LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
152
Datasheet
Document Number: 249241
Revision Number: 007
Revision Date: August 28, 2003
4.11
DTE Discovery Process
The DTE discovery process is port dependent and must be enabled through software. The process
is implemented as a next page option to the auto-negotiation flow. When the process is enabled,
manual control of auto-negotiation next pages is not allowed. This feature applies to the
LXT9785E transceiver only.
The process depends upon an IP phone, or any other DTE capable of being powered remotely,
having a specific filter that passes NLPs and FLPs. This filter should be non-polarized to insure
that the latest status of Auto-MDIX operation does not effect operation. This filter attenuates
100 Mbps MLT3 signals and 10 Mbps Manchester-encoded signals, and must be bypassed when
power is applied to the IP phone.
Figure 29
shows a typical IP telephone system connection.
4.11.1
Definitions
The following terms are used throughout the DTE discovery sections:
Figure 29. Typical IP Telephone System Connection
Power
Outlet
Computer
1
2
3
4
7
5
8
6
9
*
8
#
IP Telephone
UPS/
Generator
Power cable
SD
Power
Fault
1
2
3
4
5
6
7
8
9 10 11 12
Link
Mode
Link
Mode
13 14 15 16 17 18
19
21
20
22 23 24
Mode Select
Fdx
Act
1X
2X
3X
4X
5X
6X
7X
8X
9X
10X
11X
12X
13X
14X
15X
16X
17X
18X
19X
20X
21X
22X
23X
24X
10/100Base-T Ports
100
Reset
Clear
Module Status
Self Test
Console
ProCurve Switch 2424M
HP J4122B
VoIP-Enabled Switch
Power
Outlet
Data only over
Category 5 cable
Power cable
Power and data over
Category 5 cable
Negotiation Process:
This includes auto-negotiation and parallel detection processes
System:
The switch system using the LXT9785E for DTE Discovery
Link Partner:
A device connected to the LXT9785E through twisted pair cables
DTE:
Data Terminal Equipment; any end-of-link partner
Standard Link Partner:
A link partner that is not requiring power over a Category 5 cable;
typically a PC
Remote-Power DTE:
Data Terminal Equipment requiring power over a Category 5 cable;
typically an IP telephone
Discovery:
The process of identifying the type of link partner present