This lack of visibility often leads to unexpected congestion and makes IPTV and other
services delivery potentially unpredictable.
When Does This Solution Not Fit?
Applications Don??™t Require It
One of the first things to consider when evaluating requirements for RPR is the application.
RPR transport equipment delivers strict QoS and guaranteed availability.
However, there are applications, like residential internet access where these qualities
are less important. Standard Ethernet switching or routing solutions are appropriate
solutions when the QoS and restoration requirements are less strict. With applications
Resilient Packet Ring (RPR) 359
like file transfer or internet access the key strengths of the RPR protocol are not utilized.
When a pure data application is not sensitive to delay and delay variation and when restoration
times that can be as high as 30 seconds do not affect application performance,
then RPR is not required.
Existing SONET/SDH Transport
Another case where RPR may not be required is where the Ethernet packets are already
traveling over traditional or next-generation SONET/SDH networks. Restoration,
Fairness, QoS, and OAM benefits of RPR are not required since the operation of
SONET/SDH transport already provides these characteristics, albeit by different and
less efficient methods.
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