VRRP Packets
VRRP packets are used to advertise the priority and status of the master router to all backup routers in the same VRRP backup group as the master. A VRRP packet is a multicast packet that can be forwarded only within a single broadcast domain, such as a virtual local area network (VLAN) or a virtual switching instance (VSI).
VRRP versions include VRRPv2 and VRRPv3. VRRPv2 applies only to IPv4 networks, and VRRPv3 applies to both IPv4 and IPv6 networks. VRRP is classified as VRRP for IPv4 (VRRP4) or VRRP for IPv6 (VRRP6) by network type. VRRP4 supports both VRRPv2 and VRRPv3, and VRRP6 supports only VRRPv3.
- The source address is the primary IPv4 address of the interface that sends the packet.
- The destination address is 224.0.0.18.
- The time to live (TTL) value is 255.
- The protocol number is 112.
- The source address is the link-local address of the interface that sends the packet.
- The destination address is FF02::12.
- The hop count is 255.
- The protocol number is 112.
NE20E allows you to manually switch a VRRP version. VRRP packets refer to VRRPv2 packets, unless otherwise specified in this document.
VRRP Packet Structure
Figure 5-6 and Figure 5-7 show the VRRPv2 and VRRPv3 packet structures, respectively.
Field |
Description |
---|---|
Version |
Version number of the VRRP protocol. The value is 2. |
Type |
Type of the VRRPv2 packet. The value is 1, indicating that the packet is an advertisement packet. |
Virtual Rtr ID |
Virtual router identifier. |
Priority |
Priority of the master router in a VRRP backup group. |
Count IPv4 Addrs |
Number of virtual IPv4 addresses configured for a VRRP backup group. |
Auth Type |
VRRPv2 packet authentication type. VRRPv2 defines the following authentication types:
|
Adver Int |
Interval at which VRRPv2 packets are sent, in seconds. |
Checksum |
16-bit checksum, used to check the data integrity of the VRRPv2 packet. |
IPv4 Address |
Virtual IPv4 address configured for a VRRP backup group. |
Authentication Data |
Authentication key in the VRRPv2 packet. This field applies only when simple or MD5 authentication is used. For other authentication types, this field is fixed to 0. |
Field |
Description |
---|---|
Version |
Version number of the VRRP protocol. The value is 3. |
Type |
Type of the VRRPv3 packet. The value is 1, indicating that the packet is an advertisement packet. |
Virtual Rtr ID |
Virtual router identifier. |
Priority |
Priority of the master router in a VRRP backup group. |
Count IPvX Addrs |
Number of virtual IPvX addresses configured for a VRRP backup group. |
rsvd |
Field reserved for the VRRPv3 packet. The value must be set to 0. |
Adver Int |
Interval at which VRRPv3 packets are sent, in centiseconds. |
Checksum |
16-bit checksum, used to check the data integrity of the VRRPv3 packet. |
IPvX Address |
Virtual IPvX address configured for a VRRP backup group. |
VRRPv2 supports authentication, whereas VRRPv3 does not.
VRRPv2 supports a second-level interval between sending VRRP Advertisement packets, whereas VRRPv3 supports a centisecond-level interval.