draft-ietf-bess-evpn-etree-06.txt   draft-ietf-bess-evpn-etree-07.txt 
L2VPN Workgroup A. Sajassi, Ed. BESS Workgroup A. Sajassi, Ed.
INTERNET-DRAFT S. Salam INTERNET-DRAFT S. Salam
Intended Status: Standards Track Cisco Intended Status: Standards Track Cisco
J. Drake Updates: RFC7385 J. Drake
Juniper Juniper
J. Uttaro J. Uttaro
ATT ATT
S. Boutros S. Boutros
VMware VMware
J. Rabadan J. Rabadan
Nokia Nokia
Expires: December 10, 2016 June 10, 2016 Expires: March 1, 2017 September 1, 2016
E-TREE Support in EVPN & PBB-EVPN E-TREE Support in EVPN & PBB-EVPN
draft-ietf-bess-evpn-etree-06 draft-ietf-bess-evpn-etree-07
Abstract Abstract
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree). A solution Ethernet service known as Ethernet Tree (E-Tree). A solution
framework for supporting this service in MPLS networks is proposed in framework for supporting this service in MPLS networks is proposed in
and RFC called "A Framework for E-Tree Service over MPLS Network". and RFC called "A Framework for E-Tree Service over MPLS Network".
This document discusses how those functional requirements can be This document discusses how those functional requirements can be
easily met with (PBB-)EVPN and how (PBB-)EVPN offers a more efficient easily met with (PBB-)EVPN and how (PBB-)EVPN offers a more efficient
implementation of these functions. implementation of these functions. This document makes use of the
most significant bit of the scope governed by the IANA registry
created by RFC7385, and hence updates that RFC accordingly.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
skipping to change at page 2, line 40 skipping to change at page 2, line 42
3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 7 3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 7 3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 7
3.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.1 BUM traffic originated from a single-homed site on a 3.2.1 BUM traffic originated from a single-homed site on a
leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 9 leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.2 BUM traffic originated from a single-homed site on a 3.2.2 BUM traffic originated from a single-homed site on a
root AC . . . . . . . . . . . . . . . . . . . . . . . . 9 root AC . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.3 BUM traffic originated from a multi-homed site on a 3.2.3 BUM traffic originated from a multi-homed site on a
leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 9 leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.4 BUM traffic originated from a multi-homed site on a 3.2.4 BUM traffic originated from a multi-homed site on a
root AC . . . . . . . . . . . . . . . . . . . . . . . . 9 root AC . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 E-TREE Traffic Flows for EVPN . . . . . . . . . . . . . . . 10 3.3 E-TREE Traffic Flows for EVPN . . . . . . . . . . . . . . . 10
3.3.1 E-Tree with MAC Learning . . . . . . . . . . . . . . . . 10 3.3.1 E-Tree with MAC Learning . . . . . . . . . . . . . . . . 10
3.3.2 E-Tree without MAC Learning . . . . . . . . . . . . . . 11 3.3.2 E-Tree without MAC Learning . . . . . . . . . . . . . . 11
4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 11 4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 11
4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 12 4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 12
4.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 E-Tree without MAC Learning . . . . . . . . . . . . . . . . 13 4.3 E-Tree without MAC Learning . . . . . . . . . . . . . . . . 13
5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1 E-TREE Extended Community . . . . . . . . . . . . . . . . . 13 5.1 E-TREE Extended Community . . . . . . . . . . . . . . . . . 13
5.2 PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . . 14 5.2 PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . . 14
6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 15 6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 15
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 15 7 Security Considerations . . . . . . . . . . . . . . . . . . . . 15
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 15 8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 15
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8.1 Considerations for PMSI Tunnel Types . . . . . . . . . . . . 15
9.1 Normative References . . . . . . . . . . . . . . . . . . . 15 9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.2 Informative References . . . . . . . . . . . . . . . . . . 15 9.1 Normative References . . . . . . . . . . . . . . . . . . . 16
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.2 Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
1 Introduction 1 Introduction
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree). In an E-Tree Ethernet service known as Ethernet Tree (E-Tree). In an E-Tree
service, endpoints are labeled as either Root or Leaf sites. Root service, endpoints are labeled as either Root or Leaf sites. Root
sites can communicate with all other sites. Leaf sites can sites can communicate with all other sites. Leaf sites can
communicate with Root sites but not with other Leaf sites. communicate with Root sites but not with other Leaf sites.
[RFC7387] proposes the solution framework for supporting E-Tree [RFC7387] proposes the solution framework for supporting E-Tree
skipping to change at page 5, line 5 skipping to change at page 5, line 5
- Leaf OR Root site(s) per AC - Leaf OR Root site(s) per AC
- Leaf OR Root site(s) per MAC - Leaf OR Root site(s) per MAC
2.1 Scenario 1: Leaf OR Root site(s) per PE 2.1 Scenario 1: Leaf OR Root site(s) per PE
In this scenario, a PE may receive traffic from either Root sites OR In this scenario, a PE may receive traffic from either Root sites OR
Leaf sites for a given MAC-VRF/bridge table, but not both Leaf sites for a given MAC-VRF/bridge table, but not both
concurrently. In other words, a given EVI on a PE is either concurrently. In other words, a given EVI on a PE is either
associated with a root or leaf. The PE may have both Root and Leaf associated with root(s) or leaf(s). The PE may have both Root and
sites albeit for different EVIs. Leaf sites albeit for different EVIs.
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+---ES1----+--+ | | | MPLS | | | +--+----ES2-----+CE2| |CE1+---ES1----+--+ | | | MPLS | | | +--+----ES2-----+CE2|
+---+ (Root) | |MAC| | | /IP | | |MAC| | (Leaf) +---+ +---+ (Root) | |MAC| | | /IP | | |MAC| | (Leaf) +---+
| |VRF| | | | | |VRF| | | |VRF| | | | | |VRF| |
| | | | | | | | | | +---+ | | | | | | | | | | +---+
| | | | | | | | +--+----ES3-----+CE3| | | | | | | | | +--+----ES3-----+CE3|
| +---+ | +------+ | +---+ | (Leaf) +---+ | +---+ | +------+ | +---+ | (Leaf) +---+
+---------+ +---------+ +---------+ +---------+
Figure 1: Scenario 1 Figure 1: Scenario 1
In such scenario, an EVPN PE implementation MAY provide E-TREE In such scenario, topology constraint, provided by BGP Route Target
service using topology constraint among the PEs belonging to the same (RT) import/export policies among the PEs belonging to the same EVI,
EVI. The purpose of this topology constraint is to avoid having PEs can be used to restrict the communications among Leaf PEs. The
with only Leaf sites importing and processing BGP MAC routes from purpose of this topology constraint is to avoid having PEs with only
each other. To support such topology constrain in EVPN, two BGP Leaf sites importing and processing BGP MAC routes from each other.
Route-Targets (RTs) are used for every EVPN Instance (EVI): one RT is To support such topology constrain in EVPN, two BGP Route-Targets
associated with the Root sites and the other is associated with the (RTs) are used for every EVPN Instance (EVI): one RT is associated
Leaf sites. On a per EVI basis, every PE exports the single RT with the Root sites and the other is associated with the Leaf sites.
associated with its type of site(s). Furthermore, a PE with Root On a per EVI basis, every PE exports the single RT associated with
site(s) imports both Root and Leaf RTs, whereas a PE with Leaf its type of site(s). Furthermore, a PE with Root site(s) imports both
site(s) only imports the Root RT. If the number of EVIs is very large Root and Leaf RTs, whereas a PE with Leaf site(s) only imports the
(e.g., more than 64K), then RT type 0 as defined in [RFC4360] SHOULD Root RT.
be used; otherwise, RT type 2 is sufficient [RFC7153].
2.2 Scenario 2: Leaf OR Root site(s) per AC 2.2 Scenario 2: Leaf OR Root site(s) per AC
In this scenario, a PE receives traffic from either Root OR Leaf In this scenario, a PE receives traffic from either Root OR Leaf
sites (but not both) on a given Attachment Circuit (AC) of an EVI. In sites (but not both) on a given Attachment Circuit (AC) of an EVI. In
other words, an AC (ES or ES/VLAN) is either associated with a Root other words, an AC (ES or ES/VLAN) is either associated with Root(s)
or Leaf (but not both). or Leaf(s) (but not both).
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----ES1----+--+ | | | | | | +--+---ES2/AC1--+CE2| |CE1+-----ES1----+--+ | | | | | | +--+---ES2/AC1--+CE2|
+---+ (Leaf) | |MAC| | | MPLS | | |MAC| | (Leaf) +---+ +---+ (Leaf) | |MAC| | | MPLS | | |MAC| | (Leaf) +---+
| |VRF| | | /IP | | |VRF| | | |VRF| | | /IP | | |VRF| |
| | | | | | | | | | +---+ | | | | | | | | | | +---+
| | | | | | | | +--+---ES2/AC2--+CE3| | | | | | | | | +--+---ES2/AC2--+CE3|
| +---+ | +------+ | +---+ | (Root) +---+ | +---+ | +------+ | +---+ | (Root) +---+
+---------+ +---------+ +---------+ +---------+
Figure 2: Scenario 2 Figure 2: Scenario 2
In this scenario, if there are PEs with only root (or leaf) sites per In this scenario, if there are PEs with only root (or leaf) sites per
EVI, then the RT constrain procedures described in section 2.1 can EVI, then the RT constrain procedures described in section 2.1 can
also be used here. However, when a Root site is added to a Leaf PE, also be used here. However, when a Root site is added to a Leaf PE,
then that PE needs to process MAC routes from all other Leaf PEs and then that PE needs to process MAC routes from all other Leaf PEs and
add them to its forwarding table. For this scenario, if for a given add them to its forwarding table. For this scenario, if for a given
EVI, the majority of PEs will eventually have both Leaf and Root EVI, the vast majority of PEs will eventually have both Leaf and Root
sites attached, even though they may start as Root-only or Leaf-only sites attached, even though they may start as Root-only or Leaf-only
PEs, then it is recommended to use a single RT per EVI and avoid PEs, then it is recommended to use a single RT per EVI and avoid
additional configuration and operational overhead. additional configuration and operational overhead.
2.3 Scenario 3: Leaf OR Root site(s) per MAC 2.3 Scenario 3: Leaf OR Root site(s) per MAC
In this scenario, a PE may receive traffic from both Root AND Leaf In this scenario, a PE may receive traffic from both Root AND Leaf
sites on a given Attachment Circuit (AC) of an EVI. Since an sites on a single Attachment Circuit (AC) of an EVI. Since an
Attachment Circuit (ES or ES/VLAN) carries traffic from both Root and Attachment Circuit (ES or ES/VLAN) carries traffic from both Root and
Leaf sites, the granularity at which Root or Leaf sites are Leaf sites, the granularity at which Root or Leaf sites are
identifies is on a per MAC address. This scenario is considered in identified is on a per MAC address. This scenario is considered in
this draft for EVPN service with only known unicast traffic - i.e., this draft for EVPN service with only known unicast traffic - i.e.,
there is no BUM traffic. BUM traffic is not supported in this scenario and it is dropped .
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----ES1----+--+ | | | | | | +--+---ES2/AC1--+CE2| |CE1+-----ES1----+--+ | | | | | | +--+---ES2/AC1--+CE2|
+---+ (Root) | | E | | | MPLS | | | E | | (Leaf/Root)+---+ +---+ (Root) | | E | | | MPLS | | | E | | (Leaf/Root)+---+
| | V | | | /IP | | | V | | | | V | | | /IP | | | V | |
| | I | | | | | | I | | +---+ | | I | | | | | | I | | +---+
| | | | | | | | +--+---ES2/AC2--+CE3| | | | | | | | | +--+---ES2/AC2--+CE3|
| +---+ | +------+ | +---+ | (Leaf) +---+ | +---+ | +------+ | +---+ | (Leaf) +---+
skipping to change at page 7, line 48 skipping to change at page 7, line 48
to PE1 an PE2, and PE1 advertises the Ethernet A-D per EVI to PE1 an PE2, and PE1 advertises the Ethernet A-D per EVI
corresponding to this leaf site with the leaf-indication flag but PE2 corresponding to this leaf site with the leaf-indication flag but PE2
does not, then the receiving PE notifies the operator of such does not, then the receiving PE notifies the operator of such
discrepancy and ignore the leaf-indication flag on PE1. In other discrepancy and ignore the leaf-indication flag on PE1. In other
words, in case of discrepancy, the multi-homing for that pair of PEs words, in case of discrepancy, the multi-homing for that pair of PEs
is assumed to be in default "root" mode for that <ESI, EVI> or <ESI, is assumed to be in default "root" mode for that <ESI, EVI> or <ESI,
EVI/VLAN>. The leaf indication flag on Ethernet A-D per EVI route EVI/VLAN>. The leaf indication flag on Ethernet A-D per EVI route
tells the receiving PEs that all MAC addresses associated with this tells the receiving PEs that all MAC addresses associated with this
<ESI, EVI> or <ESI, EVI/VLAN> are from a leaf site. Therefore, if a <ESI, EVI> or <ESI, EVI/VLAN> are from a leaf site. Therefore, if a
PE receives a leaf indication for an AC via the Ethernet A-D per EVI PE receives a leaf indication for an AC via the Ethernet A-D per EVI
route but doesn't receive a leaf indication in the corresponding MAC route but doesn't receive a leaf indication in the corresponding
route, then it notify the operator and ignore the leaf indication on MAC/IP Advertisement route, then it notifies the operator and ignore
the Ethernet A-D per EVI route. the leaf indication on the Ethernet A-D per EVI route.
Tagging MAC addresses with a leaf indication enables remote PEs to Tagging MAC addresses with a leaf indication enables remote PEs to
perform ingress filtering for known unicast traffic - i.e., on the perform ingress filtering for known unicast traffic - i.e., on the
ingress PE, the MAC destination address lookup yields, in addition to ingress PE, the MAC destination address lookup yields, in addition to
the forwarding adjacency, a flag which indicates whether the target the forwarding adjacency, a flag which indicates whether the target
MAC is associated with a Leaf site or not. The ingress PE cross- MAC is associated with a Leaf site or not. The ingress PE cross-
checks this flag with the status of the originating AC, and if both checks this flag with the status of the originating AC, and if both
are Leafs, then the packet is not forwarded. are Leafs, then the packet is not forwarded.
In situation where MAC moves are allowed among Leaf and Root sites
(e.g., non-static MAC), PEs can receive multiple MAC/IP
advertisements routes for the same MAC address with different
Leaf/Root indications (and possibly different ESIs for multi-homing
scenarios). In such situations, MAC mobility procedures take
precedence to first identify the location of the MAC before
associating that MAC with a Root or a Leaf site.
To support the above ingress filtering functionality, a new E-TREE To support the above ingress filtering functionality, a new E-TREE
Extended Community with a Leaf indication flag is introduced [section Extended Community with a Leaf indication flag is introduced [section
5.2]. This new Extended Community MUST be advertised with MAC/IP 5.2]. This new Extended Community MUST be advertised with MAC/IP
Advertisement route and MAY be advertised with an Ethernet A-D per Advertisement route and MAY be advertised with an Ethernet A-D per
EVI route as described above. EVI route as described above.
3.2 BUM Traffic 3.2 BUM Traffic
For BUM traffic, it is not possible to perform filtering on the This specification does not provide support for filtering BUM traffic
ingress PE, as is the case with known unicast, because of the multi- on the ingress PE because it is not possible to perform filtering of
destination nature of the traffic. As such, the solution relies on BUM traffic on the ingress PE, as is the case with known unicast
egress filtering. In order to apply the proper egress filtering, described above, due to the multi-destination nature of BUM traffic.
which varies based on whether a packet is sent from a Leaf AC or a As such, the solution relies on egress filtering. In order to apply
root AC, the MPLS-encapsulated frames MUST be tagged with an the proper egress filtering, which varies based on whether a packet
indication when they originated from a Leaf AC. In other words, leaf is sent from a Leaf AC or a root AC, the MPLS-encapsulated frames
indication for BUM traffic is done at the granularity of AC. This can MUST be tagged with an indication when they originated from a Leaf
be achieved in EVPN through the use of a MPLS label where it can be AC. In other words, leaf indication for BUM traffic is done at the
used to either identify the Ethernet segment of origin per [RFC7432] granularity of AC. This can be achieved in EVPN through the use of a
(i.e., ESI label) or it can be used to indicate that the packet is MPLS label where it can be used to either identify the Ethernet
originated from a leaf site (Leaf label). segment of origin per [RFC7432] (i.e., ESI label) or it can be used
to indicate that the packet is originated from a leaf site (Leaf
label).
BUM traffic sent over a P2MP LSP or ingress replication, may need to BUM traffic sent over a P2MP LSP or ingress replication, may need to
carry an upstream assigned or downstream assigned MPLS label carry an upstream assigned or downstream assigned MPLS label
(respectively) for the purpose of egress filtering to indicate to the (respectively) for the purpose of egress filtering to indicate to the
egress PEs whether this packet is originated from a leaf AC. egress PEs whether this packet is originated from a leaf AC.
The main difference between downstream and upstream assigned MPLS The main difference between downstream and upstream assigned MPLS
label is that in case of downstream assigned not all egress PE label is that in case of downstream assigned not all egress PE
devices need to receive the label just like ingress replication devices need to receive the label just like ingress replication
procedures defined in [RFC7432]. procedures defined in [RFC7432].
There are four scenarios to consider as follow. In all these The PE places all Leaf Ethernet Segments of a given bridge domain in
scenarios, the imposition PE imposes the right MPLS label associated a single split-horizon group in order to prevent intra-PE forwarding
among Leaf segments. This split-horizon function applies to BUM
traffic as well as known-unicast traffic.
There are four scenarios to consider as follows. In all these
scenarios, the ingress PE imposes the right MPLS label associated
with the originated Ethernet Segment (ES) depending on whether the with the originated Ethernet Segment (ES) depending on whether the
Ethernet frame originated from a Root or a Leaf site on that Ethernet Ethernet frame originated from a Root or a Leaf site on that Ethernet
Segment (ESI or Leaf label). The mechanism by which the PE identifies Segment (ESI or Leaf label). The mechanism by which the PE identifies
whether a given frame originated from a Root or a Leaf site on the whether a given frame originated from a Root or a Leaf site on the
segment is based on the Ethernet Tag associated with the frame (e.g., segment is based on the AC identifier for that segment (e.g.,
whether the frame received on a leaf or a root AC). Other mechanisms Ethernet Tag of the frame for 802.1Q frames). Other mechanisms for
for identifying whether an ingress AC is a root or leaf is beyond the identifying root or leaf (e.g., on a per MAC address basis) is beyond
scope of this document. the scope of this document.
3.2.1 BUM traffic originated from a single-homed site on a leaf AC 3.2.1 BUM traffic originated from a single-homed site on a leaf AC
In this scenario, the ingress PE adds a special MPLS label indicating In this scenario, the ingress PE adds a special MPLS label indicating
a Leaf site. This special Leaf MPLS label, used for single-homing a Leaf site. This special Leaf MPLS label, used for single-homing
scenarios, is not on a per ES basis but rather on a per PE basis - scenarios, is not on a per ES basis but rather on a per PE basis -
i.e., a single Leaf MPLS label is used for all single-homed ES's on i.e., a single Leaf MPLS label is used for all single-homed ES's on
that PE. This Leaf label is advertised to other PE devices, using a that PE. This Leaf label is advertised to other PE devices, using a
new EVPN Extended Community called E-TREE Extended Community (section new EVPN Extended Community called E-TREE Extended Community (section
5.1) along with an Ethernet A-D per ES route with ESI of zero and a 5.1) along with an Ethernet A-D per ES route with ESI of zero and a
skipping to change at page 9, line 33 skipping to change at page 9, line 48
blocks the packet if the destination AC is of type Leaf; otherwise, blocks the packet if the destination AC is of type Leaf; otherwise,
it forwards the packet. it forwards the packet.
3.2.2 BUM traffic originated from a single-homed site on a root AC 3.2.2 BUM traffic originated from a single-homed site on a root AC
In this scenario, the ingress PE does not add any ESI or Leaf label In this scenario, the ingress PE does not add any ESI or Leaf label
and it operates per [RFC7432] procedures. and it operates per [RFC7432] procedures.
3.2.3 BUM traffic originated from a multi-homed site on a leaf AC 3.2.3 BUM traffic originated from a multi-homed site on a leaf AC
In this scenario, it is assumed that While different ACs (VLANs) on In this scenario, it is assumed that while different ACs (VLANs) on
the same ES could have different root/leaf designation (some being the same ES could have different root/leaf designation (some being
roots and some being leaves), the same VLAN does have the same roots and some being leafs), the same AC (e.g., VLAN) does have the
root/leaf designation on all PEs on the same ES. Furthermore, it is same root/leaf designation on all PEs on the same ES. Furthermore, it
assumed that there is no forwarding among subnets - ie, the service is assumed that there is no forwarding among subnets - ie, the
is EVPN L2 and not EVPN IRB. IRB use case is outside the scope of service is EVPN L2 and not EVPN IRB. IRB use case is outside the
this document. scope of this document.
In such scenarios, If a multicast packet is originated from a leaf In such scenarios, If a multicast or broadcast packet is originated
AC, then it only needs to carry Leaf label described in section from a leaf AC, then it only needs to carry Leaf label described in
3.2.1. This label is sufficient in providing the necessary egress section 3.2.1. This label is sufficient in providing the necessary
filtering of BUM traffic from getting sent to leaf ACs including the egress filtering of BUM traffic from getting sent to leaf ACs
leaf AC on the same Ethernet Segment. including the leaf AC on the same Ethernet Segment.
3.2.4 BUM traffic originated from a multi-homed site on a root AC 3.2.4 BUM traffic originated from a multi-homed site on a root AC
In this scenario, both the ingress and egress PE devices follows the In this scenario, both the ingress and egress PE devices follows the
procedure defined in [RFC7432] for adding and/or processing an ESI procedure defined in [RFC7432] for adding and/or processing an ESI
MPLS label. MPLS label.
3.3 E-TREE Traffic Flows for EVPN 3.3 E-TREE Traffic Flows for EVPN
Per [RFC7387], a generic E-Tree service supports all of the following Per [RFC7387], a generic E-Tree service supports all of the following
skipping to change at page 10, line 27 skipping to change at page 10, line 41
application. In the case where unicast flows need not be supported, application. In the case where unicast flows need not be supported,
the L2VPN PEs can avoid performing any MAC learning function. the L2VPN PEs can avoid performing any MAC learning function.
In the subsections that follow, we will describe the operation of In the subsections that follow, we will describe the operation of
EVPN to support E-Tree service with and without MAC learning. EVPN to support E-Tree service with and without MAC learning.
3.3.1 E-Tree with MAC Learning 3.3.1 E-Tree with MAC Learning
The PEs implementing an E-Tree service must perform MAC learning when The PEs implementing an E-Tree service must perform MAC learning when
unicast traffic flows must be supported among Root and Leaf sites. In unicast traffic flows must be supported among Root and Leaf sites. In
this case, the PE with Root sites performs MAC learning in the data- this case, the PE(s) with Root sites performs MAC learning in the
path over the Ethernet Segments, and advertises reachability in EVPN data-path over the Ethernet Segments, and advertises reachability in
MAC Advertisement routes. These routes will be imported by all PEs EVPN MAC Advertisement routes. These routes will be imported by all
for that EVI (i.e., PEs that have Leaf sites as well as PEs that have PEs for that EVI (i.e., PEs that have Leaf sites as well as PEs that
Root sites). Similarly, the PEs with Leaf sites perform MAC learning have Root sites). Similarly, the PEs with Leaf sites perform MAC
in the data-path over their Ethernet Segments, and advertise learning in the data-path over their Ethernet Segments, and advertise
reachability in EVPN MAC Advertisement routes. For the scenario reachability in EVPN MAC Advertisement routes. For the scenario
described in section 2.1 (or possibly section 2.2), these routes are described in section 2.1 (or possibly section 2.2), these routes are
imported only by PEs with at least one Root site in the EVI - i.e., a imported only by PEs with at least one Root site in the EVI - i.e., a
PE with only Leaf sites will not import these routes. PEs with Root PE with only Leaf sites will not import these routes. PEs with Root
and/or Leaf sites may use the Ethernet A-D routes for aliasing (in and/or Leaf sites may use the Ethernet A-D routes for aliasing (in
the case of multi-homed segments) and for mass MAC withdrawal per the case of multi-homed segments) and for mass MAC withdrawal per
[RFC7432]. [RFC7432].
To support multicast/broadcast from Root to Leaf sites, either a P2MP To support multicast/broadcast from Root to Leaf sites, either a P2MP
tree rooted at the PE(s) with the Root site(s) or ingress replication tree rooted at the PE(s) with the Root site(s) or ingress replication
skipping to change at page 11, line 21 skipping to change at page 11, line 37
with Leaf sites may be used and thus there will be no need to use the with Leaf sites may be used and thus there will be no need to use the
modified PMSI tunnel attribute in section 5.2 for composite tunnel modified PMSI tunnel attribute in section 5.2 for composite tunnel
type. type.
3.3.2 E-Tree without MAC Learning 3.3.2 E-Tree without MAC Learning
The PEs implementing an E-Tree service need not perform MAC learning The PEs implementing an E-Tree service need not perform MAC learning
when the traffic flows between Root and Leaf sites are only multicast when the traffic flows between Root and Leaf sites are only multicast
or broadcast. In this case, the PEs do not exchange EVPN MAC or broadcast. In this case, the PEs do not exchange EVPN MAC
Advertisement routes. Instead, the Inclusive Multicast Ethernet Tag Advertisement routes. Instead, the Inclusive Multicast Ethernet Tag
(IMET) routes are used to support BUM traffic. route is used to support BUM traffic.
The fields of the IMET route are populated per the procedures defined The fields of this route are populated per the procedures defined in
in [RFC7432], and the multicast tunnel setup criteria are as [RFC7432], and the multicast tunnel setup criteria are as described
described in the previous section. in the previous section.
Just as in the previous section, if the number of PEs with root sites Just as in the previous section, if the number of PEs with root sites
are only a few and thus ingress replication is desired from leaf PEs are only a few and thus ingress replication is desired from leaf PEs
to these root PEs, then the modified PMSI attribute as defined in to these root PEs, then the modified PMSI attribute as defined in
section 5.3 should be used. section 5.3 should be used.
4 Operation for PBB-EVPN 4 Operation for PBB-EVPN
In PBB-EVPN, the PE advertises a Root/Leaf indication along with each In PBB-EVPN, the PE advertises a Root/Leaf indication along with each
B-MAC Advertisement route, to indicate whether the associated B-MAC B-MAC Advertisement route, to indicate whether the associated B-MAC
skipping to change at page 11, line 50 skipping to change at page 12, line 18
In the case where a multi-homed Ethernet Segment has both Root and In the case where a multi-homed Ethernet Segment has both Root and
Leaf sites attached, two B-MAC addresses are advertised: one B-MAC Leaf sites attached, two B-MAC addresses are advertised: one B-MAC
address is per ES as specified in [RFC7623] and implicitly denoting address is per ES as specified in [RFC7623] and implicitly denoting
Root, and the other B-MAC address is per PE and explicitly denoting Root, and the other B-MAC address is per PE and explicitly denoting
Leaf. The former B-MAC address is not advertised with the E-TREE Leaf. The former B-MAC address is not advertised with the E-TREE
extended community but the latter B-MAC denoting Leaf is advertised extended community but the latter B-MAC denoting Leaf is advertised
with the new E-TREE extended community where "Leaf-indication" flag with the new E-TREE extended community where "Leaf-indication" flag
is set. In such multi-homing scenarios where and Ethernet Segment has is set. In such multi-homing scenarios where and Ethernet Segment has
both Root and Leaf ACs, it is assumed that While different ACs both Root and Leaf ACs, it is assumed that While different ACs
(VLANs) on the same ES could have different root/leaf designation (VLANs) on the same ES could have different root/leaf designation
(some being roots and some being leaves), the same VLAN does have the (some being roots and some being leafs), the same VLAN does have the
same root/leaf designation on all PEs on the same ES. Furthermore, it same root/leaf designation on all PEs on the same ES. Furthermore, it
is assumed that there is no forwarding among subnets - ie, the is assumed that there is no forwarding among subnets - ie, the
service is L2 and not IRB. IRB use case is outside the scope of this service is L2 and not IRB. IRB use case is outside the scope of this
document. document.
The ingress PE uses the right B-MAC source address depending on The ingress PE uses the right B-MAC source address depending on
whether the Ethernet frame originated from the Root or Leaf AC on whether the Ethernet frame originated from the Root or Leaf AC on
that Ethernet Segment. The mechanism by which the PE identifies that Ethernet Segment. The mechanism by which the PE identifies
whether a given frame originated from a Root or Leaf site on the whether a given frame originated from a Root or Leaf site on the
segment is based on the Ethernet Tag associated with the frame. Other segment is based on the Ethernet Tag associated with the frame. Other
skipping to change at page 12, line 34 skipping to change at page 13, line 4
For known unicast traffic, the PEs perform ingress filtering: On the For known unicast traffic, the PEs perform ingress filtering: On the
ingress PE, the C-MAC destination address lookup yields, in addition ingress PE, the C-MAC destination address lookup yields, in addition
to the target B-MAC address and forwarding adjacency, a flag which to the target B-MAC address and forwarding adjacency, a flag which
indicates whether the target B-MAC is associated with a Root or a indicates whether the target B-MAC is associated with a Root or a
Leaf site. The ingress PE cross-checks this flag with the status of Leaf site. The ingress PE cross-checks this flag with the status of
the originating site, and if both are a Leaf, then the packet is not the originating site, and if both are a Leaf, then the packet is not
forwarded. forwarded.
4.2 BUM Traffic 4.2 BUM Traffic
For BUM traffic, the PEs must perform egress filtering. When a PE For BUM traffic, the PEs must perform egress filtering. When a PE
receives a MAC advertisement route (which will be used as a source B- receives a MAC advertisement route (which will be used as a source B-
MAC), it updates its Ethernet Segment egress filtering function MAC for BUM traffic), it updates its egress filtering (based on the
(based on the source B-MAC address), as follows: source B-MAC address), as follows:
- If the MAC Advertisement route indicates that the advertised B-MAC - If the MAC Advertisement route indicates that the advertised B-MAC
is a Leaf, and the local Ethernet Segment is a Leaf as well, then the is a Leaf, and the local Ethernet Segment is a Leaf as well, then the
source B-MAC address is added to the B-MAC filtering list. source B-MAC address is added to its B-MAC list used for egress
filtering.
- Otherwise, the B-MAC filtering list is not updated. - Otherwise, the B-MAC filtering list is not updated.
When the egress PE receives the packet, it examines the B-MAC source When the egress PE receives the packet, it examines the B-MAC source
address to check whether it should filter or forward the frame. Note address to check whether it should filter or forward the frame. Note
that this uses the same filtering logic as baseline [RFC7623] and that this uses the same filtering logic as baseline [RFC7623] and
does not require any additional flags in the data-plane. does not require any additional flags in the data-plane.
The PE places all Leaf Ethernet Segments of a given bridge domain in Just as in section 3.2, the PE places all Leaf Ethernet Segments of a
a single split-horizon group in order to prevent intra-PE forwarding given bridge domain in a single split-horizon group in order to
among Leaf segments. This split-horizon function applies to BUM prevent intra-PE forwarding among Leaf segments. This split-horizon
traffic. function applies to BUM traffic as well as known-unicast traffic.
4.3 E-Tree without MAC Learning 4.3 E-Tree without MAC Learning
In scenarios where the traffic of interest is only Multicast and/or In scenarios where the traffic of interest is only Multicast and/or
broadcast, the PEs implementing an E-Tree service do not need to do broadcast, the PEs implementing an E-Tree service do not need to do
any MAC learning. In such scenarios the filtering must be performed any MAC learning. In such scenarios the filtering must be performed
on egress PEs. For PBB-EVPN, the handling of such traffic is per on egress PEs. For PBB-EVPN, the handling of such traffic is per
section 4.2 without C-MAC learning part of it at both ingress and section 4.2 without C-MAC learning part of it at both ingress and
egress PEs. egress PEs.
skipping to change at page 15, line 5 skipping to change at page 15, line 20
the remaining low-order seven bits indicate the tunnel type as the remaining low-order seven bits indicate the tunnel type as
before. When this C bit is set, the "tunnel identifier" field would before. When this C bit is set, the "tunnel identifier" field would
begin with a three-octet label, followed by the actual tunnel begin with a three-octet label, followed by the actual tunnel
identifier for the transmit tunnel. PEs that don't understand the identifier for the transmit tunnel. PEs that don't understand the
new meaning of the high-order bit would treat the tunnel type as an new meaning of the high-order bit would treat the tunnel type as an
invalid tunnel type. For the PEs that do understand the new meaning invalid tunnel type. For the PEs that do understand the new meaning
of the high-order, if ingress replication is desired when sending BUM of the high-order, if ingress replication is desired when sending BUM
traffic, the PE will use the the label in the Tunnel Identifier field traffic, the PE will use the the label in the Tunnel Identifier field
when sending its BUM traffic. when sending its BUM traffic.
Using the Composite flag for Tunnel Types 0x00 'no tunnel information
present' and 0x06 'Ingress Replication' is invalid, and should be
treated as an invalid tunnel type on reception.
6 Acknowledgement 6 Acknowledgement
We would like to thank Dennis Cai, Antoni Przygienda, and Jeffrey We would like to thank Dennis Cai, Antoni Przygienda, and Jeffrey
Zhang for their valuable comments. Zhang for their valuable comments.
7 Security Considerations 7 Security Considerations
Since this draft uses the EVPN constructs of [RFC7432] and [RFC7623], Since this draft uses the EVPN constructs of [RFC7432] and [RFC7623],
the same security considerations in these drafts are also applicable the same security considerations in these drafts are also applicable
here. Furthermore, this draft provides additional security check by here. Furthermore, this draft provides additional security check by
allowing sites (or ACs) of an EVPN instance to be designated as allowing sites (or ACs) of an EVPN instance to be designated as
"Root" or "Leaf" and preventing any traffic exchange among "Leaf" "Root" or "Leaf" and preventing any traffic exchange among "Leaf"
sites of that VPN through ingress filtering for known unicast traffic sites of that VPN through ingress filtering for known unicast traffic
and egress filtering for BUM traffic. and egress filtering for BUM traffic.
8 IANA Considerations 8 IANA Considerations
This document requests the allocation of value 5 in the "EVPN IANA has allocated value 5 in the "EVPN Extended Community Sub-Types"
Extended Community Sub-Types" registry defined in [RFC7153] and registry defined in [RFC7153] as follow:
modification of the registry as follow:
SUB-TYPE VALUE NAME Reference SUB-TYPE VALUE NAME Reference
0x05 E-TREE Extended Community This document 0x05 E-TREE Extended Community This document
6-255 Unassigned
8.1 Considerations for PMSI Tunnel Types
The "P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types"
registry in the "Border Gateway Protocol (BGP) Parameters" registry
needs to be updated to reflect the use of the most significant bit to
advertise the use of "composite tunnels" (section 5.2).
For this purpose, this document updates RFC7385.
The registry is to be updated, by removing the entries for 0xFB-0xFE
and 0x0F, and replacing them by: - 0x7B-0x7E Reserved for
Experimental Use [this document]- 0x7F Reserved [this document]-
0x80-0xFF Not Allocatable, corresponds to Composite tunnel types
[this document]
The allocation policy for values 0x00 to 0x7A is IETF Review
[RFC5226]. The range for experimental use is now 0x7B-0x7E, and value
in this range are not to be assigned. The status of 0x7F may only be
changed through Standards Action [RFC5226].
9 References 9 References
9.1 Normative References 9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", February, [RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", February,
2015. 2015.
[RFC7623] Sajassi et al., "Provider Backbone Bridging Combined with [RFC7623] Sajassi et al., "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", September, 2015. Ethernet VPN (PBB-EVPN)", September, 2015.
[RFC7385] Andersson et al., "IANA Registry for P-Multicast
Service Interface (PMSI) Tunnel Type Code Points",
October, 2014.
[RFC7153] Rosen et al., "IANA Registries for BGP Extended
Communities", March, 2014.
[RFC6514] Aggarwal et al., "BGP Encodings and Procedures
for Multicast in MPLS/BGP IP VPNs", February, 2012.
9.2 Informative References 9.2 Informative References
[RFC7387] Key et al., "A Framework for E-Tree Service over MPLS [RFC7387] Key et al., "A Framework for E-Tree Service over MPLS
Network", October 2014. Network", October 2014.
[RFC4360] S. Sangli et al, "BGP Extended Communities Attribute", [RFC4360] S. Sangli et al, "BGP Extended Communities Attribute",
February, 2006. February, 2006.
[RFC7153] Rosen et al., "IANA Registries for BGP Extended
Communities", March, 2014.
[RFC6514] Aggarwal et al., "BGP Encodings and Procedures for
Multicast in MPLS/BGP IP VPNs", February, 2012.
Contributors Contributors
In addition to the authors listed on the front page, the following In addition to the authors listed on the front page, the following
co-authors have also contributed to this document: co-authors have also contributed to this document:
Wim Henderickx Wim Henderickx
Nokia Nokia
Aldrin Isaac Aldrin Isaac
Wen Lin Wen Lin
 End of changes. 35 change blocks. 
93 lines changed or deleted 135 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/