I am a new member to this list, so apologies if this question has come up before. I was wondering if there are any IPv4 addresses reserved for communication within one logical system. For example, a system (router for example) with multiple slot cards may require one slot card to communicate via IP directly with another slot card, and even route traffic between the cards. Traffic to these destinations will always originate from within the logical system and will never leave the logical system. The system itself could be modular, and be built from several components. Is there any ip-address range reserved for this? I took a look at RFC 3330, but it's not obvious what could be used. Using the addresses reserved for private networks (10.0.0.0/8, 172.16.0.0/16, and 192.168.0.0/16 etc.) is not attractive because there could be a large number of components and we do not want to preclude use of these addresses in the rest intranet. Thanks in advance. Allwyn.