nanog mailing list archives
Re: Do network diagnostic tools need upgrade?
From: Octavio Alvarez <alvarezp () alvarezp ods org>
Date: Mon, 03 Feb 2014 10:59:14 -0800
On 02/03/2014 05:33 AM, Ammar Salih wrote:
Hello NANOG list members, I have a question for you, are you happy with the current network diagnostic tools, like ping, trace route .. etc,
What tools are you referring to by "..."? There are many others. I like tcptraceroute (there are two variants of it) and mtr.
don't you think it's time to have an upgraded version of icmp protocol?
What is it that you are thinking? ICMP is for signaling between machines. Increasing signaling for human diagnostics can lead to reconnaissance attacks. We don't want yet another option for some to incorrectly block ICMP [1], which in turn leads to other problems. [1] ... when they want to just block ICMP echo and reply, which is also bad enough and must be done really selectively.
First scenario: To be able to troubleshoot advanced networks with complex QoS and policy-based routing configuration, where ping, traceroute and other network diagnostic tools do not provide accurate readings, for example, you are troubleshooting a web server with ping, and it looks functioning quite well (packet loss and round trip time is all good), but web services are still significantly slow, the fact is icmp and tcp:80 might have different priorities and bandwidth limits on each router along the path between the client and the server, in this case, network admins usually use telnet applications like (Paping), well it may help if the forward and return path of all packets are exactly the same.
tcptraceroute.
Second scenario: So another possible scenario is that you need to determine readings for forward and return paths, TraceRoute for example gives you forward path only using icmp. But what if you need to troubleshoot a VoIP server for example, assuming that packets return path might not be the same as forward path.
It depends. Asymmetric routing is not necessarily bad unless it causes a problem like packet loss, high latency, etc. For example, if the return path has packet loss but you should 'hopefully' (yeah I know...) notice it in the traceroute if you increment the probe count or run it twice. Or try mtr, a periodic traceroute with different statistics presentation that significantly reduces the 'hopefully' problem.
Third scenario: One of the most common problems in networking, is that you don't have access to all equipment between client and server, but you have to troubleshoot the path between them and to understand where the problem exactly is in order to contact the right person without having the privilege to check the configuration on each router.
This one's more difficult but also "it depends". State a specific problem case.
Fourth scenario: Also, with trace route you can't determine the actual path, for example, the router may direct http traffic to proxy server while leaving other traffic going through a different hop.
tcptraceroute.
Current thread:
- Do network diagnostic tools need upgrade? Ammar Salih (Feb 03)
- Re: Do network diagnostic tools need upgrade? Andre Gironda (Feb 03)
- Re: Do network diagnostic tools need upgrade? Valdis . Kletnieks (Feb 03)
- Re: Do network diagnostic tools need upgrade? Octavio Alvarez (Feb 03)
- Re: Do network diagnostic tools need upgrade? Jared Mauch (Feb 03)
- Re: Do network diagnostic tools need upgrade? Bryan Socha (Feb 03)
- Re: Do network diagnostic tools need upgrade? Jared Mauch (Feb 03)