In an IS-IS broadcast network, which multicast MAC address is used by a Level-2 router for IS-IS Hello packets?

In an IS-IS broadcast network, Hello packets are used for discovering and maintaining neighbor relationships. A Level-2 router uses a specific multicast MAC address to communicate these packets to all other routers in the area. The correct multicast MAC address for IS-IS Hello packets is 0180-C200-0015.

This address is designated specifically for IS-IS protocol communications over Ethernet networks and is recognized by all devices that implement this protocol. The correct address allows routers to send the Hello packets to all other routers in the same broadcast domain, facilitating the establishment and maintenance of adjacencies required for routing decisions.

Other addresses provided in the options are not used in this context. For example, 0180-C200-0014 and 0180-C200-0016 serve different purposes in networking protocols, while 0100-5E00-0002 is a standard multicast address for Internet Group Management Protocol (IGMP) and is not related to IS-IS communications. Understanding the specific use of these multicast addresses is essential for the proper configuration and performance of IS-IS in a network environment.