church of default

There was a latent misconfiguration, specifically a cable plugged someplace it shouldn’t have been, from a few months ago. Something called the spanning tree protocol kicked in and started trying to route all of our private network traffic to a public network over a link that was much too small and slow

via WP.com Downtime Summary — Blog — WordPress.com.

That’s rough.  The spanning-tree design/config is the kind of thing that creeps up on you after years of organic growth and never really having a dedicated “network guy”.     Its just bizarre enough that you spend a lot of time and effort digging into other obscure possibilities before you stumble on it.   Its one of the ‘gotchas’ of doing stuff in-house rather than clouding it up, particularly if you mix switch vendors.

Here’s an old map of an L2 topology I inherited and caused several spanning-tree outages learning the hard way.

Was in a situation where I wanted to verify that my cdn is compressing for me, but that my origin is not.

Background on the curl flags, “-I” tells it to only request the headers not the full page. “-H” passes it request headers. The “Accept-Encoding” header tells the webserver that its OK by the client if it compresses the response. The “Host” header is… well, the host header. If you’re not sure what that means then get off my blog.

First off test the CDN:

[jim@brandt ~]$ curl -I -H "Accept-Encoding: gzip,deflate" -H "Host: www.mycorp.com" http://www.mycorp.com/foo/bar.html
HTTP/1.1 200 OK
Server: Apache/2.2.8 (Unix)
Content-Type: text/html
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 43593
Date: Mon, 22 Feb 2010 15:28:58 GMT
Connection: keep-alive

Notice the “Content-Encoding: gzip” header in the response. That means you got a gzip’d response, compression is in effect.

Now skip the CDN and test origin directly:

[jim@brandt ~]$ curl -I -H "Accept-Encoding: gzip,deflate" -H "Host: www.mycorp.com" http://origin.mycorp.com/foo/bar.html
HTTP/1.1 200 OK
Date: Mon, 22 Feb 2010 15:12:32 GMT
Server: Apache/2.2.8 (Unix)
Content-Type: text/html

The lack of a “Content-Encoding” header means its *not* compressed.

via To Puppet or to Chef, that is the Question | IverCore.

I got a kick out of this post to the point where I made a long ass comment.