Configuring An Interface As The Source For All Telnet Packets - Foundry Networks Switch and Router Installation And Configuration Manual

Foundry Switch and Router Installation and Configuration Guide

Configuring an Interface as the Source for All Telnet Packets

You can designate the lowest-numbered IP address configured an Ethernet port, POS port, loopback interface, or
virtual interface as the source IP address for all Telnet packets from the Layer 3 Switch. Identifying a single
source IP address for Telnet packets provides the following benefits:
• If your Telnet server is configured to accept packets only from specific links or IP addresses, you can use this
feature to simplify configuration of the Telnet server by configuring the Foundry device to always send the
Telnet packets from the same link or source address.
• If you specify a loopback interface as the single source for Telnet packets, Telnet servers can receive the
packets regardless of the states of individual links. Thus, if a link to the Telnet server becomes unavailable
but the client or server can be reached through another link, the client or server still receives the packets, and
the packets still have the source IP address of the loopback interface.
The software contains separate CLI commands for specifying the source interface for Telnet, TACACS/TACACS+,
and RADIUS packets. You can configure a source interface for one or more of these types of packets.
To specify an Ethernet or POS port or a loopback or virtual interface as the source for all Telnet packets from the
device, use the following CLI method. The software uses the lowest-numbered IP address configured on the port
or interface as the source IP address for Telnet packets originated by the device.
USING THE CLI
To specify the lowest-numbered IP address configured on a virtual interface as the device's source for all Telnet
packets, enter commands such as the following:
BigIron(config)# int loopback 2
BigIron(config-lbif-2)# ip address 10.0.0.2/24
BigIron(config-lbif-2)# exit
BigIron(config)# ip telnet source-interface loopback 2
The commands in this example configure loopback interface 2, assign IP address 10.0.0.2/24 to the interface,
then designate the interface as the source for all Telnet packets from the Layer 3 Switch.
Syntax: ip telnet source-interface ethernet <portnum> | pos <portnum> | loopback <num> | ve <num>
The <num> parameter is a loopback interface or virtual interface number. If you specify an Ethernet or POS port,
the <portnum> is the port's number (including the slot number, if you are configuring a chassis device).
The following commands configure an IP interface on an Ethernet port and designate the address port as the
source for all Telnet packets from the Layer 3 Switch.
BigIron(config)# interface ethernet 1/4
BigIron(config-if-1/4)# ip address 209.157.22.110/24
BigIron(config-if-1/4)# exit
BigIron(config)# ip telnet source-interface ethernet 1/4
USING THE WEB MANAGEMENT INTERFACE
You cannot configure a single Telnet source using the Web management interface.
Specifying a Simple Network Time Protocol (SNTP) Server
You can configure Layer 2 and Layer 3 Switches to consult SNTP servers for the current system time and date.
NOTE: Foundry Layer 2 and Layer 3 Switches do not retain time and date information across power cycles.
Unless you want to reconfigure the system time counter each time the system is reset, Foundry Networks
recommends that you use the SNTP feature.
USING THE CLI
To identify an SNTP server with IP address 208.99.8.95 to act as the clock reference for a switch or router, enter
the following:
BigIron(config)# sntp server 208.99.8.95
10 - 10 December 2000