Network Working Group B. Sarikaya
Internet-Draft L. Dunbar
Intended status: Best Current Practice Huawei USA
Expires: September 11, 2016 B. Khasnabish
ZTE (TX) Inc.
F. Xia
Huawei
March 10, 2016
Virtual Machine Mobility Protocol for Overlay Networks
draft-sarikaya-nvo3-vmm-dmm-pmip-09.txt
Abstract
This document describes a virtual machine mobility protocol commonly
used in data centers built with overlay-based network virtualization
approach. It is based on using a Network Virtualization Authority
(NVA)-Network Virtualization Edge (NVE) protocol to update Address
Resolution Protocol (ARP) table or neighbor cache entries at the NVA
and the source NVEs tunneling in-flight packets to the destination
NVE after the virtual machine moves from source NVE to the
destination NVE.
Status of This Memo
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This Internet-Draft will expire on September 11, 2016.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Overview of the protocol . . . . . . . . . . . . . . . . . . 4
5. Handling Packets in Flight . . . . . . . . . . . . . . . . . 5
6. Moving Local State of VM . . . . . . . . . . . . . . . . . . 6
7. Handling of Hot, Warm and Cold Virtual Machine Mobility . . . 6
8. Virtual Machine Operation . . . . . . . . . . . . . . . . . . 7
8.1. Virtual Machine Lifecycle Management . . . . . . . . . . 7
9. Security Considerations . . . . . . . . . . . . . . . . . . . 7
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
12.1. Normative References . . . . . . . . . . . . . . . . . . 8
12.2. Informative references . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Data center networks are being increasingly used by telecom operators
as well as by enterprises. In this document we are interested in
overlay-based data center networks supporting multitenancy. These
networks are organized as one large Layer 2 network geographically
distributed in several buildings.
Virtualization which is being used in almost all of today's data
centers enables many virtual machines to run on a single physical
computer or compute server. Virtual machines (VM) need hypervisor
running on the physical compute server to provide them shared
processor/memory/storage. Network connectivity is provided by the
network virtualization edge (NVE) [I-D.ietf-nvo3-arch],
[I-D.ietf-nvo3-nve-nva-cp-req]. Being able to move VMs dynamically,
or live migration, from one server to another allows for dynamic load
balancing or work distribution and thus it is a highly desirable
feature [RFC7364].
There are many challenges and requirements related to migration,
mobility, and interconnection of Virtual Machines (VMs)and Virtual
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Network Elements (VNEs). Retaining IP addresses after a move is a
key requirement [RFC7364]. Such a requirement is needed in order to
maintain existing transport connections.
In view of many virtual machine mobility schemes that exist today,
there is a desire to define a standard control plane protocol for
virtual machine mobility. The protocol should be based on IPv4 or
IPv6. In this document we specify such a protocol.
2. Conventions and 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] and
[I-D.ietf-nvo3-arch].
This document uses the terminology defined in [RFC7364]. In addition
we make the following definitions:
Hot VM Mobility. A given VM could be moved from one server to
another in running state.
Warm VM Mobility. In case of warm VM mobility, the VM states are
mirrored to the secondary server (or domain) at a predefined
(configurable) regular intervals. This reduces the overheads and
complexity but this may also lead to a situation when both servers
may not contain the exact same data (state information)
Cold VM Mobility. A given VM could be moved from one server to
another in stopped or suspended state.
3. Requirements
This section states requirements on data center network virtual
machine mobility.
Data center network SHOULD support virtual machine mobility in IPv6.
IPv4 SHOULD also be supported in virtual machine mobility.
Virtual machine mobility protocol SHOULD not support host routes.
Virtual machine mobility protocol SHOULD not support triangular
routing. Virtual machine mobility protocol SHOULD not need to use
tunneling except for handling packets in flight.
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4. Overview of the protocol
Being able to move Virtual Machines dynamically, from one server to
another allows for dynamic load balancing or work distribution and
thus it is a highly desirable feature. In a Layer-2 based data
center approach, virtual machine moving to another server does not
change its IP address. Because of this an IP based virtual machine
mobility protocol is not needed. However, when a virtual machine
moves, NVEs need to change their caches associating VM Layer 2 or MAC
address with NVE's IP address. Such a change enables NVE to send
outgoing MAC frames addressed to the virtual machine.
Virtual machine moves from its source NVE to a new, destination NVE.
The move is initiated by the source NVE and is in the same L2 link,
the virtual machine IP address(es) do not change but this virtual
machine is now under a new NVE, previously communicating NVEs will
continue to send their packets to the source NVE. Address Resolution
Protocol (ARP) cache in IPv4 [RFC0826] or neighbor cache in IPv6 in
the NVEs need to be updated.
It takes a few seconds for a VM to move from its source NVE to the
new destination one. During this period, a tunnel is needed so that
source NVE forwards packets to the destination NVE.
In IPv4, the virtual machine immediately after the move sends a
gratuitous ARP request message containing its IPv4 and Layer-2 or MAC
address in its new NVE, destination NVE. This message's destination
address is the broadcast address. NVE receives this message. NVE
should update VM's ARP entry in the central directory at the NVA.
NVE updates NVA to record IPv4 address of VM along with MAC address
of VM, and NVE IPv4 address. An NVE-to-NVA protocol is used for this
purpose [I-D.ietf-nvo3-arch].
Reverse ARP (RARP) which enables the host to discover its IPv4
address when it boots from a local server [RFC0903] is not used by
VMs because the VM already knows its IPv4 address. IPv4/v6 address
is assigned to a newly created VM, possibly using Dynamic Host
Configuration Protocol (DHCP).
All NVEs communicating with this virtual machine uses the old ARP
entry. If any VM in those NVEs need to talk to the new VM in the
destination NVE, it uses the old ARP entry. Thus the packets are
delivered to the source NVE. The source NVE MUST tunnels these in-
flight packets to the destination NVE.
When an ARP entry in those VMs times out, their corresponding NVEs
should access the NVA for an update.
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IPv6 operation is slightly different:
In IPv6, the virtual machine immediately after the move sends an
unsolicited neighbor advertisement message containing its IPv6
address and Layer-2 MAC address in its new NVE, the destination NVE.
This message is sent to the IPv6 Solicited Node Multicast Address
corresponding to the target address which is VM's IPv6 address. NVE
receives this message. NVE should update VM's neighbor cache entry
in the central directory at the NVA. IPv6 address of VM, MAC address
of VM and NVE IPv6 address are recorded to the entry. An NVE-to-NVA
protocol is used for this purpose [I-D.ietf-nvo3-arch].
All NVEs communicating with this virtual machine uses the old
neighbor cache entry. If any VM in those NVEs need to talk to the
new VM in the destination NVE, it uses the old neighbor cache entry.
Thus the packets are delivered to the source NVE. The source NVE
MUST tunnels these in-flight packets to the destination NVE.
When a neighbor cache entry in those VMs times out, their
corresponding NVEs should access the NVA for an update.
5. Handling Packets in Flight
Source hypervisor may receive packets from the virtual machine's
ongoing communications and these packets should not be lost and they
should be sent to the destination hypervisor to be delivered to the
virtual machine. The steps involved in handling packets in flight
are as follows:
Preparation Step It takes some time, possibly a few seconds for a VM
to move from its source hypervisor to a new destination one.
During this period, a tunnel needs to be established so that
source NVE forwards packets to the destination NVE.
Tunnel Establishment - IPv6 Inflight packets are tunneled to the
destination NVE using the encapsulation protocol such as VXLAN in
IPv6. Source NVE gets destination NVE address from NVA in the
request to move the virtual machine.
Tunnel Establishment - IPv4 Inflight packets are tunneled to the
destination NVE using the encapsulation protocol such as VXLAN in
IPv4. Source NVE gets destination NVE address from NVA when NVA
requests NVE to move the virtual machine.
Tunneling Packets - IPv6 IPv6 packets are received for the migrating
virtual machine encapsulated in an IPv6 header at the destination
NVE. Destination NVE decapsulates the packet and sends IPv6
packet to the migrating VM.
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Tunneling Packets - IPv4 IPv4 packets are received for the migrating
virtual machine encapsulated in an IPv4 header at the destination
NVE. Destination NVE decapsulates the packet and sends IPv4
packet to the migrating VM.
Stop Tunneling Packets When source NVE stops receiving packets
destined to the virtual machine that has just moved to the
destination NVE.
6. Moving Local State of VM
After VM mobility related signaling (VM Mobility Registration
Request/Reply), the virtual machine state needs to be transferred to
the destination Hypervisor. The state includes its memory and file
system. Source NVE opens a TCP connection with destination NVE over
which VM's memory state is transferred.
File system or local storage is more complicated to transfer. The
transfer should ensure consistency, i.e. the VM at the destination
should find the same file system it had at the source. Precopying is
a commonly used technique for transferring the file system. First
the whole disk image is transferred while VM continues to run. After
the VM is moved any changes in the file system are packaged together
and sent to the destination Hypervisor which reflects these changes
to the file system locally at the destination.
7. Handling of Hot, Warm and Cold Virtual Machine Mobility
Cold Virtual Machine mobility is facilitated by the VM initially
sending an ARP or Neighbor Discovery message at the destination NVE
but the source NVE not receiving any packets inflight. Cold VM
mobility also allows all previous source NVEs and all communicating
NVEs to time out ARP/neighbor cache entries of the VM and then get
NVA to push to NVEs or get NVEs to pull the updated ARP/neighbor
cache entry from NVA.
The VMs that are used for cold standby receive scheduled backup
information but less frequently than that would be for warm standby
option. Therefore, the cold mobility option can be used for non-
critical applications and services.
In cases of warm standby option, the backup VMs receive backup
information at regular intervals. The duration of the interval
determines the warmth of the standby option. The larger the
duration, the less warm (and hence cold) the standby option becomes.
In case of hot standby option, the VMs in both primary and secondary
domains have identical information and can provide services
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simultaneously as in load-share mode of operation. If the VMs in the
primary domain fails, there is no need to actively move the VMs to
the secondary domain because the VMs in the secondary domain already
contains identical information. The hot standby option is the most
costly mechanism for providing redundancy, and hence this option is
utilized only for mission-critical applications and services.
8. Virtual Machine Operation
Virtual machines are not involved in any mobility signalling. Once
VM moves to the destination NVE, VM IP address does not change and VM
should be able to continue to receive packets to its address(es).
This happens in hot VM mobility scenarios.
Virtual machine sends a gratuitous Address Resolution Protocol or
unsolicited Neighbor Advertisement message upstream after each move.
8.1. Virtual Machine Lifecycle Management
Managing the lifecycle of VM includes creating a VM with all of the
required resources, and managing them seamlessly as the VM migrates
from one service to another during its lifetime. The on-boarding
process includes the following steps:
1. Sending an allowed (authorized/authenticated) request to Network
Virtualization Authority (NVA) in an acceptable format with
mandatory/optional virtualized resources {cpu, memory, storage,
process/thread support, etc.} and interface information
2. Receiving an acknowledgement from the NVA regarding availability
and usability of virtualized resources and interface package
3. Sending a confirmation message to the NVA with request for
approval to adapt/adjust/modify the virtualized resources and
interface package for utilization in a service.
9. Security Considerations
Security threats for the data and control plane are discussed in
[I-D.ietf-nvo3-arch]. This document does not introduce any new
security threats.
10. IANA Considerations
This document makes no request to IANA.
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11. Acknowledgements
The authors are grateful to Qiang Zu, Tom Herbert, Andrew Malis and
Saumya Dikshit for helpful comments.
12. References
12.1. Normative References
[RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or
Converting Network Protocol Addresses to 48.bit Ethernet
Address for Transmission on Ethernet Hardware", STD 37,
RFC 826, DOI 10.17487/RFC0826, November 1982,
<http://www.rfc-editor.org/info/rfc826>.
[RFC0903] Finlayson, R., Mann, T., Mogul, J., and M. Theimer, "A
Reverse Address Resolution Protocol", STD 38, RFC 903,
DOI 10.17487/RFC0903, June 1984,
<http://www.rfc-editor.org/info/rfc903>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
DOI 10.17487/RFC2629, June 1999,
<http://www.rfc-editor.org/info/rfc2629>.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008,
<http://www.rfc-editor.org/info/rfc5213>.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, DOI 10.17487/RFC5844, May 2010,
<http://www.rfc-editor.org/info/rfc5844>.
[RFC3007] Wellington, B., "Secure Domain Name System (DNS) Dynamic
Update", RFC 3007, DOI 10.17487/RFC3007, November 2000,
<http://www.rfc-editor.org/info/rfc3007>.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022,
DOI 10.17487/RFC3022, January 2001,
<http://www.rfc-editor.org/info/rfc3022>.
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[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC6820] Narten, T., Karir, M., and I. Foo, "Address Resolution
Problems in Large Data Center Networks", RFC 6820,
DOI 10.17487/RFC6820, January 2013,
<http://www.rfc-editor.org/info/rfc6820>.
[I-D.ietf-nvo3-vm-mobility-issues]
Rekhter, Y., Henderickx, W., Shekhar, R., Fang, L.,
Dunbar, L., and A. Sajassi, "Network-related VM Mobility
Issues", draft-ietf-nvo3-vm-mobility-issues-03 (work in
progress), June 2014.
[I-D.ietf-nvo3-arch]
Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
Narten, "An Architecture for Overlay Networks (NVO3)",
draft-ietf-nvo3-arch-04 (work in progress), October 2015.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<http://www.rfc-editor.org/info/rfc7348>.
[RFC7364] Narten, T., Ed., Gray, E., Ed., Black, D., Fang, L.,
Kreeger, L., and M. Napierala, "Problem Statement:
Overlays for Network Virtualization", RFC 7364,
DOI 10.17487/RFC7364, October 2014,
<http://www.rfc-editor.org/info/rfc7364>.
[RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
Rekhter, "Framework for Data Center (DC) Network
Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
2014, <http://www.rfc-editor.org/info/rfc7365>.
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12.2. Informative references
[I-D.ietf-nvo3-nve-nva-cp-req]
Kreeger, L., Dutt, D., Narten, T., and D. Black, "Network
Virtualization NVE to NVA Control Protocol Requirements",
draft-ietf-nvo3-nve-nva-cp-req-04 (work in progress), July
2015.
[I-D.wkumari-dcops-l3-vmmobility]
Kumari, W. and J. Halpern, "Virtual Machine mobility in L3
Networks.", draft-wkumari-dcops-l3-vmmobility-00 (work in
progress), August 2011.
[I-D.shima-clouds-net-portability-reqs-and-models]
Shima, K., Sekiya, Y., and K. Horiba, "Network Portability
Requirements and Models for Cloud Environment", draft-
shima-clouds-net-portability-reqs-and-models-01 (work in
progress), October 2011.
[I-D.raggarwa-data-center-mobility]
Aggarwal, R., Rekhter, Y., Henderickx, W., Shekhar, R.,
Fang, L., and A. Sajassi, "Data Center Mobility based on
E-VPN, BGP/MPLS IP VPN, IP Routing and NHRP", draft-
raggarwa-data-center-mobility-07 (work in progress), June
2014.
[I-D.khasnabish-vmmi-problems]
Khasnabish, B., Liu, B., Lei, B., and F. Wang, "Mobility
and Interconnection of Virtual Machines and Virtual
Network Elements", draft-khasnabish-vmmi-problems-03 (work
in progress), December 2012.
Authors' Addresses
Behcet Sarikaya
Huawei USA
5340 Legacy Dr. Building 3
Plano, TX 75024
Email: sarikaya@ieee.org
Linda Dunbar
Huawei USA
5340 Legacy Dr. Building 3
Plano, TX 75024
Email: linda.dunbar@huawei.com
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Bhumip Khasnabish
ZTE (TX) Inc.
55 Madison Avenue, Suite 160
Morristown, NJ 07960
Email: vumip1@gmail.com, bhumip.khasnabish@ztetx.com
Frank Xia
Huawei
Nanjing, China
Phone: +1 972-509-5599
Email: xiayangsong@huawei.com
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