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Author Topic: UK victorian routing  (Read 2560 times)

mbb

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UK victorian routing
« on: July 11, 2015, 04:43:04 PM »

sorry if posted in wrong forum, can somebody shed some light on this? my friend in finland has just done a tracert to a popular website in helsinki. he lives roughly the same distance as i live from london approx 300k. here is his tracert


  1    <1 ms    <1 ms    <1 ms  dsldevice.lan [192.168.1.1]
  2     7 ms     6 ms     6 ms  dsl-jklbrasgw1-54fb00-1.dhcp.inet.fi [84.251.0.1
]
  3    10 ms    10 ms     9 ms  141.208.112.210
  4     9 ms     8 ms     8 ms  cdn-vip2.hard.ware.fi

he gets to where he needs to in 4 hops and the long distance is only 3-4ms according to his tracert

so why does it take me 16 hops to get to bbc.co.uk and the time taken to get to london is about 6-7 ms. even he gets to bbc.co.uk from sodding finland in 12 hops. whos to blame




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simoncraddock

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Re: UK victorian routing
« Reply #1 on: July 11, 2015, 05:14:57 PM »

Distance is irrelevent, it's all down to the network route between him and Helsinki compared to yourself and London.
From Finland to London there are obviously less networks to traverse across, possibly undersea link between Helsinki and London.
« Last Edit: July 11, 2015, 05:24:15 PM by simoncraddock »
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Fritzbox 7490 l Plusnet FTTC

Weaver

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Re: UK victorian routing
« Reply #2 on: July 11, 2015, 05:59:37 PM »

Just as the previous poster said. To illustrate though:

It takes about 10ms to get from my iPad to the router in the next room, and we haven’t even left the house yet. This is because of overheads in the 802.11n wireless networking system including big processing delays due to a WPA2 encode+decode. So gamers, don’t use wireless without comparing with a wired network connection.

The answer to your question “who’s to blame” is:
(i) your ISP, and possibly BT too, and
(ii) the BBC if some of the furthest hops are within its own network.
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ejs

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Re: UK victorian routing
« Reply #3 on: July 11, 2015, 06:23:13 PM »

That traceroute is especially short probably because the website is hosted on a Content Distribution Network (guessing by the cdn in the host name), so the CDN server is at the ISP (TeliaSonera).

The shortest traceroute I can get on Plusnet is probably similar to this, going to some CDN like Akamai:

Code: [Select]
traceroute -q 1 -N 1 -I static.bbci.co.uk
traceroute to static.bbci.co.uk (23.192.162.129), 30 hops max, 60 byte packets
 1  gateway (192.168.0.1)  1.635 ms
 2  lo0-central10.ptn-ag02.plus.net (195.166.128.191)  12.655 ms
 3  link-a-central10.ptn-gw01.plus.net (212.159.2.132)  11.561 ms
 4  xe-1-2-0.ptw-cr01.plus.net (212.159.0.112)  11.277 ms
 5  ae2.ptw-cr02.plus.net (195.166.129.5)  10.577 ms
 6  *
 7  a23-192-162-129.deploy.static.akamaitechnologies.com (23.192.162.129)  11.375 ms

That was on wireless and ADSL2. OK it's only 11g but I'm still using WPA2, wifi chips tend to have dedicated hardware for doing the necessary encryption and decryption, the extra latency from wireless shouldn't be too bad.
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kitz

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Re: UK victorian routing
« Reply #4 on: July 12, 2015, 12:58:13 PM »

Quote
so why does it take me 16 hops to get to bbc.co.uk and the time taken to get to london is about 6-7 ms. even he gets to bbc.co.uk from sodding finland in 12 hops. whos to blame

Another major difference is that some ISPs use what is known as L2TP tunnelling.   L2TP hides a lot of the core network hops.   ISPs such as Plusnet, IDnet, AAISP use L2TP so therefore any of the routing between the exchange to the ISPs gateway is hidden. 

You can see from ejs's example that hop 2 is the isp gateway in London.    Without doubt there will have been a lot of routing in there that doesnt show.
BT retail doesn't use L2TP and you can see every single router that you pass through before you get to London.

It's highly likely that someone who is with say Plusnet and on the same exchange as you will travel a very similar path as you across the core network up until the London PoP..  the difference is that your tracert will likely show about 7 additional hops that has been hidden for the person on Plusnet.

So number of hops isnt always important, its the time.

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Chrysalis

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Re: UK victorian routing
« Reply #5 on: July 12, 2015, 01:16:54 PM »

I think alot is to do with the uk network infrastructure.

Countries like germany have many POPs, DC's etc. scattered around the country.

However the UK is heavily reliant on london,  90% if not more is based in london or just outside of london with maidenhead, and the rest mostly in manchester.  So that makes things less efficient and of course isp's will route the cheapest way not the most direct way.
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mbb

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Re: UK victorian routing
« Reply #6 on: July 12, 2015, 03:25:37 PM »

interesting stuff guys thanks.

im happy with my new g.inp ping. i guess the old style error correction/interleaving will be a thing of the past soon. on a good day i can get 12 ping from manchester thats not bad atall. where is hop 8 and 9? i assume the big jump in ping is my connection going down the m6 /m1 to london? and if i had no copper/alu and had fibre into the home would that take hops 1-8 down to as low as 1ms??

  1    <1 ms    <1 ms    <1 ms  BThomehub.home [192.168.1.254]
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     6 ms     6 ms     6 ms  217.41.216.69
  5     7 ms     6 ms     7 ms  host109-159-245-138.range109-159.btcentralplus.c
om [109.159.245.138]
  6     6 ms     6 ms     6 ms  31.55.165.221
  7     7 ms     6 ms     6 ms  31.55.165.109
  8     6 ms     6 ms     6 ms  acc2-xe-4-0-2.mr.21cn-ipp.bt.net [109.159.250.23
6]
  9    11 ms    12 ms    15 ms  109.159.255.149
 10    15 ms    15 ms    14 ms  peer5-te0-9-0-6.telehouse.ukcore.bt.net [109.159
.254.152]
 11    13 ms    13 ms    13 ms  166-49-211-246.eu.bt.net [166.49.211.246]
 12    15 ms    16 ms    15 ms  be3035.ccr21.lon01.atlas.cogentco.com [130.117.1
4.169]
 13    14 ms    13 ms    14 ms  be2207.rcr21.b015589-1.lon01.atlas.cogentco.com
[130.117.51.158]
 14    15 ms    15 ms    15 ms  krystal.demarc.cogentco.com [149.6.146.18]
 15    14 ms    14 ms    14 ms  ha01.multiplay.co.uk [85.236.96.26]
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kitz

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Re: UK victorian routing
« Reply #7 on: July 12, 2015, 03:47:40 PM »

Quote
where is hop 8 and 9?

Hop 8 will be you entering the BT core network at Manchester RAS location
Hop 9 - hard to say exactly but somewhere in the London area exiting the core.   There's various locations that can be used such as Colindale/Ealing/Docklands/Central.


Quote
if i had no copper/alu and had fibre into the home would that take hops 1-8 down to as low as 1ms??

You'd still incur latency time on the backhaul.  ie exchange -> RAS.    6ms is typical for this hop and it all depends on whats going on in and around the RAS nodes.   My latency didnt change when I got FTTC.   It was still the same as ADSL.      Full and proper FTTH may shave off a few ms* but I doubt it would be able to take it any lower.   The length of copper between home and the DSLAM is relatively short - ie meters rather than kilometers so its not going to make a vast difference.


*More down to network topology rather than cable medium
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