Internet DRAFT - draft-mohanty-bess-evpn-df-election
draft-mohanty-bess-evpn-df-election
BESS Working Group S. Mohanty
Internet-Draft K. Patel
Intended status: Standards Track A. Sajassi
Expires: April 21, 2016 Cisco Systems, Inc.
J. Drake
Juniper Networks, Inc.
A. Przygienda
Ericsson
October 19, 2015
A new Designated Forwarder Election for the EVPN
draft-mohanty-bess-evpn-df-election-02
Abstract
This document describes an improved EVPN Designated Forwarder
Election (DF) algorithm which can be used to enhance operational
experience in terms of convergence speed and robustness over a WAN
deploying EVPN
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on April 21, 2016.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Finite State Machine . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. The modulus based DF Election Algorithm . . . . . . . . . . . 4
3. Problems with the modulus based DF Election Algorithm . . . . 5
4. Highest Random Weight . . . . . . . . . . . . . . . . . . . . 6
5. HRW and Consistent Hashing . . . . . . . . . . . . . . . . . 7
6. HRW Algorithm for EVPN DF Election . . . . . . . . . . . . . 7
7. Protocol Considerations . . . . . . . . . . . . . . . . . . . 9
7.1. Finite State Machine . . . . . . . . . . . . . . . . . . 10
8. Auto-Derivation of ES-Import Route Target . . . . . . . . . . 12
9. Operational Considerations . . . . . . . . . . . . . . . . . 12
10. Security Considerations . . . . . . . . . . . . . . . . . . . 12
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Ethernet MPLS VPN (EVPN) [RFC7432] is an emerging technology that is
gaining prominence in Internet Service Provider IP/MPLS networks. In
EVPN, mac addresses are disseminated as routes across the
geographical area via the Border Gateway Protocol, BGP [RFC4271]
using the familiar L3VPN model [RFC4364]. An EVPN instance that
spans across PEs is defined as an EVI. Constrained Route
Distribution [RFC4684] can be used in conjunction to selectively
advertise the routes to where they are needed. One of the major
advantages of EVPN over VPLS [RFC4761],[RFC6624] is that it provides
a solution for minimizing flooding of unknown traffic and also
provides all Active mode of operation so that the traffic can truly
be multi-homed. In technologies such as EVPN or VPLS, managing
Broadcast, Unknown Unicast and multicast traffic (BUM) is a key
requirement. In the case where the customer edge (CE) router is
multi-homed to one or more Provider Edge (PE) Routers, it is
necessary that one and only one of the PE routers should forward BUM
traffic into the core or towards the CE as and when appropriate.
Specifically, quoting Section 8.5, [RFC7432], Consider a CE that is a
host or a router that is multi-homed directly to more than one PE in
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an EVPN instance on a given Ethernet segment. One or more Ethernet
Tags may be configured on the Ethernet segment. In this scenario
only one of the PEs, referred to as the Designated Forwarder (DF), is
responsible for certain actions:
a. Sending multicast and broadcast traffic, on a given Ethernet Tag
on a particular Ethernet segment, to the CE.
b. Flooding unknown unicast traffic (i.e. traffic for which an PE
does not know the destination MAC address), on a given Ethernet
Tag on a particular Ethernet segment to the CE, if the
environment requires flooding of unknown unicast traffic.
+---------------+
| IP/MPLS |
| CORE |
+----+ ES1 +----+ +----+
| CE1|-----| |-----------| |____ES2
+----+ | PE1| | PE2| \
| |-------- +----+ \+----+
+----+ | | | CE2|
| | +----+ /+----+
| |__| |____/ |
| | PE3| ES2 /
| +----+ /
| | /
+-------------+----+ /
| PE4|____/ES2
| |
+----+
Figure 1 Multi-homing Network of E-VPN
Figure 1
Figure 1 illustrates a case where there are two Ethernet Segments,
ES1 and ES2. PE1 is attached to CE1 via Ethernet Segment ES1 whereas
PE2, PE3 and PE4 are attached to CE2 via ES2 i.e. PE2, PE3 and PE4
form a redundancy group. Since CE2 is multi-homed to different PEs
on the same Ethernet Segment, it is necessary for PE2, PE3 and PE4 to
agree on a DF to satisfy the above mentioned requirements.
Layer2 devices are particularly susceptible to forwarding loops
because of the broadcast nature of the Ethernet traffic. Therefore
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it is very important that in case of multi-homing, only one of the
links be used to direct traffic to/from the core.
One of the pre-requisites for this support is that participating PEs
must agree amongst themselves as to who would act as the Designated
Forwarder. This needs to be achieved through a distributed algorithm
in which each participating PE independently and unambiguously
selects one of the participating PEs as the DF, and the result should
be unanimously in agreement.
The DF election algorithm as described in [RFC7432] has some
undesirable properties and in some cases can be somewhat disruptive
and unfair. This document describes those issues and proposes a
mechanism for dealing with those issues. These mechanisms do involve
changes to the DF Election algorithm , but do not require any
protocol changes to the EVPN Route exchange and have minimal changes
to their content per se.
1.1. Finite State Machine
Since the specification in EVPN RFC [RFC7432] does leave several
questions open as to the precise final state machine behavior of the
DF election, the document also includes a section describing
precisely the intended behavior. The finite state machine is
presented in Section 7.1
1.2. Requirements Language
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 [RFC2119].
2. The modulus based DF Election Algorithm
The default procedure for DF election at the granularity of (ESI,EVI)
is referred to as "service carving". With service carving, it is
possible to elect multiple DFs per Ethernet Segment (one per EVI) in
order to perform load-balancing of multi-destination traffic destined
to a given Segment. The objective is that the load-balancing
procedures should carve up the EVI space among the redundant PE nodes
evenly, in such a way that every PE is the DF for a disjoint set of
EVIs.
The existing DF algorithm as described in the EVPN RFC(Section 8.5
[RFC7432]) is based on a modulus operation. The PEs to which the ES
(for which DF election is to be carried out per vlan) is multi-homed
from an ordered (ordinal) list in ascending order of the PE ip
address values. Say, there are N PEs, P0, P1, ... PN-1 ranked as per
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increasing IP addresses in the ordinal list; then for each vlan with
ethernet tag v, configured on the ethernet segment ES1, PEx is the DF
for vlan v on ES ES1 when x equals (v mod N). In the case of VLAN
bundle only the lowest VLAN is used. In the case when the vlan
density is high meaning there are significant number of vlans and the
vlan-id or ethernet-tag is uniformly distributed, the thinking is
that the DF election will be spread across the PEs hosting that
ethernet segment and good service carving can be achieved.
3. Problems with the modulus based DF Election Algorithm
There are three fundamental problems with the current DF Election.
First, the algorithm will not perform well when the ethernet tag
follows a non-uniform distribution, for instance when the ethernet
tags are all even or all odd. In such a case let us assume that
the ES is multi-homed to two PEs; all the vlans will only pick one
of the PEs as the DF. This is very sub-optimal. It defeats the
purpose of service carving as the DFs are not really evenly spread
across. In this particular case, in fact one of the PEs does not
get elected all as the DF, so it does not participate in the DF
responsibilities at all. Consider another example where referring
to Figure 1, lets assume that PE2, PE3, PE4 are in ascending order
of the IP address; and each vlan configured on ES2 is associated
with an Ethernet Tag of of the form (3x+1), where x is an integer.
This will result in PE3 always be selected as the DF.
Even in the case when the ethernet tag distribution is uniform the
instance of a PE being up or down results in re-computation ((v
mod N-1) or (v mod N+1) as is the case); The resulting modulus
value need not be uniformly distributed but subject to the
primality of N-1 or N+1 as may be the case.
The third problem is one of disruption. Consider a case when the
same Ethernet Segment is multi homed to a set of PEs. When the ES
is down in one of the PEs, say PE1, or PE1 itself reboots, or the
BGP process goes down or the connectivity between PE1 and an RR
goes down, the effective number of PEs in the system now becomes
N-1 and DFs are computed for all the vlans that are configured on
that ethernet segment. In general, if the DF for a vlan v happens
not to be PE1, but some other PE, say PE2, it is likely that some
other PE will become the new DF. This is not desirable.
Similarly when a new PE hosts the same Ethernet segment, the
mapping again changes because of the mod operation. This results
in needless churn. Again referring to Figure 1, say v1, v2 and v3
are vlans configured on ES2 with associated ethernet tags of value
999, 1000 and 10001 respectively. So PE1, PE2 and PE3 are also
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the DFs for v1, v2 and v3 respectively. Now when PE3 goes down,
PE2 will become the DF for v1 and PE1 will become the DF for v2.
One point to note is that the current DF election algorithm assumes
that all the PEs who are multi-homed to the same Ethernet Segment and
interested in the DF Election by exchanging EVPN routes have a V4
peering with each other or via a Route Reflector. This need not be
the case as there can be a v6 peering and supporting the EVPN
address-family.
Mathematically, a conventional hash function maps a key k to a number
i representing one of m hash buckets through a function h(k) i.e.
i=h(k). In the EVPN case, h is simply a modulo-m hash function viz.
h(v) = v mod N, where N is the number of PEs that are multi-homed to
the Ethernet Segment in discussion. It is well-known that for good
hash distribution using the modulus operation, the modulus N should
be a prime-number not too close to a power of 2 [CLRS2009]. When the
effective number of PEs changes from N to N-1 (or vice versa); all
the objects (vlan v) will be remapped except those for which v mod N
and v mod (N-1) refer to the same PE in the previous and subsequent
ordinal rankings respectively.
From a forwarding perspective, this is a churn, as it results in
programming the CE and PE side ports as blocking or non-blocking at
potentially all PEs when the DF changes either because (i) a new PE
is added or (ii) another one goes down or loses connectivity or else
cannot take part in the DF election process for whatever reason.
This draft addresses this problem and furnishes a solution to this
undesirable behavior.
4. Highest Random Weight
Highest Random Weight (HRW) as defined in [HRW1999] is originally
proposed in the context of Internet Caching and proxy Server load
balancing. Given an object name and a set of servers, HRW maps a
request to a server using the object-name (object-id) and server-name
(server-id) rather than the state of the server states. HRW forms a
hash out of the server-id and the object-id and forms an ordered list
of the servers for the particular object-id. The server for which
the hash value is highest, serves as the primary responsible for that
particular object, and the server with the next highest value in that
hash serves as the backup server. HRW always maps a given object
object name to the same server within a given cluster; consequently
it can be used at client sites to achieve global consensus on object-
server mappings. When that server goes down, the backup server
becomes the responsible designate.
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Choosing an appropriate hash function that is statistically oblivious
to the key distribution and imparts a good uniform distribution of
the hash output is an important aspect of the algorithm,. Fortunately
many such hash functions exist. [HRW1999] provides pseudorandom
functions based on Unix utilities rand and srand and easily
constructed XOR functions that perform considerably well. This
imparts very good properties in the load balancing context. Also
each server independently and unambiguously arrives at the primary
server selection. HRW already finds use in multicast and ECMP
[RFC2991],[RFC2992].
In the existing DF algorithm Section 2, whenever a new PE comes up or
an existing PE goes down, there is a significant interval before the
change is noticed by all peer PEs as it has to be conveyed by the BGP
update message involving the type-4 route. There is a timer to batch
all the messages before triggering the service carving procedures.
When the timer expires, each PE will build the ordered list and
follow the procedures for DF Election. In the proposed method which
we will describe shortly this "jittered" behavior is retained.
5. HRW and Consistent Hashing
HRW is not the only algorithm that addresses the object to server
mapping problem with goals of fair load distribution, redundancy and
fast access. There is another family of algorithms that also
addresses this problem; these fall under the umbrella of the
Consistent Hashing Algorithms [CHASH]. These will not be considered
here.
6. HRW Algorithm for EVPN DF Election
The applicability of HRW to DF Election can be described here. Let
DF(v) denote the Designated Forwarder and BDF(v) the Backup
Designated forwarder for the ethernet tag V, where v is the vlan, Si
is the IP address of server i and weight is a pseudorandom function
of v and Si. In case of a vlan bundle service, v denotes the lowest
vlan similar to the 'lowest vlan in bundle' logic of [RFC7432].
1. DF(v) = Si: Weight(v, Si) >= Weight(V, Sj) , for all j. In case
of a tie, choose the PE whose IP address is numerically the
least.
2. BDF(v) = Sk: Weight(v, Si) >= Weight(V, Sk) and Weight(v, Sk) >=
Weight(v, Sj). in case of tie choose the PE whose IP address is
numerically the least.
Since the Weight is a Pseudorandom function with domain as a
concatenation of (v, S), it is an efficient deterministic algorithm
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which is independent of the Ethernet Tag V sample space distribution.
Choosing a good hash function for the pseudorandom function is an
important consideration for this algorithm to perform provably better
than the existing algorithm. As mentioned previously, such functions
are described in the HRW paper. We take as candidate hash functions
two of the ones that are preferred in [HRW1999].
1. Wrand(v, Si) = (1103515245((1103515245.Si+12345)XOR
D(v))+12345)(mod 2^31) and
2. Wrand2(v, Si) = (1103515245((1103515245.D(v)+12345)XOR
Si)+12345)(mod 2^31)
Here D(v) is the 31-bit digest of the ethernet-tag v and Si is
address of the ith server. The server's IP address length does not
matter as only the low-order 31 bits are modulo significant.
Eventually we plan to choose one of the two candidate hash functions
as the preferred one.
A point to note is that the the domain of the Weight function is a
concatenation of the ethernet-tag and the PE IP-address, and the
actual length of the server IP address (whether V4 or V6) is not
really relevant, so long as the actual hash algorithm takes into
consideration the concatenated string. The existing algorithm in
[RFC7432] as is cannot employ both V4 and V6 neighbor peering
address.
HRW solves the disadvantage pointed out in Section 3 and ensures
o with very high probability that the task of DF election for
respective vlans is more or less equally distributed among the PEs
even for the 2 PE case
o If a PE, hosting some vlans on given ES, but is neither the DF nor
the BDF for that vlan, goes down or its connection to the ES goes
down, it does not result in a DF and BDF reassignment the other
PEs. This saves computation, especially in the case when the
connection flaps.
o More importantly it avoids the needless disruption case (c) that
are inherent in the existing modulus based algorithm
o In addition to the DF, the algorithm also furnishes the BDF, which
would be the DF if the current DF fails.
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7. Protocol Considerations
Note that for the DF election procedures to be globally convergent
and unanimous, it is necessary that all the participating PEs agree
on the DF Election algorithm to be used. It is not possible that
some PEs continue to use the existing modulus based DF election and
some newer PEs use the HRW. For brownfield deployments and for
interoperability with legacy boxes, its is important that all PEs
need to have the capability to fall back on the modulus algorithm. A
PE (one with a newer version of the software) can indicate its
willingness to support HRW by signaling a new extended community
along with the Ethernet-Segment Route (Type-4). This extended
community is explained in the next paragraph. When a PE receives the
Ethernet-Segment Routes from all the other PEs for the ethernet
segment in question, it checks to see if all the advertisements have
the extended community attached; in the case that they do, this
particular PE, and by induction all the other PEs proceed to do DF
Election as per the HRW Algorithm. Otherwise if even a single
advertisement for the type-4 route is not received with the extended
community or the received DF types (including locally configured
type) do not ALL match a single value, the default modulus algorithm
is used as before. Also, the HRW algorithm needs to be executed
after the "batching" time.
A new BGP extended community attribute [RFC4360] needs to be defined
to identify the DF election procedure to be used for the Ethernet
Segment. We propose to name this extended community as the DF
Election Extended Community. It is a new transitive extended
community where the Type field is 0x06, and the Sub-Type is to be
defined. It may be advertised along with Ethernet Segment routes.
Each DF Election Extended Community is encoded as a 8-octet value as
follows:
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(TBD) | DF Type(One Octet) |Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
The DF Type state is encoded as one octet. A value of 0 means that
the default (the mod based) DF election procedures are used and a
value of 1 means that the HRW algorithm will be employed. A request
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needs to registered with the IETF authority for the subtype
[I-D.ietf-idr-extcomm-iana]
7.1. Finite State Machine
Per [RFC7432], the FSM described in Figure 3 is executed per ESI/VLAN
in case of VLAN aware service or ESI/[VLANs in VLAN Bundle] in case
of VLAN Bundle on each participating PE.
Observe that currently the VLANs are derived from local configuration
and the FSM does not provide any protection against misconfiguration
where same EVI,ESI combination has different set of VLANs on
different participating PEs or one of the PEs elects to consider
VLANs as VLAN bundle and another as separate VLANs for election
purposes (service type mismatch).
The FSM is normative in the sense that any design or implementation
MUST behave towards external peers and as observable external
behavior (DF) in a manner equivalent to this FSM.
LOST_ES
RCVD_ES RCVD_ES
LOST_ES +----+
+----+ | v
| | ++----++ RCVD_ES
| +-+----+ ES_UP | DF +<--------+
+->+ INIT +---------------> WAIT | |
++-----+ +----+-+ |
^ | |
+-----------+ | |DF_TIMER |
| ANY STATE +-------+ VLAN_CHANGE | |
+-----------+ ES_DOWN +-----------------+ | ^
| LOST_ES v v |
+-----++ ++---+-+ |
| DF | | DF +---------+
| DONE +<--------------+ CALC +v-+ |
+-+----+ CALCULATED +----+-+ | |
| | | |
| +----+ |
| LOST_ES |
| VLAN_CHANGE |
| |
+-------------------------------------+
Figure 3
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States:
1. INIT: Initial State
2. DF WAIT: State in which the participants waits for enough
information to perform the DF election for the EVI/ESI/VLAN
combination.
3. DF CALC: State in which the new DF is recomputed.
4. DF DONE: State in which the according DF for the EVI/ESI/VLAN
combination has been elected.
Events:
1. ES_UP: The ESI has been locally configured as 'up'.
2. ES_DOWN: The ESI has been locally configured as 'down'.
3. VLAN_CHANGE: The VLANs configured in a bundle that uses the ESI
changed. This event is necessary for VLAN bundles only.
4. DF_TIMER: DF Wait timer has expired.
5. RCVD_ES: A new or changed Ethernet Segment Route is received in a
BGP REACH UPDATE. Receiving an unchanged UPDATE MUST NOT trigger
this event.
6. LOST_ES: A BGP UNREACH UPDATE for a previously received Ethernet
Segment route has been received. If an UNREACH is seen for a
route that has not been advertised previously, the event MUST NOT
be triggered.
7. CALCULATED: DF has been succesfully calculated.
According actions when transitions are performed or states entered/
exited:
1. ANY STATE on ES_DOWN: (i)stop DF timer (ii) assume non-DF for
local PE
2. INIT on ES_UP: (i)do nothing
3. INIT on RCVD_ES, LOST_ES: (i)do nothing
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4. DF_WAIT on entering the state: (i) start DF timer if not started
already or expired (ii) assume non-DF for local PE
5. DF_WAIT on RCVD_ES, LOST_ES: do nothing
6. DF_WAIT on DF_TIMER: do nothing
7. DF_CALC on entering or re-entering the state: (i) rebuild
according list and hashes and perform election (ii) FSM
generates CALCULATED event against itself
8. DF_CALC on LOST_ES or VLAN_CHANGE: do nothing
9. DF_CALC on RCVD_ES: do nothing
10. DF_CALC on CALCULATED: (i) mark election result for VLAN or
bundle
11. DF_DONE on exiting the state: (i)if RFC7432 election or new
election and lost primary DF then assume non-DF for local PE for
VLAN or VLAN bundle.
12. DF_DONE on VLAN_CHANGE or LOST_ES: do nothing
8. Auto-Derivation of ES-Import Route Target
Section 7.6 of RFC7432 describes how the value of the ES-Import Route
Target for ESI types 1, 2, and 3 can be auto-derived by using the
high-order six bytes of the nine byte ESI value. This document
extends the same auto-derivation procedure to ESI types 0, 4, and 5.
9. Operational Considerations
TBD.
10. Security Considerations
This document raises no new security issues for EVPN.
11. Acknowledgements
The authors would like to thank Tamas Mondal, Sami Boutros, Jakob
Heitz, Jorge Rabadan and Patrice Brissette for useful feedback and
discussions.
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12. References
12.1. Normative References
[HRW1999] Thaler, D. and C. Ravishankar, "Using Name-Based Mappings
to Increase Hit Rates", IEEE/ACM Transactions in
networking Volume 6 Issue 1, February 1998.
[I-D.ietf-idr-extcomm-iana]
Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", draft-ietf-idr-extcomm-iana-02
(work in progress), December 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
<http://www.rfc-editor.org/info/rfc4761>.
[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, <http://www.rfc-editor.org/info/rfc7432>.
12.2. Informative References
[CHASH] Karger, D., Lehman, E., Leighton, T., Panigrahy, R.,
Levine, M., and D. Lewin, "Consistent Hashing and Random
Trees: Distributed Caching Protocols for Relieving Hot
Spots on the World Wide Web", ACM Symposium on Theory of
Computing ACM Press New York, May 1997.
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[CLRS2009]
Cormen, T., Leiserson, C., Rivest, R., and C. Stein,
"Introduction to Algorithms (3rd ed.)", MIT Press and
McGraw-Hill ISBN 0-262-03384-4., February 2009.
[RFC2991] Thaler, D. and C. Hopps, "Multipath Issues in Unicast and
Multicast Next-Hop Selection", RFC 2991,
DOI 10.17487/RFC2991, November 2000,
<http://www.rfc-editor.org/info/rfc2991>.
[RFC2992] Hopps, C., "Analysis of an Equal-Cost Multi-Path
Algorithm", RFC 2992, DOI 10.17487/RFC2992, November 2000,
<http://www.rfc-editor.org/info/rfc2992>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <http://www.rfc-editor.org/info/rfc4364>.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route
Distribution for Border Gateway Protocol/MultiProtocol
Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684,
November 2006, <http://www.rfc-editor.org/info/rfc4684>.
[RFC6624] Kompella, K., Kothari, B., and R. Cherukuri, "Layer 2
Virtual Private Networks Using BGP for Auto-Discovery and
Signaling", RFC 6624, DOI 10.17487/RFC6624, May 2012,
<http://www.rfc-editor.org/info/rfc6624>.
Authors' Addresses
Satya Ranjan Mohanty
Cisco Systems, Inc.
225 West Tasman Drive
San Jose, CA 95134
USA
Email: satyamoh@cisco.com
Keyur Patel
Cisco Systems, Inc.
225 West Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
Mohanty, et al. Expires April 21, 2016 [Page 14]
Internet-Draft An Improved EVPN DF Election Algorithm October 2015
Ali Sajassi
Cisco Systems, Inc.
225 West Tasman Drive
San Jose, CA 95134
USA
Email: sajassi@cisco.com
John Drake
Juniper Networks, Inc.
1194 N. Mathilda Drive
Sunnyvale, CA 95134
USA
Email: jdrake@juniper.com
Antoni Przygienda
Ericsson
300 Holger Way
San Jose, CA 95134
USA
Email: antoni.przygienda@ericsson.com
Mohanty, et al. Expires April 21, 2016 [Page 15]
