1066 Configuring IP RoutingARP TableThe router maintains an ARP table that associates a MAC address andoutgoing port with an IP address and VLAN. The ARP table is dynamicallyupdated with the host MAC address and outgoing port information. ARPentries are associated with the VLAN on which the IP address or route isknown. The router broadcasts an ARP request in the associated VLAN for anyunknown MAC address to which it needs to route packets. The router alsorefreshes an ARP entry by sending an ARP request before a dynamicallylearned ARP entry times out and updates the ARP table if a response isreceived. Host or VM movement within the same VLAN (L2 topologychange) does not trigger an ARP refresh. Only if the ARP entry is timed out orthe port associated with the ARP entry goes down does the ARP entry getrefreshed.If the traffic to a host is bidirectional, it will result in the host ARP entrypointing to the new port. Any gratuitous ARP request sent by a host or VMresults in an ARP entry update (including a change in the MAC address andoutgoing port).Route Preference Values Preference values are as follows:• Local—0• Static—1• OSPF Intra—110• OSPF Inter—110• OSPF External—110• RIP—120Table 33-2. IP Routing Defaults (Continued)Parameter Default Value
