Saturday, October 04, 2014

iperf performance on Raspberry PI model B

iperf is  a great tool to measure the performance on your network. It works by measuring how much data can be sent  between two hosts.

When using iperf many variables come into play; like latency, bandwidth between the hosts, OS performance, the switches and the hardware on your computers. Because of this it is good have an idea of what the Raspberry can perform and what you can expect from it.

In my test there was a big difference between inbound and outbound traffic as seen from the Raspberry.

Traffic from Pi: 93Mb/sec
Traffic to Pi: 70Mb/sec

During the test the Pi CPU load was about 95 %, indicating that without overclocking you can’t expect more from this box.

Test configuration

This is the configuration I ran for test. The test was done by sending traffic in one direction successively.

My Pi was installed with Raspbian GNU/Linux 7 3.12.28 and iperf installed from apt-get. My Mac was running iperf installed via Brew. The Pi was a fresh install and only with other default daemons running.

The Raspberry Pi is equipped with a 100Mb interface.

Labels: ,

Friday, September 26, 2014

Watch out for your SHA-1 signed certificates

Microsoft and Google are with their browsers two major consumers of SSL certificates. They have both announced that they no longer will support certificates signed with SHA1.

But they both hanlde this differently. Google Chrome will on their side give a certificate warning for all SSL certificates signed with SHA1 beginning in January 2015 for certificates that expire after 2017. Microsoft will (from current statements) only give a warning after 2017 for SHA-1 signed certificates.

To ensure a smooth migration you need to make sure that both your servers and clients support the new SHA-2 (SHA-256) signing scheme. Expect older servers not to support this and plan for an upgrade.



Thursday, September 18, 2014

The exact route limit on the Cisco 3850

In a previous post I wrote about the route limit on the Cisco 3850 platform. After the issue earlier this year with the Cisco routers hitting the limit of 512k routes in hardware I think I have to clarify how many routes the Cisco 3850 platform supports. Cisco only releases these numbers for their big routers. The specification states 27000 routes.

To see the exact number of routes you can query the router directly.

my-switch#sho platform tcam utilization asic all           

CAM Utilization for ASIC# 0

 Table                                              Max Values        Used Values


 Directly or indirectly connected routes            32768/7680        119/4538

As you can see the router support 32768 directly connected routes and 7680 indirectly connected routes. A directly connected route is a host connected via L2 to the switch (like a host on a directly connected subnet) whereas indirectly connected routes are routes that are routed via another IP address.