This Gauge32 identifies the aggregate (port-channel) id of the operational border uplink that this internal link's traffic currently exits through. It matters on the internal Ethernet link that carries a blade's traffic from the chassis I/O Module up to a Fabric Interconnect over the backplane because when the border uplink itself is a port-channel rather than a single port, this field is what tells an admin which bundle — not just which single port — is actually in the traffic path. An operBorderAggrPortId on this backplane link pointing to a bundle that has lost a member is a useful cross-check when this internal link seems fine but overall throughput toward the network core has dropped.