Siemens SCALANCE XR-500 Instructions

1 Introduction
VRRP
Entry-ID: 109798556, V1.0, 09/2021
6
© Siemens AG
2021 All rights reserved
1.2 Principle of operation
The functional principle of the Virtual Router Redundancy Protocol (VRRP) lies in
providing a virtual router as a gateway for the end nodes. Two or more routers are
hidden behind this gateway. One of these routers is active and assumes the role of
the master and thus the routing. All other routers function as backup routers and
check whether the master is still active. If the master is not active, they take over.
Figure 1-3
Subnet A
Router 1
PC 1
Server 2
Server 1
Router 2
Subnet B
IP: 192.168.0.100
Subnet mask: 255.255.255.0
Gateway: 192.168.0.1
PC 2
IP: 192.168.0.101
Subnet mask: 255.255.255.0
Gateway: 192.168.0.1
Virtual router
Shared IP:
192.168.0.1
Virtual Router ID
(VRID): 1
Virtual router
Shared IP:
192.168.1.1
Virtual Router ID
(VRID): 2
IP: 192.168.1.100
Subnet mask: 255.255.255.0
Gateway: 192.168.1.1
IP: 192.168.1.101
Subnet mask: 255.255.255.0
Gateway: 192.168.1.1
Master
IP Interface: 192.168.0.2/24
Master
IP Interface: 192.168.1.2/24
Backup
IP Interface: 192.168.0.3/24
Backup
IP Interface: 192.168.1.3/24
Virtual router
The virtual router is defined via a Virtual Router ID (VRID), a defined MAC address,
and one or more IP address(es) that the virtual router "listens to", also known as
Associated IP Addresses. The term "virtual router" is misleading. To be exact, the
router is not entirely virtual, but rather individual IP interfaces. One router can be
the master on one IP interface and the backup on another IP interface.
Virtual Router ID (VRID)
To uniquely assign two or more routers to a group that together represents one
virtual router, a VRID is configured in each device. This is a number from 1 to 255
and must be unique in a subnet. All routers within a group must have the same
VRID configured. VRRP routers that belong to the same VRID exchange
information. Each group can only have one master router.
VRRP MAC address
Like every real router, the virtual router also needs a MAC address to which
Ethernet telegrams from the end nodes can be sent. This MAC address is reserved
for VRRP and is composed of a fixed part plus the VRID (in hexadecimal format):
00-00-5e-00-01-VRID.

Siemens SCALANCE XR-500 Specifications

General

Brand	Siemens
Model	SCALANCE XR-500
Category	Switch
Language	English