SNR S2989G-8TX — настройка и устранение неполадок ARP и Gratuitous ARP [192/553]

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S2989G-24TX Operation Manual

Chapter 3 IP services Configuration

3-30

Switch(Config-if-Vlan1)#exit

3.10.4

ARP Local Proxy Function Troubleshooting

ARP local proxy function is disabled by default. Users can view the current

configuration with display command. With correct configuration, by enabling debug of ARP,

users can check whether the ARP proxy is normal and send proxy ARP messages.

In the process of operation, the system will show corresponding prompts if any

operational error occurs.

3.11

Gratuitous ARP

3.11.1

Introduction to Gratuitous ARP

Gratuitous ARP is a kind of ARP request that is sent by the host with its IP address as

the destination of the ARP request.

The basic working mode for the switch is as below: The Layer 3 interfaces of the

switch can be configured to advertise gratuitous ARP packets period or the switch can be

configured to enable to send gratuitous ARP packets in all the interfaces globally.

The purpose of gratuitous ARP is as below:

1. To reduce the frequency that the host sends ARP request to the switch. The hosts in

the network will periodically send ARP requests to the gateway to update the MAC

address of the gateway. If the switch advertises gratuitous ARP requests, the host will

not have to send these requests. This will reduce the frequency the hosts’ sending

ARP requests for the gateway’s MAC address.

2. Gratuitous ARP is a method to prevent ARP cheating. The switch’s advertising

gratuitous ARP request will force the hosts to update its ARP table cache. Thus,

forged ARP of gateway cannot function.

3.11.2

Gratuitous ARP Configuration Task List

1. Enable gratuitous ARP and configure the interval to send gratuitous ARP request

2. Display configurations about gratuitous ARP

1. Enable gratuitous ARP and configure the interval to send gratuitous ARP

request.