Resolving Cisco Router/Switch Tftp Problems: Source IP Address - The 'IP TFTP Source-Interface' Command

 

Resolving Cisco Router/Switch Tftp Problems: Source IP Address - The 'IP TFTP Source-Interface' Command

 

   

When working with Cisco equipment that has multiple ip interfaces, a common problem engineers are faced with is trying to successfully tftp to or from the Cisco device. This issue is usually encountered when the Cisco device (router or multi-layer switch) uses a different source IP address which cannot reach our TFTP Server's IP address or is blocked due to access lists.

 

Luckily, there is a way around this problem, and it’s a simple one.

 

To ensure your Cisco router or multi-layer switch uses the correct interface during any tftp session, use the ip tftp source-interface command to specify the source-interface that will be used by the device.

 

The following example instructs our Cisco 3750 Layer 3 switch to use VLAN 5 interface as the source ip interface for all tftp sessions:

 

3750G-Stack(config)# ip tftp source-interface vlan 5

 

As shown below, VLAN 5 has IP address 192.168.131.1 assigned to it, therefore this IP address will be the source interface from now on:

 

• 3750G-Stack# show ip interface brief
• Interface IP-Address OK? Method Status Protocol
• Vlan1 192.168.50.1 YES NVRAM up up
• Vlan2 192.168.130.1 YES NVRAM up up
• Vlan3 192.168.135.1 YES NVRAM up up
• Vlan4 192.168.19.1 YES NVRAM up up
• Vlan5 192.168.131.1 YES NVRAM up up
• Vlan6 192.168.141.1 YES NVRAM up up
• Vlan7 192.168.170.1 YES NVRAM up up
• Vlan8 192.168.180.1 YES NVRAM up up