Internet DRAFT - draft-keyupate-bess-evpn-virtual-hub
draft-keyupate-bess-evpn-virtual-hub
BESS Working Group K. Patel
Arrcus
Internet Draft A. Sajassi
Category: Standards Track Cisco
J. Drake
Z. Zhang
Juniper Networks
W. Henderickx
Nokia
Expires: March 02, 2020 September 02, 2019
Virtual Hub-and-Spoke in BGP EVPNs
draft-keyupate-bess-evpn-virtual-hub-02
Abstract
Ethernet Virtual Private Network (EVPN) solution is becoming
pervasive for Network Virtualization Overlay (NVO) services in data
center (DC) applications and as the next generation virtual private
LAN services in service provider (SP) applications.
The use of host IP default route and host unknown MAC route within a
DC is well understood in order to ensure that leaf nodes within a DC
only learn and store host MAC and IP addresses for that DC. All other
host MAC and IP addresses from remote DCs are learned and stored in
DC GW nodes thus alleviating leaf nodes from learning host MAC and IP
addresses from the remote DCs.
This draft further optimizes the MAC and IP address learning at the
leaf nodes such that a leaf node within a DC only needs to learn and
store MAC and IP addresses associated with the sites directly
connected to it. A leaf node does not need to learn and store MAC and
IP addresses from any other leaf nodes thus reducing the number of
learned MACs and IP addresses per EVI substantially.
The modifications provided by this draft updates and extends RFC7024
for BGP EVPN Address Family.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
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Copyright and License Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Routing Information Exchange for EVPN routes . . . . . . . . . 5
5. EVPN unknown MAC route . . . . . . . . . . . . . . . . . . . . 6
5.1. Originating EVPN Unknown MAC Route by a V-Hub . . . . . . 6
5.2. Processing VPN-MAC EVPN unknown Route by a V-SPOKE . . . . 6
5.3. Aliasing . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. Split-Horizon & Mass Withdraw . . . . . . . . . . . . . . 8
6. Forwarding Considerations . . . . . . . . . . . . . . . . . . 8
6.1. IP-only Forwarding . . . . . . . . . . . . . . . . . . . . 8
6.2. MAC-only Forwarding - Bridging . . . . . . . . . . . . . . 8
6.3. MAC and IP Forwarding - IRB . . . . . . . . . . . . . . . 8
7. Handling of Broadcast and Multicast traffic . . . . . . . . . 9
7.1. Split Horizon . . . . . . . . . . . . . . . . . . . . . . 10
7.2. Route Advertisement . . . . . . . . . . . . . . . . . . . 10
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7.3. Designated Forwarder in a Cluster . . . . . . . . . . . . 11
7.4. Traffic Forwarding Rules . . . . . . . . . . . . . . . . . 11
7.4.1. Traffic from Local ACs . . . . . . . . . . . . . . . . 12
7.4.2. Traffic Received by a V-hub from Another PE . . . . . 12
7.4.3. Traffic received by a V-spoke from a V-hub . . . . . . 12
7.5. Multi-homing support . . . . . . . . . . . . . . . . . . . 12
7.5.1 Domain-wide Common Block (DCB) Label . . . . . . . . . . 13
7.5.2 Local Bias . . . . . . . . . . . . . . . . . . . . . . . 13
7.6. Direct V-spoke to V-spoke traffic . . . . . . . . . . . . 13
8. ARP/ND Suppression . . . . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
10. Security Considerations . . . . . . . . . . . . . . . . . . . 14
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
12. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 15
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
13.1. Normative References . . . . . . . . . . . . . . . . . . 15
13.2. Informative References . . . . . . . . . . . . . . . . . 15
14. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
Ethernet Virtual Private Network (EVPN) solution is becoming
pervasive for Network Virtualization Overlay (NVO) services in data
center (DC) applications and as the next generation virtual private
LAN services in service provider (SP) applications.
With EVPN, providing any-to-any connectivity among sites of a given
EVPN Instance (EVI) would require each Provider Edge (PE) router
connected to one or more of these sites to hold all the host MAC and
IP addresses for that EVI. The use of host IP default route and host
unknown MAC route within a DC is well understood in order to
alleviate the learning of host MAC and IP addresses to only leaf
nodes (PEs) within that DC. All other host MAC and IP addresses from
remote DCs are learned and stored in DC GW nodes thus alleviating
leaf nodes from learning host MAC and IP addresses from the remote
DCs.
This draft further optimizes the MAC and IP address learning at the
leaf nodes such that a leaf node within a DC only needs to learn and
store MAC and IP addresses associated with the sites directly
connected to it. A leaf node does not need to learn and store MAC
and IP addresses from any other leaf nodes thus reducing the number
of learned MACs and IP addresses per EVI substantially.
[RFC7024] provides rules for Hub and Spoke VPNs for BGP L3VPNs. This
draft updates and extends [RFC7024] for BGP EVPN Address Family. This
draft provides rules for Originating and Processing of the EVPN host
unknown MAC route and host default IP route by EVPN Virtual Hub (V-
HUB). This draft also provides rules for the handling of the BUM
traffic in Hub and Spoke EVPNs and handling of ARP suppression.
The leaf nodes and DC GW nodes in a data center are referred to as
Virtual Spokes (V-spokes) and Virtual Hubs (V-hubs) respectively. A
set of V-spoke can be associated with one or more V-hubs. If a V-
spokes is associated with more than one V-hubs, then it can load
balanced traffic among these V-hubs. Different V-spokes can be
associated with different sets of V-hubs such that at one extreme
each V-spoke can have a different V-hub set although this may not be
desirable and a more typical scenario may be to associate a set of V-
spokes to a set of V-hubs - e.g., topology for a DC POD where a set
of V-spokes are associated with a set of spine nodes or DC GW nodes.
In order to avoid repeating many of the materials covered in
[RFC7024], this draft is written as a delta document with its
sections organized to follow those of that RFC with only delta
description pertinent to EVPN operation in each section. Therefore,
it is assumed that the readers are very familiar with [RFC7024] and
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EVPN.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
be interpreted as described in [RFC2119] only when they appear in all
upper case. They may also appear in lower or mixed case as English
words, without any normative meaning.
3. Terminology
ARP: Address Resolution Protocol
BEB: Backbone Edge Bridge
B-MAC: Backbone MAC Address
CE: Customer Edge
C-MAC: Customer/Client MAC Address
ES: Ethernet Segment
ESI: Ethernet Segment Identifier
IRB: Integrated Routing and Bridging
LSP: Label Switched Path
MP2MP: Multipoint to Multipoint
MP2P: Multipoint to Point
ND: Neighbor Discovery
NA: Neighbor Advertisement
P2MP: Point to Multipoint
P2P: Point to Point
PE: Provider Edge
EVPN: Ethernet VPN
EVI: EVPN Instance
RT: Route Target
Single-Active Redundancy Mode: When only a single PE, among a group
of PEs attached to an Ethernet segment, is allowed to forward traffic
to/from that Ethernet Segment, then the Ethernet segment is defined
to be operating in Single-Active redundancy mode.
All-Active Redundancy Mode: When all PEs attached to an Ethernet
segment are allowed to forward traffic to/from that Ethernet Segment,
then the Ethernet segment is defined to be operating in All-Active
redundancy mode.
4. Routing Information Exchange for EVPN routes
[RFC7432] defines multiple Route Types NLRI along with procedures for
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advertisements and processing of these routes. Some of these
procedures are impacted as the result of hub-and-spoke architecture.
The routing information exchange among the hub, spoke, and vanilla
PEs are subject to the same rules as described in section 3 of
[RFC7024]. Furthermore, if there are any changes to the EVPN route
advisements and processing from that of [RFC7432], they are described
below.
5. EVPN unknown MAC route
Section 3 of [RFC7024] talks about how a V-hub of a given VPN must
export a VPN-IP default route for that VPN and this route must be
exported to only the V-spokes of that VPN associated with that V-hub.
[DCI-EVPN] defines the notion of the unknown MAC route for an EVI
which is analogous to a VPN-IP default route for a VPN. This unknown
MAC route is exported by a V-hub to its associated V-spokes. If
multiple V-hubs are associated with a set of V-spokes, then each V-
hub advertises it with a distinct RD when originating this route. If
a V-spoke imports several of these unknown MAC routes and they all
have the same preference, then traffic from the V-spoke to other
sites of that EVI would be load balanced among the V-hubs.
5.1. Originating EVPN Unknown MAC Route by a V-Hub
Section 7.3 of the [RFC7024] defines procedures for originating a
VPN-IP default route for a VPN. The same procuedures apply when a V-
hub wants to originate EVPN unknown MAC route for a given EVI. The
V-hub MUST announce unknown MAC route using the MAC/IP advertisement
route along with the Default Gateway extended community as defined in
section 10.1 of the [RFC7432].
5.2. Processing VPN-MAC EVPN unknown Route by a V-SPOKE
Within a given EVPN, a V-spoke MUST import all the unknown MAC routes
unless the route-target mismatch happens. The processing of the
received VPN-MAC EVPN default route follows the rules explained in
the section 3 of the [RFC7024]. The unknown MAC route MUST be
installed according to the rules of MAC/IP Advertisement route
installation rules in section 9.2.2 of [RFC7024].
In absense of any more specific VPN-MAC EVPN routes, V-spokes
installing the unknown MAC route MUST use the route when performing
ARP proxy. This behavior would allow V-Spokes to forward the traffic
towards V-Hub.
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5.3. Aliasing
[RFC7432] describes the concept and procedures for Aliasing where a
station is multi-homed to multiple PEs operating in an All-Active
redundancy mode, it is possible that only a single PE learns a set of
MAC addresses associated with traffic transmitted by the station.
[RFC7432] describes the concepts and procedures for Aliasing, which
occurs when a CE is multi-homed to multiple PE nodes, operating in
all-active redundancy mode, but not all of the PEs learn the CE's set
of MAC addresses. This leads to a situation where remote PEs receive
MAC advertisement routes, for these addresses, from a single NVE even
though multiple NVEs are connected to the multi-homed station. As a
result, the remote NVEs are not able to effectively load-balance
traffic among the NVEs connected to the multi-homed Ethernet segment.
To alleviate this issue, EVPN introduces the concept of Aliasing.
This refers to the ability of a PE to signal that it has reachability
to a given locally attached Ethernet segment, even when it has learnt
no MAC addresses from that segment. The Ethernet A-D per-EVI route is
used to that end. Remote PEs which receive MAC advertisement routes
with non-zero ESI SHOULD consider the MAC address as reachable via
all NVEs that advertise reachability to the relevant Segment using
Ethernet A-D routes with the same ESI and with the Single-Active flag
reset.
This procedure is impacted for virtual hub-and-spoke topology because
a given V-spoke does not receive any MAC/IP advertisements from
remote V-spokes; therefore, there is no point in propagating Ethernet
A-D per-EVI route to the remote V-spokes. In this solution, the V-
hubs terminate the Ethernet A-D per-EVI route (used for Aliasing) and
follows the procedures described in [RFC7432] for handling this
route.
There are scenarios for which it is desirable to establish direct
communication path between a pair of V-spokes for a given host MAC
address. In such scenario, the advertising V-spoke advertises both
the MAC/IP route and Ethernet A-D per-EVI route with the RT of V-hub
(RT-VH) per section 3 of [RFC7024]. The use of RT-VH, ensures that
these routes are received by the V-spokes associated with that V-hub
set and thus enables the V-spokes to perform the Aliasing procedure.
In summary, PE devices (V-hubs in general and V-spokes occasionally)
that receive EVPN MAC/IP route advertisements (associated with a
multi-homed site) need to also receive the associated Ethernet A-D
per-EVI route advertisement(s) in order for them to perform Aliasing
procedure.
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5.4. Split-Horizon & Mass Withdraw
[RFC7432] uses Ethernet A-D per-ES route to a) signal to remote PEs
the multi-homing redundancy type (Single-Active versus All-Active),
b) advertise ESI label for split-horizon filtering when MPLS
encapsulation is used, and c) advertise mass-withdraw when a failure
of an access interface impacts many MAC addresses. This route does
not need to be advertise from a V-spoke to any remote V-spoke unless
a direct communication path between a pair of spoke is needed for a
given flow.
Even if communication between a pair of V-spoke is needed for just a
single flow, the Ethernet A-D per ES route needs to be advertised
from the originating V-spoke for that ES which may handle tens or
hundreds of thousands of flows. This is because in order to perform
Aliasing function for a given flow, the Ethernet A-D per-EVI route is
needed and this route itself is dependent on the Ethernet A-D per-ES
route. In such scenario, the advertising V-spoke advertises the
Ethernet A-D per-ES route with the RT of V-hub (RT-VH) per section 3
of [RFC7024].
In summary, PE devices (V-hubs in general and V-spokes occasionally)
that receive EVPN MAC/IP route advertisements (associated with a
multi-homed site) need to also receive the associated Ethernet A-D
per-ES route advertisement(s).
6. Forwarding Considerations
6.1. IP-only Forwarding
When EVPN operates in IP-only forwarding mode using EVPN Route Type
5, then all forwarding considerations in section 4 of [RFC7024] are
directly applicable here.
6.2. MAC-only Forwarding - Bridging
When EVPN operates in MAC-only forwarding mode (i.e., bridging mode),
then for a given EVI, the MPLS label that a V-hub advertises with
anUnknown MAC address MUST be the label that identifies the MAC-VRF
of the V-hub in absense of a more specific MAC route. When the V-hub
receives a packet with such label, the V- hub pops the label and
determines further disposition of the packet based on the lookup in
the MAC-VRF. Otherwise, the MPLS label of the matching more specific
route is used and packet is is forwarded towards the associated
NEXTHOP of the more specific route.
6.3. MAC and IP Forwarding - IRB
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When a EVPN speaker operates in IRB mode, it implements both the IP
and MAC forwarding Modes (aka Integrated Routing and Bridging - IRB).
On a packet by packet basis, the V-spoke decides whether to do
forwarding based on a MAC address lookup (bridge) or based on a IP
address lookup (route). If the host destination MAC address is that
of the IRB interface (i.e., if the traffic is inter-subnet), then the
V-spoke performs an additional IP lookup in the IP-VRF. However, if
the host destination MAC address is that of an actual host MAC
address (i.e., the traffic is intra- subnet) , then the V-spoke only
performs a MAC lookup in the MAC-VRF. The procedure specified in
Section 6.1 and Section 6.2 are applicable to inter-subnet and intra-
subnet forwarding respectively. For intra- subnet traffic, if the
MAC address is not found in the MAC-VRF, then the V-spoke forwards
the traffic to the V-hub with the MPLS label received from the V-hub
for the unknown MAC address. For the Inter- subnet traffic, if the
IP prefix is not found in the IP-VRF, then the V-spoke forwards the
traffic to the V-hub with the MPLS label received from the V-hub for
the default IP address.
7. Handling of Broadcast and Multicast traffic
Just like that V-spoke to V-spoke known unicast traffic is relayed by
V-hubs, V-spoke to V-spoke BUM traffic can also relayed by V-hubs.
This is especially desired if Ingress Replication (IR) would be used
otherwise for V-spokes to send traffic to other V-spokes. This way,
a V-spoke can unicast BUM traffic to a single V-hub, who will then
relay the traffic. This achieves Assisted Replication, and reduces
multicast state in the core. Note that a V-hub may relay traffic
using MPLS P2MP tunnels or BIER as well as IR. While a V-spoke may
use P2MP tunnels or BIER to send traffic to V-hubs, this
specification focuses on using IR by V-spokes.
In this particular section, all traffic refers to BUM traffic unless
explicitly stated otherwise. The term PE refers to a V-hub or V-
spoke when there is no need to distinguish the two.
Consider the following topology, where V-spokes VS1/2/3 are
associated with V-hubs VH1/2 in one cluster, and V-spokes VS4/5/6 are
associated with V-hubs VH3/4 in another cluster. Note that the
lines/dots in the diagram indcate association, not connection.
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VH1 ...VH2 VH3 ...VH4
/ |. . . / |. . .
/ .| . . / .| . .
/. |. . /. |. .
VS1 VS2 VS3 VS4 VS5 VS6
7.1. Split Horizon
When VH1 relays traffic that it receives from VS1, in case of IR it
MUST not send traffic back to VS1, and in case of P2MP tunnel it must
indicate that traffic is sourced from VS1 so that VS1 will discard
the traffic. In case of IR with IP unicsat tunnels, the outer source
IP address identifies the sending PE. In case of IR with MPLS
unicast tunnels, VH1 must advertise different labels to different
PEs, so that it can identify the sending PE based on the label in the
traffic from a V-spoke.
If MPLS P2MP/multicast tunnels (including VXLAN-GPE and MPLS-over-
GRE/UDP) are used by a V-hub to relay traffic, an upstream allocated
(by the V-hub) label MUST be imposed in the label stack to identify
the source of the V-spoke. The label is advertised as part of the PE
Distinguisher (PED) Label Attribute of the Inclusive Multicast
Ethernet Tag (IMET) route from the V-hub, as specified in Section 8
of [RFC 6514].
Notice that an "upstream-assigned" label used by a V-hub to send
traffic with on a P2MP tunnel to identify the source V-spoke is the
same "downstream-assigned" label used by the V-hub to receive traffic
on the IR tunnel from the V-spoke. Therefore, the same PED Label
attribute serves two purposes. With [RFC 6514], a PED label may only
identify a PE but not a particular VPN. Here the PED label
identifies both the PE and a particular EVI/BD. A V-spoke programs
its context MPLS forwarding table for the V-hub to discard any
traffic with the PED label that the V-hub advertised for this V-
spoke, or pop other PED labels and direct traffic into a
corresponding EVI for L2 forwarding.
Note that a V-hub cannot use VXLAN/NVGRE multicast tunnels to relay
traffic because if the V-hub uses the source V-spoke's IP address in
the outer IP header (for the purpose of identifying the source V-
spoke), multicast RPF would fail and the packets will be discarded.
7.2. Route Advertisement
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As with other route types, IMET routes from V-hubs are advertised
with RT-VH and RT-EVI so they are imported by associated V-spokes and
all V-hubs. They carry the PED Label attribute as described above.
IMET routes from V-spokes are advertised with RT-EVI so they are
imported by all V-hubs. They also carry PED Label attribute for
multi-homing split horizon purpose if and only if V-hubs uses IR to
relay traffic.
If a V-hub uses RSVP-TE P2MP tunnel, IR, or BIER to send or relay
traffic, all other PEs (V-hubs or V-spokes) will receive traffic
directly because the V-hub sees all PEs. If a V-hub uses mLDP P2MP
tunnel to send or relay traffic, only its associated V-spokes and all
V-hubs will see the V-hub's IMET route and join the tunnel announced
in the route. Another V-hub need to relay traffic to its associated
V-spokes that are not associated with this V-hub.
For that V-hub to announce the mLDP relay tunnel in its cluster, it
needs to advertise a (*,*) S-PMSI AD route, as specified in [BUM-
PROCEDURE]. The route is advertised with the RT-VH for that cluster,
and associated V-spokes will join the tunnel announced in the S-SPMI
AD route.
7.3. Designated Forwarder in a Cluster
When there are multiple V-hubs in a cluster, a V-spoke in that
cluster decides by itself to which V-hub to send traffic. If the
receiving V-hub uses mLDP tunnel to relay traffic, V-hubs in other
clusters need to further relay traffic, but only one V-hub in each
cluster can do so. As a result, a DF must be elected among the V-
hubs for each cluster.
The election is similar to DF election in RFC 7432, with the
folllowing differences.
o Instead of using Ethernet Segment route to discover the PEs on a
multi-homing ES, the IMET route are used to determine the V-hubs in
the same cluster - they all carry the same pair of RT-EVI and RT-VH,
and advertises the unknown mac route.
o Instead of using VLAN to do per-VLAN DF election, the Local
Administration Field of the RT-EVI is used to do per-EVI DF election.
7.4. Traffic Forwarding Rules
When a PE needs to forward received traffic from local Attachment
Circuits (ACs) or remote PEs to local ACs, it follows the rules in
RFC 7432, except that traffic sourced from this local PE but relayed
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back on a p2mp tunnel is discarded. It may also need to forward to
other PEs, subject to rules in the following sections.
7.4.1. Traffic from Local ACs
Traffic from a V-hub's local ACs is forwarded using the tunnel
announced in its IMET route, as specified in RFC 7432. In case of an
mLDP tunnel, the traffic need to be relayed by V-hubs of other
clusters to their associated V-spokes. For other tunnel types, no
relay is needed.
Traffic from a V-spoke's local ACs is forwarded to an associated V-
hub of its choice. In case of MPLS IR, the label in the V-hub's IMET
route's PED attribute corresponding to this V-spoke is used.
7.4.2. Traffic Received by a V-hub from Another PE
When a V-hub receives traffic from an associated V-spoke, it needs to
relay to other PEs, using the tunnel announced in its IMET route. In
case of IR or BIER, the source V-spoke, which is determined from the
incoming label or source IP address, is excluded from the replication
list. In case of a P2MP tunnel, the popped incoming label is imposed
again to identify the source PE, before the tunnel label is imposed.
When a V-hub receives traffic from another V-hub on a P2MP tunnel,
and the tunnel is announced in an IMET route carrying the same RT-VH
as this V-hub is configured with, it does not need to relay the
traffic. Otherwise, the traffic is from a V-hub in a different
cluster, and this V-hub needs to relay to its associated V-spokes, if
and only if it is the DF for this cluster, using the tunnel announced
in its (*,*) S-PMSI route carrying its RT-VH.
When a V-hub recevies traffic from another V-hub via IR or BIER, it
does not further relay the traffic as that V-hub can reach all PEs.
7.4.3. Traffic received by a V-spoke from a V-hub
In case of P2MP tunnel, the V-spoke discards the traffic if the label
following the tunnel label identifies the V-spoke itself.
7.5. Multi-homing support
Consider that an ES spans across two V-spokes in the same cluster and
the V-hub uses MPLS IR to relay traffic. With ESI Label split
horizon method, a source V-spoke uses the ESI label advertised by the
V-hub for the ES, and the V-hub must change that to the ESI label
advertised by receiving v-spokes when it relays traffic. That means
V-hubs must advertise ESI labels for all multi-homing segments, even
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when they're not on those segments. They must also do double label
swap (EVI/BD label and ESI label) or mac lookup when relaying
traffic.
There are two methods detailed below to avoid that complexity. Either
one MAY be used.
7.5.1 Domain-wide Common Block (DCB) Label
[draft-zzhang-bess-mvpn-evpn-aggregation-label] proposes for all PEs
on an MHES to use the same ESI label allocated from a Domain-wide
Common Block. Not only does that have the advantages described in
that document, but also It avoids the MHES complexity with Virtual
Hub and Spoke as mentioned above, because the V-Hubs do not need to
care about the ESI label at all any more.
7.5.2 Local Bias
If DCB labels cannot be used, then Local Bias can be used even For
EVPN MPLS. The PED label following the mpls transport tunnel label or
BIER header identifies the PE that originated the traffic in addition
to identifying the EVI/BD.
If a V-hub uses P2MP or BIER to relay traffic, the PED label is one
of the labels in the PE Distinguiser Label attribute in the V-hub's
IMET route, allocated by the V-hub for the source V-spoke.
If a V-hub uses IR to relay traffic, for each V-spoke that it relays
to, the PED label advertised by that receiving V-spoke for the source
V-spoke needs to be imposed by the V-hub. For that purpose, each V-
spoke must include the PED Label attribute in its IMET route, to
advertise different labels for different PEs. It discovers the PEs
that it needs to advertise labels for via the PED label Attribute in
the V-hub's IMET route.
7.6. Direct V-spoke to V-spoke traffic
It may be desired for allow direct V-spoke to V-spoke traffic in a
cluster, without the relay by a V-hub. To do that, V-spokes advertise
their IMET routes with both RT-VH and RT-EVI. Forwarding rules will
be specified in future revisions.
8. ARP/ND Suppression
[RFC7432] defines the procedures for ARP/ND suppression where a PE
can terminate gratuitous ARP/ND request message from directly
connected site and advertises the associated MAC and IP addresses in
an EVPN MAC/IP advertisement route to all other remote PEs. The
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remote PEs that receive this EVPN route advertisement, install the
MAC/IP pair in their ARP/ND cache table thus enabling them to
terminate ARP/ND requests and generate ARP/ND responses locally thus
suppressing the flooding of ARP/ND requests over the EVPN network.
In this hub-and-spoke approach, the ARP suppression needs to be
performed by both the EVPN V-hubs as well V-spokes as follow. When a
V-Spoke receives a gratuitous ARP/ND request, it terminates it and
stores the source MAC/IP pair in its ARP/ND cache table. Then, it
advertises the source MAC/IP pair to its associated V-Hubs using EVPN
MAC/IP advertisement route. The V-Hubs upon receiving this EVPN
route advertisement, create an entry in their ARP/ND cache table for
this MAC/IP pair.
Now when a V-Spoke receives an ARP/ND request, it first looks up its
ARP cache table, if an entry for that MAC/IP pair is found, then an
ARP/ND response is generated locally and sent to the CE. However, if
an entry is not found, then the ARP/ND request is unicasted to one of
the V-hub associated with this V-spoke. Since, the associated V-hub
keeps all the MAC/IP ARP entries in its cache table, it can formulate
and ARP/ND response and forward it to that CE via the corresponding
V-spoke.
9. IANA Considerations
There is no additional IANA considerations for PBB-EVPN beyond what
is already described in [RFC7432].
10. Security Considerations
All the security considerations in [RFC7432] apply directly to this
document because this document leverages [RFC7432] control plane and
their associated procedures - although not the complete set but
rather a subset.
This draft does not introduce any new security considerations beyond
that of [RFC7432] and [RFC4761] because advertisements and processing
of B-MAC addresses follow that of [RFC7432], and processing of C-MAC
addresses follow that of [RFC4761] - i.e, B-MAC addresses are learned
in control plane and C-MAC addresses are learned in data plane.
11. Acknowledgements
The authors would like to thank Yakov Rekhter for initial idea
discussions.
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12. Change Log
Initial Version: Sep 21 2014 Original Name: draft-keyupate-evpn-
virtual-hub-00.txt
13. References
13.1. Normative References
[RFC7024] Jeng, H., Uttaro, J., Jalil, L., Decraene, B., Rekhter,
Y., and R. Aggarwal, "Virtual Hub-and-Spoke in BGP/MPLS
VPNs", RFC 7024, October 2013.
[RFC7432] A. Sajassi, et al., "BGP MPLS Based Ethernet VPN", RFC
7432 , February 2015.
13.2. Informative References
[RFC7080] A. Sajassi, et al., "Virtual Private LAN Service (VPLS)
Interoperability with Provider Backbone Bridges", RFC
7080, December 2013.
[RFC7209] D. Thaler, et al., "Requirements for Ethernet VPN (EVPN)",
RFC 7209, May 2014.
[RFC4389] A. Sajassi, et al., "Neighbor Discovery Proxies (ND
Proxy)", RFC 4389, April 2006.
[RFC4761] K. Kompella, et al., "Virtual Private LAN Service (VPLS)
Using BGP for Auto-Discovery and Signaling", RFC 4761,
Jauary 2007.
[OVERLAY] A. Sajassi, et al., "A Network Virtualization Overlay
Solution using EVPN", draft-ietf-bess-evpn-overlay-01,
work in progress, February 2015.
14. Authors' Addresses
Keyur Patel
Arrcus, Inc.
2077 Gateway Pl, Suite 400
San Jose, CA 95110, US
Email: keyur@arrcus.com
Ali Sajassi
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Cisco
170 West Tasman Drive
San Jose, CA 95134, US
Email: sajassi@cisco.com
Yakov Rekhter
Juniper Networks, Inc.
Email: yakov@juniper.net
John E. Drake
Juniper Networks, Inc.
Email: jdrake@juniper.net
Zhaohui Zhang
Juniper Networks, Inc.
Email: zzhang@juniper.net
Wim Henderickx
Nokia
Email: wim.henderickx@nokia.com
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