Configuration of Address Resolution Protocol (ARP) on Sx500 Series Stackable Switches

Objective

Address Resolution Protocol (ARP) is a telecommunication protocol which is used to resolve the network layer addresses into link layer addresses. The switch maintains an ARP table for all the devices that are present in its directly connected subnets. Whenever a switch needs to send or route packets to a local device, it first searches the ARP table to obtain the MAC address of the device. ARP is also very helpful for troubleshooting purposes.

ARP Configuration needs the following to be done:

1. Choose whether ARP configuration needs to work on Layer 2 mode or Layer 3 mode. Please refer to the article Stack Settings on Sx500 Series Stackable Switches if this configuration needs to be changed.
2. Create a VLAN; this is done only when the switch is in the Layer 3 mode because when switch is in Layer 2 mode it only operates in management VLAN which is created by default. This configuration can be found in the article VLAN Creation on Sx500 Series Stackable Switches.
3. Create IPv4 Interface, which is created only when the switch is in the Layer 3 mode, which can be configured under IP Configuration > Management and IP Interface > IPv4 Interface.
4. Configure ARP, this is covered in this article.

If the switch is in Layer 3 mode Proxy ARP can also be configured. Proxy ARP is a method by which a device on a given network replies to ARP queries for a network address which is not on that network. The Proxy ARP knows about the location where the incoming traffic is destined and gives its own MAC address in reply to the ARP request. This article also explains how to enable ARP proxy on the switch. Once the ARP proxy is enabled in this page, it is enabled on all interfaces.

This article explains the steps for the configuration of ARP in both Layer 2 and Layer 3 mode.

Applicable Devices

• Sx500 Series Stackable Switches

Software Version

• 1.3.0.62

Basic ARP Configuration

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP (Layer 2 or Layer 3). The ARP page opens:

 

 

Step 2. Enter the number of seconds the dynamic addresses can remain in the ARP Table in the ARP Entry Age Out field. A dynamic address ages out after the time in the table exceeds the ARP entry age out time. When a dynamic address ages out it is deleted from the table and it is added back in the table only when it is learned again. The default value for Layer 2 mode is 300 and 60000 for Layer 3 mode.

 

Step 3. Click the radio button which corresponds to the type of ARP entries to be cleared from the system in the Clear ARP Table Entries field.

• All — Deletes all the static and the dynamic addresses immediately.

• Dynamic — Deletes all the dynamic addresses immediately. Dynamic addresses are added from the ARP replies the switch gets so they age out after a configured time. 

• Static — Deletes all the static addresses immediately. Static addresses are configured manually so they do not age out with time.

• Normal Age Out — Deletes dynamic addresses based on the configured ARP Entry Age Out Time. 

Step 4. Click Apply to save the settings.

ARP Configuration in Layer 2 Mode

Add Entry to the ARP Table

Note: You may have to refer Basic ARP Configuration before this procedure.

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP. The ARP page opens:

 

The ARP Table displays the following fields.

• Interface — IPv4 Interface of the directly connected IP subnet where the IP device resides.

• IP Address — IP address of the IP device.

• MAC Address — MAC Address of the IP device.

• Status — Whether the entry was manually entered or dynamically learned.

Step 2. Click Add. The Add ARP Entry window appears.

 

The IP Version field displays the IP address format supported by the host. Only IPv4 is supported.

Note: The Interface field displays the IPv4 interface on the switch. For Layer 2 mode, there is only one directly connected IP subnet which is always in the management VLAN. All the static and dynamic addresses in the ARP table reside in the management VLAN. 

 

Step 3. Enter the IP address of the local device in the IP Address field.

Step 4. Enter the MAC address of the local device in the MAC Address field.

 

Step 5. Click Apply which causes the ARP entry to be written to the running configuration file.

 

Edit ARP Entry

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP. The ARP page opens:

 

Step 2. Check the desired entry and click Edit. The Edit ARP Table page opens:

 

Step 3. Edit the desired fields. The descriptions of the fields can be found in Steps 1 to 4 in the Add Entry to the ARP Table subsection of the article. The status of the fields can be changed to Static or Dynamic.

 

Step 4. Click Apply. The settings are applied.

 

Delete ARP Entry

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP. The ARP page opens:

 

Step 2. Check the desired entry and click Delete. The interface is deleted.

 

ARP Configuration in Layer 3 Mode

Add Entry to the ARP Table

Note: You may have to refer Basic ARP Configuration before this procedure.

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP. The ARP page opens:

 

The ARP Table displays the following fields.

• Interface — IPv4 interface of the directly connected IP subnet where the IP device resides.

• IP Address — IP address of the IP device.

• MAC Address — MAC address of the IP device.

• Status — Whether the entry was manually entered or dynamically learned.

Step 2. The Layer 3 mode has a Filter field. Choose the interface type from the drop-down list in the Filter field and click Go.

Step 3. Click Add. The Add ARP Entry window appears.

 

The IP Version field displays the IP address format supported by the host. Only IPv4 is supported.

Step 4. For Layer 3 mode, an IPv4 interface can be configured in a port, LAG, or VLAN. Choose the IPv4 interface which is needed from the list of configured IPv4 addresses. 

Note: In the above image Port and LAG cannot be selected as they are not configured with an IPv4 address. For LAG configuration, refer to article Link Aggregation Group (LAG) Management and Settings on Sx500 Series Stackable Switches and assign port with an IPv4 address.

 

Step 5. Enter the IP address of the local device in the IP Address field.

 

Step 6. Enter the MAC address of the local device in the MAC Address field.

 

Step 7. Click Apply which causes the ARP entry to be written to the running configuration file.

 

Edit ARP Entry

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP (Layer 2 or Layer 3). The ARP page opens:

 

Step 2. Check the desired entry and click Edit. The Edit ARP Table page opens:

Step 3. Edit the desired fields. The descriptions of the fields can be found in Steps 1 to 6 in the Add Entry to the ARP Table subsection of the article. The status can be changed to Static or Dynamic.

Note: In the above image Port and LAG cannot be selected as they are not configured with an IPv4 address. For LAG configuration, refer to article Link Aggregation Group (LAG) Management and Settings on Sx500 Series Stackable Switches and assign port with an IPv4 address.

 

Step 4. Click Apply. The settings are applied.

 

To Delete ARP Configuration

Step 1. Log in to the web configuration utility and choose IP Configuration > ARP. The ARP page opens:

 

Step 2. Check the desired entry and click Delete. The entry is deleted.

 

ARP Proxy Configuration in Layer 3 Mode

Step 1. Log in to the web configuration utility to choose IP Configuration > ARP Proxy (Layer 3). The ARP Proxy page opens:

 

Step 2. Check Enable in the ARP Proxy field to enable the switch to reply to ARP requests through the use of the MAC address of the switch for the nodes that are located remotely.

Step 3. Click Apply. The settings are applied.