Netgear XSM4324FS CLI Manual Software Version 12.x - Page 712

M4300 Intelligent Edge Series Fully Managed Stackable Switches The system limits the number of relay entries to four times the maximum number of routing interfaces. The network administrator can allocate the relay entries as he likes. There is no limit to the number of relay entries on an individual interface, and no limit to the number of servers for a given interface and UDP port pair. The relay agent relays DHCP packets in both directions. It relays broadcast packets from the client to one or more DHCP servers, and relays to the client packets that the DHCP server unicasts back to the relay agent. For other protocols, the relay agent only relays broadcast packets from the client to the server. Packets from the server back to the client are assumed to be unicast directly to the client. Because there is no relay in the return direction for protocols other than DHCP, the relay agent retains the source IP address from the original client packet. The relay agent uses a local IP address as the source IP address of relayed DHCP client packets. When a switch receives a broadcast UDP packet on a routing interface, the relay agent checks if the interface is configured to relay the destination UDP port. If so, the relay agent unicasts the packet to the configured server IP addresses. Otherwise, the relay agent checks if there is a global configuration for the destination UDP port. If so, the relay agent unicasts the packet to the configured server IP addresses. Otherwise the packet is not relayed. Note that if the packet matches a discard relay entry on the ingress interface, then the packet is not forwarded, regardless of the global configuration. The relay agent only relays packets that meet the following conditions: • The destination MAC address must be the all-ones broadcast address (FF:FF:FF:FF:FF:FF) • The destination IP address must be the limited broadcast address (255.255.255.255) or a directed broadcast address for the receive interface. • The IP time-to-live (TTL) must be greater than 1. • The protocol field in the IP header must be UDP (17). • The destination UDP port must match a configured relay entry. clear ip helper statistics Use this command to reset to zero the statistics displayed in the output of the show ip helper statistics command. Format Mode clear ip helper statistics Privileged EXEC Command example: (NETGEAR Switch) #clear ip helper statistics Routing Commands 712 CLI Command Reference Manual