Chapter 9: LightStream Switches

In Depth

The demand for high−speed network communications has skyrocketed in the past 20 to 30 years. In the early 1970s, 9.6Kbps was considered a high−speed network. Now that we have entered the next century, network speeds have surpassed 1Gbps with the introduction of 10Gbps technologies. This advancement has led to the introduction of many applications that require massive quantities of data to be transferred over LAN and WAN physical connections.

As we learned in Chapter 8, Asynchronous Transfer Mode (ATM) has become an industry standard for transporting large quantities of data through the network. However, ATM is not supported on all Cisco Catalyst switches. To meet the need for ATM support, Cisco introduced the LightStream series; this line of switches is used primarily for ATM cell switching.

The LightStream series of Cisco switches are ATM switches meant primarily to run multiservice applications. The LightStream series works well for campus backbones, service provider backbones, ATM workgroups, metropolitan area networks (MANs), and multiple service applications. The LightStream can be found in three primary versions: LightStream 100 (LS100), LightStream 1010 (LS1010), and LightStream 2020 (LS2020).

In Chapter 8, we looked at ATM and how ATM is configured on Catalyst switches. This chapter will supplement Chapter 8 by discussing the features and benefits of the LightStream series of Cisco switches. The configuration steps for each switch feature discussed in this chapter will be explained in the Immediate Solutions section.

LightStream 100

As with all the LightStream switches, the LS100 switch shown in Figure 9.1 is a desktop ATM switch used in the LAN, WAN, or campus backbone. This switch supports a maximum of 16 ATM lines; it supports a maximum of 155Mbps per line, for an aggregate throughput of 2.5Gbps.

Figure 9.1: The LS100 switch.

This switch carries a unique core called the expandable ATM output−buffer modular switch (XATOMSW). The XATOMSW component supports the buffering that takes place in order to allow the switch to provide a guaranteed Quality of Service (QoS), making this switch a great asset in a multimedia environment. The switch also supports mixed−media interfaces. Interface types can be mixed on an LS100 ATM switch used as a backbone, workgroup, or WAN access switch. Table 9.1 shows the supported media types and the supported line speeds.

Table 9.1: LS100 supported interface types and media speeds.

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LightStream 1010

The LS1010, shown in Figure 9.2, is the most recent addition to the LightStream series of ATM switches used for multiservice applications. The switch has a five−slot, modular chassis with two fault−tolerant,

load−sharing power supplies. The switch contains a central slot that is dedicated to a single, field−replaceable switch processor module. The switch processor module supports 5Gbps of shared memory that is fully non−blocking. Non−blocking means the switch fabric can process and switch just as much or more data than all the ports on the switch combined can possibly bring in. This is possible because the switch uses a feature card and a high−performance reduced instruction set computer (RISC) processor that provides the speed and routing intelligence for the architecture.

Figure 9.2: The LS1010 switch.

The RISC processor provides traffic management mechanisms that allow for bursty data traffic and QoS for such data as voice, video, multimedia, and other applications that require guaranteed bandwidth. The LS1010 can buffer up to 65,536 cells in its on−board shared buffers; this buffering minimizes the possibility of cell loss. Policies and scheduling with user−definable thresholds permit flexible support of multiple service classes.

The LS1010 family’s architecture is flexible. The switch architecture is scalable and can support WAN interfaces with speeds ranging from a T1 to an OC−12. The LS1010 supports many traffic classes, such as those listed in Table 9.2.

Table 9.2: Traffic classes supported on the LightStream 1010.

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