Number of Labels Carried in an MPLS Packet in Various Scenarios

MPLS VPN Scenario	Number of Labels	Remarks
Intra-AS VPN	One VPN label and N public network labels.	Value of N (depending on a public network tunnel type): N is 1 when packets are transmitted on an LDP LSP. N is 1 when packets are transmitted on a static LSP. N is 1 when packets are transmitted on a TE tunnel. N is 2 when packets are transmitted on a TE tunnel in the LDP over TE scenario. N is 3 when packets are transmitted on a TE fast reroute (FRR) bypass tunnel in the LDP over TE scenario. NOTE: The preceding N values take effect when PHP is disabled. If PHP is enabled and performed, N minus 1 (N – 1) takes effect.
Inter-AS VPN Option A	A packet transmitted within an AS carries one VPN label and N public network labels. A packet transmitted between ASs carries no labels.
Inter-AS VPN Option B	A packet transmitted within an AS carries one VPN label and N public network labels. A packet transmitted between ASs carries one VPN label.
Inter-AS VPN Option C	A packet sent within the first AS carries one VPN label, one Border Gateway Protocol (BGP) label, and N public network labels. NOTE: For solution 1 (configuring inter-AS VPN Option C), an MPLS packet sent within the first AS carries one VPN label, one BGP label, and N public network labels. For solution 2 (configuring inter-AS VPN Option C), an MPLS packet sent within the first AS carries one VPN label and N public network labels. A packet transmitted between ASs carries one VPN label and one BGP label. A packet sent within the second AS carries one VPN label, one BGP label, and N public network labels. NOTE: For solution 1 (configuring inter-AS VPN Option C), an MPLS packet sent within the second AS carries one VPN label, one BGP label, and N public network labels. For solution 2 (configuring inter-AS VPN Option C), an MPLS packet sent within the second AS carries one VPN label and N public network labels.
HoVPN and HVPLS	A packet transmitted within the core layer carries one inner label and N public network labels. A packet transmitted between a user-end provider edge (UPE) and a superstratum provider edge (SPE) carries one inner label.