> Source: [sk44898](https://support.checkpoint.com/results/sk/sk44898)

# sk44898 - Configuring Cisco Switch / Router to work with ClusterXL Multicast ARPs

| Property | Value |
|----------|-------|
| Solution ID | sk44898 |
| Date Created | 2010-06-03 |
| Last Modified | 2018-01-02 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- Communication between Cisco equipment and Check Point ClusterXL fails.

## Cause

Check Point clusters use Unicast IP addresses and Multicast MAC addresses.

Cisco adheres to [RFC1812 "Requirements for IP Version 4 Routers"](http://tools.ietf.org/html/rfc1812), which states:   

"A router MUST not believe any ARP reply that claims that the Link Layer address of another host or router is a broadcast or multicast address."

## Solution

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