bess Z. Zhang
Internet-Draft Juniper Networks
Intended status: Standards Track R. Parekh
Expires: May 7, 2020 Cisco Systems
Z. Zhang
ZTE
Bidgoli
Nokia
November 4, 2019
MVPN and EVPN BUM Signaling with Controllers
draft-zzhang-mvpn-evpn-controller-00
Abstract
This document specifies optional procedures for BGP-MVPN and EVPN BUM
signaling with controllers. When P2MP tunnels used for BGP-MVPN and
EVPN BUM are to be signaled from controllers, the controllers can
learn tunnel information (identifier, root, leaf) by participating
BGP-MVPN and EVPN BUM signaling, instead of relying on ingress PEs to
collect the information and then pass to the controllers.
Additionally, Inclusive/Selective PMSI Auto Discovery Routes can be
originated from controllers based on central provisioning, instead of
from PEs based on local provisioning.
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.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on May 7, 2020.
Copyright Notice
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Table of Contents
1. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Controller Address Extended Community . . . . . . . . . . 4
3.2. Targeting Leaf A-D Routes to Controllers . . . . . . . . 4
3.3. Controller Originated I/S-PMSI Routes . . . . . . . . . . 5
3.3.1. Inter-AS/Region Segmentation . . . . . . . . . . . . 5
3.4. Automatic DCB Label Allocation by Controllers . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Terminologies
Familiarity with MVPN/EVPN protocols and procedures is assumed. Some
terminologies are listed below for convenience.
o PMSI: P-Multicast Service Interface - a conceptual interface for a
PE to send customer multicast traffic to all or some PEs in the
same VPN/BD.
o I-PMSI: Inclusive PMSI - to all PEs in the same VPN/BD.
o S-PMSI: Selective PMSI - to some of the PEs in the same VPN/BD.
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o Leaf A-D routes: For explicit leaf tracking purpose. Triggered by
S-PMSI A-D routes and targeted at triggering route's originator.
o IMET A-D route: Inclusive Multicast Ethernet Tag A-D route. The
EVPN equivalent of MVPN Intra-AS I-PMSI A-D route.
As pointed out above, the EVPN IMET route is the equivalent of MVPN
I-PMSI A-D route. In the rest of the document, unless explicitly
stated, I-PMSI A-D route refers to MVPN Intra-AS I-PMSI A-D route
and/or EVPN IMET route.
2. Introduction
Consider a provider network with BGP-MVPN/EVPN where controllers are
used to set up P2MP tunnels per [draft-zzhang-bess-bgp-multicast-
controller] or [draft-voyer-pim-sr-p2mp-policy]. For a controller to
calculate the corresponding trees and set up the tunnels, it needs to
learn the (ID, root, leaf) information for those trees. Currently,
[draft-parekh-bess-mvpn-sr-p2mp] specifies that an ingress PE assigns
the SR P2MP ID and collects leaf information via Leaf A-D routes, and
then pass onto the controller. Observing that BGP-MVPN/EVPN
signaling typically involves Router Reflectors, which may typically
be hosted on or co-located with controllers, it makes sense to have
the controllers participating BGP-MVPN/EVPN signaling to learn (ID,
root, leaf) information. This will relieve the PEs from maintaining
Leaf A-D routes, and remove the extra hop of leaf information
propagation.
Also Consider that in the same network many selective tunnels are
used, and their usages are dynamically provisioned based on specific
needs at different time. For example, the provider provides video
transmission services for events at various time, location and to
various receivers. With traditional methods the provider would
provision the PEs at the transmission sources with various selective
tunnels, which triggers corresponding S-PMSI A-D routes. The
provisioning is put in place shortly before an event takes place and
removed shortly after the event ends. Alternatively and preferrably,
a controller can originate S-PMSI A-D routes based on centralized
provisioning on behalf of the source PEs. The controller also
collects the leaf information (either based on centralized
provisioning or based on Leaf A-D routes), calculates the tree and
signal tree nodes. Additionally, when tunnel aggregation labels are
allocated from Domain-wide Common Block (DCB), originating I/S-PMSI
A-D routes from controllers makes the DCB label allocation a lot
easier.
It is possible that an operator prefers automatic DCB aggregation
label allocation by the controller but prefers I/S-PMSI A-D routes
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origination from individual PEs. In that case, a PE can target an I/
S-PMSI A-D route at the controller and the controller will allocate a
DCB label and return it in a corresponding Leaf A-D route.
3. Specification
The procedures specified in this section applies if one or more
controllers participate MVPN/EVPN signaling for the purpose of leaf
discovery for P2MP tree calculation, and/or if controllers are to
originate I/S-PMSI A-D routes or BGP-MVPN and/or BGP-EVPN BUM.
3.1. Controller Address Extended Community
This document defines a new Transitive IPv4-Address-Specific Extended
Community Sub-Type: "Controller Address". This document also defines
a new BGP Transitive IPv6-Address-Specific Extended Community Sub-
Type: "Controller Address".
A Controller Address Extended Community (referred to as Controller
EC) is constructed by setting the Global Administrator field to the
IP address of the controller and the Local Administrator field to 0.
3.2. Targeting Leaf A-D Routes to Controllers
When a PE originates an I/S-PMSI A-D route with PTA's tunnel type set
to PIM-SSM/ASM, mLDP or SR P2MP that are to be set up by controllers,
the PE MUST attach a Controller EC constructed as above. If there
are multiple controllers, then one Controller EC is attached for each
of the controllers.
In case of tunnel segmentation and a new controller is used for the
next segmentation region, when an ABR/ASBR/RBR re-advertises the I/
S-PMSI A-D route to the next segmentation region it MUST modify the
Controller EC to specify the new controller address.
When a PE/ABR/ASBR/RBR receives an I/S-PMSI A-D route with the
Controller EC, it MUST originate a corresponding Leaf A-D route. The
PTA from the I/S-PMSI A-D route is copied to the Leaf A-D route, and
an IP Address Specific Route Target to attached to the Leaf A-D
route. The Global Administrator field of the RT is set to the
address of the controller (as encoded in the received Controller EC),
and the Local Administrator field is set to 0.
Note that, the above is done even if the Leaf Information Required
(LIR) bit in the Flags field of the I/S-PMSI A-D route's PMSI Tunnel
Attribute (PTA) is not set. If the LIR bit in the Flags field of the
I/S-PMSI A-D route's PTA is set, then the above mentioned RTs are in
addition to the RT that the PE attaches according to the procedures
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in [RFC6514], [RFC7524], or [draft-zzhang-bess-evpn-bum-procedure-
updates]. In other words, the Leaf A-D route will have RTs for both
the controllers and the upstream PE or segmentation points.
When a controller receives the advertisement and/or withdrawl of Leaf
A-D routes, it derives the set of leaves for the tunnel identified in
the PTA, calculate and set up the tree according to procedurs in
[draft-zzhang-bess-bgp-multicast-controller] or [draft-voyer-pim-sr-
p2mp-policy]. The controller does not further propagate the received
advertisement and/or withdrawl, unless there are other RTs attached.
3.3. Controller Originated I/S-PMSI Routes
When I/S-PMSI A-D routes are to be originated from the controllers,
it is expected that the controller, based on central planning, has
the knowledge of each VPN/BD's Route Target, each PE's RD for the
VPN/BD, and the Tunnel Type and Identifier for each I/S-PMSI. If the
tunnel aggregation is used, the controllers also allocate labels from
the DCB for the I/S-PMSIs.
The controller constructs the I/S-PMSI A-D route the same way as if
an ingress PE would be originating the routes. There are some
exceptions in case inter-AS/region segmentation is used, as specified
in Section 3.3.1.
Specifically, the controller uses the ingress PE's RD and RTs for the
VPN/BD, and use the ingress PE's address as "Originating Router's IP
Address" when constructing the I/S-PMSI A-D routes. The routes are
sent with the controller's address as next-hop initially, though the
next-hop may change as the routes propagates.
When the Ingress PE router receives the I/S-PMSI A-D routes, it sets
up corresponding forwarding state as if it originated the routes per
its local provisioning. Note that the next-hop address of the routes
will be different from the case where the ingress PE originates the
routes, but this should not matter.
3.3.1. Inter-AS/Region Segmentation
In case of segmentation, instead of using the Route Target for the
VPN/BD, the controller constructs an IP Address specific Route Target
with the Global Administrator Field set to the corresponding ingress
PE's address and the Local Administrator Field set to 0. This
targets the I/S-PMSI A-D routes to the Ingress PEs only.
The controller also sets the Originating Router's IP Address field of
the I/S-PMSI A-D route to its own address.
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The receiving Ingress PE associate the I/S-PMSI A-D route to the
corresponding VRF/BD based on the RD of the received route. It then
re-originate a corresponding I/S-PMSI A-D route based on the received
I/S-PMSI A-D route from the controller by doing the following:
o Changing the Originating Router's IP address to its own
o Replacing the Route Target with the Route Target for the VPN/BD
3.4. Automatic DCB Label Allocation by Controllers
If it is desired for a PE to originate I/S-PMSI A-D routes on its own
but with DCB labels dynamically allcated by a controller, the PE
originates the I/S-PMSI A-D route with the Tunnel Type in the PTA set
to "no tunnel information present", the LIR bit in the PTA'S Flags
field set to 1, and attaches an IP Address Specific RT. The RT's
Global Administrator Field is set to the Controller's address and
Local Administrator field is set to 0.
When the controller receives the I/S-PMSI A-D route, it allocates a
DCB label and responds with a Leaf A-D route. The Label field of the
Leaf A-D route's PTA is set to the allocated DCB label.
When the PE receives the Leaf A-D route, it re-advertises the I/
S-PMSI A-D route, with an additional RT for the corresponding VPN/BD.
The PTA's tunnel information is set as needed and the Label field is
set to the DCB label received in the Leaf A-D route. The LIR bit in
the Flags field of the PTA is set to 1 or 0 as needed. If it is set
to 0, the controller withdraws the Leaf A-D route but does not
release the allocated label.
When the PE withdraws the I/S-PMSI A-D route, the controller release
the DCB label and withdraws the corresponding Leaf A-D route if it
had not been withdrawn before.
4. Security Considerations
This document does not change security aspects as discussed in
[RFC4360], [6514], [7432], and [ietf-bess-evpn-bum-procedure-
updates].
5. IANA Considerations
To be added.
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6. Acknowledgements
7. References
7.1. Normative References
[I-D.ietf-bess-evpn-bum-procedure-updates]
Zhang, Z., Lin, W., Rabadan, J., Patel, K., and A.
Sajassi, "Updates on EVPN BUM Procedures", draft-ietf-
bess-evpn-bum-procedure-updates-07 (work in progress),
August 2019.
[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>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<https://www.rfc-editor.org/info/rfc6514>.
[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>.
7.2. Informative References
[I-D.ietf-bess-mvpn-evpn-aggregation-label]
Zhang, Z., Rosen, E., Lin, W., Li, Z., and I. Wijnands,
"MVPN/EVPN Tunnel Aggregation with Common Labels", draft-
ietf-bess-mvpn-evpn-aggregation-label-03 (work in
progress), October 2019.
[I-D.parekh-bess-mvpn-sr-p2mp]
Parekh, R., Filsfils, C., Venkateswaran, A., Bidgoli, H.,
daniel.voyer@bell.ca, d., and C. Hassen, "Multicast VPN
with Segment Routing Point-to-Multipoint Segment", draft-
parekh-bess-mvpn-sr-p2mp-00 (work in progress), March
2019.
[I-D.voyer-pim-sr-p2mp-policy]
daniel.voyer@bell.ca, d., Filsfils, C., Parekh, R.,
Bidgoli, H., and Z. Zhang, "Segment Routing Point-to-
Multipoint Policy", draft-voyer-pim-sr-p2mp-policy-00
(work in progress), October 2019.
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[I-D.zzhang-bess-bgp-multicast-controller]
Zhang, Z., Raszuk, R., Pacella, D., and A. Gulko,
"Controller Based BGP Multicast Signaling", draft-zzhang-
bess-bgp-multicast-controller-01 (work in progress),
February 2019.
[RFC7524] Rekhter, Y., Rosen, E., Aggarwal, R., Morin, T.,
Grosclaude, I., Leymann, N., and S. Saad, "Inter-Area
Point-to-Multipoint (P2MP) Segmented Label Switched Paths
(LSPs)", RFC 7524, DOI 10.17487/RFC7524, May 2015,
<https://www.rfc-editor.org/info/rfc7524>.
Authors' Addresses
Zhaohui Zhang
Juniper Networks
EMail: zzhang@juniper.net
Rishabh Parekh
Cisco Systems
EMail: riparekh@cisco.com
Zheng Zhang
ZTE
EMail: zhang.zheng@zte.com.cn
Hooman Bidgoli
Nokia
EMail: hooman.bidgoli@nokia.com
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