draft-ietf-bess-evpn-df-election-framework-08.txt   draft-ietf-bess-evpn-df-election-framework-09.txt 
skipping to change at page 1, line 14 skipping to change at page 1, line 14
Internet Draft Nokia Internet Draft Nokia
Updates: 7432 S. Mohanty, Ed. Updates: 7432 S. Mohanty, Ed.
Intended status: Standards Track A. Sajassi Intended status: Standards Track A. Sajassi
Cisco Cisco
J. Drake J. Drake
Juniper Juniper
K. Nagaraj K. Nagaraj
S. Sathappan S. Sathappan
Nokia Nokia
Expires: July 22, 2019 January 18, 2019 Expires: July 28, 2019 January 24, 2019
Framework for EVPN Designated Forwarder Election Extensibility Framework for EVPN Designated Forwarder Election Extensibility
draft-ietf-bess-evpn-df-election-framework-08 draft-ietf-bess-evpn-df-election-framework-09
Abstract Abstract
An alternative to the Default Designated Forwarder (DF) selection An alternative to the Default Designated Forwarder (DF) selection
algorithm in Ethernet VPN (EVPN) networks is defined. The DF is the algorithm in Ethernet VPN (EVPN) networks is defined. The DF is the
Provider Edge (PE) router responsible for sending broadcast, unknown Provider Edge (PE) router responsible for sending broadcast, unknown
unicast and multicast (BUM) traffic to multi-homed Customer Equipment unicast and multicast (BUM) traffic to multi-homed Customer Equipment
(CE) on a particular Ethernet Segment (ES) within a VLAN. In (CE) on a particular Ethernet Segment (ES) within a VLAN. In
addition, the capability to influence the DF election result for a addition, the capability to influence the DF election result for a
VLAN based on the state of the associated Attachment Circuit (AC) is VLAN based on the state of the associated Attachment Circuit (AC) is
skipping to change at page 2, line 12 skipping to change at page 2, line 12
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This Internet-Draft will expire on July 22, 2019. This Internet-Draft will expire on July 28, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 11 skipping to change at page 3, line 11
5. The Attachment Circuit Influenced DF Election Capability . . . 21 5. The Attachment Circuit Influenced DF Election Capability . . . 21
5.1. AC-Influenced DF Election Capability For VLAN-Aware 5.1. AC-Influenced DF Election Capability For VLAN-Aware
Bundle Services . . . . . . . . . . . . . . . . . . . . . . 23 Bundle Services . . . . . . . . . . . . . . . . . . . . . . 23
6. Solution Benefits . . . . . . . . . . . . . . . . . . . . . . . 24 6. Solution Benefits . . . . . . . . . . . . . . . . . . . . . . . 24
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 25
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 25 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 25
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.1. Normative References . . . . . . . . . . . . . . . . . . . 26 9.1. Normative References . . . . . . . . . . . . . . . . . . . 26
9.2. Informative References . . . . . . . . . . . . . . . . . . 27 9.2. Informative References . . . . . . . . . . . . . . . . . . 27
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 28 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
The Designated Forwarder (DF) in EVPN networks is the Provider Edge The Designated Forwarder (DF) in EVPN networks is the Provider Edge
(PE) router responsible for sending broadcast, unknown unicast and (PE) router responsible for sending broadcast, unknown unicast and
multicast (BUM) traffic to a multi-homed Customer Equipment (CE) multicast (BUM) traffic to a multi-homed Customer Equipment (CE)
device, on a given VLAN on a particular Ethernet Segment (ES). The DF device, on a given VLAN on a particular Ethernet Segment (ES). The DF
is selected out of a list of candidate PEs that advertise the same is selected out of a list of candidate PEs that advertise the same
skipping to change at page 19, line 11 skipping to change at page 19, line 11
to the same server within a given cluster; consequently it can be to the same server within a given cluster; consequently it can be
used at client sites to achieve global consensus on object-server used at client sites to achieve global consensus on object-server
mappings. When that server goes down, the backup server becomes the mappings. When that server goes down, the backup server becomes the
responsible designate. responsible designate.
Choosing an appropriate hash function that is statistically oblivious Choosing an appropriate hash function that is statistically oblivious
to the key distribution and imparts a good uniform distribution of to the key distribution and imparts a good uniform distribution of
the hash output is an important aspect of the algorithm. Fortunately the hash output is an important aspect of the algorithm. Fortunately
many such hash functions exist. [HRW1999] provides pseudo-random many such hash functions exist. [HRW1999] provides pseudo-random
functions based on the Unix utilities rand and srand and easily functions based on the Unix utilities rand and srand and easily
constructed XOR functions that perform considerably well. This constructed XOR functions that satisfy the desired hashing
imparts very good properties in the load balancing context. Also each properties. HRW already finds use in multicast and ECMP
server independently and unambiguously arrives at the primary server [RFC2991],[RFC2992].
selection. HRW already finds use in multicast and ECMP [RFC2991],
[RFC2992].
4.1. HRW and Consistent Hashing 4.1. HRW and Consistent Hashing
HRW is not the only algorithm that addresses the object to server HRW is not the only algorithm that addresses the object to server
mapping problem with goals of fair load distribution, redundancy and mapping problem with goals of fair load distribution, redundancy and
fast access. There is another family of algorithms that also fast access. There is another family of algorithms that also
addresses this problem; these fall under the umbrella of the addresses this problem; these fall under the umbrella of the
Consistent Hashing Algorithms [CHASH]. These will not be considered Consistent Hashing Algorithms [CHASH]. These will not be considered
here. here.
skipping to change at page 19, line 43 skipping to change at page 19, line 41
Note that while the DF election algorithm in [RFC7432] uses PE Note that while the DF election algorithm in [RFC7432] uses PE
address and vlan as inputs, this document uses Ethernet Tag, PE address and vlan as inputs, this document uses Ethernet Tag, PE
address and ESI as inputs. This is because if the same set of PEs are address and ESI as inputs. This is because if the same set of PEs are
multi-homed to the same set of ESes, then the DF election algorithm multi-homed to the same set of ESes, then the DF election algorithm
used in [RFC7432] would result in the same PE being elected DF for used in [RFC7432] would result in the same PE being elected DF for
the same set of broadcast domains on each ES, which can have adverse the same set of broadcast domains on each ES, which can have adverse
side-effects on both load balancing and redundancy. Including ESI in side-effects on both load balancing and redundancy. Including ESI in
the DF election algorithm introduces additional entropy which the DF election algorithm introduces additional entropy which
significantly reduces the probability of the same PE being elected DF significantly reduces the probability of the same PE being elected DF
for the same set of broadcast domains on each ES. Therefore, the ESI for the same set of broadcast domains on each ES. Therefore, when
value in the Weight function below SHOULD be set to that of using the HRW Algorithm for EVPN DF Election, the ESI value in the
corresponding ES. The ESI value MAY be set to all 0's in the Weight Weight function below SHOULD be set to that of the corresponding ES.
function below if the operator so chooses.
In case of a VLAN Bundle service, v denotes the lowest VLAN similar In case of a VLAN Bundle service, v denotes the lowest VLAN similar
to the 'lowest VLAN in bundle' logic of [RFC7432]. to the 'lowest VLAN in bundle' logic of [RFC7432].
1. DF(v) = Si: Weight(v, Es, Si) >= Weight(v, Es, Sj), for all j. In 1. DF(v) = Si| Weight(v, Es, Si) >= Weight(v, Es, Sj), for all j. In
case of a tie, choose the PE whose IP address is numerically the case of a tie, choose the PE whose IP address is numerically the
least. Note 0 <= i,j < Number of PEs in the redundancy group. least. Note 0 <= i,j < Number of PEs in the redundancy group.
2. BDF(v) = Sk: Weight(v, Es, Si) >= Weight(v, Es, Sk) and Weight(v, 2. BDF(v) = Sk| Weight(v, Es, Si) >= Weight(v, Es, Sk) and Weight(v,
Es, Sk) >= Weight(v, Es, Sj). In case of tie choose the PE whose Es, Sk) >= Weight(v, Es, Sj). In case of tie choose the PE whose
IP address is numerically the least. IP address is numerically the least.
Where: Where:
DF(v): is defined to be the address Si (index i) for which weight(v, DF(v): is defined to be the address Si (index i) for which weight(v,
Es, Si) is the highest, 0 <= i < N-1 Es, Si) is the highest, 0 <= i < N-1
BDF(v) is defined as that PE with address Sk for which the computed BDF(v) is defined as that PE with address Sk for which the computed
weight is the next highest after the weight of the DF. j is the weight is the next highest after the weight of the DF. j is the
skipping to change at page 21, line 51 skipping to change at page 21, line 46
of the IP addresses of all the PE nodes attached to the Ethernet of the IP addresses of all the PE nodes attached to the Ethernet
Segment (including itself), in increasing numeric value. The Segment (including itself), in increasing numeric value. The
candidate list is based on the Originator Router's IP addresses of candidate list is based on the Originator Router's IP addresses of
the ES routes, but excludes any PE from whom no Ethernet A-D per the ES routes, but excludes any PE from whom no Ethernet A-D per
ES route has been received, or from whom the route has been ES route has been received, or from whom the route has been
withdrawn. Afterwards, the DF Election algorithm is applied on a withdrawn. Afterwards, the DF Election algorithm is applied on a
per <ES, Ethernet Tag>, however, the IP address for a PE will not per <ES, Ethernet Tag>, however, the IP address for a PE will not
be considered candidate for a given <ES, Ethernet Tag> until the be considered candidate for a given <ES, Ethernet Tag> until the
corresponding Ethernet A-D per EVI route has been received from corresponding Ethernet A-D per EVI route has been received from
that PE. In other words, the ACS on the ES for a given PE must be that PE. In other words, the ACS on the ES for a given PE must be
UP so that the PE is considered as candidate for a given BD. If UP so that the PE is considered as candidate for a given BD.
the Default DF Alg is used, every PE in the resulting candidate
If the Default DF Alg is used, every PE in the resulting candidate
list is then given an ordinal indicating its position in the list is then given an ordinal indicating its position in the
ordered list, starting with 0 as the ordinal for the PE with the ordered list, starting with 0 as the ordinal for the PE with the
numerically lowest IP address. The ordinals are used to determine numerically lowest IP address. The ordinals are used to determine
which PE node will be the DF for a given Ethernet Tag on the which PE node will be the DF for a given Ethernet Tag on the
Ethernet Segment, using the following rule: Ethernet Segment, using the following rule:
Assuming a redundancy group of N PE nodes, for VLAN-based service, Assuming a redundancy group of N PE nodes, for VLAN-based service,
the PE with ordinal i is the DF for an <ES, Ethernet Tag V> when the PE with ordinal i is the DF for an <ES, Ethernet Tag V> when
(V mod N)= i. In the case of VLAN-(aware) bundle service, then the (V mod N)= i. In the case of VLAN-(aware) bundle service, then the
numerically lowest VLAN value in that bundle on that ES MUST be numerically lowest VLAN value in that bundle on that ES MUST be
 End of changes. 9 change blocks. 
17 lines changed or deleted 15 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/