the numbers in this diagram refer to numbered sections in the text. a 24-port unit is shown.

    front panel

    1 24 rj-45 10/100/1000 ports

    rj-45 ports. these are shielded rj-45 data sockets. they cannot be used as standard traditional telephone sockets, or to connect the unit to a traditional pbx or public telephone network. only connect rj-45 data connectors, network telephony systems, or network telephones to these sockets. either shielded or unshielded data cables with shielded or unshielded jacks can be connected to these data sockets.

    les ports rj-45. ceux-ci sont proteges par des prises de donnees. ils ne peuvent pas être utilises comme prises de telephone conventionnelles standard, ni pour la connection de l'unite a un reseau telephonique central prive ou public. raccorder seulement connecteurs de donnees rj-45, systemes de reseaux de telephonie ou telephones de reseaux a ces prises. il est possible de raccorder des cables proteges ou non proteges avec des jacks proteges ou non proteges a ces prises de don.

    rj-45-porte. diese porte sind geschutzte datensteckdosen. sie durfen weder wie normale traditionelle telefonsteckdosen noch fur die verbindung der einheit mit einem traditionellem privatem oder offentlichem telefonnetzwerk gebraucht werden. nur rj-45-datenansclube, telefonnetzsysteme or netztelefone an diese steckdosen anschlieben. entweder geschutzte oder ungeschutzte buchsen durfen an diese datensteckdosen angeschlossen werden.

    the switch has 24/16 10/100/1000 mbps auto-negotiating ports. each port automatically negotiates with the attached device to determine the correct speed and duplex mode of operation. once negotiated, the port will operate in one of the following modes:

    1 10base-t half duplex

    2 10base-t full duplex

    3 100base-tx half duplex

    4 100base-tx full duplex

    5 1000base-t full duplex

    caution: the switch supports full duplex auto-negotiation. if the connected device does not support auto-negotiation, the switch will operate in half duplex mode, and therefore can only operate at 10 mbps or 100 mbps. in such a configuration, you may notice some degradation of network performance. 3com recommends that you use devices that are capable of auto-negotiation (and that you ensure that auto-negotiation is enabled, if it is a configurable option).

    all ports auto-sense an mdi/mdix connection so each port can be connected to a device with a normal ‘straight through’ tp (twisted pair) cable or a ‘cross-over’ tp cable. any port can therefore be used to connect to either another switch port, server, or workstation without additional configuration.

    traffic prioritization

    the switch offers priority queuing, which means all packets that are received are examined to see if they have been priority encoded. when a packet is received, the switch will read the priority level and determine the appropriate channel to forward the packet based on the priority level. this feature can be useful, for example, during excessive loads when one type of traffic may require priority over another. the switch is configured to comply with 802.1p, vlan tagged frames.

    traffic prioritization ensures that high priority data is forwarded through the switch without being delayed by lower priority data. it differentiates traffic into classes and prioritizes those classes automatically. traffic prioritization uses the multiple traffic queues that are present in the hardware of the switch to ensure that high priority traffic is forwarded on a different queue from lower priority traffic, and is given preference over that traffic. this ensures that time-sensitive traffic gets the highest level of service. the 802.1d standard specifies eight distinct levels of priority (0 to 7), each of which relates to a particular type of traffic. the priority levels and their traffic types are shown in the following table.

   

    the traffic prioritization feature supported by the switch is compatible with the relevant sections of the ieee 802.1d standard (incorporating ieee 802.1p).

    2 activity/link/speed status leds

    the top and third row of status leds, labelled “link/activity,” show the link and activity status of the related ports:

   

    duplex status leds

    the second and fourth row of status leds, which are colored yellow, show the duplex status of the related ports:

   

    1000base-t only operates in full duplex mode. 10base-t/100base-tx can be in half or full duplex mode.

    4 power led

    the power led shows the power status of the switch:

   

    rear panel connections

    5 power supply

    the switch automatically adjusts to the supply voltage. only use the power cord that is supplied with the unit.