Internet DRAFT - draft-fu-bess-evpn-umr-application
draft-fu-bess-evpn-umr-application
Network Working Group Z. Fu
Internet-Draft T. Zhu
Intended status: Standards Track H. Wang
Expires: 20 May 2024 J. Dai
D. Wang
Huawei Technologies
17 November 2023
UMR application in Ethernet VPN(EVPN)
draft-fu-bess-evpn-umr-application-01
Abstract
This document describes an application scenario that how unknown MAC-
route(UMR) is used in the EVPN network. In particular, this document
describes how MAC address route and UMR route are advertised on DC's
GW or NVE. This document also describes the soloution that MAC
mobility issue due to the lack of advertisement of specific MAC
routes. However, some incremental work is required, which will be
covered in a separate document.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 20 May 2024.
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Copyright Notice
Copyright (c) 2023 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
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The procedure of UMR . . . . . . . . . . . . . . . . . . . . 3
4. MAC Mobility for UMR . . . . . . . . . . . . . . . . . . . . 5
4.1. MAC Mobility Issue . . . . . . . . . . . . . . . . . . . 5
4.2. MAC Mobility Solution . . . . . . . . . . . . . . . . . . 5
5. E-tree for UMR . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Scenario 1: Leaf or Root Site(s) per EVI . . . . . . . . 6
5.2. Scenario 2: Leaf or Root Site(s) per AC . . . . . . . . . 7
5.3. Known Unicast Traffic For Leaf or Root Site(s) per EVI . 8
5.4. Known Unicast Traffic For Leaf or Root Site(s) per AC . . 8
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
In DCI scenario, if multiple DCs are interconnected into a single
EVI, each DC will have to import all of the MAC addresses from each
of the other DCs. [RFC9014]. In addition, in user authentication
scenario, a large number of users send authentication packets to the
aggregation device through the access device, as a result, there are
large scale of MAC addresses on RRs and aggregation devices. This
document describes the use of the Unknown MAC-route(UMR). The
solution advertises an unknown MAC-route (UMR) route[RFC9014] instead
of advertising all specific MAC routes and reducing the MAC scale.
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However, since the solution only sends UMR routes instead of
advertising specific MAC routes, the MAC mobility function of EVPN
cannot take effect normally. In particular, this document describes
a MAC mobility procedure in UMR scenario.
Also, This document discusses how the functional requirements for
E-Tree service[RFC8317] can be met with a solution based on UMR
application in EVPN. The details of this function are described in
Section 5.
2. Terminology
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
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
"GW": Gateway or Data Center Gateway
"DC": Data Center
"NVE": Network Virtualization Edge
"UMR": Unknown MAC Route
"E-Tree": Ethernet-Tree
"I-ES and I-ESI": Interconnect Ethernet Segment and Interconnect
Ethernet Segment Identifier. An I-ES is defined on the GWs for
multihoming to/from the WAN.
3. The procedure of UMR
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+----------+
| |
| GW |
| |
+----,-----+
/ `.
.' ',
.` .
/ `,
EVPN EVPN
,' `.
/ ',
` .
,' `,
+------+ +---'--+
| | | |
| NVE1| | NVE2|
| | | |
+------+ +------+
|---DC1---| |--DC2--|
Figure 1
1. All the MAC addresses are learned on NVE1/NVE2 within DC should
advertised to DC's GW device accrording EVPN MAC/IP routes in the
control plane.
2. All the MAC addresses are learned on NVE within DC should
advertised to the other NVE that in the same DC, so that the NVE to
NVE that in the same DC communication is always direct and does not
go through the GW[RFC7543].
3. The MAC addresses are learned on NVE should not advertised to the
other NVE that in the different DC.
4. The DC's GW advertise UMR route to NVE1/NVE2 instead of
advertising the specific MAC in order to reduce the device's routes
pressure. The UMR route is defined in [RFC7543] [RFC9014]and is a
regular EVPN MAC/IP advertisement route in which the MAC address
length is set to 48, the MAC address is set to 0, and the ESI field
is set to DC's GW I-ES.
5. NVE1/NVE2 need to understand and process the UMR route, send
frame to GW. Then GW will forward the packet to correct NVE.
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4. MAC Mobility for UMR
As shown above, since GW only sends UMR routes to NVE devices, NVE
will not import the MAC addresses of NVEs in different DCs. When the
MAC of DC1 migrates from NVE1 to DC2's NVE2, NVE1 will not perceive
this migration and keep learning the MAC that has migrated to NVE2.
As a result, the frame traffic to MAC from GW may go to wrong site.
4.1. MAC Mobility Issue
Step1: The user first goes online from NVE1, NVE1 learns the user's
MAC1, and advertise EVPN MAC1 route to GW.
Step2: The GW receives the MAC1 route from NVE1, installs MAC1 to the
local MAC-VRF table which the next hop of MAC1 is NVE1. Since it
only sends UMR routes to NVE, it will not send EVPN MAC1 route to
NVE2.
Step3: The user migrates to NVE2 and goes online. NVE2 learns the
user's MAC1 and advertise EVPN MAC1 route to GW.
Step4: The GW receives the MAC1 route from NVE2, which has the same
prefix as the MAC1 route from NVE1, as a result, the GW will form
load balancing MAC-VRF table.
Step5: As a result, the frame traffic sent to MAC1 via the GW may be
sent to NVE1 by mistake until MAC1 on NVE1 ages out.
4.2. MAC Mobility Solution
In order to solve this mac migration issue, the GW SHOULD advertise
the MAC route to the NVE when the GW detect the MAC has been
migrated. There are two scenarios as follows.
1. One of the scenario:
Step1: When the GW receives MAC routes that have the same prefix,
rather than different next hop and different ESI, the following
conclusion can be drawn, which the MAC has been migrated. At the
same time, the GW only send UMR route.
Step2: If MAC route from NVE1 is selected as the best, the GW
advertise MAC1 route to NVE2 with a MAC mobility extended
community[RFC7432], that carrying the increased seq number.
Step3: The NVE2 receives the MAC1 route with MAC mobility extended
community, and will select the MAC1 from the GW as the best, and
withdraw the MAC1 originally sent to the GW.
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Step4: The traffic from user will re-triggers NVE2 to learn the local
MAC1, which resulting in migration, and the NVE2 will advertise MAC1
route with MAC mobility extended community that carrying the seq + 1.
Step5: When the GW receives the MAC1 route with MAC mobility extended
community that carrying seq + 1, the GW will select the MAC1 from
NVE2 as best, and send MAC1 route with seq + 1 to NVE1.
Step6: After receiving the MAC1 route with MAC mobility extended
community that carrying seq + 1, the NVE1 will select the MAC1 from
the GW as the best, and withdraw the MAC1 originally sent to the GW.
2. The other scenario:
Step1: When the GW receives MAC routes that have the same prefix,
rather than different next hop and different ESI, the following
conclusion can be drawn, which the MAC has been migrated. At the
same time, the GW only send UMR route.
Step2: If MAC route from NVE2 is selected as the best, the GW
advertise MAC1 route to NVE1 with a MAC mobility extended community,
that carrying the increased seq number.
Step3: After receiving the MAC1 route with MAC mobility extended
community that carrying seq + 1, the NVE1 will select the MAC1 from
the GW as the best, and withdraw the MAC1 originally sent to the GW.
5. E-tree for UMR
In this scenario, since PE only sends UMR routes to remote PE devices
instead of advertising the specific MAC, In this case, it is not
possible to identify whether the UMR routes originates from Root ACs
or Leaf ACs. In this way, unicast traffic isolation between Leafs
cannot be achieved.
5.1. Scenario 1: Leaf or Root Site(s) per EVI
In this scenario, a given EVPN Instance (EVI) on PE device is either
associated with Root(s) or Leaf(s), but not both. PE may receive
traffic from either Root ACs or Leaf ACs for a given MAC-VRF/bridge
table with UMR route. So the UMR route to Leaf ACs or Root ACs of a
given EVPN Instance need to be colored with a Root or Leaf-Indication
before advertising to remote PE. E-Tree Extended Community[RFC8317]
can be used for such coloring. The leaf-indication indicates the UMR
route has a leaf attribute. When the E-Tree extended community is
advertised with the UMR advertisement route, the Leaf-Indication flag
MUST be set to one and the Leaf label SHOULD be set to zero.
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+---------+ +---------+
| PE1 | | PE2 |
+---+ | +---+ | | +---+ | +---+
|CE1+---AC1----+--+ | | | | +--+----AC3-----+CE3|
+---+ (Leaf) | |MAC| | ---EVPN--- | |MAC| | (Leaf) +---+
| |VRF| | | |VRF| |
+---+ | | | | | | | |
|CE2+---AC2----+--| | | | | | |
+---+ (Leaf) | +---+ | | +---+ |
+---------+ +---------+
Figure 2
5.2. Scenario 2: Leaf or Root Site(s) per AC
In this scenario, a given EVPN Instance (EVI) on PE device can be
associated with both Root(s) and Leaf(s). For example, in the figure
below, PE for an EVPN Instance (EVI) has both Leaf and Root ACs. In
this scenario, ingress filtering for known unicast traffic is not
performed just like scenario-1 and thus need to receive the unicast
traffic and perform egress filtering.
In order to perform egress filtering for unicast traffic received at
the egress PE, the ingress PE need to color the unicast traffic in
data-plane to indicate if the traffic is coming from a Root or Leaf
AC. E-Tree Extended Community[RFC8317] also can be used for such
scenario. When the E-Tree extended community is advertised with the
UMR advertisement route for such scenario, the Leaf-Indication flag
MUST be set to zero and the Leaf label MUST be valid.
+---------+ +---------+
| PE1 | | PE2 |
+---+ | +---+ | | +---+ | +---+
|CE1+---AC1----+--+ | | | | +--+----AC3-----+CE3|
+---+ (Leaf) | |MAC| | ---EVPN--- | |MAC| | (Leaf) +---+
| |VRF| | | |VRF| |
+---+ | | | | | | | | +---+
|CE2+---AC2----+--| | | | | +--+----AC4-----+CE4|
+---+ (Root) | +---+ | | +---+ | (Root) +---+
+---------+ +---------+
Figure 3
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5.3. Known Unicast Traffic For Leaf or Root Site(s) per EVI
To provide the ingress filtering for known unicast traffic, a PE MUST
indicate to other PEs what kind of sites (Root or Leaf) its UMR MAC
address are associated with. This is done by advertising a Leaf-
Indication flag via E-Tree extended community [RFC8317] along with
its UMR MAC/IP Advertisement routes learned from a Leaf site. This
E-Tree extended community MUST be advertised with UMR MAC/IP
Advertisement routes learned from a Leaf site. The lack of such a
flag indicates that the UMR MAC address is associated with a Root
site. This scheme applies to scenario-1 (Leaf or Root Site(s) per
EVI) described in Section 5.
Tagging UMR MAC address with a Leaf-Indication enables remote PEs to
perform ingress filtering for known unicast traffic. After receiving
the UMR, PE2 generates a default MAC address entry comprising a full
zero MAC address and the a leaf-indication. So, on the ingress PE,
the MAC destination address lookup yields (in addition to the UMR
forwarding adjacency) a flag than indicates whether or not the target
UMR MAC is associated with a Leaf site. The ingress PE(e.g. PE2)
cross-checks this flag with the status of the originating AC, and if
both are Leafs, then the packet is dropped. Otherwise, if both are
not leafs, then the packet is forwarded.
5.4. Known Unicast Traffic For Leaf or Root Site(s) per AC
This section specifies the procedure for egress filtering of known
unicast traffic with MPLS encapsulation. To support scenario-2
efficiently, egress filtering of known unicast traffic is required as
described below. In order to apply the proper egress filtering,
which varies based on whether a packet is sent from a Leaf AC or a
Root AC, the MPLS-encapsulated frames MUST be tagged with an
indication of when they originated from a Leaf AC. This Leaf label
allows for disposition PE (e.g., egress PE) to perform the necessary
egress filtering function in a data plane similar to the MPLS label1
in [RFC7432].
If a PE receive UMR route with E-Tree extended community that has
both Root-Indication and Leaf-Indication set along with a valid Leaf
label, then the receiving PE (Root-only, Root-and-Leaf, or Leaf-only)
add both MPLS label1 [RFC7432] and Leaf label to MAC-VRF/bridge
table.
The ingress PE cross-checks this flag with the status of the
originating AC. If the originating AC is Leaf, then the packet is
encapsulated in the EVPN Leaf label advertised by the remote PE, for
that MAC address, and in the MPLS LSP label stack to reach the remote
PE[RFC7432]. Accroding to receiving the packet with Leaf label, the
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egress PE checks the MAC-VRF/bridge table according to the
destination MAC and filtering the Leaf AC before forwarding. If the
originating AC is Root, then the packet is encapsulated in the EVPN
MPLS label addvertised by the remote PE, for that MAC address, and in
the MPLS LSP label stack to reach the remote PE. If the top MPLS
label ends up being an EVPN label that was advertised in the unicast
MAC advertisements, then the PE either forwards the packet based on
CE next-hop forwarding information associated with the label or does
a destination MAC address lookup to forward the packet to a
CE[RFC7432].
6. IANA considerations
TBD
7. Security Considerations
TBD
8. References
8.1. Normative References
[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>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7543] Jeng, H., Jalil, L., Bonica, R., Patel, K., and L. Yong,
"Covering Prefixes Outbound Route Filter for BGP-4",
RFC 7543, DOI 10.17487/RFC7543, May 2015,
<https://www.rfc-editor.org/info/rfc7543>.
[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>.
[RFC8317] Sajassi, A., Ed., Salam, S., Drake, J., Uttaro, J.,
Boutros, S., and J. Rabadan, "Ethernet-Tree (E-Tree)
Support in Ethernet VPN (EVPN) and Provider Backbone
Bridging EVPN (PBB-EVPN)", RFC 8317, DOI 10.17487/RFC8317,
January 2018, <https://www.rfc-editor.org/info/rfc8317>.
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[RFC9014] Rabadan, J., Ed., Sathappan, S., Henderickx, W., Sajassi,
A., and J. Drake, "Interconnect Solution for Ethernet VPN
(EVPN) Overlay Networks", RFC 9014, DOI 10.17487/RFC9014,
May 2021, <https://www.rfc-editor.org/info/rfc9014>.
8.2. Informative References
Authors' Addresses
Zheng Fu
Huawei Technologies
No.101 Software Avenue, Yuhuatai District
Nanjing
210012
China
Email: fuzheng7@huawei.com
Tong Zhu
Huawei Technologies
No.101 Software Avenue, Yuhuatai District.
Nanjing
210012
China
Email: zhu.tong@huawei.com
Haibo Wang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Email: rainsword.wang@huawei.com
Jian Dai
Huawei Technologies
No.101 Software Avenue, Yuhuatai District
Nanjing
210012
China
Email: daijian2@huawei.com
Dawei Wang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
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Beijing
100095
China
Email: wang.dawei@huawei.com
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