8-2 User Guide for the Avaya P580 and P882 Multiservice Switches, v6.1
Chapter 8
Physical Port Features
This section describes the following features that are available when
configuring the physical parameters on the ports:
■Auto-negotiation
■Remote Fault Detection
■Flow Control
Auto-negotiation Autonegotiation is an extension of the link test methods used by 10Base-T
and 10Base-FL to verify the integrity of the link between devices.
Autonegotiation advertises a device’s abilities by encoding a 16-bit data
packet, called a link code word (LC W), within a burst of 17 to 33 link
pulses, called a fast link pulse (FLP) burst. FLP bursts have an approximate
duration of 2 µs and are transmitted in 16.8 µs intervals (the same interval
as for the normal link pulses used by 10Base-T and 10Base-FL).
However, this does not hold true for the Half Duplex/Full Dupl ex (HD/FD)
selection. If a non-autonegotiating device running FD is connected to a
negotiating device, the negotiating device runs at HD, and the link does not
operate properly.
* Note: A Gigabit Ethernet device negotiates at HD or FD, speed is
always one Gigabit.
* Note: M5520-TX (P/N M5520-100TX) boards manufactured with a
Quality Phy do not auto-negotiate with Xircom brand adapter
cards. If you have this problem, disable auto-negoti at ion on the
affected ports, and set the port speed and duplex st ate manually.
* Note: You may experience difficulties with auto-negotiation between
some releases of the 10/100Base-TX Module (M5510-100TX,
M5520-100TX, M5510R-100TX, M5512R-100TX) and
adapter cards using physical interfaces manufactured by
National Semiconductor. The symptom is loss of connectivity.
If you do. do one of the following:
• Disa ble auto-negotiation
• Use a patch cable that is longer that 5 meters
*Note: The factory default for the National Phy Mode is Enable.
The LCW contains two fields (the selector field and the technology ability
field), which together serve to ide ntify a device's capabilities.