Cabletron Systems CyberSWITCH CSX150 User Manual

Also see for CyberSWITCH CSX150: User guide Quick start guide

Contents

USER’S GUIDE104 CyberSWITCHwith a remote device on a different subnet, the local device will ARP for the remote host’s MACaddress.Since routers do not forward ARP requests across subnets, ARPs sent for hosts which are noton the same physical network segment will go unanswered. The proxy ARP feature willpotentially generate an ARP reply for remote hosts. If the CyberSWITCH determines that itprovides the best route to the remote device, it will respond with an ARP reply containing theMAC address of the CyberSWITCH. Further communication between the two hosts will thenbe routed through the CyberSWITCH.• Secondary IP AddressingIf only one IP network interface (i.e., one subnet) per LAN port is configured, any traffic fromhosts on different subnets attached to the LAN port would be dropped.With the secondary IP addressing feature, multiple IP network interfaces may be configuredfor each LAN port. All existing subnets which are to be reached will have an associated IPnetwork interface on the CyberSWITCH. By allowing each LAN port to be configured withmultiple IP network interfaces, the CyberSWITCH can route packets from hosts on any of thesubnets attached to the LAN port. (See following example.)Example: IP Host Communications in Flattened NetworksTo communicate with destination hosts which are not on the same physical wire, you must have arouter attached to the edge of the flattened network which can forward packets to those destinationnetworks. In the following illustration, we are using a CyberSWITCH as our “edge” router:ISDNCSX1501.1.1.12.2.2.1Host A Host B1.1.1.22.2.2.2Host DHost C3.3.3.31.1.1.3