--- Warning kitz is about to commence one of her blurb type posts that could be techy and make good bedtime reading ----
>> i live in the north-east of england. so basically whats happening is that im routing up to edingburgh then back down london
It certainly would appear so.
>> it has changed around 10 weeks ago.
BT on occasion do 'reRAS' some dslams. Ive had it happen to me several times between kingston,london and manchester.
An important point to note is that the first hidden hop to the RAS on the ATM part of the network will always take longer than the bit when on the Colossus part of the network.
Eg with my own line it would be typical to see say 12ms to get to the RAS at Mancester which comparatively isnt that far.. yet it would only take a further 6ms from manchester to london on the Colossus IP network, which is the 'backbone of the UK'.
Something else to point out which may give you some hope.. but in the past I myself have experienced some weird ATM routing several times. It may help if I explain what the ATM cloud is taken from my page
how adsl works - ATM cloudBT's ATM network between various points, which can take many different paths/routes.
It carries traffic in pure ATM form and is called the Multi-Service intranet Platform (MSiP). Since it is impossible to know exactly which route traffic will traverse, an ATM network is depicted as a cloud.
BT's ATM network was originally built in the 1990's to handle traffic for business customers who required such services as intranets on leased lines. Today it also carries IP packets as an ATM stream for internet customers to and from the Colossus backbone.
The important point being that traffic on the ATM part of the network can take many different routes and its like one big network mesh with routers and switches going all over the UK. What I have experienced is traversing down to london purely on the ATM network... and a couple of times being routed what appeared to be something like all the way down south and back up again north before joining the Colossus network.
The very first time this happened was many years ago and it had the effect of doubling my latency from around 17-18ms to something in the very high 30's. I was at the time able to pinpoint it down to the ATM network and my ISP took it up with BTw who would do nothing about it since there is no SLA for latency. Ian Wild even took it up further with some bod higher in BT who just basically said sorry nothing can do about ATM routing.
Now comes the good news.. after about 2 or 3 months.. one day it just vanished completely out of the blue all by itself and I was back to around 17ms to the beeb.
However.. over the past 6 years it has happened about 4 times in total with various degrees of increased latency and each time it did eventually clear. Ive also seen mention on other forums of it cropping up occasionally - then vanish a more or so later.
I still have the tracert of the last times it happened which wasnt admittedly wasnt as bad, but it still turned a 17ms ping to the beeb into a 28ms ping.
I kept this particular trace because it shows a nice example of part of the BTw that is normally well hidden away, but it may be interesting for someone who is interested in the BTw network, just to see what goes on all the time but is normally hidden away because of LT2P tunnelling.
1 1 ms 1 ms 1 ms 192.168.7.100 < --- my router
L2TP tunnel would normally start here.
2 22 ms 23 ms 23 ms 217.47.204.58 <--------- culprit routing before here @ RAS ERX3.Manchester2
3 22 ms 22 ms 22 ms 217.47.204.161 bouncing around various manchester switches
4 22 ms 22 ms 23 ms 217.41.173.9 " " "
5 22 ms 21 ms 22 ms 217.41.173.74 " " "
6 22 ms 22 ms 22 ms 212.140.206.42 " " "
7 21 ms 22 ms 22 ms 217.47.158.42 " " "
8 22 ms 22 ms 22 ms core1-pos1-3.manchester.ukcore.bt.net [194.72.2.33] < --- joining Colossus at Manchester
9 30 ms 29 ms 30 ms core1-pos0-6-5-0.ilford.ukcore.bt.net [62.6.204.21] <---- passing through Ilford core (another key location and RAS site)
10 28 ms 27 ms 27 ms core1-pos9-0-0.telehouse.ukcore.bt.net [62.6.201.118] <--- London Docklands
L2TP tunnel would normally end here and you would normally see your ISP central pipe location
11 28 ms 28 ms 27 ms 194.74.65.6 <---- This would be your ISP peer point with the BBC
12 27 ms 27 ms 27 ms 212.58.238.153 <--- BBC network
13 28 ms 27 ms 27 ms rdirwww-vip.thdo.bbc.co.uk [212.58.224.131]
Finally whilst this will probably account for a large part of the increase, it may not account for the further increased rise you see at certain times of the day. That could be your ISP centrals or it could be the ras. It would be interesting if and when you next see the really high ping times.. to log back in to the bttestuser account and see if its the RAS... if not.. then its likely something on your ISP centrals... would be interesting to try for the sake of elimination.
