Product ManualXG-7100-1U
2.1.3 Interface Assignments
Interfaces must be assigned in the same order on all nodes exactly. If the interfaces are not aligned, configuration
synchronization and other tasks will not behave correctly. The default configuration has all interfaces assigned by
default, as seen in the IO Ports section of the unit’s product manual, which makes a good starting point for this guide.
If any adjustments have been made to the interface assignments, they must be replicated identically on both nodes.
2.1.4 IP Address Requirements
A High Availability cluster needs three IP addresses in each subnet along with a separate unused subnet for the Sync
interface. For WANs, this means that a /29 subnet or larger is required for an optimal configuration. One IP address is
used by each node, plus a shared CARP VIP address for failover. The synchronization interface only requires one IP
address per node.
The IP addresses used in this guide are shown in the following tables, substitute the real IP addresses as needed.
Table 1: WAN IP Address Assignments
IP Address Usage
198.51.100.200/24 CARP shared IP address
198.51.100.201/24 Primary node WAN IP address
198.51.100.202/24 Secondary node WAN IP address
Table 2: LAN IP Address Assignments
IP Address Usage
192.168.1.1/24 CARP shared IP address
192.168.1.2/24 Primary node LAN IP address
192.168.1.3/24 Secondary node LAN IP address
Table 3: Sync IP Address Assignments
IP Address Usage
172.16.1.2/24 Primary node Sync IP address
172.16.1.3/24 Secondary node Sync IP address
Single address CARP
It is technically possible to configure an interface with a CARP VIP as the only IP address in a given subnet, but
it is not generally recommended. When used on a WAN, this type of configuration will only allow communication
from the primary node to the WAN, which greatly complicates tasks such as updates, package installations, gateway
monitoring, or anything that requires external connectivity from the secondary node. It can be a better fit for an internal
interface, however internal interfaces do not typically suffer from the same IP address limitations as a WAN, so it is
still preferable to configure IP addresses on all nodes. Such a configuration is not covered in this guide.
2.1.5 Determine CARP VHID Availability
CARP can interfere with VRRP, HSRP, or other systems using CARP if conflicting identifiers are used. In order to
ensure that a segment is clear of conflicting traffic, perform a packet capture on each interface looking for CARP/VRRP
traffic. A given VHID must be unique on each layer 2, so each interface must be checked separately. The same VHID
may be used on different segments so long as they are separate broadcast domains.
2.1. High Availability Prerequisites 49
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