20IPv4 RoutingThe Dell Networking Operating System (OS) supports various IP addressing features. This chapterdescribes the basics of domain name service (DNS), address resolution protocol (ARP), and routingprinciples and their implementation in the Dell Networking OS.IP Feature DefaultDNS DisabledDirected Broadcast DisabledProxy ARP EnabledICMP Unreachable DisabledICMP Redirect DisabledIP AddressesDell Networking OS supports IP version 4 (as described in RFC 791), classful routing, and variable lengthsubnet masks (VLSM).With VLSM, you can configure one network with different masks. Supernetting, which increases thenumber of subnets, is also supported. To subnet, you add a mask to the IP address to separate thenetwork and host portions of the IP address.At its most basic level, an IP address is 32-bits composed of network and host portions and representedin dotted decimal format. For example, 00001010110101100101011110000011 is represented as10.214.87.131.For more information about IP addressing, refer to RFC 791, Internet Protocol.Implementation InformationYou can configure any IP address as a static route except IP addresses already assigned to interfaces.NOTE: Dell Networking OS supports 31-bit subnet masks (/31, or 255.255.255.254) as defined byRFC 3021. This feature allows you to save two more IP addresses on point-to-point links than 30-bitmasks. Dell Networking OS supports RFC 3021 with ARP.NOTE: Even though Dell Networking OS listens to all ports, you can only use the ports starting from35001 for IPv4 traffic. Ports starting from 0 to 35000 are reserved for internal use and you cannotuse them for IPv4 traffic.420 IPv4 Routing
