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Posts in Networking
Solaris 802.1Q interface format
While reviewing some notes last night, I came across an entry in my notebook that described how to configure Solaris interfaces to support 802.1Q tagged queing. Given a physical interface named "ce0" that will be associated with VLAN 500, the formula to create the interface would be: So in the example above, you would use an interface named ce500000 to tell the host to process 802.1Q tagged Ethernet frames destined for VLAN 500. I am still not sure why Sun chose to use this format, since you can't just look at a name and know what it is. Luckily this annoyance will be fixed when the clearview project integrates into Solaris (clearview will allow you to use vanity names with interfaces).
$ read more →Monitoring connections on OpenBSD hosts
I received a comment from a reader regarding the trafshow utility. Trafshow is definitely a cool piece of software, and I use it one some of my Linux hosts. On my OpenBSD systems, I have been using the pktstat utility, which provides connection statistics for all traffic on the system: Since trafshow contains numerous features that aren't present in pktstat, I reckon I should upgrade my OpenBSD image to use trafshow. Thanks for the comment!
$ read more →Using jumbo frames with Fujitsu gigabit Ethernet adaptors
While performing some testing a few weeks back, I needed to enable jumbo frames on one of our Fujitsu 250s. This was accomplished with the following three steps: 1. Add the following line to /etc/system: $ 2. If the default 9000 byte MTU isn't ideal, add the preferred MTU to the /etc/fjmtu.fjgiX file $ 3…
$ read more →Measuring DNS latency with nsping
While debugging a DNS problem a few weeks back, I needed a way to measure the time it took a name server to respond to a DNS request. After poking around the OpenBSD ports collection, I came across the nsping utility. Nsping queries a DNS server passed on the command line, and reports the time it took the server to resolve a name. The following example shows how to use nsping to measure the time it takes to resolve the name prefetch.net on the name server ns2.dreamhost.com: Each line contains the size of the response, the time it took to complete the request, and a sequence number…
$ read more →NFSv3 guarded writes
While debugging another NFSv3 problem this week, I came across a create procedure with the "GUARDED" flag set: This was the first time I have reviewed an NFSv3 packet capture with the GUARDED flag set, so I decided to read RFC 1813 to see how the create procedure should be implemented. Here is what the RFC says about the GUARDED flag: "Creation modes: One of UNCHECKED, GUARDED, and EXCLUSIVE. UNCHECKED means that the file should be created without checking for the existence of a duplicate file in the same directory. In this case, how.obj_attributes is a sattr3 describing the initial attributes for the file…
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