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  1. #1
    Join Date
    Sep 2004
    Beaverton, OR

    Thumbs up Make Comcast faster!

    I thought this was worth sharing. I've been troubled by some of Comcast's polices in the past, particularly with the bit torrent throttling and now the alleged NetFlix throttling. In the end, I just didn't like the idea of them inspecting and shaping my network activity.

    So, I picked up an inexpensive Xen VPN (sub $7 / month) to route traffic through and setup OpenVPN as a server on it. After setting up the VPN client locally I ran some speed tests to see what the difference was in network performance. I'm pleased to say that for the majority of cases things are FASTER than before. I'm not entirely surprised, I always thought Comcast had a dog of a backbone.

    I'm certainly no statistician but these tests seem pretty conclusive to me:

    Test 1 - Run each speedtest on twice:

    Seattle,WA (Comcast): 25.51 Mbps / 4.43 Mbps
    Seattle,WA (Comcast): 24.69 Mbps / 4.61 Mbps
    Seattle,WA (via VPN): 20.86 Mbps / 13.15 Mbps
    Seattle,WA (via VPN): 20.75 Mbps / 12.73 Mbps
    San Francisco,CA (Comcast): 14.77 Mbps / 4.44 Mbps
    San Francisco,CA (Comcast): 17.61 Mbps / 4.49 Mbps
    San Francisco,CA (via VPN): 21.15 Mbps / 4.41 Mbps
    San Francisco,CA (via VPN): 20.19 Mbps / 4.30 Mbps
    Los Angeles,CA (Comcast): 11.72 Mbps / 4.55 Mbps
    Los Angeles,CA (Comcast): 16.67 Mbps / 4.61 Mbps
    Los Angeles,CA (Comcast): 15.18 Mbps / 4.59 Mbps
    Los Angeles,CA (via VPN):20.94 Mbps / 10.77 Mbps
    Los Angeles,CA (via VPN):20.82 Mbps / 11.06 Mbps
    Los Angeles,CA (via VPN):19.33 Mbps / 10.61 Mbps
    Dallas,TX (Comcast):7.10 Mbps / 4.34 Mbps
    Dallas,TX (Comcast):8.07 Mbps / 4.45 Mbps
    Dallas,TX (via VPN):20.01 Mbps / 3.92 Mbps
    Dallas,TX (via VPN):20.59 Mbps / 4.09 Mbps
    Chicago,IL (Comcast):5.17 Mbps / 4.19 Mbps
    Chicago,IL (Comcast):5.37 Mbps / 4.16 Mbps
    Chicago,IL (via VPN):20.09 Mbps / 8.74 Mbps
    Chicago,IL (via VPN):19.22 Mbps / 7.87 Mbps
    Atlanta, GA (Comcast):5.13 Mbps / 4.29 Mbps
    Atlanta, GA (Comcast):5.61 Mbps / 4.30 Mbps
    Atlanta, GA (via VPN):19.67 Mbps / 3.82 Mbps
    Atlanta, GA (via VPN):18.44 Mbps / 4.11 Mbps
    New York, NY (Comcast):4.86 Mbps / 4.39 Mbps
    New York, NY (Comcast):5.76 Mbps / 4.28 Mbps
    New York, NY (via VPN):12.30 Mbps / 2.28 Mbps
    New York, NY (via VPN):18.48 Mbps / 6.0 Mbps
    Washington, DC (Comcast):5.27 Mbps / 4.27 Mbps
    Washington, DC (Comcast):5.49 Mbps / 4.18 Mbps
    Washington, DC (via VPN):9.76 Mbps / 3.92 Mbps
    Washington, DC (via VPN):12.67 Mbps / 5.76 Mbps
    Test 2 - Do a 100MB Download from Softlayer in Dallas:

    Four tests through VPN:
    100%[======================================>] 104,874,307 1.87M/s   in 51s
    2011-03-28 19:13:46 (1.95 MB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307 1.45M/s   in 61s
    2011-03-28 19:14:52 (1.64 MB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307 1.53M/s   in 61s
    2011-03-28 19:15:56 (1.63 MB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307 1.48M/s   in 61s
    2011-03-28 19:17:01 (1.65 MB/s) - `' saved [104874307/104874307]
    Direct tests:
    100%[======================================>] 104,874,307  441K/s   in 3m 56s
    2011-03-28 19:21:20 (434 KB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307  803K/s   in 2m 28s
    2011-03-28 19:23:54 (690 KB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307  791K/s   in 2m 11s
    2011-03-28 19:26:10 (782 KB/s) - `' saved [104874307/104874307]
    100%[======================================>] 104,874,307  801K/s   in 2m 43s
    2011-03-28 19:28:58 (630 KB/s) - `' saved [104874307/104874307]
    And one more via the VPN:
    100%[======================================>] 104,874,307 2.43M/s   in 64s
    2011-03-28 19:30:21 (1.55 MB/s) - `' saved [104874307/104874307]
    Oh yeah, and this is all over a Blowfish 128 bit encrypted channel. It's amazing because there is barely a blip in CPU usage on both the client and server. I guess the processors must be providing some hardware assistance.


  2. #2
    Join Date
    Sep 2004
    Beaverton, OR
    Two more thoughts:

    1) I selected a VPS in a city that I knew had good backbone connectivity AND Comcast had good, consistent ping times to. In this case Seattle.

    2) I plan on setting up a site to site VPN with hardware. I'll probably need to switch the VPS to an IPSEC based VPN at that time.

  3. #3
    Join Date
    Apr 2002
    Seattle, WA
    Maybe you have a weak modem or something. The VPN tests I think are skewed though as it is showing a radical jump in your upstream, which I am guessing you don't actually have.

    FWIW, Comcast's actual backbone is pretty nice. Some folks have issues with their residential offerings though.
    I <3 Linux Clusters

  4. #4
    Join Date
    Sep 2004
    Beaverton, OR
    I don't believe so. These tests were performed during peak traffic periods and I believe they have capacity issues with their backbone in California, which most of Oregon's traffic is routed through.

    The eratic upload speeds is most likely because of their "Powerboost" feature. Essentially, when bandwidth is available they *may* let you use higher up/down speeds for brief periods. My plan is 25/5, so anything above 5 upstream has to be "Powerboost".

    This isn't the first time I've noticed issues with Comcast and their backbone. We have a business location which also uses Comcast and last year we actually noticed a slow down in traffic between one of our servers and the office when the provider started peering directly with Comcast.

    Quite the opposite of what I thought would happen.

  5. #5
    Join Date
    Jan 2004
    As a comcast customer I have no issues with limiting BitTorrent and Netflix streams.

    Why? Because Netflix HD works just fine when I watch a movie with the family. Also, since BitTorrent is pretty much nothing but illegal activity file transferring I wouldn't be upset to see it blocked.

  6. #6
    Join Date
    Dec 2004
    New York, NY
    Comcast has poor routing overall so I'm not surprised to see that you have better performance this way. It should be noted that a VPN can skew tests like this though, as usually all data transfered over the VPN is going to be compressed.

  7. #7
    Join Date
    Aug 2008
    San Francisco
    Quote Originally Posted by layer0 View Post
    Comcast has poor routing overall so I'm not surprised to see that you have better performance this way. It should be noted that a VPN can skew tests like this though, as usually all data transfered over the VPN is going to be compressed.
    Agreed. It's comparable to HE's routing, not optimal to say the least.

  8. #8
    Join Date
    Apr 2002
    Seattle, WA
    Odd, I actually find Comcast to have pretty logical routing. Just remember, the Comcast you get on a Cable modem is very different than their network, they aren't exactly going to give you primo stuff on a $50/mo plan.

    As for performance and peering, layer0 is right, the compression would skew it. You would have almost damn near perfect routing to the Seattle test server (which is actually hosted by Comcast) as you probably are going through Seattle for it and not SFO or LA. There is a major Comcast data center just outside of Beaverton, OR.
    I <3 Linux Clusters

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