ping using TCP rather than ICMP

[kanupriya]

Hi all,

We are facing problem of high RTT on our ISP link. Wondering that it could be the policy restriction on ICMP rate configured on other side of border router, we want to know the RTT using other protocol than ICMP. Can we ping using TCP, if yes then how.

Thank you very much

[Richard Burts]

Kanupriya

Strictly speaking, no you can not ping using TCP. You might be able to write something that would send a TCP packet to a destination, wait for the response, and calculate the RTT. But that would depend on the remote destination generating a response to your TCP packet. One of the nice aspects of ICMP is that it deals with destination IP address but does not have the concept of port number. But TCP does use port numbers and you must send a TCP packet to a particular destination and a particular TCP port number. And the remote device must be listening on that particular TCP port and must generate a response to you. I think that is way more complicated than it is worth.

If you are worried about the rate limiting of ICMP by the router beyond your border router you might see if there is some other device that you could ping which does not rate limit ICMP.

HTH

Rick

[Bobby Thekkekandam]

To add on to what Rick described, the ping tool is an awful measure of network performance, response time, throughput, etc. Ping was designed for one thing, which is reachability. Most vendors place a very low process priority on responding to ICMP messages, so while there may be absolutely no problems with a particular device or link, ping times could incorrectly imply a latency issue.

Now with that said, a TCP based ping does have merits in troubleshooting certain issues, and there are various freeware TCP based ping apps out there. I don't have experience with any of them in particular, so I can't recommend any of them specifically.

HTH,

Bobby

[b-ulrich]

Hi, you may be able to get away with ttcp if your router supports it. I have used this on a point to point high speed link and it seemed to be a viabable way to test throughput above layer 3. But the ISP will have to let that connection (ttcp accept)take place on their router, of which they probably will balk at.

[Harold Ritter]

You could use the Test TCP tool (TTCP) but this would require you to have access to the target router as well as the source router. This tool is not officially supported I think but it still works ;o)

For more information on this TTCP, please refer to the following URL:

http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a0080094694.shtml

Hope this helps,

[kanupriya]

Thanks all for your valuable suggsestions, I will try with ttcp also.

Thank you very much.