Nortel Networks 10BASE-T manual Configuration Parameters, Autosensing and Autonegotiation

Using the BayStack 410-24T 10BASE-T Switch

Configuration Parameters

Certain configuration parameters, including the system characteristics strings, some VLAN parameters, IGMP configuration parameters, and the MultiLink Trunk names are stored in flash memory. These parameters are updated every 10 minutes or whenever you issue the Save Current Settings command (also, whenever you issue the Reset command).

Note: Do not power off the switch within ten minutes of changing any configuration parameters, unless you first issue the Save Current Settings command. Powering down the switch within 10 minutes of changing configuration parameters (without resetting) can cause the changed configuration parameters to be lost.

Autosensing and Autonegotiation

BayStack 410-24T switches are autosensing and autonegotiating devices. The term autosense refers to a port’s ability to sense the speed of an attached device. The term autonegotiation refers to a standardized protocol (IEEE 802.3u) that exists between two IEEE 802.3u-capable devices.

Because the BayStack 410-24T switch uses fixed 10BASE-T ports, the autonegotiation feature does not negotiate the port speed when connecting to another IEEE 802.3u-capable device. The BayStack 410-24T switch only negotiates the best duplex mode.

When an optional 10/100 BASE-T MDA is installed, the autonegotiation feature selects the best of both speed and duplex modes for that connection. The MDA ports negotiate down from 100 Mb/s speed and full-duplex mode until a supported speed and duplex mode is acknowledged by the attached device.

Autosensing is used when the attached device is not capable of autonegotiation or is using a form of autonegotiation that is not compatible with the IEEE 802.3u autonegotiation standard. In this case, because it is not possible to sense the duplex mode of the attached device, the BayStack 410-24T switch reverts to half-duplex mode.

For more information about autosensing and autonegotiation modes, see “Autonegotiation Modes” on page 4-7.

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