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INTERNET-DRAFT R. Hott
March 6, 2006 NSWC-DD
Timer Enhancements to Reduce Failover Times for the
Virtual Router Redundancy Protocol for IPv4
<draft-ietf-vrrp-ipv4-timers-02.txt>
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six
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documents at any time. It is inappropriate to use Internet-Drafts
as reference material or to cite them other than as "work in
progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on September 6, 2006.
Abstract
The router survivability capability provided by the Virtual
Router Redundancy Protocol for IPv4 (VRRPv4) satisfies the
requirements for many LAN environments. There are, however,
LAN environments that have sub-second failover requirements and
thus a need for finer granularity of the VRRP timers. This draft
proposes extensions to VRRPv4 [RFC 3768] for specifying sub-second
Advertisement Intervals. A new message type is introduced which
permits the timer granularity for the Advertisement Interval to
be specified. In addition, a new field is introduced permitting
the specification of the number of missed ADVERTISEMENTs before
a Virtual Router Master is declared down.
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Table of Contents
1. Introduction...............................................3
1.1. Requirements notation................................3
1.2. Contributors.........................................3
1.3. Scope................................................4
2. Update to the VRRPv4 Protocol..............................4
2.1. Updates to the VRRPv4 Packet Format..................4
2.2. Updates to the VRRPv4 Field Descriptions.............5
3. Update to the VRRPv4 Protocol State Machine................6
3.1. Updates to the Parementers per Virtual Router........6
3.2. Update to the Timers.................................8
3.3. Updates to the State Descriptions....................8
4. Updates for Sending and Receiving VRRPv4 Packets..........15
4.1. Receiving VRRPv4 Packets............................15
4.2. Transmitting VRRPv4 Packets.........................16
5. Operational Issues........................................17
5.1. Sub-second Timers...................................17
5.2. Interoperability / Backward Compatibility...........17
6. Security Considerations...................................17
7. Intellectual Property.....................................17
8. Acknowledgments...........................................18
9. IANA Considerations.......................................18
10. Normative References......................................18
11. Informative References....................................18
12. Authors' Address..........................................19
13. Disclaimer of Validity....................................19
14. Copyright Statement.......................................19
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1. Introduction
VRRPv4 [RFC 3768] specifies an election protocol that dynamically
assigns responsibility for a virtual router to one of the VRRP
routers on a LAN. This election process provides dynamic fail
over in the forwarding responsibility should the Master become
unavailable. While this capability may meet the survivability
requirements for many LAN environments, there are environments
in which sub-second recovery from outages is required.
To achieve sub-second failovers for VRRPv4, the granularity of
the timers within VRRPv4 must be reduced from one second
intervals to sub-second intervals. This document proposes an
optional message type which permits the specification of the
timer granularity. By specifying finer granularity timers, the
Advertisement Interval can be specified, in increments, based
upon the timer granularity.
In addition to specifying the timer granularity and the
Advertisement Interval in these new time increments, this
document also proposes the ability to specify the number of
ADVERTISEMENTS that must be missed prior to declaring a MASTER
inactive. In the current specification for VRRPv4 [RFC 3768],
the number of ADVERTISEMENTS missed prior to delaring a MASTER
inactive is three, based upon the calculation of the
Master_Down_Interval. In permitting the sub-second Advertisement
Interval, the potential for VRRP instability is increased.
Instability could occur due to processing requirements within the
router preventing the processing of ADVERTISEMENTS or loading
conditions on the network preventing reception of these
ADVERTISEMENTS. Specifiying the number of ADVERTISEMENTS that
can be missed offers a mechanism to address stability issues
with VRRPv4, regardless of the timer granularity specified.
1.1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
1.2. Contributors
The following people contributed to the text in this document: K.
O'Donoghue, R. Hinden, S. Bates, S. Mathur, and M. Gupta. In
addition, the authors of VRRPv4 [RFC 3768] are recognized as the
basis for the text and concepts within this document.
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1.3. Scope
The remainder of this document provides a description of the
optional message type for VRRPv4 and the associated changes to
VRRPv4 to support this new message type and the added funtionality.
A separate document will be produced if it is decided that similar
functionality is desirable in the IPv6 environment.
2. Update to the VRRPv4 Protocol
This section outlines the changes to Section 5 (Protocol) of the
VRRPv4 [RFC 3768] to accommodate the optional FAST ADVERTISEMENT,
Type 2, message. Changes were made to the VRRPv4 packet format
and VRRPv4 field descriptions. There were no changes made to
the IP field descriptions.
2.1. Updates to the VRRPv4 Packet Format
This section outlines the VRRPv4 packet format for the optional
Fast Advertisement, Type 2, message and the relevant fields in
packet.
The following is the VRRPv4 packet format for the mandatory
ADVERTISEMENT, Type 1, message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Type | Virtual Rtr ID| Priority | Count IP Addrs|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Adver Int | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (n) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication Data (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication Data (2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The VRRPv4 packet format for the optional FAST ADVERTISEMENT,
Type 2, message is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Type | Virtual Rtr ID| Priority | Count IP Addrs|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Adv Cnt|AIG| Adver Int | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (n) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2.2. Updates to the VRRPv4 Field Descriptions
The following updates the VRRPv4 field descriptions. The Type and
Advertisement Interval are updated and two new fields are added.
2.2.1. Type
The Type field specifies the type of this VRRPv4 packet. There are
two types defined
1 ADVERTISEMENT
2 FAST ADVERTISEMENT (optional)
A packet with an unknown type MUST be discarded.
2.2.2. Advertisement Count (Adv_Cnt)
This field is only present in the FAST ADVERTISEMENT, Type 2,
message. The Advertisement Count field specifies the number of FAST
ADVERTISEMENT messages that can be missed before a BACKUP will
declare a MASTER down. Configurable item in the range 1-15. Default
is 3.
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2.2.3. Advertisement Interval Granularity (AIG)
This field is only present in the FAST ADVERTISEMENT, Type 2,
message. The Advertisement Interval Granularity field specifies the
timer granularity. The currently recognized values are
0 seconds (default)
1 centiseconds
2 milliseconds
A packet with an unknown Advertisement Interval Granularity MUST
be discarded.
2.2.4. Advertisement Interval (Adver Int)
The Advertisement Interval field is present in both the
ADVERTISEMENT and the FAST ADVERTISEMENT messages. The field
indicates the number of time intervals between the respective
advertisements. For the ADVERTISEMENT, Type 1, message the
interval is measured in seconds and is an 8 bit field. For the
FAST ADVERTISEMENT, Type 2, message the interval is measured in
the units specified in the AIG field and is a 10 bit field. The
default for the Advertisement Interval is 1 second.
3. Update to the VRRPv4 Protocol State Machine
This section outlines the changes to Section 6 (Protocol State
Machine) of the VRRPv4 [RFC 3768] to accommodate the optional
FAST ADVERTISEMENT, Type 2, message.
With the introduction of the optional FAST ADVERTISEMENT message,
time values MUST reflect the granularity supported in the FAST
ADVERTISEMENT message. Thus all time values for both the
ADVERTISEMENT and FAST ADVERTISEMENT message are specified
according to the message format but are reflected internally
in milliseconds.
The state machines have also been updated to deal with
interoperability issues due to addition of the new message type.
3.1. Updates to the Parameters per Virtual Router
VR_Type The message type for this VRRP router
Configurable item with values 1 for
ADVERTISEMENT and 2 for FAST
ADVERTISEMENT.
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VR_Mode The mode of operation for this VRRP
router environment. Values are 0 for
a homogeneous VRRP router environment
and 1 for a heterogeneous VRRP router
environment (i.e., both message types
are used). The default is 0.
VR_AIG The Advertisement Interval Granularity
for this VRRP router. Configurable item
with values 0 for seconds (default),
1 for centiseconds, and 2 for
milliseconds.
VR_Adver_Interval Time interval between ADVERTISEMENTs
or FAST ADVERTISEMENTs (milliseconds).
Configurable item. Default is 1,000
milliseconds (1 second) for both
message types.
Advertisement_Interval Time interval between ADVERTISEMENTs
or FAST ADVERTISEMENTs (milliseconds).
Type1_Adver_Interval Time interval between ADVERTISEMENTs
(seconds).
Skew_Time Time to skew Master_Down_Interval in
milliseconds. Calculated as:
( ( ( 256 - Priority ) *
Advertisement_Interval ) / 256 ).
VR_Adver_Count The number of ADVERTISEMENTS or FAST
ADVERTISEMENTS that can be missed
before a BACKUP will declare a MASTER
down. Configurable item. When
ADVERTISEMENTs are used this is set to
3. When FAST ADVERTISEMENTs are used,
the range is 1-15. The default is 3.
Advertisement_Count The number of ADVERTISEMENTS or FAST
ADVERTISEMENTs that can be missed before
a BACKUP will declare a MASTER down.
Master_Down_Interval Time interval for Backup to declare Master
down (milliseconds). Calculated as:
( Advertisement_Count *
Advertisement_Interval ) + Skew_time
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3.2. Updates to the Timers
With the introduction of the optional FAST ADVERTISEMENT message,
time values MUST reflect the granularity supported in the FAST
ADVERTISEMENT message. Thus all timers MUST reflect the granularity
for FAST ADVERTISEMENT messages (milliseconds).
Master_Down_Timer Timer that fires when ADVERTISEMENT or
FAST ADVERTISEMENT has not been heard
for Master_Down_Interval.
Adver_Timer Timer that fires to trigger sending of
ADVERTISEMENT based on
Advertisement_Interval.
Adver_2_Timer Timer that fires to trigger sending of
FAST ADVERTISEMENT based on
Advertisement_Interval.
3.3. Updates to the State Descriptions
The State Transition Diagram does not change with the addition of
the FAST ADVERTISMENT message type. The following updates the
descriptions for the three states.
In the state descriptions below, the state names are identified by
{state-name}, and the packets are identified by all upper case
characters.
A VRRP router implements an instance of the state machine for each
virtual router election it is participating in.
3.3.1. Initialize
The purpose of this state is to wait for a Startup event. If a
Startup event is received, then:
o Initialize local Virtual Router settings (VR_Mode, VR_Type,
VR_AIG, VR_Adver_Interval, and VR_Adver_Count)
- If the Priority = 255, then: (i.e., the router owns the IP
address(es) associated with the virtual router)
If the VR_Type is 1, then:
o Send an ADVERTISEMENT
o Set the Adver_Timer to Advertisement_Interval
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else:
o Send a FAST ADVERTISEMENT
o Set the Adver_2_Timer to Advertisement_Interval
endif
o Broadcast a gratuitous ARP request containing the virtual
router MAC address for each IP address associated with the
virtual router.
o Transition to the {Master} state
else:
o Set the Master_Down_Timer to Master_Down_Interval
o Transition to the {Backup} state
endif
3.3.2. Backup
The purpose of the {Backup} state is to monitor the
availability and state of the Master Router.
While in this state, a VRRP router MUST do the following:
- MUST NOT respond to ARP requests for the IP address(s)
associated with the virtual router.
- MUST discard packets with a destination link layer MAC
address equal to the virtual router MAC address.
- MUST NOT accept packets addressed to the IP address(es)
associated with the virtual router.
- If a Shutdown event is received, then:
o Cancel the Master_Down_Timer
o Transition to the {Initialize} state
endif
- If the Master_Down_Timer fires, then:
If the VR_Mode is 0, then:
If the VR_Type is 1, then:
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o Send an ADVERTISEMENT
o Set the Adver_Timer to Advertisement_Interval
else:
o Send a FAST ADVERTISEMENT
o Set the Adver_2_Timer to Advertisement_Interval
endif
else:
o Send an ADVERTISEMENT
o Send a FAST ADVERTISEMENT
o Set the Adver_Timer to Maximum of (1 second,
Advertisement_Interval)
o Set the Adver_2_Timer to Advertisement_Interval
endif
o Broadcast a gratuitous ARP request containing the virtual
router MAC address for each IP address associated with the
virtual router
o Transition to the {Master} state
endif
- If an ADVERTISEMENT is received, then:
If VR_Type is 2, then:
o Set the VR_Mode to 1 (mixed message type VRRP
environment)
endif
If the Priority in the ADVERTISEMENT is Zero, then:
o Set the Master_Down_Timer to Skew_Time
else:
If Preempt_Mode is False, or If the Priority in the
ADVERTISEMENT is greater than or equal to the local
Priority, then:
o Reset the Master_Down_Timer to Master_Down_Interval
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else:
o Discard the ADVERTISEMENT
endif
endif
endif
- If a FAST ADVERTISEMENT is received, then:
If VR_Type is 1, then:
o Set the VR_Mode to 1 (mixed message type VRRP
environment)
endif
If the Priority in the FAST ADVERTISEMENT is Zero,
then:
o Set the Master_Down_Timer to Skew_Time
else:
If Preempt_Mode is False, or If the Priority in the
FAST ADVERTISEMENT is greater than or equal to the
local Priority, then:
o Reset the Master_Down_Timer to Master_Down_Interval
else:
o Discard the FAST ADVERTISEMENT
endif
endif
endif
3.3.3. Master
While in the {Master} state the router functions as the forwarding
router for the IP address(es) associated with the virtual router.
While in this state, a VRRP router MUST do the following:
- MUST respond to ARP requests for the IP address(es) associated
with the virtual router.
- MUST forward packets with a destination link layer MAC address
equal to the virtual router MAC address.
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- MUST NOT accept packets addressed to the IP address(es) associated
with the virtual router if it is not the IP address owner.
- MUST accept packets addressed to the IP address(es) associated
with the virtual router if it is the IP address owner.
- If a Shutdown event is received, then:
o Cancel the Adver_Timer
o Cancel the Adver_2_Timer
If the VR_Mode is 0, then
If the VR_Type is 1, then:
o Send an ADVERTISEMENT with Priority = 0
else
o Send a FAST ADVERTISEMENT with Priority = 0
endif
else
o Send an ADVERTISEMENT with Priority = 0
o Send a FAST ADVERTISEMENT with Priority = 0
endif
- If the Adver_Timer fires, then:
If the VR_Mode is 1
or
if the VR_Type is 1, then:
o Send an ADVERTISEMENT
o Reset the Adver_Timer to Maximum of (1 second,
VR_Adver_Interval)
endif
endif
- If the Adver_2_Timer fires, then:
If the VR_Mode is 1
or
if the VR_Type is 2, then:
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o Send a FAST ADVERTISEMENT
o Reset the Adver_2_Timer to VR_Adver_Interval
endif
endif
- If an ADVERTISEMENT is received, then:
If the VR_Mode is 0
and
If the VR_Type is 2, then
o Set VR_Mode to 1 (heterogeneous VRRP environment)
o Set the Adver_Timer to Maximum of 1 second and
VR_Adver_Interval
endif
If the Priority in the ADVERTISEMENT is Zero, then:
If the VR_Mode is 0, then
If the VR_Type is 1, then:
o Send an ADVERTISEMENT
o Reset the Adver_Timer to Maximum of 1 second and
VR_Adver_Interval
else
o Send a FAST ADVERTISEMENT
o Reset the Adver_2_Timer to VR_Adver_Interval
endif
else
o Send an ADVERTISEMENT
o Send a FAST ADVERTISEMENT
o Reset the Adver_Timer to Maximum of 1 second and
VR_Adver_Interval
o Reset the Adver_2_Timer to VR_Adver_Interval
endif
else:
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If the Priority in the ADVERTISEMENT is greater than the
local Priority,
or
If the Priority in the ADVERTISEMENT is equal to the
local Priority and the primary IP Address of the sender
is greater than the local primary IP Address, then:
o Cancel Adver_Timer
o Cancel Adver_2_Timer
o Set Master_Down_Timer to Master_Down_Interval
o Transition to the {Backup} state
else:
o Discard ADVERTISEMENT
endif
endif
endif
- If a FAST ADVERTISEMENT is received, then:
If the VR_Mode is 0
and
If the VR_Type is 1, then
o Set VR_Mode to 1 (heterogeneous VRRP environment)
o Set the Adver_2_Timer to VR_Adver_Interval
endif
If the Priority in the FAST ADVERTISEMENT is Zero, then:
If the VR_Mode is 0, then
o Send a FAST ADVERTISEMENT
o Reset the Adver_2_Timer to VR_Adver_Interval
else
o Send an ADVERTISEMENT
o Send a FAST ADVERTISEMENT
o Reset the Adver_Timer to Maximum of 1 second and
VR_Adver_Interval
o Reset the Adver_2_Timer to VR_Adver_Interval
endif
else:
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If the Priority in the FAST ADVERTISEMENT is greater
than the local Priority,
or
If the Priority in the FAST ADVERTISEMENT is equal to
the local Priority and the primary IP Address of the
sender is greater than the local primary IP Address, then:
o Cancel Adver_Timer
o Cancel Adver_2_Timer
o Set Master_Down_Timer to Master_Down_Interval
o Transition to the {Backup} state
else:
o Discard FAST ADVERTISEMENT
endif
endif
endif
4. Updates for Sending and Receiving VRRPv4 Packets
This section outlines the changes to Section 7 (Sending and
Receiving VRRP Packets) of the VRRPv4 [RFC 3768] to accommodate
the optional FAST ADVERTISEMENT, Type 2, message.
4.1. Receiving VRRPv4 Packets
Perform the following functions when a VRRP packet is received:
- MUST verify that the IP TTL is 255.
- MUST verify the VRRP version is 2.
- MUST verify that the received packet contains the complete VRRP
packet (including fixed and variable fields) for either Type 1
or Type 2 messages.
- MUST verify the VRRP checksum.
- MUST verify that the VRID is configured on the receiving
interface and the local router is not the IP Address owner
(Priority equals 255 (decimal)).
- For Type 1 (ADVERTISEMENT) messages, MUST verify that the
Auth Type matches the locally configured authentication
method for the virtual router and perform that
authentication method.
If any one of the above checks fails, the receiver MUST discard
the packet, SHOULD log the event and MAY indicate via network
management that an error occurred.
- MAY verify that the message Type matches the locally
configured VRRP Advertisement Type for the virtual router
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(either Type 1 for ADVERTISEMENT or Type 2 for FAST
ADVERTISEMENT).
If the above check fails, the receiver SHOULD log the event
and MAY indicate via network management that a misconfiguration
was detected.
- MAY verify that "Count IP Addrs" and the list of IP Address
matches the IP_Addresses configured for the VRID.
If the above check fails, the receiver SHOULD log the event
and MAY indicate via network management that a misconfiguration
was detected. If the packet was not generated by the address
owner (Priority does not equal 255 (decimal)), the receiver
MUST drop the packet, otherwise continue processing.
- For Type 2 (FAST ADVERTISEMENT) messages, MUST verify that
the Advertisement Count is the same as locally configured
for this virtual router.
- For Type 2 (FAST ADVERTISEMENT) messages, MUST verify that
the Advertisement Interval Granularity is the same as
locally configured for this virtual router.
- MUST verify that the Advertisement Interval in the packet
is the same as locally configured for this virtual router.
If any of the above checks fail, the receiver SHOULD log the
event and MAY indicate via network management that a
misconfiguration was detected.
4.2. Transmitting VRRPv4 Packets
The following operations MUST be performed when transmitting a VRRP
packet.
- Fill in the VRRP packet fields with the appropriate virtual router
configuration state (based on the message Type)
- Compute the VRRP checksum
- Set the source MAC address to Virtual Router MAC Address
- Set the source IP address to interface primary IP address
- Set the IP protocol to VRRP
- Send the VRRP packet to the VRRP IP multicast group
Note: VRRP packets are transmitted with the virtual router MAC
address as the source MAC address to ensure that learning bridges
correctly determine the LAN segment the virtual router is attached
to.
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5. Operational Issues
5.1 Sub-second Timers
The changes proposed to VRRP for IPv4 are intended to provide
additional capabilities to address specific operational requirements,
specifically, sub-second fail over from the Master. The use of
sub-second timers is not recommended for general purpose networking
environments. Missed ADVERTISEMENTS can lead to fail overs. Reducing
the time period for fail over, the MASTER_DOWN_TIMER, increases the
potential for missed ADVERTISEMENTS, due to router processing
requirements, network congestion, or even denial of service attacks.
The new message type provides extensions to VRRPv4 allowing the
specification of sub-second timers. It also provides the ability to
specify the number of advertisement messages that can be missed by
a BACKUP before declaring a MASTER down.
5.2. Interoperability / Backward Compatibility
The addition of the new message type introduces the potential for
routers that do not support the new message type configured on
the same network with routers that use the new message type.
The state machines have been updated to interoperate with routers
only supporting Type 1 Advertisements. When routers configured to
send Type 2 Fast Advertisements discover routers sending Type 1
Advertisements, it sends both types of advertisements. In the
Type 1 Advertisements, the Advertisement Interval is set to the
larger of the interval value from the MASTER or one second (the
minimum setting for Type 1 Advertisements). Type 2 messages will
not support authentication.
6. Security Considerations
This draft does not address the security issues relating to VRRP
that have been identified in RFC 3768.
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7. Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC
documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
8. Acknowledgments
The work presented in this document is based upon the VRRP
specification in RFC3768 and the current work in progress for VRRP
for IPv6. The authors and contributors of these works are R.
Hinden, P. Higginson, R. Hinden, P. Hunt, S. Knight, A. Lindem,
D. Mitzel, M. Shand, D. Weaver, and D. Whipple.
The author of this document would also like to thank Karen
O'Donoghue, Leon Sangroniz, Changming Liu, Sonum Mathur,
Mukesh Gupta, Steve Bates, and Bob Hinden for their
guidance and helpful suggestions.
9. IANA Considerations
This document has no actions for IANA.
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10. Normative References
[RFC3768] Hinden, R., Ed., "Virtual Router Redundancy Protocol
(VRRP)", RFC 3768, April 2004.
11. Informative References
[RFC2338] Knight, S., et. al., "Virtual Router Redundancy Protocol",
RFC2338, April 1998.
[VRRP-IPv6]
Hinden, R., "Virtual Router Redundancy Protocol for IPv6",
draft-ietf-vrrp-ipv6-spec-07 (work in progress),
September 2004.
12. Author's Address
Robert W. Hott
Naval Surface Warfare Center Dahlgren Division
Code B35
17320 Dahlgren Road
Dahlgren, VA 22448-5100
USA
Phone: +1 540 653-1497
EMail: robert.hott@navy.mil
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14. Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
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except as set forth therein, the authors retain all their rights.
draft-ietf-vrrp-ipv4-timers-02.txt [Page 19]
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