draft-ietf-bess-evpn-pref-df-00.txt   draft-ietf-bess-evpn-pref-df-01.txt 
BESS Workgroup J. Rabadan, Ed. BESS Workgroup J. Rabadan, Ed.
Internet Draft S. Sathappan Internet Draft S. Sathappan
Intended status: Standards Track Nokia Intended status: Standards Track Nokia
S. Boutros T. Przygienda S. Boutros T. Przygienda
VMware W. Lin Individual W. Lin
J. Drake J. Drake
Juniper Networks Juniper Networks
A. Sajassi A. Sajassi
S. Mohanty S. Mohanty
Cisco Systems Cisco Systems
Expires: December 23, 2017 June 21, 2017 Expires: October 11, 2018 April 9, 2018
Preference-based EVPN DF Election Preference-based EVPN DF Election
draft-ietf-bess-evpn-pref-df-00 draft-ietf-bess-evpn-pref-df-01
Abstract Abstract
RFC7432 defines the Designated Forwarder (DF) in (PBB-)EVPN networks RFC7432 defines the Designated Forwarder (DF) in (PBB-)EVPN networks
as the PE responsible for sending broadcast, multicast and unknown as the PE responsible for sending broadcast, multicast and unknown
unicast traffic (BUM) to a multi-homed device/network in the case of unicast traffic (BUM) to a multi-homed device/network in the case of
an all-active multi-homing ES, or BUM and unicast in the case of an all-active multi-homing ES, or BUM and unicast in the case of
single-active multi-homing. single-active multi-homing.
The DF is selected out of a candidate list of PEs that advertise the The DF is selected out of a candidate list of PEs that advertise the
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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 December 23, 2017. This Internet-Draft will expire on October 11, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Table of Contents Table of Contents
1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . . 3 1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . . 3
2. Solution requirements . . . . . . . . . . . . . . . . . . . . . 3 2. Solution requirements . . . . . . . . . . . . . . . . . . . . . 3
3. EVPN BGP Attributes for Deterministic DF Election . . . . . . . 4 3. EVPN BGP Attributes for Deterministic DF Election . . . . . . . 4
4. Solution description . . . . . . . . . . . . . . . . . . . . . 5 4. Solution description . . . . . . . . . . . . . . . . . . . . . 5
4.1 Use of the Preference algorithm . . . . . . . . . . . . . . 5 4.1 Use of the Preference algorithm . . . . . . . . . . . . . . 5
4.2 Use of the Preference algorithm in RFC7432 4.2 Use of the Preference algorithm in RFC7432
Ethernet-Segments . . . . . . . . . . . . . . . . . . . . . 7 Ethernet-Segments . . . . . . . . . . . . . . . . . . . . . 7
4.3 The Non-Revertive option . . . . . . . . . . . . . . . . . . 7 4.3 The Non-Revertive option . . . . . . . . . . . . . . . . . . 8
5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 10
11. Conventions used in this document . . . . . . . . . . . . . . 10 11. Conventions used in this document . . . . . . . . . . . . . . 10
12. Security Considerations . . . . . . . . . . . . . . . . . . . 11 12. Security Considerations . . . . . . . . . . . . . . . . . . . 11
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
15.1 Normative References . . . . . . . . . . . . . . . . . . . 11 15.1 Normative References . . . . . . . . . . . . . . . . . . . 11
15.2 Informative References . . . . . . . . . . . . . . . . . . 11 15.2 Informative References . . . . . . . . . . . . . . . . . . 11
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
17. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11 17. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11
17. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 11 17. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
1. Problem Statement 1. Problem Statement
RFC7432 defines the Designated Forwarder (DF) in (PBB-)EVPN networks RFC7432 defines the Designated Forwarder (DF) in (PBB-)EVPN networks
as the PE responsible for sending broadcast, multicast and unknown as the PE responsible for sending broadcast, multicast and unknown
unicast traffic (BUM) to a multi-homed device/network in the case of unicast traffic (BUM) to a multi-homed device/network in the case of
an all-active multi-homing ES or BUM and unicast traffic to a multi- an all-active multi-homing ES or BUM and unicast traffic to a multi-
homed device or network in case of single-active multi-homing. homed device or network in case of single-active multi-homing.
The DF is selected out of a candidate list of PEs that advertise the The DF is selected out of a candidate list of PEs that advertise the
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even if the former DF PE comes back up after a failure. This is even if the former DF PE comes back up after a failure. This is
also known as "non-revertive" behavior, as opposed to the RFC7432 also known as "non-revertive" behavior, as opposed to the RFC7432
DF election procedures that are always revertive. DF election procedures that are always revertive.
e) The solution MUST work for single-active and all-active multi- e) The solution MUST work for single-active and all-active multi-
homing Ethernet Segments. homing Ethernet Segments.
3. EVPN BGP Attributes for Deterministic DF Election 3. EVPN BGP Attributes for Deterministic DF Election
This solution reuses and extends the DF Election Extended Community This solution reuses and extends the DF Election Extended Community
defined in [EVPN-HRW-DF] that is advertised along with the ES route: defined in [DF] that is advertised along with the ES route:
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 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 |DP| Reserved=0 | | Type=0x06 | Sub-Type(0x06)| DF Type |DP| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved = 0 | DF Preference (2 octets) | | Reserved = 0 | DF Preference (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where the following fields are re-defined as follows: Where the following fields are re-defined as follows:
o DF Type can have the following values: o DF Type can have the following values:
- Type 0 - Default, mod based DF election as per RFC7432. - Type 0 - Default, mod based DF election as per RFC7432.
- Type 1 - HRW algorithm as per [EVPN-HRW-DF] - Type 1 - HRW algorithm as per [DF]
- Type 2 - Preference algorithm (this document) - Type 2 - Preference algorithm (this document)
o DP or 'Don't Preempt' bit, determines if the PE advertising the ES o DP or 'Don't Preempt' bit, determines if the PE advertising the ES
route requests the remote PEs in the ES not to preempt it as DF. route requests the remote PEs in the ES not to preempt it as DF.
The default value is DP=0, which is compatible with the current The default value is DP=0, which is compatible with the current
'preempt' or 'revertive' behavior in RFC7432. The DP bit SHOULD be 'preempt' or 'revertive' behavior in RFC7432. The DP bit SHOULD be
ignored if the DF Type is different than 2. ignored if the DF Type is different than 2.
o DF Preference defines a 2-octet value that indicates the PE o DF Preference defines a 2-octet value that indicates the PE
preference to become the DF in the ES. The allowed values are preference to become the DF in the ES. The allowed values are
within the range 0-65535, and default value MUST be 32767. This within the range 0-65535, and default value MUST be 32767. This
value is the midpoint in the allowed Preference range of values, value is the midpoint in the allowed Preference range of values,
which gives the operator the flexibility of choosing a significant which gives the operator the flexibility of choosing a significant
number of values, above or below the default Preference. number of values, above or below the default Preference. The DF
Preference field is specific to DF Type 2 and does not represent
any Preference value for other Types.
4. Solution description 4. Solution description
Figure 1 illustrates an example that will be used in the description Figure 1 illustrates an example that will be used in the description
of the solution. of the solution.
EVPN network EVPN network
+-------------------+ +-------------------+
| +-------+ ENNI Aggregation | +-------+ ENNI Aggregation
| <---ESI1,500 | PE1 | /\ +----Network---+ | <---ESI1,500 | PE1 | /\ +----Network---+
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o Assuming ES3 is defined in PE1 and PE2, PE1 may be configured as o Assuming ES3 is defined in PE1 and PE2, PE1 may be configured as
[500,0,Preference] for ES3 and PE2 as [100,0,Preference]. [500,0,Preference] for ES3 and PE2 as [100,0,Preference].
o In addition, assuming vlan-based service interfaces, the PEs will o In addition, assuming vlan-based service interfaces, the PEs will
be configured with (vlan/ISID-range,high_or_low), e.g. (1- be configured with (vlan/ISID-range,high_or_low), e.g. (1-
2000,high) and (2001-4000, low). 2000,high) and (2001-4000, low).
o This will result in PE1 being DF for EVI/ISIDs 1-2000 and PE2 being o This will result in PE1 being DF for EVI/ISIDs 1-2000 and PE2 being
DF for EVI/ISIDs 2001-4000. DF for EVI/ISIDs 2001-4000.
For Ethernet Segments attached to three or more PEs, any other logic
that provides a fair distribution of the DF function among the PEs is
valid, as long as that logic is consistent in all the PEs in the ES.
4.3 The Non-Revertive option 4.3 The Non-Revertive option
As discussed in section 2(d), an option to NOT preempt the existing As discussed in section 2(d), an option to NOT preempt the existing
DF for a given EVI/ISID is required and therefore added to the DF DF for a given EVI/ISID is required and therefore added to the DF
Election extended community. This option will allow a non-revertive Election extended community. This option will allow a non-revertive
behavior in the DF election. behavior in the DF election.
Note that, when a given PE in an ES is taken down for maintenance Note that, when a given PE in an ES is taken down for maintenance
operations, before bringing it back, the Preference may be changed in operations, before bringing it back, the Preference may be changed in
order to provide a non-revertive behavior. The DP bit and the order to provide a non-revertive behavior. The DP bit and the
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listed above. This convention aids reviewers in quickly identifying listed above. This convention aids reviewers in quickly identifying
or finding the explicit compliance requirements of this RFC. or finding the explicit compliance requirements of this RFC.
12. Security Considerations 12. Security Considerations
This section will be added in future versions. This section will be added in future versions.
13. IANA Considerations 13. IANA Considerations
This document solicits the allocation of DF type = 2 in the registry This document solicits the allocation of DF type = 2 in the registry
created by [EVPN-HRW-DF] for the DF type field. created by [DF] for the DF type field, and the DP bit in the [DF]
Bitmap registry.
15. References 15. References
15.1 Normative References 15.1 Normative References
[RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet
VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc- VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015,
editor.org/info/rfc7432>. <https://www.rfc-editor.org/info/rfc7432>.
[DF] Rabadan J., Mohanty S. et al. "Framework for EVPN Designated
Forwarder Election Extensibility", draft-ietf-bess-evpn-df-election-
framework-00, work-in-progress, March 5, 2018.
15.2 Informative References 15.2 Informative References
[vES] Sajassi et al. "EVPN Virtual Ethernet Segment", draft-sajassi- [vES] Sajassi et al. "EVPN Virtual Ethernet Segment", draft-sajassi-
bess-evpn-virtual-eth-segment-01, work-in-progress, July 6, 2015. bess-evpn-virtual-eth-segment-03, work-in-progress, August 26, 2018.
[EVPN-HRW-DF] Mohanty S. et al. "A new Designated Forwarder Election
for the EVPN", draft-mohanty-bess-evpn-df-election-02, work-in-
progress, October 19, 2015.
16. Acknowledgments 16. Acknowledgments
The authors would like to thank Kishore Tiruveedhula for his review The authors would like to thank Kishore Tiruveedhula for his review
and comments. and comments.
17. Contributors 17. Contributors
In addition to the authors listed, the following individuals also In addition to the authors listed, the following individuals also
contributed to this document: contributed to this document:
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Ali Sajassi Ali Sajassi
Cisco Systems, Inc. Cisco Systems, Inc.
Email: sajassi@cisco.com Email: sajassi@cisco.com
Satya Ranjan Mohanty Satya Ranjan Mohanty
Cisco Systems, Inc. Cisco Systems, Inc.
Email: satyamoh@cisco.com Email: satyamoh@cisco.com
Sami Boutros Sami Boutros
VMware, Inc. Email: boutros.sami@gmail.com
Email: sboutros@vmware.com
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