Edge-Core ECS4660-28F, Management Manual, Page: 749 / 2020

C
HAPTER
18
| General IP Routing
Address Resolution Protocol
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When a node in the attached subnetwork does not have routing or a
default gateway configured, Proxy ARP can be used to forward ARP requests
to a remote subnetwork. When the router receives an ARP request for a
remote network and Proxy ARP is enabled, it determines if it has the best
route to the remote network, and then answers the ARP request by
sending its own MAC address to the requesting node. That node then sends
traffic to the router, which in turn uses its own routing table to forward the
traffic to the remote destination.
Figure 445: Proxy ARP
P
ARAMETERS
These parameters are displayed:
◆
Timeout – Sets the aging time for dynamic entries in the ARP cache.
(Range: 300 - 86400 seconds; Default: 1200 seconds or 20 minutes)
The ARP aging timeout can be set for any configured VLAN.
The aging time determines how long dynamic entries remain in the
cache. If the timeout is too short, the router may tie up resources by
repeating ARP requests for addresses recently flushed from the table.
When a ARP entry expires, it is deleted from the cache and an ARP
request packet is sent to re-establish the MAC address.
◆
Proxy ARP – Enables or disables Proxy ARP for specified VLAN
interfaces, allowing a non-routing device to determine the MAC address
of a host on another subnet or network. (Default: Disabled)
End stations that require Proxy ARP must view the entire network as a
single network. These nodes must therefore use a smaller subnet mask
than that used by the router or other relevant network devices.
Extensive use of Proxy ARP can degrade router performance because it
may lead to increased ARP traffic and increased search time for larger
ARP address tables.
W
EB
I
NTERFACE
To configure the timeout for the ARP cache or to enable Proxy ARP for a
VLAN (i.e., IP subnetwork):
1.
Click IP, ARP.
2.
Select Configure General from the Step List.
3.
Set the timeout to a suitable value for the ARP cache, or enable Proxy
ARP for subnetworks that do not have routing or a default gateway.
no routing,
no default
gateway
Remote
ARP Server
Proxy ARP
ARP
request