On 04 Jul 2007 12:36:37 GMT, Gordon Henderson
<gordon+(E-Mail Removed)> wrote:
>so any clues about their network would be appreciated.
>
>Cheers,
>
>Gordon
I can clue you in a little on the network side.
5 x 622Mbps BT Centrals
3 fully lit
1 with 2 x 155 lit
1 with 1 x 155 lit
....so 5 x 155Mbps is available to light at short notice if required.
2 more 622 Centrals are on order with the usual long BT lead times,
but both are scheduled for activation before the end of October 2007.
There is spare Central capacity most of the time as can be seen at
http://noc.enta.net/?page_id=166. The "Anti Loss Tool" (ALT)
sacrifices speed for all users connected to any Central, which is
seeing potential congestion on the horizon, in order to preserve low
latency and eliminate packet loss, which is essential for VoIP and
other delay senstive apps, like gaming. Speeds are reduced in 500Kbps
steps as a Central gets full and they're increased in 200Kbps steps as
the demand wanes. This means that users syncing at higher speeds get
slowed down first, users syncing at lower speeds might not even notice
the tool coming into effect.
Due to the way the packages are structured there is a 10 'o' clock
rush as everyone schedules their downloads to start on the dot. It
could be avoided if customers could get into the habit of scheduling
downloads later on whilst asleep when there's more available capacity
than you can shake a stick at, as can be seen by referring to the
graphs. The rush tends to last around two hours then tails off
sharply. Due to the unavailability of session steering from BT (i.e.
they "round robin" session delivery to Centrals, rather than allowing
us to direct each new session to the quietest Central) potential
imbalance of sessions on Centrals means users on one Central may see a
slowdown whilst at the same time users on another may enjoy full
speed.
Centrals are delivered in multiple locations in London, currently
Telehouse East and Global Switch 1, various London datacentre
locations (9 in total) are interconnected with 2 x DF rings currently
lit at 10Gbps.
Amsterdam, Paris and Frankfurt are currently on a 1Gbps ring, an
upgrade to 2 x 10GE rings is planned by end of Q3 2007.
Peering is at LINX, Ams-IX, Dec-IX, etc. Full peering information is
available at
http://www.as8468.net/
There is full commitment to move off 20CN IP Stream network and on to
21CN network as 21CN rolls out. That should see >20Gbps overall
interconnection with 21CN at the outset.
HTH
Jake
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