Advanced Clustering Configuration

This section presents several advanced cluster scenarios and procedures for their configuration.

Clusters on the Same Layer-2 Segment

The recommended cluster architecture contains interfaces connected to a Layer-2 segment that is isolated from other clusters.

However, in a deployment where multiple clusters need to connect to the same Layer-2 segment, the same MAC address may be used by more than one cluster for Cluster Control Protocol (CCP) communication. This may direct traffic to the incorrect cluster.

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Source Cluster MAC Addresses

Cluster members use CCP to communicate with each other. In order to distinguish CCP packets from ordinary network traffic, CCP packets are given a unique source MAC address.

• The first four bytes of the source MAC address are all zero: 00.00.00.00
• The fifth byte of the source MAC address is a "magic" number, a number that encodes critical information in a way intended to be opaque. Its value indicates its purpose:

  Default Value Of Fifth Byte	Purpose
  0xfe	CCP traffic
  0xfd	Forwarding layer traffic

• The sixth byte is the ID of the source cluster member

When multiple clusters are connected to the same Layer-2 segment, setting a unique value to the fifth byte of the MAC source address of each cluster allows them to coexist on the same Layer-2 segment.

Changing a Cluster's MAC Source Address

To change a cluster's MAC source address, run these commands on each cluster member:

fw ctl set int fwha_mac_magic <value>

fw ctl set int fwha_mac_forward_magic <value>

Parameter	Default value
fwha_mac_magic	0xfe
fwha_mac_forward_magic	0xfd

Use any value, as long as the two gateway configuration parameters are different. To avoid confusion, do not use the value 0x00.

Making the Change Permanent

You can configure the above parameters to persist following reboot.

1. Use a text editor to open the file fwkern.conf, located at $FWDIR/boot/modules/.
2. Add the line Parameter=<value in hex>. Make sure there are no spaces.