From 993fa4ee723c69a32a5e49530b296709b77e026c Mon Sep 17 00:00:00 2001 From: Tomek Mrugalski Date: Fri, 13 Dec 2019 16:29:11 +0100 Subject: [PATCH] [#876] avalanche description tweaks --- doc/sphinx/man/perfdhcp.8.rst | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/doc/sphinx/man/perfdhcp.8.rst b/doc/sphinx/man/perfdhcp.8.rst index 72d40ac946..6e3d31340d 100644 --- a/doc/sphinx/man/perfdhcp.8.rst +++ b/doc/sphinx/man/perfdhcp.8.rst @@ -26,17 +26,25 @@ from simulated multiple clients. It is able to test both IPv4 and IPv6 servers, and provides statistics concerning response times and the number of requests that are dropped. +The tool supports scenarios, which offer certain behaviours. By default (basic scenario) tests are run using the full four-packet exchange sequence (DORA for DHCPv4, SARR for DHCPv6). An option is provided to run tests using the initial two-packet exchange (DO and SA) instead. It is also possible to configure ``perfdhcp`` to send DHCPv6 RENEW and RELEASE messages -at a specified rate in parallel with the DHCPv6 four-way exchanges. +at a specified rate in parallel with the DHCPv6 four-way exchanges. By +default, if there is no response received with 1 second, a response is +considered lost and perfdhcp continues with other transactions. Second scenario is called avalanche, which is selected by ``--scenario avalanche``. It first sends as many Discovery or Solicit messages as request in -R option then -back off mechanism is used for each simulated client until all requests are +a retransmission (with exponential back off mechanism) is used for each simulated client until all requests are answered. It will generate report when all clients get their addresses or when -it will be manually stopped. Option ``-p`` is ignored in avalanche scenario. +it will be manually stopped. This scenario attempts to replicate a +case where the server is not able to handle the traffic swiftly +enough. Real clients will assume the packet or the response was lost +and will retransmit, further increasing DHCP traffic. This is +sometimes called avalanche effect, thus the scenario name. +Option ``-p`` is ignored in avalanche scenario. When running a performance test, ``perfdhcp`` will exchange packets with the server under test as fast as possible unless the ``-r`` parameter is used to