China Mobile China Mobile Huawei Technologies Recommendations for Interoperable Networks using Intermediate System to Intermediate System (IS-IS) [RFC3719] highlights a number of differences between the IS-IS protocol as described in ISO 10589 and the protocol as it is deployed today. This document outlines a number of differences found in the China Mobile backbone network, which is constructed using routers from several manufacturers. These differences include LSP checksum calculation, zero checksum LSP processing, zero remaining lifetime LSP processing, and corrupt LSP processing. This document is intended to provide best current practices to facilitate interoperability and maintain network stability.