Specifying a single source interface for specified packet types

NOTE
This feature is supported on the ICX 7750 switch.

When the Layer 3 switch originates a packet of one of the following types, the source address of the packet is the lowest-numbered IP address on the interface that sends the packet:

  • Telnet
  • TACACS/TACACS+
  • TFTP
  • RADIUS
  • Syslog
  • SNTP
  • SNMP traps

You can configure the Layer 3 switch to always use the lowest-numbered IP address on a specific Ethernet, loopback, or virtual interface as the source addresses for these packets. When configured, the Layer 3 switch uses the same IP address as the source for all packets of the specified type, regardless of the ports that actually sends the packets.

Identifying a single source IP address for specified packets provides the following benefits:

  • If your server is configured to accept packets only from specific IP addresses, you can use this feature to simplify configuration of the server by configuring the Brocade device to always send the packets from the same link or source address.
  • If you specify a loopback interface as the single source for specified packets, servers can receive the packets regardless of the states of individual links. Thus, if a link to the 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 specific packets. You can configure a source interface for one or more of these types of packets separately.

The following sections show the syntax for specifying a single source IP address for specific packet types.

Telnet packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all Telnet packets, enter commands such as the following. 

device(config)# interface loopback 2
device(config-lbif-2)# ip address 10.0.0.2/24
device(config-lbif-2)# exit
device(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.

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. 

device(config)# interface ethernet 1/1/4
device(config-if-1/1/4)# ip address 10.157.22.110/24
device(config-if-1/1/4)# exit
device(config)# ip telnet source-interface ethernet 1/1/4

Syntax: [no] ip telnet source-interface { ethernet unit / slot / port | loopback num | management num |venum }

TACACS/TACACS+ packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all TACACS/TACACS+ packets, enter commands such as the following. 

device(config)# interface ve 1
device(config-vif-1)# ip address 10.0.0.3/24
device(config-vif-1)# exit
device(config)# ip tacacs source-interface ve 1

The commands in this example configure virtual interface 1, assign IP address 10.0.0.3/24 to the interface, then designate the interface as the source for all TACACS/TACACS+ packets from the Layer 3 switch.

Syntax: [no] ip tacacs source-interface { ethernet unit / slot / port | loopback num | management num |venum }

RADIUS packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all RADIUS packets, enter commands such as the following. 

device(config)# interface ve 1
device(config-vif-1)# ip address 10.0.0.3/24
device(config-vif-1)# exit
device(config)# ip radius source-interface ve 1

The commands in this example configure virtual interface 1, assign IP address 10.0.0.3/24 to the interface, then designate the interface as the source for all RADIUS packets from the Layer 3 switch.

Syntax: [no] ip radius source-interface { ethernet unit / slot / port | loopback num | management num |venum }

TFTP packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all TFTP packets, enter commands such as the following. 

device(config)# interface ve 1
device(config-vif-1)# ip address 10.0.0.3/24
device(config-vif-1)# exit
device(config)# ip tftp source-interface ve 1

The commands in this example configure virtual interface 1, assign IP address 10.0.0.3/24 to the interface, then designate the interface's address as the source address for all TFTP packets.

Syntax: [no] ip tftp source-interface { ethernet unit / slot / port | loopback num | management num |venum }

The default is the lowest-numbered IP address configured on the port through which the packet is sent. The address therefore changes, by default, depending on the port.

Syslog packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all Syslog packets, enter commands such as the following. 

device(config)# interface ve 1
device(config-vif-1)# ip address 10.0.0.4/24
device(config-vif-1)# exit
device(config)# ip syslog source-interface ve 1

The commands in this example configure virtual interface 1, assign IP address 10.0.0.4/24 to the interface, then designate the interface's address as the source address for all Syslog packets.

Syntax: [no] ip syslog source-interface { ethernet unit / slot / port | loopback num | management num |venum }

The default is the lowest-numbered IP or IPv6 address configured on the port through which the packet is sent. The address therefore changes, by default, depending on the port.

SNTP packets

To specify the lowest-numbered IP address configured on a virtual interface as the device source for all SNTP packets, enter commands such as the following. 

device(config)# interface ve 1
device(config-vif-1)# ip address 10.0.0.5/24
device(config-vif-1)# exit
device(config)# ip sntp source-interface ve 1

The commands in this example configure virtual interface 1, assign IP address 10.0.0.5/24 to the interface, then designate the interface's address as the source address for all SNTP packets.

Syntax: [no] ip sntp source-interface { ethernet unit / slot / port | loopback num | management num |venum }

The default is the lowest-numbered IP or IPv6 address configured on the port through which the packet is sent. The address therefore changes, by default, depending on the port.

SNMP packets

To specify a loopback interface as the SNMP single source trap, enter commands such as the following. 

device(config)# interface loopback 1
device(config-lbif-1)# ip address 10.0.0.1/24
device(config-lbif-1)# exit
device(config)# snmp-server trap-source loopback 1

The commands in this example configure loopback interface 1, assign IP address 10.00.1/24 to the loopback interface, then designate the interface as the SNMP trap source for this device. Regardless of the port the Brocade device uses to send traps to the receiver, the traps always arrive from the same source IP address.

Syntax: [no] snmp-server trap-source { ethernet unit / slot / port | loopback num | venum }

Parent topic: Configuring IP parameters - Layer 3 switches