Design Reference

the power budget is exceeded or margin is insufficient, you can either use a transceiver rated
for longer distance operation, or calculate budget and losses using actual values rather than
specified limit values. Either method can improve link budget by 4 to 5 dB or more.
10/100BASE-X and 1000BASE-TX reach
The following table lists maximum transmission distances for 10/100BASE-X and 1000BASE-
TX Ethernet cables.
Table 7: Maximum cable distances
10BASE-T 100BASE-TX 1000BASE-TX
IEEE standard 802.3 Clause 14 802.3 Clause 21 802.3 Clause
40
Date rate 10 Mb/s 100 Mb/s 1000 Mb/s
Cat 5 UTP distance 100 m 100 m 100 Ω, 4 pair:
100 m
10/100/1000BASE-TX Auto-Negotiation recommendations
Auto-Negotiation lets devices share a link and automatically configures both devices so that
they take maximum advantage of their abilities. Auto-Negotiation uses a modified 10BASE-T
link integrity test pulse sequence to determine device ability.
The Auto-Negotiation feature allows the devices to switch between the various operational
modes in an ordered fashion and allows management to select a specific operational mode.
The Auto-Negotiation feature also provides a parallel detection (also called autosensing)
function to allow the recognition of 10BASE-T, 100BASE-TX, 100BASE-T4, and 1000BASE-
TX compatible devices, even if they do not support Auto-Negotiation. In this case, only the link
speed is sensed; not the duplex mode. Avaya recommends the Auto-Negotiation configuration
as shown in the following table, where A and B are two Ethernet devices.
Table 8: Recommended Auto-Negotiation configuration on 10/100/1000BASE-TX ports
Port on A Port on B Remarks Recommendations
Auto-Negotiation
enabled
Auto-Negotiation
enabled
Ports negotiate on
highest supported
mode on both sides.
Avaya recommends
that you use this
configuration if both
ports support Auto-
Negotiation mode.
Hardware fundamentals and guidelines
28 Network Design Reference for Avaya VSP 4000 February 2014
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