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My company is considering moving some internal infrastructure to my location, that will be accessed, over vpn, from other company locations. Currently we are reluctant to do this because of the network quality in my location (ADSL 2+, 20Mbit / 800kbit).

I am investigating other options for network access, and one of these options is SDSL. What kind of latency can I expect with SDSL? Will it be better than ADSL?

As the tracert below shows, I currently have a latency of 30ms to get out of the office, i.e. to go from digital to analog and back again.

Edit: If someone could post a similar traceroute over an SDSL line I would be grateful.

Edit: I am located in Spain, and both services are offered by the same ISP (Telefonica).

C:\Windows\system32>tracert serverfault.com

Tracing route to serverfault.com [69.59.196.212]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  WINROUTER2 [10.101.30.6]
  2     4 ms     5 ms     2 ms  192.168.1.1
  3    29 ms    29 ms    29 ms  10.3.42.1
  4    30 ms    29 ms    29 ms  98.red-81-46-41.staticip.rima-tde.net [81.46.41.
98]
  5     *       41 ms    40 ms  so7-0-0-0-grtmadad1.red.telefonica-wholesale.net
.10.16.84.in-addr.arpa [84.16.10.77]
  6    62 ms    66 ms    61 ms  xe0-1-0-0-grtpartv1.red.telefonica-wholesale.net
 [84.16.13.186]
  7    61 ms    61 ms    61 ms  xe0-1-1-0-grtparix1.red.telefonica-wholesale.net
 [84.16.13.230]
  8     *       62 ms    61 ms  cogent-1-0-0-grtparix1.red.telefonica-wholesale.
net [213.140.52.134]
  9   173 ms    62 ms    62 ms  te3-4.mpd02.par01.atlas.cogentco.com [130.117.1.
69]
 10    62 ms    63 ms    63 ms  te1-3.mpd03.par01.atlas.cogentco.com [130.117.50
.1]
 11    63 ms    63 ms    63 ms  te1-4.ccr01.par04.atlas.cogentco.com [130.117.1.
62]
 12   149 ms   149 ms   169 ms  te3-8.mpd03.jfk02.atlas.cogentco.com [154.54.1.9
3]
 13   162 ms   164 ms   157 ms  te4-2.mpd01.bos01.atlas.cogentco.com [66.28.4.20
1]
 14   190 ms   190 ms   190 ms  te2-2.ccr01.ord01.atlas.cogentco.com [154.54.6.1
54]
 15   187 ms   188 ms   188 ms  te4-2.mpd01.mci01.atlas.cogentco.com [154.54.6.1
58]
 16   200 ms   199 ms   199 ms  te4-4.mpd01.den01.atlas.cogentco.com [154.54.24.
81]
 17   203 ms   203 ms   203 ms  gi4-0-0.core01.den01.atlas.cogentco.com [154.54.
5.29]
 18   234 ms   234 ms   235 ms  po2-0.core01.pdx01.atlas.cogentco.com [154.54.3.
126]
 19   233 ms     *      232 ms  38.104.104.98
 20   238 ms   237 ms     *     vl-12-ptldorpbcr01.lsnetworks.net [216.110.192.2
1]
 21   234 ms   236 ms   234 ms  vl16-eugnor53cr01.lsnetworks.net [216.110.192.19
0]
 22   238 ms   241 ms   238 ms  206-192-226-18.lsnetworks.net [206.192.226.18]
 23   244 ms   243 ms   243 ms  ge-3-2.cvo-core1.peak.org [69.59.218.209]
 24   241 ms   241 ms     *     69.59.192.16
 25   244 ms   238 ms   243 ms  stackoverflow.com [69.59.196.212]

Trace complete.
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4 Answers 4

up vote 3 down vote accepted

We have several SDSL lines and the latency is slightly better than ADSL but not stunningly so. In any case the latency is likely to be dominated by all the other routers between your SDSL access multiplexer and wherever the end user is.

However, we find that SDSL is much, much better for RDP. ADSL upload is generally rubbish and gets especially rubbish as the upload link nears saturation. SDSL behaves much more like a leased line and degrades in a much more graceful way as the link gets loaded. In fact I find there is little difference between SDSL and a leased line of the same bandwidth.

Mind you, this is in the UK where SDSL takeup is low so the contention is effectively 1:1.

JR

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Most DSL connections use a PPP over ATM connection to a router at the ISP. In this case the latency is determined by the routing.

Some DSL connections are pure ATM and go straight onto the ATM backbone which will have lower latency. However these are fairly rare. Check with your ISP or local telcos to see if such services are available.

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Latency for SDSL (and ADSL) is much more a function of the ISP's network rather than SDSL or ADSL technology in general.

If you're sticking with the same ISP, your latency is unlikely to change at all.

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Not sure where you sit. But I would consider to read the service levels for the Internet connection very thoroughly as some are really ridicilous - or you will need two ISPs...

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