E3Switch DS3 Operating Information Manual - page 14
Chapter 5: Operating Modes and Configuration
SFP Second LAN Port
The SFP LAN Port 1 hardware exists on all gateways shipped and allows an SFP transceiver to enable out-
of-band management, through either LAN port, or fiber-optic LAN connections of 10km or more. Refer to
interoperability section of this document for compatible SFP transceivers.
Dedicated Management/Data LAN Ports
If the SFP Second LAN Port is in use, then either LAN port may be configured to pass TDM data packets
or, selectively, to pass only management or only TDM data packets when such can be determined.
LAN-to-LAN forwarding should be used cautiously in combination with management or data-only LAN
port settings. The blocking of a subset of traffic can result in network and spanning tree topologies which
can be inappropriate or difficult to diagnose.
If a LAN port is configured for TDM data-only packets, the unit will drop incoming management packets
destined for an E3Switch MAC address. This provides a moderate level of security. On a “data-only” LAN
port, these management unicast packets and management broadcast/multicast packets may not be
forwarded to the second LAN even if LAN-to-LAN traffic flow is configured.
VLAN
In some firmware versions it is possible to configure a VLAN ID for packets containing TDM data.
VLAN configuration settings shown at the HTTP management page may also be set for communication
with the gateway's management entity.
As shipped, the unit will accept management packets with any VLAN tags and attempt to respond to the
same. For more robust performance, specific VLAN tag settings can be configured.
Port Auto-Disable and Return-to-Service Delay
In addition to manually configuring a port as disabled, the gateway has the ability to delay a DS3/E3 port's
return to service for a specified period of time after it has failed or disable a LAN port if both TDM circuits
are down.
DS3/E3 Return to Service delay
The return-to-service delay prevents network topology thrashing if a TDM circuit is flapping up and down.
Some TDM carriers will interrupt service for 50msec, once per day as a link test. A configurable, failure-
time setting exists to prevent such tests from triggering a link-down, retun-to-service delay.
To exit the return-to-service delay, power-cycle the gateway or click the button which appears on the
configuration HTTP screen of a gateway that is in configuration delay.
LAN Auto-Disable
The LAN port can be configured to automatically disable itself when no TDM circuit exists. This setting is
useful for attached LAN equipment which requires the LAN port to go down in order to understand that the
path to the remote network is no longer available. Use this setting cautiously, as management of the
gateway will also no longer be possible through a disabled LAN port.
To exit the LAN-port-disabled condition, power-cycle the gateway, which will allow communication with
the gateway for approximately one minute even if TDM ports are down.
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