Internet Engineering Task Force S. Pallagatti, Ed.
Internet-Draft B. Saji
Intended status: Standards Track S. Paragiri
Expires: January 7, 2016 Juniper Networks
V. Govindan
M. Mudigonda
Cisco
G. Mirsky
Ericsson
July 6, 2015
BFD for VXLAN
draft-spallagatti-bfd-vxlan-01
Abstract
This document describes use of Bidirectional Forwarding Detection
(BFD) protocol for VXLAN . Comments on this draft should be directed
to nvo3@ietf.org, rtg-bfd@ietf.org.
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 RFC 2119 [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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 7, 2016.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. BFD Packet Encapsulation . . . . . . . . . . . . . . . . . . 5
5. Reception of BFD packet . . . . . . . . . . . . . . . . . . . 5
5.1. Demux of the BFD packet . . . . . . . . . . . . . . . . . 6
6. Echo BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
11. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
"Virtual eXtensible Local Area Network (VXLAN)" has been defined in
[RFC7348] that provides an encapsulation scheme which allows VM's to
communicate in data centre network.
VXLAN is typically deployed in data centres on virtualized hosts,
which may be spread across multiple racks. The individual racks may
be parts of a different Layer 3 network or they could be in a single
Layer 2 network. The VXLAN segments/overlay networks are overlaid on
top of these Layer 2 or Layer 3 networks.
A VM can communicate with a VM in other host only if they are on same
VXLAN. VM's are unaware of VXLAN tunnels as VXLAN tunnel terminates
on VTEP (hypervisor/TOR). VTEP (hypervisor/TOR) are responsible for
encapsulating and decapsulating frames sent from VM's.
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Since underlay is a L3 network, connectivity check for these tunnels
becomes important. BFD as defined in [RFC5880] can be used to
monitor the VXLAN tunnels.
This draft addresses requirements outlined in
[I-D.ashwood-nvo3-operational-requirement]. Specifically with
reference to the OAM model to Figure 3 of
[I-D.ashwood-nvo3-operational-requirement], this draft outlines
proposal to implement the OAM mechanism between the NV Edges using
BFD.
2. Use cases
Main use case of BFD for VXLAN is for tunnel connectivity check.
There are other use cases such as
Layer 2 VM's:
Most deployments will have VM's with only L2 capabilities and
may not understand L3. BFD being a L3 protocol can be used for
tunnel connectivity check, where BFD will start and terminate
at the NV Edge (VTEPs).
It is possible to aggregate the connectivity checks for
multiple tenants by running a BFD session between the VTEPs
over VxLAN tunnel. In rest of this document terms NV Edge and
VTEP are used interchangeably.
Fault localization:
It is also possible that VM's are L3 aware and can possibly
host a BFD session. In these cases BFD sessions can be
established between VM's for connectivity check. In addition a
BFD session can be established between VTEPs for tunnel
connectivity check. Having a hierarchical OAM model helps
localize faults.
Service node reachability:
Service node is responsible for sending BUM traffic. In case
of service node tunnel terminates at VTEP and it might not even
host VM's. If TOR's/Hypervisor wants to check service node
reachability then it would like run BFD session over VXLAN
tunnel to service node.
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3. Deployment
+------------+-------------+
| Server 1 |
| |
| +----+----+ +----+----+ |
| |VM1-1 | |VM1-2 | |
| |VNI 100 | |VNI 200 | |
| | | | | |
| +---------+ +---------+ |
| Hypervisor VTEP (IP1) |
+--------------------------+
|
|
|
| +-------------+
| | Layer 3 |
|---| Network |
| |
+-------------+
|
|
+-----------+
|
|
+------------+-------------+
| Hypervisor VTEP (IP2) |
| +----+----+ +----+----+ |
| |VM2-1 | |VM2-2 | |
| |VNI 100 | |VNI 200 | |
| | | | | |
| +---------+ +---------+ |
| Server 2 |
+--------------------------+
Figure 1
Figure 1 illustrates a scenario where we have two servers, each of
them hosting two VMs. These VTEPs terminate two VXLAN tunnels with
VNI number 100 and 200 between them. Separate BFD sessions can be
established between the VTEPs (IP1 and IP2) for monitoring each of
the VXLAN tunnels (VNI 100 and 200). No BFD packet intended to
Hypervisor VTEP should be forwarded to VM's as VM's may drop this
leading to false negative. This method is also applicable VTEP which
are either software or physical device.
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4. BFD Packet Encapsulation
VxLAN packet format has been defined in Section 5 of [RFC7348]. The
Outer IP/UDP and VXLAN headers MUST be encoded by the sender as per
[RFC7348].
If VTEP is equipped with GPE header capitalises and decides to use
GPE instead of VXLAN then GPE header MUST be encoded as per
Section 3.3 of [I-D.quinn-vxlan-gpe]. Next Protocol Field in GPE
header MUST be set to IPv4 or IPv6.
Details of how VTEP decides to use VXLAN or GPE header is outside the
scope of this document.
The BFD packet MUST be carried inside the inner MAC frame of the
VxLAN packet. The inner MAC frame carrying the BFD payload has the
following format:
Ethernet Header:
Destination MAC: This MUST be a well-known MAC [TBD] OR the MAC
address of the destination VTEP. The details of how the
destination MAC address is obtained is outside the scope of
this document.
Source MAC: MAC address of the originating VTEP
IP header:
Source IP: IP address of the originating VTEP.
Destination IP: IP address of the terminating VTEP.
TTL: This MUST be set to 1. This is to ensure that the BFD
packet is not routed within the L3 underlay network.
Note: Inner source and destination IP needs more discussion in
WG.
The fields of the UDP header and the BFD control packet are
encoded as specified in RFC 5881.
5. Reception of BFD packet
Once a packet is received, VTEP MUST validate the packet as described
in Section 4.1 of [RFC7348]. If the Destination MAC of the inner MAC
frame matches the well-known MAC or the MAC address of the VTEP the
packet MUST be processed further.
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The UDP destination port and the TTL of the inner MAC frame MUST be
validated to determine if the received packet can be processed by
BFD. BFD packet with inner MAC set to VTEP or well-known MAC address
MUST not be forwarded to VM's.
5.1. Demux of the BFD packet
Demux of IP BFD packet has been defined in Section 3 of [RFC5881].
Since multiple BFD sessions may be running between two VTEPs, there
needs to be a mechanism for demultiplexing received BFD packets to
the proper session. The procedure for demultiplexing packets with
Your Discriminator = 0 is different from [RFC5880]. For such
packets, the BFD session is identified using the VNID, the source IP
and the destination IP of the packet. If BFD packet is received with
non-zero your discriminator then BFD session should be demultiplexed
only with your discriminator as the key.
6. Echo BFD
Support for echo BFD is outside the scope of this document.
7. IANA Considerations
The well-known MAC to be used for the Destination MAC address of the
inner MAC frame needs to be defined
8. Security Considerations
Document recommends setting of inner IP TTL to 1 which could lead to
DDoS attack, implementation MUST have throttling in place.
Throttling MAY be relaxed for BFD packeted based on port number.
Other than inner IP TTL set to 1 this specification does not raise
any additional security issues beyond those of the specifications
referred to in the list of normative references.
9. Contributors
Reshad Rahman
rrahman@cisco.com
Cisco
10. Acknowledgements
Authors would like to thank Jeff Hass of Juniper Networks for his
reviews and feedback on this material.
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11. Normative References
[I-D.ashwood-nvo3-operational-requirement]
Ashwood-Smith, P., Iyengar, R., Tsou, T., Sajassi, A.,
Boucadair, M., Jacquenet, C., and M. Daikoku, "NVO3
Operational Requirements", draft-ashwood-nvo3-operational-
requirement-03 (work in progress), July 2013.
[I-D.ietf-bfd-seamless-base]
Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J.
Networks, "Seamless Bidirectional Forwarding Detection
(S-BFD)", draft-ietf-bfd-seamless-base-05 (work in
progress), June 2015.
[I-D.quinn-vxlan-gpe]
Quinn, P., Manur, R., Kreeger, L., Lewis, D., Maino, F.,
Smith, M., Agarwal, P., Yong, L., Xu, X., Elzur, U., Garg,
P., and D. Melman, "Generic Protocol Extension for VXLAN",
draft-quinn-vxlan-gpe-04 (work in progress), February
2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June
2010.
[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, August 2014.
Authors' Addresses
Santosh Pallagatti (editor)
Juniper Networks
Embassy Business Park
Bangalore, KA 560093
India
Email: santoshpk@juniper.net
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Basil Saji
Juniper Networks
Embassy Business Park
Bangalore, KA 560093
India
Email: sbasil@juniper.net
Sudarsan Paragiri
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, California 94089-1206
USA
Email: sparagiri@juniper.net
Vengada Prasad Govindan
Cisco
Email: venggovi@cisco.com
Mallik Mudigonda
Cisco
Email: mmudigon@cisco.com
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
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