This is the metric value to announce this summary address with in LSPs generated by this system. Because it is a single fixed value applied to the whole summarized block, an admin must pick it carefully -- too low and it could make the summary look artificially attractive compared to the real, more-specific component routes elsewhere in the network, causing suboptimal path selection. For example, setting this metric to 20 for a /16 summary covering several /24s with individually lower internal metrics could cause traffic from outside the area to take a less direct path than if the individual /24s were still visible.