wireless, and normal data servicesRedundancyQoSGraphic:
9Distribution layer requirements: Redundant components and links Utilize the Hierarchical Design Model to Develop a Cost-Effective Network DesignDistribution layer requirements:Redundant components and linksHigh-density routingTraffic filteringQoS implementationHigh-bandwidth connectivityFast convergenceRoute summarizationGraphic:
10Core Layer requirements: High-speed connectivity Utilize the Hierarchical Design Model to Develop a Cost-Effective Network DesignCore Layer requirements:High-speed connectivityRouted interconnectionsHigh-speed redundant linksGraphic:
11Flat Versus Hierarchy Flat Loop Topology Headquarters in MedfordAshland Branch OfficeKlamath Falls Branch OfficeGrants Pass Branch OfficeWhite City Branch OfficeHeadquarters in MedfordGrants Pass Branch OfficeAshland Branch OfficeKlamath Falls Branch OfficeFlat Loop TopologyHierarchical Redundant Topology
14A Hub-and-Spoke Hierarchical Topology for small company Corporate HeadquartersBranch OfficeHome OfficeBranch Office
15Avoid Chains and Backdoors Chain: extra layerBack door: connection between devices in the same layer, makes unexpected routing and switching problems.Core LayerDistribution LayerAccess LayerBackdoorChain
16Campus Topology Design Use a hierarchical, modular approachMinimize the size of bandwidth domainsMinimize the size of broadcast domainsProvide redundancy
17A Simple Campus Redundant Design Host ALAN XSwitch 1Switch 2LAN YHost B
18Bridges and Switches use Spanning-Tree Protocol (STP) to Avoid Loops Host ALAN XXSwitch 1Switch 2LAN YHost B
19Virtual LANs (VLANs) VLANs versus Real LANs Switch ASwitch BTo understand VLANs, it helps to think about real (non-virtual) LANs first. Imagine two switches that are not connected to each other in any way. Switch A connects stations in Network A and Switch B connects stations in Network B,When Station A1 sends a broadcast, Station A2 and Station A3 receive the broadcast, but none of the stations in Network B receive the broadcast, because the two switches are not connected. This same configuration can be implemented through configuration options in a single switch, with the result looking like the next slide.Station A1Station A2Station A3Station B1Station B2Station B3Network ANetwork BTwo switches that are not connected to each other in any way. When Station A1 sends a broadcast, Station A2 and Station A3 receive the broadcast, but none of the stations in Network B receive the broadcast
20A Switch with VLANsThrough the configuration of the switch there are now two virtual LANs implemented in a single switch. The broadcast, multicast, and unknown-destination traffic originating with any member of VLAN A is forwarded to all other members of VLAN A, and not to a member of VLAN B. VLAN A has the same properties as a physically separate LAN bounded by routers.Station A1Station A2Station A3VLAN AStation B1Station B2Station B3VLAN BThrough the configuration of the switch there are now two virtual LANs implemented in a single switch, instead of two separate physical LANs. This is the beauty of VLANs. The broadcast, multicast, and unknown-destination traffic originating with any member of VLAN A is forwarded to all other members of VLAN A, and not to a member of VLAN B. VLAN A has the same properties as a physically separate LAN bounded by routers. The protocol behavior in this slide is exactly the same as the protocol behavior in the previous slide.
21VLANs Span Switches VLANs can span multiple switches. Switch A Station B1Station B2Station B3Switch BStation B4Station B5Station B6Station A1Station A2Station A3Station A4Station A5Station A6VLAN BVLAN AVLANs can span multiple switches. In this slide, both switches contain stations that are members of VLAN A and VLAN B. This design introduces a new problem, the solution to which is specified in the IEEE 802.1Q standard and the Cisco proprietary Inter-Switch Link (ISL) protocol. The problem has to do with the forwarding of broadcast, multicast, or unknown-destination frames from a member of a VLAN on one switch to the members of the same VLAN on the other switch.In this slide, all frames going from Switch A to Switch B take the same interconnection path. The 802.1Q standard and Cisco's ISL protocol define a method for Switch B to recognize whether an incoming frame belongs to VLAN A or to VLAN B. As a frame leaves Switch A, a special header is added to the frame, called the VLAN tag. The VLAN tag contains a VLAN identifier (ID) that specifies to which VLAN the frame belongs.Because both switches have been configured to recognize VLAN A and VLAN B, they can exchange frames across the interconnection link, and the recipient switch can determine the VLAN into which those frames should be sent by examining the VLAN tag. The link between the two switches is sometimes called a trunk link or simply a trunk.Trunk links allow the network designer to stitch together VLANs that span multiple switches. A major design consideration is determining the scope of each VLAN and how many switches it should span. Most designers try to keep the scope small. Each VLAN is a broadcast domain. In general, a single broadcast domain should be limited to a few hundred workstations (or other devices, such as IP phones).VLANs can span multiple switches.
22Incorporate Wireless Connectivity into the LAN Design Factors influencing availability in a wireless network:Location of the APSignal strength of the APNumber of usersDynamicreconfigurationCentralizationGraphic:
23WLANs and VLANs A wireless LAN (WLAN) is often implemented as a VLAN WLAN should be a separate subnetClients roaming but Users remain in the same VLAN and IP subnet as they roam, so there’s no need to change addressing informationAlso makes it easier to set up filters ACL(Access Control Lists) to protect the wired network from wireless users.
24Security Topologies DMZ Enterprise Internet Network Web, File, DNS, Mail Servers
25DMZDMZ: demilitarized zone: is a physical or logical subnetwork that contains and exposes an organization's external-facing services to a larger untrusted network, usually the Internet.The purpose of a DMZ is to add an additional layer of security to an organization's local area network (LAN); an external attacker only has access to equipment in the DMZ, rather than any other part of the network.In a computer network, the hosts most vulnerable to attack are those that provide services to users outside of the local area network, such as , web and Domain Name System (DNS) servers.
26Security Topologies Firewall: boundary between two or more networks InternetFirewallDMZEnterprise NetworkWeb, File, DNS, Mail Servers
27FirewallA firewall can either be software-based or hardware-based and is used to help keep a network secure. Its primary objective is to control the incoming and outgoing network traffic by analyzing the data packets and determining whether it should be allowed through or not, based on a predetermined rule set.
28Summary Use a systematic, top-down approach Plan the logical design before the physical designTopology design should feature hierarchy, redundancy, modularity, and security
29Review QuestionsWhy are hierarchy and modularity important for network designs?What are the three layers of Cisco’s hierarchical network design?What are the major components of Cisco’s enterprise composite network model?What are the advantages and disadvantages of the various options for multihoming an Internet connection?
30Chapter Six Designing Models for Addressing and Naming Copyright 2010 Cisco Press & Priscilla Oppenheimer
31Guidelines for Addressing and Naming Use a structured model for addressing and namingAssign addresses and names hierarchicallyDecide in advance
32Advantages of Structured Models for Addressing & Naming It makes it easier toRead network mapsOperate network management softwareRecognize devices in protocol analyzer tracesMeet goals for usabilityDesign filters on firewalls and routersImplement route summarization
33Public IP AddressesManaged by the Internet Assigned Numbers Authority (IANA)Users are assigned IP addresses by Internet Service Providers (ISPs).ISPs obtain allocations of IP addresses from their appropriate Regional Internet Registry (RIR)Public address is essential for web server or other servers that external users access. But not necessary for all internal hosts and networks. Private address is ok.Addressing for internal host that need access to outside services can be handled by NAT (Network Address Translation) gateway.
34Regional Internet Registries (RIR) American Registry for Internet Numbers (ARIN) serves North America and parts of the Caribbean.RIPE Network Coordination Centre (RIPE NCC) serves Europe, the Middle East, and Central Asia.Asia-Pacific Network Information Centre (APNIC) serves Asia and the Pacific region.Latin American and Caribbean Internet Addresses Registry (LACNIC) serves Latin America and parts of the Caribbean.African Network Information Centre (AfriNIC) serves Africa.
35Private AddressingAn enterprise network administrator assigns to internal networks and hosts without any coordination from an ISP or RIRs.–––Advantages:Security. Private network numbers are not advertised.Flexibility. Easy to change to new ISP.Save IP address resources.
36The Two Parts of an IP Address 32 BitsPrefixHostPrefix Length
37Designing Networks with Subnets Determining subnet sizeComputing subnet maskComputing IP addresses
38SubnetsSubnetting is the process to divide a network into several smaller networks.Within a subnet, all the hosts have the same network ID in their IP addresses.With subnets, a physical network can be divided into logical units.The hosts in each unit can directly communicate with each other and use the same router to communicate with the hosts in the other subnets.Local broadcasting is limited within a subnet.
39Reasons for Using Subnets To efficiently use IP addressesTo reduce the number of collisionsTo reduce broadcasting trafficTo strengthen network security controlTo implement the network structure at the site, building, department, and office levelsTo reduce the cost of paying the ISP for public IP addresses
40Subnet MasksA subnet mask is a string of 32-bit binary code used to determine which part of an IP address is used as the network ID.Binary Subnet MaskDecimal Subnet MaskThe leftmost bits in a subnet mask are a sequence of consecutive 1s and rightmost bits must be consecutive 0s. Invalid masks are listed below.BinaryDecimal
41Addresses to Avoid When Subnetting A node address of all ones (broadcast)A node address of all zeros (network)A subnet address of all ones (all subnets)A subnet address of all zeros (confusing)
42Classful IP Addressing Class First First Byte Prefix IntentFew Bits LengthA * 8 Very large networksB Large networksC Small networksD NA IP multicastE NA Experimental*Addresses starting with 127 are reserved for IP traffic local to a host.
43Division of the Classful Address Space Class Prefix Number of AddressesLength per NetworkA = 16,777,214B = 65,534C = 254
44Classful IP is Wasteful Class A uses 50% of address spaceClass B uses 25% of address spaceClass C uses 12.5% of address spaceClass D and E use 12.5% of address space
45Classless Addressing Prefix/host boundary can be anywhere Less wastefulSupports route summarization (Aggregation)Also known asAggregationSupernettingClassless routingClassless inter-domain routing (CIDR)Prefix routing
46Enterprise Core Network Branch-Office Networks SupernettingBranch-Office RouterEnterprise Core NetworkBranch-Office NetworksMove prefix boundary to the leftBranch office advertises /14
47Guidelines for Assigning Names Names should beShortMeaningfulClearDistinctCase insensitiveAvoid names with unusual charactersHyphens, underscores, asterisks, and so on
48Domain Name System (DNS) Maps names to IP addressesSupports hierarchical namingexample: eent3.lsbu.ac.ukA DNS server has a database of resource records (RRs) that maps names to addresses in the server’s “zone of authority”Client queries serverUses UDP port 53 for name queries and repliesUses TCP port 53 for zone transfers
49Describe IPv6 Implementations and IPv6 to IPv4 Interactions Enhancements available with IPv6:Mobility and securitySimpler headerAddress formattingGraphic:
50SummaryUse a systematic, structured, top-down approach to addressing and namingAssign addresses in a hierarchical fashionDistribute authority for addressing and naming where appropriateIPv6 looms in our future
51Review QuestionsWhy is it important to use a structured model for addressing and naming?When is it appropriate to use IP private addressing versus public addressing?When is it appropriate to use static versus dynamic addressing?What are some approaches to upgrading to IPv6?
53Switching and Routing Choices Layer 2 transparent bridging (switching)Multilayer switchingSpanning Tree Protocol enhancementsVLAN technologiesRoutingStatic or dynamicDistance-vector and link-state protocolsInterior and exteriorEtc.
54Selection Criteria for Switching and Routing Protocols Network traffic characteristicsBandwidth, memory, and CPU usageThe number of peers supportedThe capability to adapt to changes quicklySupport for authentication
56Transparent Bridging (Switching) Tasks Forward frames transparentlyLearn location of devices by source address in each frameBridge develops a switch/bridge table, or MAC address table, or Content Address Memory (CAM) table.Floods unknown or broadcast framesLayer 1 and 2 device (physical address), don’t look at IP address.Store-and-forward device. Receive a complete frame, determines outgoing port, calculates CRC then transmits the frame when the port is free
58Protocols for Transporting VLAN Information Switches need a method to make sure intra- VLAN traffic goes to the correct interfaces.IEEE 802.1QVLAN Trunk Protocol (VTP)VLAN management protocolSwitch AStation B1Station B2Station B3Switch BStation B4Station B5Station B6Station A1Station A2Station A3Station A4Station A5Station A6VLAN BVLAN A
59Routing vs. Bridging and Switching Routing is operating at the Network Layer of the OSI Model. Bridging and switching occur on the Data Link Layer.
60Selecting Routing Protocols A routing protocol lets a router dynamically learn how to reach other networks and exchange this information with other routers.They all have the same general goal:To share network reachability information among routersThey differ in many ways:Interior versus exteriorMetrics supportedDynamic versus static and defaultDistance-vector versus link-sateClassful versus classlessScalability
61Interior Versus Exterior Routing Protocols Interior routing protocols are used within one organization. The current lead Interior Routing Protocol is OSPF. Other Interior Protocols include IS-IS, RIP, and EIGRP.Exterior routing protocols are used between organizations. The current lead Exterior Gateway Protocol is BGP. The current revision of BGP is BGP4. There are no other Exterior Gateway Routing protocols in current competition with BGP4.
62Routing Protocol Metrics Metric: the determining factor used by a routing algorithm to decide which route to a network is better than anotherExamples of metrics:Bandwidth - capacityDelay - timeLoad - amount of network trafficReliability - error rateHop count - number of routers that a packet must travel through before reaching the destination networkCost - arbitrary value defined by the protocol or administrator
63Routing Algorithms Static routing Default routing Calculated beforehand, offlineDefault routing“If I don’t recognize the destination, just send the packet to Router X”Cisco’s On-Demand RoutingRouting for stub networksUses Cisco Discovery Protocol (CDP)Dynamic routing protocolDistance-vector algorithmsLink-state algorithms
64Distance-Vector Vs. Link-State Distance-vector algorithms keep a list of networks, with next hop and distance (metric) informationLink-state algorithms keep a database of routers and links between themLink-state algorithms think of the internetwork as a graph instead of a listWhen changes occur, link-state algorithms apply Dijkstra’s shortest-path algorithm to find the shortest path between any two nodes
65Choosing Between Distance-Vector and Link-State Choose Distance- VectorSimple, flat topologyHub-and-spoke topologyJunior network administratorsConvergence time not a big concernChoose Link-StateHierarchical topologyMore senior network administratorsFast convergence is critical
66Dynamic IP Routing Protocols Distance-VectorRouting Information Protocol (RIP) Version 1 and 2Interior Gateway Routing Protocol (IGRP)Enhanced IGRPBorder Gateway Protocol (BGP)Link-StateOpen Shortest Path First (OSPF)Intermediate System-to-Intermediate System (IS-IS)
68SummaryThe selection of switching and routing protocols should be based on an analysis ofGoalsScalability and performance characteristics of the protocolsTransparent bridging is used on modern switchesBut other choices involve enhancements to STP and protocols for transporting VLAN informationThere are many types of routing protocols and many choices within each type
69Review QuestionsWhat are some options for enhancing the Spanning Tree Protocol?What factors will help you decide whether distance-vector or link-state routing is best for your design customer?What factors will help you select a specific routing protocol?Why do static and default routing still play a role in many modern network designs?
71Network Security Design The 12 Step Program Identify network assetsAnalyze security risksAnalyze security requirements and tradeoffsDevelop a security planDefine a security policyDevelop procedures for applyingsecurity policiesch2The first three steps were covered more in Chapter 2. Chapter 8 picks up that discussion and focuses on selecting the right security mechanisms for the different components of a modular network design.ch8
72The 12 Step Program (continued) Develop a technical implementation strategyAchieve buy-in from users, managers, and technical staffTrain users, managers, and technical staffImplement the technical strategy and security proceduresTest the security and update it if any problems are foundMaintain securityoutch12Maintain security by scheduling periodic independent audits, reading audit logs, responding to incidents, reading current literature and agency alerts, installing patches and security fixes, continuing to test and train, and updating the security plan and policy.ch8
73Network Assets Hardware Software Applications Data Intellectual propertyTrade secretsCompany’s reputation
74Security Risks Hacked network devices Data can be intercepted, analyzed, altered, or deletedUser passwords can be compromisedDevice configurations can be changedReconnaissance attacks (gather information )Denial-of-service attacks (make a computer resource unavailable to its intended users)Intercept—obstructHome : Intrusion Detection System : Reconnaissance Attacksto a friend Print version CommentsReconnaissance AttacksReconnaissance Attacks Reconnaissance attacks are used to gather information about a target network or system. Such attacks may seem harmless at the time and may be overlooked by security administrators as "network noise" or pestering behavior, but it is usually the information gained through reconnaissance attacks that is used in subsequent Access or DoS attacks. Several means may be used to gather information about an organization and could include automated and manual technological attacks as well as human social attacks. Examples might include ICMP ping sweeps against a network or SNMP walking techniques to gather network map and device configuration data. Likewise, application-level scanners could be used to search for vulnerabilities such as web server CGI or ASP weaknesses.No specific damage may be caused by the reconnaissance attack, but it is akin to burglars staking out a neighborhood, watching for times of inactivity, and occasionally testing windows and doors for access.Reconnaissance attacks are quite common and should be considered a serious threat to an organization as they may give potential attackers the information required to perform access or DoS attacks.A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person, or multiple people to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely. Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers. The term is generally used with regards to computer networks, but is not limited to this field; for example, it is also used in reference to CPU resource management.One common method of attack involves saturating the target machine with external communications requests, such that it cannot respond to legitimate traffic, or responds so slowly as to be rendered effectively unavailable. Such attacks usually lead to a server overload. In general terms, DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consuming its resources so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.Denial-of-service attacks are considered violations of the IAB's Internet proper use policy, and also violate the acceptable use policies of virtually all Internet service providers. They also commonly constitute violations of the laws of individual nations.[
75Security TradeoffsTradeoffs must be made between security goals and other goals:AffordabilityUsabilityPerformanceAvailabilityManageabilityAn example of a tradeoff is that security can reduce network redundancy. If all traffic must go through an encryption device, for example, the device becomes a single point of failure. This makes it hard to meet availability goals.Security adds to management work (user ID, passwords ), and affects network performance. Encryption consume upto 15% of CPU power on a router or network throughput.
76A Security PlanHigh-level document that proposes what an organization is going to do to meet security requirementsSpecifies time, people, and other resources that will be required to develop a security policy and achieve implementation of the policy
77A Security Policy A security policy is a The policy should address “Formal statement of the rules by which people who are given access to an organization’s technology and information assets must abide.”The policy should addressAccess, accountability, authentication, privacy, and computer technology purchasing guidelines
78Security Mechanisms Physical security Authentication Authorization Accounting (Auditing)Data encryptionPacket filtersFirewallsIntrusion Detection Systems (IDS)Intrusion Prevention Systems (IPS)
79Modularizing Security Design Security defense in depthNetwork security should be multilayered with many different techniques used to protect the networkBelt-and-suspenders approachDon’t get caught with your pants down
80Modularizing Security Design Secure all components of a modular design:Internet connectionsPublic servers and e-commerce serversRemote access networks and VPNsNetwork services and network managementServer farmsUser servicesWireless networks
81Securing Internet Connections Physical securityFirewalls and packet filtersAudit logs, authentication, authorizationWell-defined exit and entry pointsRouting protocols that support authentication
82Securing Public Servers Place servers in a DMZ that is protected via firewallsRun a firewall on the server itselfEnable DoS protectionLimit the number of connections per timeframeUse reliable operating systems with the latest security patchesMaintain modularityFront-end Web server doesn’t also run other services (FTP services not run on the same server as Web services, e-commerce database should not be on the web server.)Security experts recommend that FTP services not run on the same server as Web services. FTP users have more opportunities for reading and possibly changing files than Web users do. A hacker could use FTP to damage a company’s Web pages, thus damaging the company’s image and possibly compromising Web-based electronic-commerce and other applications. In addition, any e-commerce database server that holds sensitive customer financial information should be separate from the front-end Web server that users see.
83Securing Remote-Access and Virtual Private Networks (VPN) Physical securityFirewallsAuthentication, authorization, and auditingEncryptionOne-time passwordsSecurity protocolsCHAPRADIUSIPSec
84Securing Network Services Treat each network device (routers, switches, and so on) as a high-value host and harden it against possible intrusionsRequire login IDs and passwords for accessing devicesRequire extra authorization for risky configuration commandsUse SSH rather than TelnetChange the welcome banner to be less welcoming
85Securing Server FarmsDeploy network and host IDSs to monitor server subnets and individual serversConfigure filters that limit connectivity from the server in case the server is compromisedFix known security bugs in server operating systemsRequire authentication and authorization for server access and managementLimit root password to a few peopleAvoid guest accounts
86Securing User Services Specify which applications are allowed to run on networked PCs in the security policyRequire personal firewalls and antivirus software on networked PCsImplement written procedures that specify how the software is installed and kept currentEncourage users to log out when leaving their desksConsider using 802.1X port-based security on switches
87Securing Wireless Networks Place wireless LANs (WLANs) in their own subnet or VLANSimplifies addressing and makes it easier to configure packet filtersRequire all wireless (and wired) laptops to run personal firewall and antivirus softwareDisable beacons that broadcast the SSID, and require MAC address authenticationExcept in cases where the WLAN is used by visitors
88WLAN Security Options Wired Equivalent Privacy (WEP) (danger) IEEE iWi-Fi Protected Access (WPA)IEEE 802.1X Extensible Authentication Protocol (EAP)Lightweight EAP or LEAP (Cisco)Protected EAP (PEAP)Virtual Private Networks (VPNs)Any other acronyms we can think of? :-)
89Wired Equivalent Privacy (WEP) Defined by IEEEUsers must possess the appropriate WEP key that is also configured on the access point64 or 128-bit key (or passphrase)WEP encrypts the data using the RC4 stream cipher methodInfamous for being crackable (within 30 minutes by normal laptop)
90WEP Alternatives Vendor enhancements to WEP Temporal Key Integrity Protocol (TKIP)Every frame has a new and unique WEP keyAdvanced Encryption Standard (AES)IEEE iWi-Fi Protected Access (WPA) from the Wi- Fi Alliance
91Extensible Authentication Protocol (EAP) With 802.1X and EAP, devices take on one of three roles:The supplicant resides on the wireless LAN clientThe authenticator resides on the access pointAn authentication server resides on a RADIUS server
92EAP (Continued)An EAP supplicant on the client obtains credentials from the user, which could be a user ID and passwordThe credentials are passed by the authenticator to the server and a session key is developedPeriodically the client must reauthenticate to maintain network connectivityReauthentication generates a new, dynamic WEP key
93VPN Software on Wireless Clients Safest way to do wireless networking for corporationsWireless client requires VPN softwareConnects to VPN concentrator at HQCreates a tunnel for sending all trafficVPN security provides:User authenticationStrong encryption of dataData integrity
94Summary Use a top-down approach Chapter 2 talks about identifying assets and risks and developing security requirementsChapter 5 talks about logical design for security (secure topologies)Chapter 8 talks about the security plan, policy, and proceduresChapter 8 also covers security mechanisms and selecting the right mechanisms for the different components of a modular network design
95Review QuestionsHow does a security plan differ from a security policy?Why is it important to achieve buy-in from users, managers, and technical staff for the security policy?What are some methods for keeping hackers from viewing and changing router and switch configuration information?How can a network manager secure a wireless network?
97Network ManagementHelps an organization achieve availability, performance, and security goalsHelps an organization measure how well design goals are being met and adjust network parameters if they are not being metFacilitates scalabilityHelps an organization analyze current network behavior, apply upgrades appropriately, and troubleshoot any problems with upgrades
98Network Management Design Consider scalability, traffic patterns, data formats, cost/benefit tradeoffsDetermine which resources should be monitoredDetermine metrics for measuring performanceDetermine which and how much data to collect
99Proactive Network Management Plan to check the health of the network during normal operation, not just when there are problemsRecognize potential problems as they developOptimize performancePlan upgrades appropriately
100Network Management Processes According to the ISO Fault managementConfiguration managementAccounting managementPerformance managementSecurity management
101Fault Management Detect, isolate, diagnose, and correct problems Report status to end users and managersTrack trends related to problems
102Configuration Management Keep track of network devices and their configurationsMaintain an inventory of network assetsLog versions of operating systems and applications
103Accounting Management Keep track of network usage by departments or individualsFacilitate usage-based billingFind abusers who use more resources than they should
105Security Management Maintain and distribute user names and passwords Generate, distribute, and store encryption keysAnalyze router, switch, and server configurations for compliance with security policies and proceduresCollect, store, and examine security audit logs
106Network Management Components A managed device is a network node that collects and stores management informationAn agent is network-management software that resides in a managed deviceA network-management system (NMS) runs applications to display management data, monitor and control managed devices, and communicate with agents
108Architecture Concerns In-band versus out-of-band monitoringIn-band control passes control data on the same connection as main data. Out-of-band control passes control data on a separate connection from main data. In-band is easier to develop, but results in management data being impacted by network problemsCentralized versus distributed monitoringCentralized management is simpler to develop and maintain, but may require huge amounts of information to travel back to a centralized network operations center (NOC)In-band control is a characteristic of network protocols with which data control is regulated. In-band control passes control data on the same connection as main data. Protocols that use in-band control include HTTP and SMTP. This is as opposed to Out-of-band control used by protocols such as FTP.Out-of-band control is a characteristic of network protocols with which data control is regulated. Out-of-band control passes control data on a separate connection from main data. Protocols such as FTP use out-of-band control.FTP sends its control information, which includes user identification, password, and put/get commands, on one connection, and sends data files on a separate parallel connection. Because it uses a separate connection for the control information, FTP uses out-of-band control.
109Simple Network Management Protocol (SNMP) Most popular network management protocolSNMPv3 should gradually supplant versions 1 and 2 because it offers better authenticationSNMP works with Management Information Bases (MIBs)
110Remote Monitoring (RMON) Developed by the IETF in the early 1990s to address shortcomings in standard MIBsProvides information on data link and physical layer parametersNine groups of data for EthernetThe statistics group tracks packets, octets, packet-size distribution, broadcasts, collisions, dropped packets, fragments, CRC and alignment errors, jabbers, and undersized and oversized packets
111Cisco Tools Cisco Discovery Protocol NetFlow Accounting With the show cdp neighbors detail command, you can display detailed information about neighboring routers and switches, including which protocols are enabled, network addresses for enabled protocols, the number and types of interfaces, the type of platform and its capabilities, and the version of Cisco IOS Software running on the neighbor.NetFlow AccountingAn integral part of Cisco IOS Software that collects and measures data as it enters router or switch interfaces
112SummaryDetermine which resources to monitor, which data about these resources to collect, and how to interpret that dataDevelop processes that address performance, fault, configuration, security, and accounting managementDevelop a network management architectureSelect management protocols and tools
113Review Questions Why is network management design important? Define the five types of network management processes according to the ISO.What are some advantages and disadvantages of using in-band network management versus out-of-band network management?What are some advantages and disadvantages of using centralized network management versus distributed network management?