[ Pobierz całość w formacie PDF ]
.By deploying switches rather than traditionalshared hubs, network designers can increase performance and leverage the current investments in existing LAN media andadapters.These switches also offer functionality not previously available, such as VLANs, that provide the flexibility to usesoftware to move, add, and change users across the network.LAN switches are also suited to provide segment switching and scalable bandwidth within network data centers by deliveringswitched links to interconnect existing hubs in wiring closets, LAN switches, and server farms.Cisco provides the Catalystfamily of multilayer switches for connecting multiple wiring closet switches or shared hubs into a backbone configuration.ATM SwitchesEven though all ATM switches perform cell relay, ATM switches differ markedly in the following capabilities:Variety of interfaces and services that are supportedRedundancyDepth of ATM internetworking softwareSophistication of traffic management mechanismJust as there are routers and LAN switches available at various price/performance points with different levels of functionality,ATM switches can be segmented into the following four distinct types that reflect the needs of particular applications andhttp://www.cisco.com/cpress/cc/td/cpress/ccie/ndcs798/nd2002.htm (30 of 35) [9/16/2000 5:03:39 PM] Internetworking Design Basicsmarkets:Workgroup ATM switchesCampus ATM switchesEnterprise ATM switchesMultiservice access switchesCisco offers a complete range of ATM switches.Workgroup and Campus ATM SwitchesWorkgroup ATM switches have Ethernet switch ports and an ATM uplink to connect to a campus ATM switch.An example ofa workgroup ATM switch is the Cisco Catalyst 5000.Campus ATM switches are generally used for small-scale ATM backbones (for example, to link ATM routers or LANswitches).This use of ATM switches can alleviate current backbone congestion and enable the deployment of such newservices as VLANs.Campus switches need to support a wide variety of both local backbone and WAN types, but beprice/performance optimized for the local backbone function.In this class of switches, ATM routing capabilities that allowmultiple switches to be tied together is very important.Congestion control mechanisms for optimizing backbone performanceis also important.The LightStream 1010 family of ATM switches is an example of a campus ATM switch.For moreinformation on deploying workgroup and campus ATM switches in your internetwork, see "Designing Switched LANInternetworks."Enterprise ATM SwitchesEnterprise ATM switches are sophisticated multiservice devices that are designed to form the core backbones of large,enterprise networks.They are intended to complement the role played by today's high-end multiprotocol routers.EnterpriseATM switches are used to interconnect campus ATM switches.Enterprise-class switches, however, can act not only as ATMbackbones but can serve as the single point of integration for all of the disparate services and technology found in enterprisebackbones today.By integrating all of these services onto a common platform and a common ATM transport infrastructure,network designers can gain greater manageability and eliminate the need for multiple overlay networks.Cisco's BPX/AXIS is a powerful broadband ATM switch designed to meet the demanding, high-traffic needs of a large privateenterprise or public service provider.For more information on deploying enterprise ATM switches in your internetwork, see"Designing ATM Internetworks."Multiservice Access SwitchesBeyond private networks, ATM platforms will also be widely deployed by service providers both as customer premisesequipment (CPE) and within public networks.Such equipment will be used to support multiple MAN and WAN services---forexample, Frame Relay switching, LAN interconnect, or public ATM services---on a common ATM infrastructure.EnterpriseATM switches will often be used in these public network applications because of their emphasis on high availability andredundancy, their support of multiple interfaces, and capability to integrate voice and data.Switches and Routers ComparedTo highlight the differences between switches and routers, the following sections examine the different roles of these devicesin the following situations:Implementation of VLANsImplementation of switched internetworksRole of Switches and Routers in VLANsVLANs address the following two problems:Scalability issues of a flat network topologySimplification of network management by facilitating network reconfigurations (moves and changes)http://www.cisco.com/cpress/cc/td/cpress/ccie/ndcs798/nd2002.htm (31 of 35) [9/16/2000 5:03:39 PM] Internetworking Design BasicsA VLAN consists of a single broadcast domain and solves the scalability problems of large flat networks by breaking a singlebroadcast domain into several smaller broadcast domains or VLANs.Virtual LANs offer easier moves and changes in anetwork design than traditional networks.LAN switches can be used to segment networks into logically defined virtualworkgroups.This logical segmentation, commonly referred to as VLAN communication, offers a fundamental change in howLANs are designed, administered, and managed.Although logical segmentation provides substantial benefits in LANadministration, security, and management of network broadcast across the enterprise, there are many components of VLANsolutions that network designers should consider prior to large scale VLAN deployment.Switches and routers each play an important role in VLAN design.Switches are the core device that controls individualVLANs while routers provide interVLAN communication, as shown in Figure 2-23.Figure 2-23: Role of switches and routers in VLANs [ Pobierz całość w formacie PDF ]
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.By deploying switches rather than traditionalshared hubs, network designers can increase performance and leverage the current investments in existing LAN media andadapters.These switches also offer functionality not previously available, such as VLANs, that provide the flexibility to usesoftware to move, add, and change users across the network.LAN switches are also suited to provide segment switching and scalable bandwidth within network data centers by deliveringswitched links to interconnect existing hubs in wiring closets, LAN switches, and server farms.Cisco provides the Catalystfamily of multilayer switches for connecting multiple wiring closet switches or shared hubs into a backbone configuration.ATM SwitchesEven though all ATM switches perform cell relay, ATM switches differ markedly in the following capabilities:Variety of interfaces and services that are supportedRedundancyDepth of ATM internetworking softwareSophistication of traffic management mechanismJust as there are routers and LAN switches available at various price/performance points with different levels of functionality,ATM switches can be segmented into the following four distinct types that reflect the needs of particular applications andhttp://www.cisco.com/cpress/cc/td/cpress/ccie/ndcs798/nd2002.htm (30 of 35) [9/16/2000 5:03:39 PM] Internetworking Design Basicsmarkets:Workgroup ATM switchesCampus ATM switchesEnterprise ATM switchesMultiservice access switchesCisco offers a complete range of ATM switches.Workgroup and Campus ATM SwitchesWorkgroup ATM switches have Ethernet switch ports and an ATM uplink to connect to a campus ATM switch.An example ofa workgroup ATM switch is the Cisco Catalyst 5000.Campus ATM switches are generally used for small-scale ATM backbones (for example, to link ATM routers or LANswitches).This use of ATM switches can alleviate current backbone congestion and enable the deployment of such newservices as VLANs.Campus switches need to support a wide variety of both local backbone and WAN types, but beprice/performance optimized for the local backbone function.In this class of switches, ATM routing capabilities that allowmultiple switches to be tied together is very important.Congestion control mechanisms for optimizing backbone performanceis also important.The LightStream 1010 family of ATM switches is an example of a campus ATM switch.For moreinformation on deploying workgroup and campus ATM switches in your internetwork, see "Designing Switched LANInternetworks."Enterprise ATM SwitchesEnterprise ATM switches are sophisticated multiservice devices that are designed to form the core backbones of large,enterprise networks.They are intended to complement the role played by today's high-end multiprotocol routers.EnterpriseATM switches are used to interconnect campus ATM switches.Enterprise-class switches, however, can act not only as ATMbackbones but can serve as the single point of integration for all of the disparate services and technology found in enterprisebackbones today.By integrating all of these services onto a common platform and a common ATM transport infrastructure,network designers can gain greater manageability and eliminate the need for multiple overlay networks.Cisco's BPX/AXIS is a powerful broadband ATM switch designed to meet the demanding, high-traffic needs of a large privateenterprise or public service provider.For more information on deploying enterprise ATM switches in your internetwork, see"Designing ATM Internetworks."Multiservice Access SwitchesBeyond private networks, ATM platforms will also be widely deployed by service providers both as customer premisesequipment (CPE) and within public networks.Such equipment will be used to support multiple MAN and WAN services---forexample, Frame Relay switching, LAN interconnect, or public ATM services---on a common ATM infrastructure.EnterpriseATM switches will often be used in these public network applications because of their emphasis on high availability andredundancy, their support of multiple interfaces, and capability to integrate voice and data.Switches and Routers ComparedTo highlight the differences between switches and routers, the following sections examine the different roles of these devicesin the following situations:Implementation of VLANsImplementation of switched internetworksRole of Switches and Routers in VLANsVLANs address the following two problems:Scalability issues of a flat network topologySimplification of network management by facilitating network reconfigurations (moves and changes)http://www.cisco.com/cpress/cc/td/cpress/ccie/ndcs798/nd2002.htm (31 of 35) [9/16/2000 5:03:39 PM] Internetworking Design BasicsA VLAN consists of a single broadcast domain and solves the scalability problems of large flat networks by breaking a singlebroadcast domain into several smaller broadcast domains or VLANs.Virtual LANs offer easier moves and changes in anetwork design than traditional networks.LAN switches can be used to segment networks into logically defined virtualworkgroups.This logical segmentation, commonly referred to as VLAN communication, offers a fundamental change in howLANs are designed, administered, and managed.Although logical segmentation provides substantial benefits in LANadministration, security, and management of network broadcast across the enterprise, there are many components of VLANsolutions that network designers should consider prior to large scale VLAN deployment.Switches and routers each play an important role in VLAN design.Switches are the core device that controls individualVLANs while routers provide interVLAN communication, as shown in Figure 2-23.Figure 2-23: Role of switches and routers in VLANs [ Pobierz całość w formacie PDF ]