Combo Ports - Allied Telesis FS750 SERIES Installation Manual

Chapter 1: Overview

Combo Ports

18
The FS750 Series Fast Ethernet switches have two pairs of combo ports.
Each combo port consists of one 10/100/1000Base-T twisted-pair port and
one slot for an optional 100Base-FX or 1000Base-SX/LX SFP transceiver.
The twisted-pair ports are identified with the letter "R" for "Redundant" on
the front face plates of the units. The combo ports and SFP slots are listed
in Table 1.
Switch
AT-FS750/20
AT-FS750/28
AT-FS750/28PS
AT-FS750/52
The combo ports have the guidelines listed here:
Only one port in a pair, either the twisted-pair port or a

corresponding SFP module, can be active at a time.
The twisted-pair port is the active port when its SFP slot is empty,

or when an SFP module is installed, but has not established a link
to an end node.
The twisted-pair port automatically changes to the redundant

status mode when an SFP module establishes a link with an end
node.
A twisted-pair port automatically transitions back to the active

status when the link is lost on the SFP module.
In nearly all cases, a twisted-pair port and an SFP module share

the same configuration settings, including port settings, VLAN
assignments, access control lists, and spanning tree.
An exception to the shared settings is port speed. If you disable

Auto-Negotiation on a twisted-pair port and set the speed and
duplex mode manually, the speed reverts to Auto-Negotiation
when an SFP module establishes a link with an end node.
Table 1. Combo Ports
Twisted-Pair Port
19R
20R
27R
28R
25R
26R
51R
52R
SFP Slot
19
20
27
28
25
26
51
52