8.12 Summary

Multi-board architectures are required both for increased port densities and higher performance. It is preferred that the communications software is architected to run over both single-board and multi-board architectures. Using a message-based interface and facilities like a Distribution Abstraction Layer over an Inter-Card Communication Protocol can help in this regard.

The two common architectures for implementing a multi-board communications system are the Single Control Card + Multiple Line Card Architecture and the Multiple Line Card Fully Distributed Architecture. The former is more common while the latter is more complex but scalable. 1:1 and 1:N redundancy schemes with hot-standby and warm-standby configurations are common in multi-board architectures which need to provide high availability.