A first router comprising processing circuitry configured to: receive, from a first client device connected to the first router via a first Open Systems Interconnection, OSI, Model Layer-2, L2, network, an L2 frame destined for a second client device, the L2 frame comprising an L2 header and a non-session-based payload, wherein the first router is connected to a second router via an OSI Model Layer-3, L3, network, and wherein the second router is connected to the second client device via a second L2 network; identify, based on the L2 header of the L2 frame, an L3 network service associated with the L2 frame; generate, in response to determining the L2 frame comprises the non-session-based payload, a placeholder session identifier for the L2 frame, wherein the placeholder session identifier comprises a placeholder source IP address, a placeholder source port, a placeholder destination IP address, a placeholder destination port, and a first network protocol; form an L3 packet comprising: an L3 header, wherein the L3 header comprises a source Internet Protocol, IP, address and a source port of the first router, a destination IP address and a destination port of the second router, and a second network protocol, the second network protocol selected based on the identified L3 network service associated with the L2 frame from a plurality of network protocols; a payload comprising the L2 frame; and metadata comprising the placeholder session identifier; and perform, based on the placeholder session identifier, L3 session-based routing of the L3 packet to forward the L3 packet via the L3 network to the second router. receive, from a first client device connected to the first router via a first Open Systems Interconnection, OSI, Model Layer-2, L2, network, an L2 frame destined for a second client device, the L2 frame comprising an L2 header and a non-session-based payload, wherein the first router is connected to a second router via an OSI Model Layer-3, L3, network, and wherein the second router is connected to the second client device via a second L2 network; identify, based on the L2 header of the L2 frame, an L3 network service associated with the L2 frame; generate, in response to determining the L2 frame comprises the non-session-based payload, a placeholder session identifier for the L2 frame, wherein the placeholder session identifier comprises a placeholder source IP address, a placeholder source port, a placeholder destination IP address, a placeholder destination port, and a first network protocol; form an L3 packet comprising: an L3 header, wherein the L3 header comprises a source Internet Protocol, IP, address and a source port of the first router, a destination IP address and a destination port of the second router, and a second network protocol, the second network protocol selected based on the identified L3 network service associated with the L2 frame from a plurality of network protocols; a payload comprising the L2 frame; and metadata comprising the placeholder session identifier; and an L3 header, wherein the L3 header comprises a source Internet Protocol, IP, address and a source port of the first router, a destination IP address and a destination port of the second router, and a second network protocol, the second network protocol selected based on the identified L3 network service associated with the L2 frame from a plurality of network protocols; a payload comprising the L2 frame; and metadata comprising the placeholder session identifier; and perform, based on the placeholder session identifier, L3 session-based routing of the L3 packet to forward the L3 packet via the L3 network to the second router.