Virtual Subnet: A BGP/MPLS IP VPN-Based Subnet Extension Solution
RFC 7814
Internet Engineering Task Force (IETF) X. Xu
Request for Comments: 7814 Huawei Technologies
Category: Informational C. Jacquenet
ISSN: 2070-1721 Orange
R. Raszuk
T. Boyes
Bloomberg LP
B. Fee
Extreme Networks
March 2016
Virtual Subnet: A BGP/MPLS IP VPN-Based Subnet Extension Solution
Abstract
This document describes a BGP/MPLS IP VPN-based subnet extension
solution referred to as "Virtual Subnet", which can be used for
building Layer 3 network virtualization overlays within and/or
between data centers.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7814.
Xu, et al. Informational [Page 1]
RFC 7814 Virtual Subnet March 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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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Solution Description . . . . . . . . . . . . . . . . . . . . 5
3.1. Unicast . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. Intra-subnet Unicast . . . . . . . . . . . . . . . . 5
3.1.2. Inter-subnet Unicast . . . . . . . . . . . . . . . . 6
3.2. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Host Discovery . . . . . . . . . . . . . . . . . . . . . 9
3.4. ARP/ND Proxy . . . . . . . . . . . . . . . . . . . . . . 9
3.5. Host Mobility . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Forwarding Table Scalability on Data-Center Switches . . 10
3.7. ARP/ND Cache Table Scalability on Default Gateways . . . 10
3.8. ARP/ND and Unknown Unicast Flood Avoidance . . . . . . . 10
3.9. Path Optimization . . . . . . . . . . . . . . . . . . . . 10
4. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Non-support of Non-IP Traffic . . . . . . . . . . . . . . 11
4.2. Non-support of IP Broadcast and Link-Local Multicast . . 11
4.3. TTL and Traceroute . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Normative References . . . . . . . . . . . . . . . . . . 12
6.2. Informative References . . . . . . . . . . . . . . . . . 13
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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RFC 7814 Virtual Subnet March 2016
1. Introduction
For business continuity purposes, Virtual Machine (VM) migration
across data centers is commonly used in situations such as data-
center maintenance, migration, consolidation, expansion, or disaster
avoidance. The IETF community has recognized that IP renumbering of
servers (i.e., VMs) after the migration is usually complex and
costly. To allow the migration of a VM from one data center to
another without IP renumbering, the subnet on which the VM resides
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