Cisco Systems RJ-45-to-AUX manual Cisco WAN Switches, MGX 8200 Series

STS−n is an interleaving of multiple (n) STS−1s. The size of the payload and the overhead are multiplied by n. Figure 3.4 displays an STS diagram.

Figure 3.4: The STS−1 framing and STS−n framing. The overhead and payload are proportionate to the n value, with the STS−1 frame as the base.

You may wonder why we’re talking about synchronous transmission when we said it is only used over short distances. Where did the asynchronous transmission go? Well, the asynchronous traffic is encapsulated in the STS payload. The asynchronous serial transmission eliminates the need for the synchronization of the end transmitting equipment. In SONET, most WAN links are a point−to−point connection utilizing light as the signaling source. The time required for the signal to travel the link does not distort the synchronization. The OC−n signal itself is used for the synchronization between equipment. This combination of asynchronous and synchronous serial transmission enables signals to reach across long distances with minimal overhead.

Cisco WAN Switches

The current Cisco WAN product line consists of the following switches:

∙MGX 8200 series

∙IGX 8400 series

∙BPX 8600 series wide−area switches

∙MGX 8800 series wide−area edge switches

MGX 8200 Series

The Cisco MGX 8200 series is designed to function as a WAN edge device. It combines multiple narrowband transmissions into a single broadband trunk. It functions as a standalone unit to connect to the ATM network or it can be used as a feeder device to other WAN switches. The series consists of the MGX 8220 Edge Concentrator, the MGX 8240 Private Line Service Gateway, and the MGX 8260 Media Gateway.

The MGX 8220 Edge Concentrator has 16 slots with the capability for full redundancy. It accepts two classes of modules: common control cards and function modules. Six slots are reserved for common control cards, and 10 slots are reserved for function modules. The common control card consists of an AXIS Shelf Controller (ASC) card, a Service Resource Module (SRM) card, and a service trunk card. Each card can use either of two specific slots. When both slots are occupied, one of them acts as a hot standby. The ASC card provides a user interface for the overall control, configuration, and management of the unit. The SRM controls the flow of traffic from the trunk card to various function modules. The service trunk module is the only broadband interface (OC−3 or T3) that transports the aggregated traffic to the ATM network. The function modules are narrowband interface cards. The narrowband transmission can be T1, high−speed Frame Relay,

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