Modular chassis arrangement with separately cooled logic and logic power modules

1. A modular packet network device comprising:

a chassis;

a plurality of logic cards located in a first cooling path within the chassis;

an electrical signaling backplane having front side signaling connectors to which the plurality of logic cards connect, the electrical signaling backplane distributing signaling between the plurality of logic cards;

a plurality of power converter cards located in a second cooling path within the chassis, the second cooling path passing substantially behind the backplane, the plurality of power converter cards converting primary power to logic power, each power converter card supplying logic power to a strict subset of the plurality of logic cards;

a primary power distribution backplane having primary power connectors, the primary power distribution backplane distributing primary power to the plurality of power converter cards through the primary power connectors; and

at least two redundant primary power supplies, the primary power distribution backplane independently distributing power from at least two of the redundant primary power supplies to each of the power converter cards through the primary power connectors.

2. The modular packet network device of claim 1 , wherein the electrical signaling backplane and primary power distribution backplane are arranged vertically in the chassis, the primary power distribution backplane extending below the electrical signaling backplane.

3. The modular packet network device of claim 2 , wherein the primary power distribution backplane lies behind the plane of the electrical signaling backplane.

4. The modular packet network device of claim 1 , further comprising a logic power distribution backplane having logic power connectors, the logic power distribution backplane distributing logic power from the plurality of power converter cards to the plurality of logic cards through the logic power connectors.

5. The modular packet network device of claim 4 , wherein the logic power distribution backplane is arranged vertically in the chassis, the logic power distribution backplane extending above the electrical signaling backplane.

6. The modular packet network device of claim 5 , wherein the logic power distribution backplane lies behind the plane of the electrical signaling backplane.