get_iplayer suddenly relatively slow

[Christopher Woods (CustomMade)]

> [snip]
> 
> > Same experiences here and I'm on Virgin Media 20MB out of 
> Coventry, and Windows Vista, though 32 bit. Some nights, when 
> I have d/l nothing, speed is sooo sloooowww that I often give 
> up and try the following night - and then it runs like a 
> train. For me, late afternoon is slow (kids home from 
> school?) and early evening. Mid-evening and well into the 
> night is generally OK.
> > 
> > So, no help from me, but just recognition that I think the 
> logjam is elsewhere. Now, where, is almost impossible to find 
> out, though I think there are tracer applications which can 
> time each leg of the route so that might give you a hint of 
> where the problem is.
> 
> I'm happily retrieving Top Gear at ~2.2MB/sec so it's 
> definitely not something involving the BBC (which is only 
> used to discover the stream URLs) or CDN networks (who are 
> paid mega$ to ensure their end is hugely available and rarely 
> congested). That reduces the likely scope to congestion or 
> active traffic management in a network that your traffic is 
> routing through. Most ISPs, especially large ones, will have 
> direct peering and interconnect arrangements with the CDN 
> providers so unless your ISP has a persistent network issue 
> that causes traffic to route the-long-way it's most likely to 
> be traffic shaping. Of course, there's always the possibility 
> that Vista has decided to fubar (it's not unheard of) and 
> since its popular (in the multiple people using it sense, 
> most people seem to hate it) it's not impossible that more 
> than one person is having a "software quality" issue at the 
> same time, and not network issues. I'd put my money on the 
> ISP though..


If all the suffering customers are on VM connections, it could be one of
three things:

1) peak time oversubscription to local UBRs manifesting as slow downstream
(very likely)
2) customers are downloading over the thresholds for STM triggering during
peak time (quite likely)
3) VM are experiencing routing problems, or forcing iPlayer traffic over
less preferential routes to alternative CDNs down narrower pipes (Akamai,
Limelight, Level3 are all available) (less likely)

When iPlayer downloads are slow, go to
http://openoffice.virginmedia.com/stable/3.3.0/ and pick a large file
(hundreds of megabytes). Monitor your peak download test. Then go to
http://www.virginmedia.com/customers/speedtesters/ , pick a speed tester of
your choice and give it a whirl. If your speeds are noticeably slower,
sounds like you're being STMed (read: throttled).

VM's STM policy: http://bit.ly/l3SjmF (obscenely long system-generated
helpcentre URL). Also note the "check status" buttons at the top, you may
have known issues in your area affecting absolute throughput. Long and short
of it though is explained in this graph:
http://www.virginmedia.com/images/tm-table-su-large.jpg

Even though the page says you can continue to use services like the iPlayer
unaffected, an outside possibility is that they've defined their QoS
policies strictly as only applying to web-based requests for iPlayer content
- or rtmpdump presents itsself in such a way that's identifiable as a
regular streamripper app to VM so they class it in their bulk traffic
category.

Perhaps this is just excessive paranoia on my part... However having been a
VM customer during the year they first implemented STM (Double the headline
speed sir? And how about half the available throughput?) we suffered all
three of those problems in the order I listed. If you continue to notice
degraded peaktime speeds, hassle customer services to be moved to a new UBR.
This may or may not resolve the problem though, get them to confirm there's
a congestion / contention issue on the UBR before getting moved.
Oversubscription tends to affect all traffic uniformly on a 'time of day'
basis though.