Internet DRAFT - draft-boutros-nvo3-mac-move-over-geneve
draft-boutros-nvo3-mac-move-over-geneve
INTERNET-DRAFT Sami Boutros
Intended Status: Standard Track Jerome Catrouillet
Sri Mohana Singamsetty
VMware
Parag Jain
Cisco
Expires: March 22, 2020 September 19, 2019
MAC move over Geneve encapsulation
draft-boutros-nvo3-mac-move-over-geneve-02
Abstract
This document specifies a mechanism to signal Media Access Control
(MAC) addresses move over a Network Virtualization Overlays over
Layer 3 (NVO3) virtual tunnel. Such notification is useful in
redundancy scenarios when a Layer 2 service that was active on a
Network Virtualization Edge (NVE) fails over to a standby NVE. This
notification can be used only when data plane mac learning is enabled
over the NVO3 tunnels.
Status of this Memo
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Copyright and License Notice
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . 3
2. MAC Move Frame Format . . . . . . . . . . . . . . . . . . . . . 5
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Operation of Sender . . . . . . . . . . . . . . . . . . . . 6
3.2 Operation of Receiver . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Normative References . . . . . . . . . . . . . . . . . . . 8
6.2 Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1 Introduction
In multi-homing scenarios a Layer 2 service can be multi-homed to
more than one Network virtualization Edge (NVE). Only one NVE can be
active for a given Layer 2 service, and a standby NVE can be chosen
to take over the Layer 2 service when the active NVE goes down. The
mechanisms to elect which NVE will be active or standby to provide
single active redundancy for a given Layer 2 service is outside the
scope of this document.
When a standby NVE gets activated, Standby NVE needs to send a MAC
Move message to all remote NVE(s) that spans this L2 service over the
Geneve tunnels to Move all MAC learned in data plane via the old
active NVE.
The MAC Move message will contain the NVE Identifier(s) of the old
Active NVE and the new active NVE.
MAC Move can be used to optimize network convergence and reduce
blackholes, when an active NVE hosting a logical L2 service fails
over to a standby NVE.
The protocol defined in this document addresses possible loss of the
MAC Move messages due to network congestion, but does not guarantee
delivery.
In the event that MAC Move messages does not reach the intended
target, the fallback to MAC re-learning or as a last resort aging out
of MAC addresses in the absence of frames from the sources, will
resume the traffic via new active NVE.
1.1 Terminology
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 RFC 2119 [RFC2119].
1.2 Abbreviations
NVO3 Network Virtualization Overlays over Layer 3
OAM Operations, Administration, and Maintenance
TLV Type, Length, and Value
VNI Virtual Network Identifier
NVE Network Virtualization Edge
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NVA Network Virtualization Authority
NIC Network interface card
VTEP Virtual Tunnel End Point
Transit device Underlay network devices between NVE(s).
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2. MAC Move Frame Format
Geneve Header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| Opt Len |O|C| Rsvd. | Protocol Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Virtual Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Geneve Option Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Class | Type |R|R|R| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Option Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Class = To be assigned by IANA (TBA).
Type = TBA.
'C' bit, Endpoints must drop if they do not recognize this option)
Length = 2 (8 bytes)
Variable option data:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version|Flags |A|R| old active VTEP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Reserved | new active VTEP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Version (4 bits): Initially the Version will be 0.
A (1 bit): Set by a receiver to acknowledge receipt and processing
of a MAC Move message.
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R (1 bit): Set to indicate if the sender is requesting reset of
the sequence numbers. The sender sets this bit when it has no
local record of previous send and expected receive sequence
numbers.
Flags(6): Reserved and should be set to 0.
VTEP ID (20 bits): Identifies old and new active NVE(s).
Sequence Number (32) bits: For overflow detection a sequence
number that exceeds (0x7FFFFFFF) is considered an overflow and
reset to 1.
3. Operation
This section describes how the initial MAC Move Messages are sent and
retransmitted, as well as how the messages are processed and
retransmitted messages are identified. The mechanisms described are
very similar to the one defined in [RFC 7769].
3.1 Operation of Sender
At the NVE , each L2 logical switch identified by a VNI is associated
with a counter to keep track of the sequence number of the
transmitted MAC Move messages. Whenever a node sends a MAC Move
message, it increments the transmitted sequence-number counter and
includes the new sequence number in the message.
The transmit sequence number is initialized to 1 at the onset, after
the wrap and after the sequence number reset request receipt. Hence
the transmit sequence number is set to 2 in the first MAC Move
message sent after the sequence number is initialized to 1.
The sender expects an ACK from the receiver within a retransmit time
interval, which can be either a default (1 second) or a configured
value. If the ACK is not received within the Retransmit time, the
sender retransmits the message with the same sequence number as the
original message. The retransmission MUST cease when an ACK is
received. In order to avoid continuous re-transmissions in the
absence of acknowledgements, the sender MUST cease retransmission
after a small number of transmissions, two retries is RECOMMENDED.
Alternatively, an increasing backoff delay with a larger number of
retries MAY be implemented to improve scaling issues.
During the period of retransmission, if a need to send a new MAC Move
message with updated sequence number arises, then retransmission of
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the older unacknowledged Move message MUST be suspended and
retransmit time for the new sequence number MUST be initiated. In
essence, a sender engages in retransmission logic only for the most
recently sent Move message for a given L2 Logical Switch identified
by a VNI.
In the event that the L2 logical switch is deleted and re-added or
the VTEP node is restarted with new configuration, the NVE may lose
information about the previously sent sequence number. This becomes
problematic for the remote peer as it will continue to ignore the
received MAC Move messages with lower sequence numbers. In such
cases, it is desirable to reset the sequence numbers, the reset R-bit
is set in the first MAC Move to notify the remote peer to reset the
send and receive sequence numbers. The R-bit must be cleared in
subsequent MAC Move messages after the acknowledgement is received.
3.2 Operation of Receiver
Each L2 logical switch identified by a VNI is associated with a
receive sequence number per remote NVE to keep track of the expected
sequence number of the MAC Move message.
Whenever a MAC Move message is received, and if the sequence number
on the message is greater than the value in the receive sequence
number of this remote NVE, the MAC addresses learned from the NVE
associated with the NVE identifier in the message are moved to be
associated with the new active NVE identifier, and the receive
sequence number of the remote NVE is updated with the received
sequence number. The receiver sends an ACK with the same sequence
number in the received message.
If the sequence number in the received message is smaller than or
equal to the value in the receive sequence number per remote NVE, the
MAC Move is not processed. However, an ACK with the received sequence
number MUST be sent as a response to stop the sender retransmission.
A MAC Move message with the R-bit set MUST be processed by resetting
the receive sequence number of the remote NVE, and Moving the MACs as
described above. The acknowledgement is sent with the R-bit cleared.
4. Security Considerations
This document does not introduce any additional security constraints.
5. IANA Considerations
IANA is requested to assign a new option class from the "Geneve
Option Class" registry for the Geneve MAC Move option.
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Option Class Description
------------ ---------------------
XXXX Geneve MAC Move
6 References
6.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2 Informative References
[Geneve] "Generic Network Virtualization Encapsulation", [I-D.ietf-
nvo3-geneve]
[RFC 7769] "MAC Address Withdrawal over Static PW", [RFC 7769]
Authors' Addresses
Sami Boutros
VMware
Email: boutross@vmware.com
Jerome Catrouillet
VMware
Email: jcatrouillet@vmware.com
Sri Mohana Singamsetty
Email: msingamsetty@vmware.com
Ankur Sharma
VMware
Email: ankursharma@vmware.com
Parag Jain
Cisco
Email: paragj@cisco.com
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