I am tasked with sizing appropriate links for our frame-relay network and I'm using Solarwind's Orion to monitor the serial and serial sub-interfaces on our Cisco routers. When I look at the interface min/max/avg utilization charts for 1, 7 or 30day periods I see utilization but my question is how does one determine what is an appropriate size CIR and overall link capacity. Example: A hub site has a T1 access port and remote has a 256 access port speed. The PVC between these two sites has a CIR of 64k. Looking at the hub site's PVC graph between these two, if I see a Transmit AVERAGE utilization during production hours consistantly around 60k and a Receive average of 34k during the same period. The big question is: Am I to assume I'm safe with the 64k CIR because in one direction I'm below the CIR or do I need to add both the TX+RX (94k) together to determine if I'm exceeding my frame-provider's CIR limit? How should peaks come into play on my decision? The links are all full-duplex in most of our locations. What difference would I need to considering if there is a half-duplex interface in the mix? Thanx.
