TFTP Transfer on a VRF Using ip tftp source-interface Command

I was trying to transfer an IOS image via TFTP to a remote Cisco router but it got timed out. My troubleshooting showed the TFTP server was only reachable from a VRF and not via the router's global routing table.


Router#copy tftp://172.27.5.4/c2900-universalk9-mz.SPA.155-3.M6a.bin flash
Destination filename [c2900-universalk9-mz.SPA.155-3.M6a.bin]?
Accessing tftp://172.27.5.4/c2900-universalk9-mz.SPA.155-3.M6a.bin...
%Error opening tftp://172.27.5.4/c2900-universalk9-mz.SPA.155-3.M6a.bin (Timed out)

Router#ping 172.27.5.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.27.25.254, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

Router#ping vrf MGMT 172.27.5.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.27.5.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/19/20 ms

Router#show run interface g0/1
Building configuration...

Current configuration : 158 bytes
!
interface GigabitEthernet0/1
 vrf forwarding MGMT
 ip address 172.27.4.6 255.255.255.0
 duplex auto
 speed auto
end


I configured the ip tftp source-interface <INTERFACE> command and TFTP transfer worked afterwards.

Router#configure terminal                                                              
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#ip tftp ?
  blocksize         Specify TFTP client blocksize
  boot-interface    Force interface to use for TFTP booting
  min-timeout       Set minimum timeout period for retransmission
  source-interface  Specify interface for source address in TFTP connections

Router(config)#ip tftp source-interface ?
  Async                    Async interface
  Auto-Template            Auto-Template interface
  BVI                      Bridge-Group Virtual Interface
  CDMA-Ix                  CDMA Ix interface
  CTunnel                  CTunnel interface
  Dialer                   Dialer interface
  Embedded-Service-Engine  cisco embedded service engine module
  GigabitEthernet          GigabitEthernet IEEE 802.3z
  LongReachEthernet        Long-Reach Ethernet interface
  Loopback                 Loopback interface
  Lspvif                   LSP virtual interface
  MFR                      Multilink Frame Relay bundle interface
  Multilink                Multilink-group interface
  Null                     Null interface
  Port-channel             Ethernet Channel of interfaces
  Tunnel                   Tunnel interface
  Vif                      PGM Multicast Host interface
  Virtual-PPP              Virtual PPP interface
  Virtual-Template         Virtual Template interface
  Virtual-TokenRing        Virtual TokenRing
  vmi                      Virtual Multipoint Interface

Router(config)#ip tftp source-interface GigabitEthernet0/1
Router(config)#end
Router#copy tftp://172.27.5.4/c2900-universalk9-mz.SPA.155-3.M6a.bin flash:
Destination filename [c2900-universalk9-mz.SPA.155-3.M6a.bin]?
Accessing tftp://172.27.5.4/c2900-universalk9-mz.SPA.155-3.M6a.bin...
Loading c2900-universalk9-mz.SPA.155-3.M6a.bin from 172.27.5.4 (via GigabitEthernet0/1): !.!!!.!!.!

<SNIP>