Virgin Media entered into an agreement with Spotify in 2011 that meant Virgin Media customers got special deals to access some time ago, but it appears that the streamed music service has been running less than smoothly for consumers, with tracks playing for a few seconds and then stalling, and playing again.
The Register has quotes from several Virgin Media customers, and comments from Virgin Media, who seek to reassure customers that the poor performance of Spotify on their network was not down to its traffic management policy. Alas the real reason is more fundamental, and appears to be due to a lack of capacity on some peering links at peak times.
"Virgin Media has been investigating a problem some customers have had with streaming music from Spotify during busier times of the day...
We have identified a recent issue with congestion between the Virgin Media network and Spotify's data centre which can occur intermittently during peak times.
Following some routing configuration changes, this congestion should now be alleviated; however further analysis is being conducted and additional routing changes or capacity upgrades will be implemented as needed to avoid re-occurrence of this issue as the popularity of the service grows. We apologise for any inconvenience."Virgin Media statement
What is most worrying is that these peering links should have been monitored, and the congestion noticed previously, suggesting perhaps there is a policy of running their peering links close to full or full at times. The end result of this is that customers would be able to get full speed to any test located on the Virgin Media network, but those on external links may or may not have been affected depending on which route the data entered or left the Virgin Media network on.
As access speeds increase between consumers homes and the providers network, this traditional bottleneck is vanishing, and the important of peering increases, along with the ability to cache popular content on a providers own network.