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Ali Razavi
Beginner

TFTP Speed Increase

Hey everyone,

Does anyone know of a way to increase TFTP transfer speeds over the WAN?  We're in the process of distributing new IOS and ASA releases and transferring images using TFTP over the WAN is dreadfully slow.  It works great on the LAN of course with gigabit speeds but there's no scalable way of doing it with numerous remote locations.

Thanks,

Ali

1 ACCEPTED SOLUTION

Accepted Solutions
Steve Fuller
Engager

Hi Ali,

As you may be aware, the way TFTP works is that it transfers a single data packet containing one block of data, and that packet must be acknowledged before the next packet can be sent. With this in mind there are really only two ways to increase TFTP performance.

1. Increase the TFTP blocksize

The default TFTP blocksize is 512-bytes, but if your client and server both support RFC 2348 TFTP Blocksize Option then the blocksize can be increased to approximately 1450-bytes. There are measurements in the aforementioned RFC that show a 2.8x performance improvement when using 1428-byte blocks compared to 512-byte blocks.

2. Decrease the latency

Slow tranfer over the WAN is sometimes caused by low bandwidth, but more usually it's due to high latency. If you have a round-trip latency of 100ms between your client and server then you can at most transfer 10-blocks of data per second. If you can reduce the latency, then you can transfer more blocks in any given period of time.

If you have a number of routers/sites that have direct connectivity between themselves and they are geographically closer to each other than back to your hub, one option you have is to set up a router as the TFTP server.

Other than the above, there's perhaps the option of using some other protocol which is TCP based e.g., FTP, SCP etc., as this might give better performance than TFTP.

Regards

View solution in original post

1 REPLY 1
Steve Fuller
Engager

Hi Ali,

As you may be aware, the way TFTP works is that it transfers a single data packet containing one block of data, and that packet must be acknowledged before the next packet can be sent. With this in mind there are really only two ways to increase TFTP performance.

1. Increase the TFTP blocksize

The default TFTP blocksize is 512-bytes, but if your client and server both support RFC 2348 TFTP Blocksize Option then the blocksize can be increased to approximately 1450-bytes. There are measurements in the aforementioned RFC that show a 2.8x performance improvement when using 1428-byte blocks compared to 512-byte blocks.

2. Decrease the latency

Slow tranfer over the WAN is sometimes caused by low bandwidth, but more usually it's due to high latency. If you have a round-trip latency of 100ms between your client and server then you can at most transfer 10-blocks of data per second. If you can reduce the latency, then you can transfer more blocks in any given period of time.

If you have a number of routers/sites that have direct connectivity between themselves and they are geographically closer to each other than back to your hub, one option you have is to set up a router as the TFTP server.

Other than the above, there's perhaps the option of using some other protocol which is TCP based e.g., FTP, SCP etc., as this might give better performance than TFTP.

Regards

View solution in original post