Material worth reading

Just found a few interesting articles in the Cisco blog:

3 comments:

  1. I just want one think to presentation at this site. If you need some kind diff tool you may use internal commands in IOS to track changes in configs.
    you probably know about archive command

    ReplyDelete
  2. Hm. Our friend JC doesn't really understand QoS - he wants SHAPING, not POLICING.

    A good link to understand the differences between one and the other is available at

    http://tinyurl.com/b999c

    Specially worth reading and understanding is this part:

    "Drops excess packets (when configured), throttling TCP window sizes and reducing the overall output rate of affected traffic streams. Overly aggressive burst sizes may lead to excess packet drops and throttle the overall output rate, particularly with TCP-based flows."

    when talking about policing.

    I bet if JC went ahead and installed something like MRTG he would be able to clearly see the saw-tooth effect. And considering he's backing up files to a remote FTP server . . . I think his transfer rate goes from 0 to 80 to 0 to 80 . . . funny.

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  3. @nikolay: Thanks for the tip, I know about the archive command (I wrote an article detailing how it works and where it fails). But sometimes you need offline diff, for example, when you upload the router configuration to a central repository and want to find out what has changed since the last upload.

    @anonymous: You're right. One of my students (no, I'm not teaching at a university, I'm just co-mentoring a few people) did his BSc thesis on exactly this topic - what's the influence of shaping versus policing on the TCP throughput in combination with the number of TCP sessions running over the same link.

    What I liked in the post I've quoted, though, is the idea of using time-based access-lists to influence QoS policy maps.

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Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.