Date: Fri, 19 Feb 2010 10:20:24 +0700 (ICT) From: Olivier Nicole <Olivier.Nicole@cs.ait.ac.th> To: freebsd-questions@freebsd.org Subject: Re: is there a tool for estimating loss rates Message-ID: <201002190320.o1J3KOOS045254@banyan.cs.ait.ac.th> In-Reply-To: <a9f4a3861002181856jde95852l7c56277f1a36dd8d@mail.gmail.com> (message from Kurt Buff on Thu, 18 Feb 2010 18:56:46 -0800) References: <8CCEB7E2804F4187B322D59004AAA8A1@desktop2002> <a9f4a3861002181856jde95852l7c56277f1a36dd8d@mail.gmail.com>
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Hi, > I have 2 leasedlines for internet. the one is in a country. other one is in > a another country. > I am looking for a tool for estimating loss packets between 2 lines. > is there a tool for it? > for instance , while searching, I found badabing tool for that. But I > couldn't understand how it estimates loss packets. > could you give me an example? I think that the data loss can occur at two levels: at the physical layer, the leased line, and at the IP/TCP/UDP level. The physical layer should be able to detect the data loss and retransmit the data, so upper layer will not even notice that there have been retrsnamission (except that there may be some delay). Of course TCP will also detect when something goes wrong and retransmit the data (UDP does not retransmit the lost data, this is left to the application). TCP/UDP packet loss are from end to end: from one computer to another computer. While I presume you are more interested in the data loss specific to the leased line (to ask your telco to improve their service). For IP/TCP/UDP level, there are many counters that keep a log of what is being lost. These are accessible through SNMP. At the leased line level, it really depends on what kind of leased line you are using and what data the "modem" can give you. Best regards, Olivier
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