ARP

The Address Resolution Protocol (ARP) determines the MAC address that belongs to an IP address.

With this dialog you can:

Setting ARP parameters

Tab. ARP parameters

Parameter

Meaning

Possible Values

Default Setting

Aging Time

With “Aging Time” you specify the time for which an entry remains before being deleted from the table. If there is a data transfer with the device within this time period, then the time measuring begins from the start again.

15-21600 s

1200

Response Time

With “Response Time” you specify how long ARP waits for a response before the query is seen to have failed.

1-10

1

Retries

With “Retries” you specify how often ARP repeats a failed query before stopping the query to this address.

0-10

4

Cache Size

“Cache Size” enables you to limit the maximum number of entries in the table. When the maximum number is reached, ARP deletes the oldest entry.

PowerMICE: 192-2112
MACH 4000: 212-2132
MACH 4000 24/48G:
212-3584

Maximum

Dynamic Renew

When the “Dynamic Renew” is switched on, ARP starts a new query to a device for which the entry has exceeded the aging time. If this query is not answered, the Switch removes the entry from the table.

on/off

on

Selective Learning

In the default setting, the router learns ARP entries passively. This means that the router receives all ARP requests and automatically learns the IP/MAC address assignment of the sending device. The automatic learning of all connected devices means that time-consuming ARP queries are excluded if the router has to send a data packet to an unknown device. In this case, the ARP tables may also be filled with unnecessary ARP entries (e.g. from devices that only wish to communicate locally).
If “Selective Learning” is activated, then the router only learns the source IP/MAC address assignment if the ARP request was directed to the router itself (i.e. if the router address was explicitly queried).

on/off

off


ARP Statistics Display

Tab. ARP Statistics

Parameter

Meaning

Total Entry Current Count

Current number of ARP entries in the ARP table

Total Entry Peak Count

Highest number of ARP entries in the ARP table

Static Entry Current Count

Current number of static ARP entries in the ARP table

Static Entry Max. Count

Maximum possible number of static ARP entries in the ARP table


ARP Table Display

Tab. ARP Table

Parameter

Meaning

Module

Router module

Port

Port to which this entry applies.

IP Address

IP address of a device that responded to an ARP query on this port.

MAC Address

MAC address of a device that responded to an ARP query on this port.

Type

Type of entry:
– static: static ARP entry that is retained even after the ARP table is deleted.
– dynamic: dynamic entry that is deleted from the table after the "Aging Time" if no data is received by this device during this time.
– local: IP and MAC address of the device's own port


Editing the ARP table

Deleting dynamic entries

By clicking on "Reset" you delete the dynamic entries from the ARP table.

Editing static entries

Using an assistant, you can add, edit and delete static entries.

The prerequisites for adding static entries are:

Buttons

Tab. Buttons (Forts.)

Button

Meaning

“Set”

Transfers the changes to the volatile memory (RAM) of the device. To permanently save the changes, open the Basic Settings:Load/Save dialog, select the location to save the configuration, and click “Save”.

“Reload”

Updates the fields with the values that are saved in the volatile memory (RAM) of the device.

“Remove”

Removes the selected table entry.

“Reset”

Deletes the dynamic entries from the routing APR table.

“Wizard”

Opens the “Wizard”.

With the “Wizard” you assign the permitted MAC addresses to a port.

“Help”

Opens the online help.