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Dell™ PowerEdge™ 1655MC Integrated Switch User's Guide


Description of Hardware

Management Agent

Features and Benefits 


Dell’s PowerEdge 1655MC Integrated Switch is designed to interface server blades over the chassis middle plane, and uplink the chassis to the enterprise network.

The Integrated Switch includes 6 Gigabit Ethernet ports (1000BASE-SX) that connect to server cards over the chassis middle plane, one Fast Ethernet port (10/100BASE-TX) that connects to the system management channel over the chassis middle plane, plus four Gigabit Ethernet uplink ports (1000BASE-T) for external connections, also known as uplink ports. The port are numbered as follows:

A Simple Network Management Protocol (SNMP) management agent embedded in the switch. It supports on-site management access via the RJ-11 console port and remote access via a network connection to any of the uplink ports on the switch. You can also manage the switch via the DB-9 console port on the remote access module.

Switch Architecture

This switch delivers a dedicated 1000 Mbps link to each attached server card as a separate LAN segment (independent collision domain). It provides 10, 100 or 1000 Mbps to any uplink device attached directly to the switch. It completely eliminates the bottlenecks of shared Ethernet networks by providing a wide bandwidth of up to 20 Gbps. This makes it ideal for increasing the throughput of server farms. The switch includes up to six Gigabit Ethernet ports that connect to server blades over the chassis middle plane, and four external Gigabit Ethernet ports that can be used to uplink to a collapsed backbone or for a high-speed server connection.

Switching Concepts

A network switch allows simultaneous transmission of multiple packets via non-crossbar switching. This means that it can partition a network more efficiently than bridges or routers. The switch has, therefore, been recognized as one of the most important building blocks for today’s networking technology.

Performance bottlenecks caused by congestion at the network access point (e.g., a high-volume file server) can be significantly reduced by attaching the server directly to a switch over the chassis backplane. And, by using full-duplex mode, the bandwidth of the dedicated segment can be doubled to maximize throughput.

When networks are based on repeater (hub) technology, the maximum distance between end stations is limited. For Ethernet, there may be up to four hubs between any pair of stations; for Fast Ethernet, the maximum is two. This is known as the hop count. However, a switch turns the hop count back to zero. So subdividing the network into smaller and more manageable segments, and linking them to the larger network by means of a switch, removes this limitation.

Management Options

The switch provides a management agent that allows it to be managed remotely via SNMP or Remote Monitoring (RMON Groups 1, 2, 3 and 9) protocols, Web browser, or Telnet. The switch can also be managed on-site through the serial DB-9 COM port on the remote access module in the chassis or through the switch's on-board RJ-11 connector.

Description of Hardware

Ethernet Ports

The PowerEdge 1655MC Integrated Switch contains 6 Gigabit Ethernet ports for connecting to server cards over the chassis middle plane, one Fast Ethernet port that connects to the system management channel over the chassis middle plane, and 4 Gigabit Ethernet ports for uplinking to the network.

The uplink Gigabit Ethernet ports can operate at 10, 100 or 1000 Mbps. These uplink ports support auto-negotiation of speed, duplex mode (half or full duplex), and flow control. When using auto-negotiation, the speed, transmission mode and flow control can be automatically set if this feature is also supported by the attached device. Otherwise, these items can be manually configured for any connection. The six Gigabit Ethernet ports that connect to server blades can only operate at 1000 Mbps, full-duplex. These six ports support flow control also.

note.gif (1135 bytes) NOTE: You can connect the Gigabit Ethernet ports to a high-speed server or network backbone up to 100 meters (328 ft) away using Category 5 Unshielded Twisted Pair (UTP) or Shielding Twisted Pair (STP) cable. However, you should test the cable installation for IEEE 802.3ab compliance.

Status LEDs

The switch also includes 9 Light Emitting Diodes (LEDs) on the external bracket for “at-a-glance” monitoring of switch power and port status (one for the switch and two for each port). The LEDs can be used to simplify installation and network troubleshooting.

Table 1. Port and System LEDs

Port and System Status LEDs
LED Condition Status
Power Green Power ON, diagnostics passed
  Amber Power ON, diagnostics failed
  Off Power OFF
Link Green Port has established a valid network connection.
Off Port has no connection.
Activity Orange (flashing) Traffic is crossing the port.
Off No traffic on port.

Management Agent

This switch includes a built-in management agent that offers a variety of management options, including SNMP, RMON and a Web-based interface. The switch also includes an RJ-11 port for on-site management. A system may be connected to this port for configuration and monitoring. A DB-9-to-RJ-11 cable is provided with the switch for this purpose. You can also manage the switch on-site using the DB-9 console port on the remote access module.

The management agent provides a wide range of advanced performance-enhancing features. Multicast filtering provides support for real-time network applications. Port-based and tagged Virtual Local Area Networks (VLANs) provide traffic security and efficient use of network bandwidth. Quality of Service (QoS) priority queuing ensures the minimum delay for moving real-time multimedia data across the network. Flow control eliminates the loss of packets due to bottlenecks caused by port saturation.

Some of the switch’s advanced features are described below.

Spanning Tree Protocol

The switch supports the IEEE 802.1D Spanning Tree Protocol (default: enabled). This protocol adds a level of fault tolerance by allowing two or more redundant connections to be created between a pair of Local Area Network (LAN) segments. When there are multiple physical paths between segments, this protocol will choose a single path and disable all others to ensure that only one route exists between any two stations on the network. This prevents the creation of network loops. However, if the chosen path should fail for any reason, an alternate path will be activated to maintain the connection.

This switch does not support multiple spanning trees. If the chassis acts as an end node, this is not important. However, if the chassis is configured as an interconnection device between separate LAN segments, where traffic can flow directly between two uplink ports, then some VLANs may become isolated from the chassis.


The switch supports up to 32 VLANs. A Virtual LAN is a collection of network nodes that share the same collision domain regardless of their physical location or connection point in the network. By segmenting your network into VLANs, you can:

Multicast Switching

Specific multicast traffic can be assigned to its own VLAN to ensure that it does not interfere with normal network traffic and to guarantee real-time delivery by setting the required priority level for the designated VLAN. The switch uses Internet Group Management Protocol (IGMP) Snooping and IGMP to manage multicast group registration.

Traffic Priority

This switch provides Class of Service (CoS) by prioritizing each packet based on the required level of service, using four distinct queues with Weighted Round Robin Queuing. It uses IEEE 802.1p and 802.1Q tags to prioritize incoming traffic based on input from the end-station application. These functions can be used to provide independent priorities for delay-sensitive data and best-effort data.

Features and Benefits



Management Agent

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