Routing
226
M4100 Series Managed Switch
7. Select Routingï€ ï€¾ VLAN VLAN Routing.
The screen displays the port interface and MAC address assigned to the VLAN for
routing.
8. Use IP Address to enter the IP address to be configured for the VLAN routing interface.
9. Use Subnet Mask to enter the subnet mask to be configured for the VLAN routing interface.
10. T
o add the VLAN routing Interface specified in the VLAN ID field to the switch configuration,
click the ADD button.
11. T
o remove the VLAN routing interface specified in the VLAN ID field from the switch
configuration, click the DELETE button.
ARP Overview
The ARP protocol associates a Layer 2 MAC address with a layer 3 IPv4 address. managed
switch software features both dynamic and manual ARP configuration. With manual ARP
configuration, you can statically add entries into the ARP table.
ARP is a necessary part of the Internet Protocol (IP) and is used to translate an IP address to
a media (MAC) address, defined by a local area network (LAN) such as Ethernet.
A station
needing to send an IP packet must learn the MAC address of the IP destination, or of the next
hop router, if the destination is not on the same subnet. This is achieved by broadcasting an
ARP request packet, to which the intended recipient responds by unicasting an ARP reply
containing its MAC address. Once learned, the MAC address is used in the destination
address field of the Layer 2 header prepended to the IP packet.
The ARP cache is a table maintained locally in each station on a network. ARP cache entries
are learned by examining the source information in the
ARP packet payload fields, regardless
of whether it is an ARP request or response. Thus, when an ARP request is broadcast to all
stations on a LAN segment or virtual LAN (VLAN), all recipients store the sender’s IP and
MAC address in their respective ARP cache. The ARP response, being unicast, is normally
seen only by the requestor, who stores the sender information in its ARP cache. Newer
information always replaces existing content in the ARP cache.
The number of supported ARP entries is platform dependent.
Devices can be moved in a network, which means that the IP address that was at one time
associated with a certain MAC address is now found using a dif
ferent MAC address, or might
no longer be in use (for example, it was reconfigured, disconnected, or powered off). This
leads to stale information in the ARP cache unless entries are updated in reaction to new
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