iansltx
join:2007-02-19
Golden, CO
kudos:2 Reviews:
 ·Comcast
| reply to odog
Re: [Connectivity] ibone vs cbone Actually, SimpleCDN also uses Anycast for their CDN presence, so I've heard of the term. I assumed L3 was using Anycast on their DNS servers, as I've been on the east coast and gotten nice response times to their DNS servers there  |
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iansltx
join:2007-02-19
Golden, CO
kudos:2 | Additionally, it would seem that, if configured properly, an anycast CDN would get around the DNS server probblem... |
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1 edit | reply to iansltx
traceroute to a1526.g.akamai.net (96.17.171.33), 64 hops max, 40 byte packets
1 edgerouter (192.168.1.102) 2.137 ms 1.560 ms 1.150 ms
2 * * *
3 ge-2-6-ur01.quincy.ma.boston.comcast.net (68.85.160.69) 23.003 ms 9.904 ms 9.308 ms
4 te-9-1-ur02.quincy.ma.boston.comcast.net (68.87.145.26) 10.295 ms 7.705 ms 7.699 ms
5 te-9-2-ur01.weymouth.ma.boston.comcast.net (68.87.145.30) 7.832 ms 7.907 ms 8.005 ms
6 te-9-1-ur02.weymouth.ma.boston.comcast.net (68.87.145.58) 7.885 ms 7.906 ms 11.729 ms
7 te-8-1-ur01.scituate.ma.boston.comcast.net (68.87.145.45) 8.644 ms 8.139 ms 18.855 ms
8 te-9-4-ur02.brockton.ma.boston.comcast.net (68.87.144.45) 8.130 ms 11.279 ms 8.026 ms
9 po-20-ur01.brockton.ma.boston.comcast.net (68.87.144.33) 8.491 ms 11.799 ms 7.879 ms
10 po-22-ar02.needham.ma.boston.comcast.net (68.87.144.29) 10.816 ms 9.922 ms 9.208 ms
11 68.85.162.70 (68.85.162.70) 15.241 ms 12.168 ms 13.877 ms
12 te-0-4-0-1-cr01.newyork.ny.ibone.comcast.net (68.86.90.61) 16.735 ms 15.823 ms 15.990 ms
13 pos-1-13-0-0-cr01.mclean.va.ibone.comcast.net (68.86.85.97) 22.321 ms 21.151 ms 23.745 ms
14 68.86.86.26 (68.86.86.26) 25.977 ms 25.238 ms 23.960 ms
15 a96-17-171-33.deploy.akamaitechnologies.com (96.17.171.33) 23.022 ms 21.702 ms 21.666 ms
I stay on the Comcast network the whole time...and I'm using Comcast DNS servers. I'm located in Boston.
Ran it again just for the hell of it...and got even a closer server on the Akamai network.....
Mikeys_Laptop:~ michaelefaherty$ traceroute a1526.g.akamai.net
traceroute: Warning: a1526.g.akamai.net has multiple addresses; using 96.17.72.97
traceroute to a1526.g.akamai.net (96.17.72.97), 64 hops max, 40 byte packets
1 edgerouter (192.168.1.102) 1.952 ms 1.437 ms 3.777 ms
2 * * *
3 ge-2-5-ur01.quincy.ma.boston.comcast.net (68.85.160.65) 26.132 ms 32.331 ms 28.664 ms
4 te-9-1-ur02.quincy.ma.boston.comcast.net (68.87.145.26) 23.345 ms 24.390 ms 7.651 ms
5 te-9-2-ur01.weymouth.ma.boston.comcast.net (68.87.145.30) 25.915 ms 14.169 ms 8.138 ms
6 te-9-1-ur02.weymouth.ma.boston.comcast.net (68.87.145.58) 10.763 ms 9.336 ms 8.444 ms
7 te-8-1-ur01.scituate.ma.boston.comcast.net (68.87.145.45) 11.065 ms 8.664 ms 13.947 ms
8 te-9-4-ur02.brockton.ma.boston.comcast.net (68.87.144.45) 9.288 ms 10.522 ms 13.011 ms
9 po-20-ur01.brockton.ma.boston.comcast.net (68.87.144.33) 10.974 ms 10.835 ms 7.648 ms
10 po-22-ar02.needham.ma.boston.comcast.net (68.87.144.29) 8.845 ms 9.256 ms 9.792 ms
11 68.85.162.70 (68.85.162.70) 14.630 ms 13.123 ms 21.464 ms
12 te-0-4-0-1-cr01.newyork.ny.ibone.comcast.net (68.86.90.61) 19.803 ms 15.034 ms 16.192 ms
13 a96-17-72-97.deploy.akamaitechnologies.com (96.17.72.97) 16.764 ms 15.524 ms 16.541 ms |
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 espaethDigital PlumberPremium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2
 ·Clear Wireless
| reply to iansltx
said by iansltx:Additionally, it would seem that, if configured properly, an anycast CDN would get around the DNS server probblem... Anycast CDN is tricky because any routing change could result in termination at a different host over the term of the session. Short sessions like DNS carry low risk because it's a single request and single response packet in stateless UDP, so even if your route changes after you send your DNS request it's no big deal.
With the more common use of intelligent route reflectors to add some load distribution / performance intelligence to BGP, it's highly likely for routes to change dynamically. Since TCP is stateful if that lands you on a different cache that breaks the connection since the other cache can't pick up the session mid flow; your app needs to reset the TCP session and start again.
That's why all of the major CDN players use DNS to balance out traffic to different caches; it's the only safe way to get this done. |
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