User Manual

Enterasys X-Pedition User Reference Manual 143
Configuring IP Interfaces and Parameters
You can configure the XP to drop packets for hosts whose MAC addresses the XP has been unable
to resolve. To enable dropping of packets for hosts with unresolved MAC addresses:
When you enable packets to be dropped for hosts with unresolved MAC addresses, the XP will still
attempt to periodically resolve these MAC addresses. By default, the XP sends ARP requests at 30-
second intervals to try to resolve up to 50 dropped entries.
To change the interval for sending ARP requests for unresolved entries to 45 seconds:
To change the number of unresolved entries that the XP attempts to resolve to 75:
Local Proxy ARP
Local Proxy ARP is used to help hosts with no knowledge of routing to reach other subnets. When
you enable proxy arp, the XP will process each ARP request it receives and check to ensure that the
requested address is within the subnet making the request. If the address request is not from the
subnet that received the request, the XP will respond to the ARP request with its own MAC
address, regardless of whether or not it is the owner of the IP address being requested—otherwise,
normal forwarding will occur. This allows completely isolated hosts to act as if they exist in a
single, flat network. By default, proxy arp is enabled on all IP interfaces.
Note: Enable this feature only after carefully considering its implications on network design. For
more information on the implications of this feature, please see ip enable local-proxy-arp
interface in the Enterasys X-Pedition Command Line Interface Reference Manual.
The following command enables local proxy ARP on a specific interface:
Configuring Reverse Address Resolution Protocol (RARP)
Reverse Address Resolution Protocol (RARP) works exactly the opposite of ARP. Taking a MAC
address as input, RARP determines the associated IP address. RARP is useful for X-terminals and
diskless workstations that may not have an IP address when they boot. They can submit their MAC
address to a RARP server on the XP, which returns an IP address.
Configuring RARP on the XP consists of two steps:
1. Letting the XP know which IP interfaces to respond to
xp# arp set drop-unresolved enabled
xp# arp set unresolve-timer 45
xp# arp set unresolve-threshold 75
xp(config)# ip enable local-proxy-arp interface 10.136.64.5