Network Working Group R. Hinden, Ed.
Request for Comments: 3768 Nokia
Obsoletes: 2338 April 2004
Category: Standards Track
Virtual Router Redundancy Protocol (VRRP)
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This memo defines the Virtual Router Redundancy Protocol (VRRP). VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router to one of the VRRP routers on a LAN. The VRRP router controlling the IP address(es) associated with a virtual router is called the Master, and forwards packets sent to these IP addresses. The election process provides dynamic fail over in the forwarding responsibility should the Master become unavailable. This allows any of the virtual router IP addresses on the LAN to be used as the default first hop router by end-hosts. The advantage gained from using VRRP is a higher availability default path without requiring configuration of dynamic routing or router discovery protocols on every end-host.
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Contributors. . . . . . . . . . . . . . . . . . . . . . 3
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Definitions . . . . . . . . . . . . . . . . . . . . . . 4
2. Required Features . . . . . . . . . . . . . . . . . . . . . . 5
2.1. IP Address Backup . . . . . . . . . . . . . . . . . . . 5
2.2. Preferred Path Indication . . . . . . . . . . . . . . . 5
2.3. Minimization of Unnecessary Service Disruptions . . . . 5
2.4. Efficient Operation over Extended LANs. . . . . . . . . 6
3. VRRP Overview . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Sample Configurations . . . . . . . . . . . . . . . . . . . . 7
4.1. Sample Configuration 1. . . . . . . . . . . . . . . . . 7
4.2. Sample Configuration 2. . . . . . . . . . . . . . . . . 9
5. Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. VRRP Packet Format. . . . . . . . . . . . . . . . . . . 10
5.2. IP Field Descriptions . . . . . . . . . . . . . . . . . 10
5.3. VRRP Field Descriptions . . . . . . . . . . . . . . . . 11
6. Protocol State Machine. . . . . . . . . . . . . . . . . . . . 13
6.1. Parameters per Virtual Router . . . . . . . . . . . . . 13
6.2. Timers. . . . . . . . . . . . . . . . . . . . . . . . . 14
6.3. State Transition Diagram. . . . . . . . . . . . . . . . 15
6.4. State Descriptions. . . . . . . . . . . . . . . . . . . 15
7. Sending and Receiving VRRP Packets. . . . . . . . . . . . . . 18
7.1. Receiving VRRP Packets. . . . . . . . . . . . . . . . . 18
7.2. Transmitting Packets. . . . . . . . . . . . . . . . . . 19
7.3. Virtual MAC Address . . . . . . . . . . . . . . . . . . 19
8. Operational Issues. . . . . . . . . . . . . . . . . . . . . . 20
8.1. ICMP Redirects. . . . . . . . . . . . . . . . . . . . . 20
8.2. Host ARP Requests . . . . . . . . . . . . . . . . . . . 20
8.3. Proxy ARP . . . . . . . . . . . . . . . . . . . . . . . 20
8.4. Potential Forwarding Loop . . . . . . . . . . . . . . . 21
9. Operation over FDDI, Token Ring, and ATM LANE . . . . . . . . 21
9.1. Operation over FDDI . . . . . . . . . . . . . . . . . . 21
9.2. Operation over Token Ring . . . . . . . . . . . . . . . 21
9.3. Operation over ATM LANE . . . . . . . . . . . . . . . . 23
10. Security Considerations . . . . . . . . . . . . . . . . . . . 23
11. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 24
12. References. . . . . . . . . . . . . . . . . . . . . . . . . . 24
12.1. Normative References. . . . . . . . . . . . . . . . . . 24
12.2. Informative References. . . . . . . . . . . . . . . . . 25
13. Changes from RFC2338. . . . . . . . . . . . . . . . . . . . . 25
14. Editor's Address. . . . . . . . . . . . . . . . . . . . . . . 26
15. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 27