Transit traffic is any packet that merely traverses the device without being destined for—or generated by—the local Routing Engine. Such traffic is switched in hardware by the PFE and therefore bypasses control-plane processing. Consequently, it needs no Routing Engine intervention (statement C) and is physically forwarded by the PFE to the next hop (statement D).

A. Routing-protocol packets terminate on the local device; they are handled by the control plane, so they are exception, not transit, traffic.

B. Packets destined for the Routing Engine are by definition not in transit; they are exception or local traffic.

1. Juniper Networks, “Transit Traffic Versus Exception Traffic,” Junos Platform Fundamentals Guide, Chapter 5, p. 104.

2. Juniper Networks, “Understanding Packet Forwarding,” Junos OS Documentation, section “Control-Plane and Data-Plane Separation,” para. 3-4.