What routing protocol does China Telecom use in its network?

Network operators like telecom generally use some powerful protocols! But you can't use too many public network addresses, because public network addresses need to be bought, so I use IS-IS protocol. I won't say the specific technical details. This protocol saves addresses, but it doesn't just use routing addresses. If telecom needs to connect the network to the backbone network, it also needs BGP border gateway protocol. . Therefore, telecommunications networks will use a variety of network routing protocols, and there will be many strategies. More complicated!