When non-recursive accounting is enabled, this counter tracks packets switched via this prefix that fall into the external bucket, traffic whose forwarding required resolving through a recursive route lookup rather than a direct next hop. This is the recursive-lookup counterpart to cefPrefixInternalNRPkts, so a prefix showing heavy external-bucket traffic but light internal-bucket traffic indicates most of its forwarding decisions depend on another route, such as a BGP next-hop resolved via an IGP route, rather than a directly attached path. A BGP-learned prefix whose next hop itself needs to be resolved via an interior route would accumulate its packet counts here in the external bucket rather than the internal one.