Service Level Agreements are important to compare when you are pricing your MPLS wide area network. The problem is that many carriers utilize different cities to base their latency statistics. This can make a precise comparison challenging.
When obtaining quotations from different carriers, one needs to “normalize” the SLA numbers to provide our clients a better comparison. In essense, the latency of a network is determined by the distance and the number of hops. Different networks use different paths. A good consultant will be vendor neutral, and have access to the network maps for more carriers than you can imagine.
SLAs are published from POP to POP. You will always need to add the local loop factor to both sides of your network. For instance, if a POP is 75 miles from your facility, then you need to add 10ms to the SLA number, plus the loop length at the other end of the circuit.
To help you with this, the following are average numbers to account for loop lengths:
0 – 10 miles: +0ms
11 – 50 miles: +5ms
51-100 miles: +10ms
101-200 miles: +15ms
201-400 miles: +30ms
401-600 miles: +40ms
601-800 miles: +50ms
801-1000 miles: +60ms
1000-1200 miles: +80ms
