A system and method for aggregating performance characteristics for core network paths allows computation of message traffic performance over each of the available candidate paths through the core for identifying an optimal core network path. Particular network traffic, or messages, include attributes indicative of performance, such as transport time, delay, jitter, and drop percentage, over individual hops along the candidate path. A diagnostic processor parses these messages to identify the attributes corresponding to performance, and analyzes the resulting parsed routing information to compute an expected performance, such as available bandwidth (e.g. transport rate) over the path. Messages including such attributes may include link state attribute (LSA) messages, diagnostic probe messages specifically targeted to enumerate such attributes, or other network suitable network traffic. In a particular configuration, the messages may be Path Verification Protocol (PVP) messages.