| RFC : | rfc9722 |
| Title: | Secure Frame (SFrame): Lightweight Authenticated Encryption for Real-Time Media |
| Date: | May 2025 |
| Status: | PROPOSED STANDARD |
| Updates: | 8584 |
Internet Engineering Task Force (IETF) P. Brissette
Request for Comments: 9722 A. Sajassi
Updates: 8584 LA. Burdet, Ed.
Category: Standards Track Cisco
ISSN: 2070-1721 J. Drake
Independent
J. Rabadan
Nokia
May 2025
Fast Recovery for EVPN Designated Forwarder Election
Abstract
The Ethernet Virtual Private Network (EVPN) solution in RFC 7432
provides Designated Forwarder (DF) election procedures for multihomed
Ethernet Segments. These procedures have been enhanced further by
applying the Highest Random Weight (HRW) algorithm for DF election to
avoid unnecessary DF status changes upon a failure. This document
improves these procedures by providing a fast DF election upon
recovery of the failed link or node associated with the multihomed
Ethernet Segment. This document updates RFC 8584 by optionally
introducing delays between some of the events therein.
The solution is independent of the number of EVPN Instances (EVIs)
associated with that Ethernet Segment, and it is performed via a
simple signaling in BGP between the recovered node and each of the
other nodes in the multihoming group.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9722.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction
1.1. Requirements Language
1.2. Terminology
1.3. Challenges with Existing Mechanism
1.4. Design Principles for a Solution
2. DF Election Synchronization Solution
2.1. BGP Encoding
2.2. Timestamp Verification
2.3. Updates to RFC 8584
3. Synchronization Scenarios
3.1. Concurrent Recoveries
4. Backwards Compatibility
5. Security Considerations
6. IANA Considerations
7. References
7.1. Normative References
7.2. Informative References
Acknowledgements
Contributors
Authors' Addresses
1. Introduction
The Ethernet Virtual Private Network (EVPN) solution [RFC7432] is
widely used in data center (DC) applications for Network
Virtualization Overlay (NVO) and Data Center Interconnect (DCI)
services and in service provider (SP) applications for next-
generation virtual private LAN services.
[RFC7432] describes Designated Forwarder (DF) election procedures for
multihomed Ethernet Segments. These procedures are enhanced further
in [RFC8584] by applying the Highest Random Weight (HRW) algorithm
for DF election in order to avoid unnecessary DF status changes upon
a link or node failure associated with the multihomed Ethernet
Segment.
This document makes further improvements to the DF election
procedures in [RFC8584] by providing an option for a fast DF election
upon recovery of the failed link or node associated with the
multihomed Ethernet Segment. This DF election is achieved
independent of the number of EVPN Instances (EVIs) associated with
that Ethernet Segment, and it is performed via straightforward
signaling in BGP between the recovered node and each of the other
nodes in the multihomed Ethernet Segment redundancy group.
This document updates the DF Election Finite State Machine (FSM)
described in Section 2.1 of [RFC8584] by optionally introducing
delays between some events, as further detailed in Section 2.3. The
solution is based on a simple one-way signaling mechanism.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Terminology
PE: Provider Edge
DF: Designated Forwarder. A PE that is currently forwarding
(encapsulating/decapsulating) traffic for a given VLAN in and out
of a site.
NDF: Non-Designated Forwarder. A PE that is currently blocking
traffic (see DF above).
EVI: EVPN Instance. It spans the PE devices participating in that
EVPN.
HRW: Highest Random Weight algorithm [HRW98]
Service carving: This refers to DF election, as defined in
[RFC7432].
SCT: Service Carving Time. Defined in this document as the time at
which all nodes participating in an Ethernet Segment perform DF
Election.
1.3. Challenges with Existing Mechanism
In EVPN technology, multiple PE devices encapsulate and decapsulate
data belonging to the same VLAN. Under certain conditions, this may
cause duplicated Ethernet packets and potential loops if there is a
momentary overlap in forwarding roles between two or more PE devices,
potentially also leading to broadcast storms of frames forwarded back
into the VLAN.
EVPN [RFC7432] currently specifies timer-based synchronization among
PE devices within an Ethernet Segment redundancy group. This
approach can lead to duplications and potential loops due to multiple
DFs if the timer interval is too short or can lead to packet drops if
the timer interval is too long.
Split-horizon filtering, as described in Section 8.3 of [RFC7432],
can prevent loops but does not address duplicates. However, if there
are overlapping DFs of two different sites simultaneously for the
same VLAN, the site identifier will differ when the packet re-enters
the Ethernet Segment. Consequently, the split-horizon check will
fail, resulting in Layer 2 loops.
The updated DF procedures outlined in [RFC8584] use the well-known
HRW algorithm to prevent the reshuffling of VLANs among PE devices
within the Ethernet Segment redundancy group during failure or
recovery events. This approach minimizes the impact on VLANs not
assigned to the failed or recovered ports and eliminates the
occurrence of loops or duplicates during such events.
However, upon PE insertion or a port being newly added to a
multihomed Ethernet Segment, the HRW cannot help either, as a
transfer of the DF role to the new port must occur while the old DF
is still active.
+---------+
+-------------+ | |
| | | |
/ | PE1 |----| | +-------------+
/ | | | MPLS/ | | |---CE3
/ +-------------+ | VxLAN/ | | PE3 |
CE1 - | Cloud | | |
\ +-------------+ | |---| |
\ | | | | +-------------+
\ | PE2 |----| |
| | | |
+-------------+ | |
+---------+
Figure 1: CE1 Multihomed to PE1 and PE2
In Figure 1, when PE2 is inserted in the Ethernet Segment or its
CE1-facing interface is recovered, PE1 will transfer the DF role of
some VLANs to PE2 to achieve load-balancing. However, because there
is no handshake mechanism between PE1 and PE2, overlapping of DF
roles for a given VLAN is possible, which leads to duplication of
traffic as well as Layer 2 loops.
Current EVPN specifications [RFC7432] and [RFC8584] rely on a timer-
based approach for transferring the DF role to the newly inserted
device. This can cause the following issues:
* Loops and duplicates, if the timer value is too short
* Prolonged traffic loss, if the timer value is too long
1.4. Design Principles for a Solution
The clock-synchronization solution for fast DF recovery presented in
this document follows several design principles and offers multiple
advantages, namely:
* Complex handshake signaling mechanisms and state machines are
avoided in favor of a simple unidirectional signaling approach.
* The fast DF recovery solution maintains backwards compatibility
(see Section 4) by ensuring that PEs reject any unrecognized new
BGP EVPN Extended Community.
* Existing DF Election algorithms remain supported.
* The fast DF recovery solution is independent of any BGP delays in
propagation of Ethernet Segment routes (Route Type 4)
* The fast DF recovery solution is agnostic of the actual time
synchronization mechanism used; however, an NTP-based
representation of time is used for EVPN signaling.
The solution in this document relies on nodes in the topology, more
specifically the peering nodes of each Ethernet-Segment, to be clock-
synchronized and to advertise the Time Synchronization capability.
When this is not the case, or when clocks are badly desynchronized,
network convergence and DF Election is no worse than that described
in [RFC7432] due to the timestamp range checking (Section 2.2).
2. DF Election Synchronization Solution
The fast DF recovery solution relies on the concept of common clock
alignment between partner PEs participating in a common Ethernet
Segment, i.e., PE1 and PE2 in Figure 1. The main idea is to have all
peering PEs of that Ethernet Segment perform DF election and apply
the result at the same previously announced time.
The DF Election procedure, as described in [RFC7432] and as
optionally signaled in [RFC8584], is applied. All PEs attached to a
given Ethernet Segment are clock-synchronized using a networking
protocol for clock synchronization (e.g., NTP, Precision Time
Protocol (PTP)). Whenever possible, recovery activities for failed
PEs SHOULD NOT be initiated until after the underlying clock
synchronization protocol has converged to benefit from this
document's fast DF recovery procedures. When a new PE is inserted in
an Ethernet Segment or when a failed PE of the Ethernet Segment
recovers, that PE communicates to peering partners the current time
plus the value of the timer for partner discovery from step 2 in
Section 8.5 of [RFC7432]. This constitutes an "end time" or
"absolute time" as seen from the local PE. That absolute time is
called the Service Carving Time (SCT).
A new BGP EVPN Extended Community, the Service Carving Time, is
advertised along with the Ethernet Segment Route Type 4 (RT-4) and
communicates the SCT to other partners to ensure an orderly transfer
of forwarding duties.
Upon receipt of the new BGP EVPN Extended Community, partner PEs can
determine the SCT of the newly inserted PE. To eliminate any
potential for duplicate traffic or loops, the concept of "skew" is
introduced: a small time offset to ensure a controlled and orderly
transition when multiple PE devices are involved. The previously
inserted PE(s) must perform service carving first for NDF to DF
transitions. The receiving PEs subtract this skew (default = 10 ms)
to the Service Carving Time and apply NDF to DF transitions first.
This is followed shortly by the NDF to DF transitions on both PEs,
after the skew delay. On the recovering PE, all services are already
in NDF state, and no skew for DF to NDF transitions is required.
This document proposes a default skew value of 10 ms to allow
completion of programming the DF to NDF transitions, but
implementations may make the skew larger (or configurable) taking
into consideration scale, hardware capabilities, and clock accuracy.
To summarize, all peering PEs perform service carving almost
simultaneously at the time announced by the newly added/recovered PE.
The newly inserted PE initiates the SCT and triggers service carving
immediately on its local timer expiry. The previously inserted PE(s)
receiving Ethernet Segment route (RT-4) with an SCT BGP extended
community perform service carving shortly before the SCT for DF to
NDF transitions and at the SCT for NDF to DF transitions.
2.1. BGP Encoding
A BGP extended community, with Type 0x06 and Sub-Type 0x0F, is
defined to communicate the SCT for each Ethernet Segment:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x06 | Sub-Type(0x0F)| Timestamp Seconds ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Timestamp Seconds | Timestamp Fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Service Carving Time
The timestamp exchanged uses the NTP prime epoch of 0 h 1 January
1900 UTC [RFC5905] and an adapted form of the 64-bit NTP timestamp
format.
The 64-bit NTP timestamp format consists of a 32-bit unsigned seconds
field and a 32-bit fraction field, which are encoded in the Service
Carving Time as follows:
Timestamp Seconds: 32-bit NTP seconds are encoded in this field.
Timestamp Fraction: The high-order 16 bits of the NTP "Fraction"
field are encoded in this field.
When rebuilding a 64-bit NTP timestamp format using the values from a
received SCT BGP extended community, the lower-order 16 bits of the
NTP "Fraction" field are set to 0. The use of a 16-bit fractional
seconds value yields adequate precision of 15 microseconds (2^-16 s).
The format of the DF Election Extended Community that is used in this
document is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x06 | Sub-Type(0x06)| RSV | DF Alg | Bitmap ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Bitmap | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: DF Election Extended Community (RFC 8584)
The Bitmap field (2 octets) encodes "capabilities" [RFC8584], where
this document introduces a new Time Synchronization capability
indicated by "T".
1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |A| |T| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Bitmap Field in the DF Election Extended Community
Bit 3: Time Synchronization (corresponds to Bit 27 of the DF
Election Extended Community). When set to 1, it indicates the
desire to use the Time Synchronization capability with the rest of
the PEs in the Ethernet Segment.
This capability is utilized in conjunction with the agreed-upon DF
Election Type. For instance, if all the PE devices in the Ethernet
Segment indicate the desire to use the Time Synchronization
capability and request the DF Election Type to be the HRW, then the
HRW algorithm is used in conjunction with this capability. A PE that
does not support the procedures set out in this document or that
receives a route from another PE in which the capability is not set
MUST NOT delay DF election as this could lead to duplicate traffic in
some instances (overlapping DFs).
2.2. Timestamp Verification
The NTP Era value is not exchanged, and participating PEs may
consider the timestamps to be in the same Era as their local value.
A DF Election operation occurring exactly at the next Era transition
will be some time on February 7, 2036. Implementors and operators
may address credible cases of rollover ambiguity (adjacent Eras n and
n+1) as well as the security issue of unreasonably large or
unreasonably small NTP timestamps in the following manner.
The procedures in this document address implicitly what occurs with
receiving an SCT value in the past. This would be a naturally
occurring event with a large BGP propagation delay: the receiving PE
treats the DF Election at the peer as having already occurred and
proceeds without starting any timer to further delay service carving,
effectively falling back on behavior as specified in [RFC7432]. A PE
that receives an SCT value smaller than its current time MUST discard
the Service Carving Time and SHALL treat the DF Election at the peer
as having occurred already.
The more problematic scenario is the PE in Era n+1 that receives an
SCT advertised by the PE still in Era n, with a very large SCT value.
To address this Era rollover as well as the large values attack
vector, implementations MUST validate the received SCT against an
upper bound.
It is left to implementations to decide what constitutes an
"unreasonably large" SCT value. A recommended approach, however, is
to compare the received offset to the local peering timer value. In
practice, peering timer values are configured uniformly across
Ethernet Segment peers and may be treated as an upper bound on the
offset of received SCT values. A PE that receives an SCT
representing an offset larger than the local peering timer MUST
discard the SCT and SHALL treat the DF Election at the peer as having
already occurred, as above.
2.3. Updates to RFC 8584
This document introduces an additional delay to the events and
transitions defined for the default DF election algorithm FSM in
Section 2.1 of [RFC8584] without changing the FSM state or event
definitions themselves.
Upon receiving an RCVD_ES message, the peering PE's FSM transitions
from the DF_DONE state (indicating the DF election process was
complete) to the DF_CALC state (indicating that a new DF calculation
is needed). Due to the SCT included in the Ethernet Segment update,
the completion of the DF_CALC state and the subsequent transition
back to the DF_DONE state are delayed. This delay ensures proper
synchronization and prevents conflicts. Consequently, the
accompanying forwarding updates to the DF and NDF states are also
deferred.
Item 9 in Section 2.1 of [RFC8584], in the list "Corresponding
actions when transitions are performed or states are entered/exited",
is changed as follows:
| 9. DF_CALC on CALCULATED: Mark the election result for the VLAN
| or VLAN bundle.
|
| 9.1 If no Service Carving Time is present during the RCVD_ES
| event of Action 11, proceed to step 9.4
|
| 9.2 If a Service Carving Time is present during the RCVD_ES
| event of Action 11, wait until the time indicated by the
| SCT minus skew before proceeding to step 9.3.
|
| 9.3 Assume the role of NDF for the local PE concerning the
| VLAN or VLAN bundle. Wait the remaining skew time before
| proceeding to step 9.4.
|
| 9.4 Assume the election result's role (DF or NDF) for the
| local PE concerning the VLAN or VLAN bundle and
| transition to the DF_DONE state.
This revised approach ensures proper timing and synchronization in
the DF election process, avoiding conflicts and ensuring accurate
forwarding updates.
3. Synchronization Scenarios
Consider Figure 1 as an example, where initially PE2 has failed and
PE1 has taken over. This scenario illustrates the problem with the
DF Election mechanism described in Section 8.5 of [RFC7432],
specifically in the context of the timer value configured for all PEs
on the Ethernet Segment.
The following procedure is based on Section 8.5 of [RFC7432] with the
default 3-second timer in step 2.
1. Initial state: PE1 is in a steady-state and PE2 is recovering.
2. Recovery: PE2 recovers at an absolute time of t=99.
3. Advertisement: PE2 advertises RT-4, sent at t=100, to its partner
(PE1).
4. Timer Start: PE2 starts a 3-second timer to allow the reception
of RT-4 from other PE nodes.
5. Immediate carving: PE1 performs service carving immediately upon
RT-4 reception, i.e., t=100 plus some BGP propagation delay.
6. Delayed Carving: PE2 performs service carving at time t=103.
[RFC7432] favors traffic drops over duplicate traffic. With the
above procedure, traffic drops will occur as part of each PE recovery
sequence since PE1 transitions some VLANs to an NDF immediately upon
RT-4 reception. The timer value (default = 3 seconds) directly
affects the duration of the packet drops. A shorter (or zero) timer
may result in duplicate traffic or traffic loops.
The following procedure is based on the SCT approach:
1. Initial state: PE1 is in a steady state, and PE2 is recovering.
2. Recovery: PE2 recovers at an absolute time of t=99.
3. Timer Start: PE2 starts at t=100 a 3-second timer to allow the
reception of RT-4 from other PE nodes.
4. Advertisement: PE2 advertises RT-4, sent at t=100, with a target
SCT value of t=103 to its partner (PE1).
5. Service Carving Timer: PE1 starts the service carving timer, with
the remaining time until t=103.
6. Simultaneous Carving: Both PE1 and PE2 carve at an absolute time
of t=103.
To maintain the preference for minimal loss over duplicate traffic,
PE1 SHOULD carve slightly before PE2 (with skew). The recovering PE2
performs both DF-to-NDF and NDF-to-DF transitions per VLAN at the
timer's expiry. The original PE1, which received the SCT, applies
the following:
* DF-to-NDF Transition(s): at t=SCT minus skew, where both PEs are
NDF for the skew duration.
* NDF-to-DF Transition(s): at t=SCT.
This split behavior ensures a smooth DF role transition with minimal
loss.
The SCT approach mitigates the negative effect of requiring a timer
for discovery of Ethernet Segment (ES) RT-4 from other PE nodes.
Furthermore, the BGP transmission delay (from PE2 to PE1) of the ES
RT-4 becomes a non-issue. The SCT approach shortens the 3-second
timer window to the order of milliseconds.
The peering timer is a configurable value where 3 seconds represents
the default. Configuring a timer value of 0, or so small as to
expire during propagation of the BGP routes, is outside the scope of
this document. In reality, the use of the SCT approach presented in
this document encourages the use of larger peering timer values to
overcome any sort of BGP route propagation delays.
3.1. Concurrent Recoveries
In the eventuality that two or more PEs in a peering Ethernet Segment
group are recovering concurrently or roughly at the same time, each
will advertise a SCT. This SCT value would correspond to what each
recovering PE considers the "end time" for DF Election. A similar
situation arises in sequentially recovering PEs, when a second PE
recovers approximately at the time of the first PE's advertised SCT
expiry and with its own new SCT-2 outside of the initial SCT window.
In the case of multiple concurrent DF elections, each initiated by
one of the recovering PEs, the SCTs must be ordered chronologically.
All PEs SHALL execute only a single DF Election at the service
carving time corresponding to the largest (latest) received timestamp
value. This DF Election will lead peering PEs into a single
coordinated DF Election update.
Example:
1. Initial State: PE1 is in a steady state, with services elected at
PE1.
2. Recovery of PE2: PE2 recovers at time t=100 and advertises RT-4
with a target SCT value of t=103 to its partner (PE1).
3. Timer Initiation by PE2: PE2 starts a 3-second timer to allow the
reception of RT-4 from other PE nodes.
4. Timer Initiation by PE1: PE1 starts the service carving timer,
with the remaining time until t=103.
5. Recovery of PE3: PE3 recovers at time t=102 and advertises RT-4
with a target SCT value of t=105 to its partners (PE1, PE2).
6. Timer Initiation by PE3: PE3 starts a 3-second timer to allow the
reception of RT-4 from other PE nodes.
7. Timer Update by PE2: PE2 cancels the running timer and starts the
service carving timer with the remaining time until t=105.
8. Timer Update by PE1: PE1 updates its service carving timer, with
the remaining time until t=105.
9. Service Carving: PE1, PE2, and PE3 perform service carving at the
absolute time of t=105.
In the eventuality that a PE in an Ethernet Segment group recovers
during the discovery window specified in Section 8.5 of [RFC7432] and
does not support or advertise the T-bit, all PEs in the current
peering sequence SHALL immediately revert to the default behavior
described in [RFC7432].
4. Backwards Compatibility
For the DF election procedures to achieve global convergence and
unanimity within a redundancy group, it is essential that all
participating PEs agree on the DF election algorithm to be employed.
However, it is possible that some PEs may continue to use the
existing modulo-based DF election algorithm from [RFC7432] and not
utilize the new SCT BGP extended community. PEs that operate using
the baseline DF election mechanism will simply discard the new SCT
BGP extended community as unrecognized.
A PE can indicate its willingness to support clock-synchronized
carving by signaling the new "T" DF Election Capability and including
the new SCT BGP extended community along with the Ethernet Segment
Route Type 4. If one or more PEs attached to the Ethernet Segment do
not signal T=1, then all PEs in the Ethernet Segment SHALL revert to
the timer-based approach as specified in [RFC7432]. This reversion
is particularly crucial in preventing VLAN shuffling when more than
two PEs are involved.
In the event a new or extra RT-4 is received without the new "T" DF
Election Capability in the midst of an ongoing DF Election sequence,
all SCT-based delays are canceled, and the DF Election is immediately
applied as specified in [RFC7432], as if no SCT had been previously
exchanged.
5. Security Considerations
The mechanisms in this document use the EVPN control plane as defined
in [RFC7432]. Security considerations described in [RFC7432] are
equally applicable.
For the new SCT Extended Community, attack vectors may be setting the
value to zero, to a value in the past, or to large times in the
future. Handling of this attack vector is addressed in Section 2.2
alongside NTP Era rollover ambiguity.
This document uses MPLS- and IP-based tunnel technologies to support
data plane transport. Security considerations described in [RFC7432]
and [RFC8365] are equally applicable.
6. IANA Considerations
IANA has made the following assignment in the "EVPN Extended
Community Sub-Types" registry set up by [RFC7153].
+================+======================+===========+
| Sub-Type Value | Name | Reference |
+================+======================+===========+
| 0x0F | Service Carving Time | RFC 9722 |
+----------------+----------------------+-----------+
Table 1
IANA has made the following assignment in the "DF Election
Capabilities" registry set up by [RFC8584].
+=====+======================+===========+
| Bit | Name | Reference |
+=====+======================+===========+
| 3 | Time Synchronization | RFC 9722 |
+-----+----------------------+-----------+
Table 2
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>.
[RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
March 2014, <https://www.rfc-editor.org/info/rfc7153>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8365] Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
Uttaro, J., and W. Henderickx, "A Network Virtualization
Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
DOI 10.17487/RFC8365, March 2018,
<https://www.rfc-editor.org/info/rfc8365>.
[RFC8584] Rabadan, J., Ed., Mohanty, S., Ed., Sajassi, A., Drake,
J., Nagaraj, K., and S. Sathappan, "Framework for Ethernet
VPN Designated Forwarder Election Extensibility",
RFC 8584, DOI 10.17487/RFC8584, April 2019,
<https://www.rfc-editor.org/info/rfc8584>.
7.2. Informative References
[HRW98] Thaler, D. and C. Ravishankar, "Using Name-Based Mappings
to Increase Hit Rates", IEEE/ACM Transactions on
Networking, vol. 6, no. 1, February 1998,
<https://www.microsoft.com/en-us/research/wp-
content/uploads/2017/02/HRW98.pdf>.
Acknowledgements
Authors would like to acknowledge helpful comments and contributions
of Satya Mohanty and Bharath Vasudevan. Also thank you to Anoop
Ghanwani and Gunter van de Velde for their thorough review with
valuable comments and corrections.
Contributors
In addition to the authors listed on the front page, the following
coauthors have also contributed substantially to this document:
Gaurav Badoni
Cisco
Email: gbadoni@cisco.com
Dhananjaya Rao
Cisco
Email: dhrao@cisco.com
Authors' Addresses
Patrice Brissette
Cisco
Email: pbrisset@cisco.com
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Luc André Burdet (editor)
Cisco
Email: lburdet@cisco.com
John Drake
Independent
Email: je_drake@yahoo.com
Jorge Rabadan
Nokia
Email: jorge.rabadan@nokia.com
ERRATA