US Patent 9055000 Distributed network subnet

In general, techniques for facilitating a distributed network (L3) subnet by which multiple independent control planes of network devices connected to physically separate L2 networks provide L2 reachability to/from a single L3 subnet. In some examples, a shared L2 network physically situated to connect a plurality of physically separate L2 networks “stitches” the L2 networks together within the respective, independent control planes of switches such that the control planes bridge L2 traffic for a single bridge domain for the separate L2 networks to the shared L2 network and visa-versa. Each of the independent control planes may be configured with a virtual IRB instance associated with the bridge domain and with a common network subnet. Each of the virtual IRBs provides a functionally similar routing interface for the single bridge domain for the separate L2 networks and allows the shared network subnet to be distributed among the independent control planes.