BFD for VXLAN
draft-spallagatti-bfd-vxlan-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Santosh Pallagatti , Sudarsan Paragiri , sajibasil@gmail.com | ||
| Last updated | 2015-05-04 | ||
| Replaced by | draft-ietf-bfd-vxlan, RFC 8971 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-spallagatti-bfd-vxlan-00
Internet Engineering Task Force S. Pallagatti, Ed.
Internet-Draft S. Paragiri
Intended status: Standards Track B. Saji
Expires: November 5, 2015 Juniper Networks
May 4, 2015
BFD for VXLAN
draft-spallagatti-bfd-vxlan-00
Abstract
This document describes use of Bidirectional Forwarding Detection
(BFD) protocol for VXLAN . Comments on this draft should be directed
to nvo3@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 November 5, 2015.
Copyright Notice
Copyright (c) 2015 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Packet Format . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Transmission of BFD Packet: . . . . . . . . . . . . . . . . . 6
6. Reception of BFD Packet: . . . . . . . . . . . . . . . . . . 7
6.1. Demux of BFD Packet: . . . . . . . . . . . . . . . . . . 7
7. Echo BFD: . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8. S-BFD: . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Transmission of S-BFD: . . . . . . . . . . . . . . . . . 8
8.2. Reception of S-BFD: . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
12. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
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). VETP (hypervisor/TOR) are responsible for
encapsulating and decapsulating frames sent from VM's.
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.
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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 aware and may not
understand L3. BFD being a L3 protocol can be used for tunnel
connectivity check, where BFD will start and terminate at VTEP
on different host.
Fault localization:
It is also possible that VM's are L3 aware and can possible
host a BFD session. In these cases BFD session can be used to
run between VM's for VM's connectivity check, also BFD session
between VTEP's for tunnel connectivity check. With both VM's
BFD session and tunnel BFD can easily localize the fault to
either VM or tunnel.
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.
3. Deployment
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+------------+-------------+
| 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 |
+--------------------------+
Consider the above diagram, where we have two servers with IP1 and
IP2 and each of them are hosting two VM's. There are two VXLAN
tunnels with VNI number 100 and 200. For connectivity check of these
two VXLAN tunnels, BFD sessions needs to be established per tunnel.
In the diagram above two BFD will be established between server 1's
Hypervisor VTEP (IP1) and server2 Hypervisor VTEP(IP2). BFD session
will originate from Hypervisor VTEP (IP1) and terminate at Hypervisor
VTEP (IP2) and visa versa. Each BFD session on Hypervisor VTEP will
be identified by its VNI in VXLAN header. 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. Packet Format
Packet format has been defined in Section 5 of [RFC7348]. Outer IP/
UDP and VXLAN header will remain same and they should be filled by
sending VTEP as per [RFC7348]. Inner packet format has been defined
as below for BFD packet which terminates at VETP. BFD packet MUST
have a inner IP/UDP header followed by BFD payload.
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
Inner IPv4 Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| IHL |Type of Service| Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identification |Flags| Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL = 1 |Protocl=17(UDP)| Header Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Source IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Destination Ipv4 Address = 127/8 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inner IPv6 Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Traffic Class | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | NxtHdr=17(UDP)| Hop Limit = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Inner Source IPv6 Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Inner Destination IPv6 Address = +
| 0:0:0:0:0:FFFF:7F00/104 |
+ +
| |
+ +
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inner UDP Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port | Dest Port = 3784 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BFD packet:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers | Diag |Sta|P|F|C|A|D|M| Detect Mult | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Your Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Desired Min TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min Echo RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5. Transmission of BFD Packet:
This section describes BFD packet encapsulation while transmitting
BFD packet from VTEP
Outer IP/UDP and VXLAN header:
VETP which is transmitting the packet MUST encapsulate the BFD
packet in outer IP/UDP and VXLAN header as described in
Section 5 of [RFC7348]. IP TOS value MUST be set to
"Internetwork Control".
Inner IP/UDP header:
Srouce IP address:
MUST be set to outgoing interface of sending VTEP interface.
Destination IP address:
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MUST be set to non-routable 127/8 or 0:0:0:0:0:FFFF:7F00/104
range address.
IP TTL/HOP LIMIT:
MUST be set to 1.
UDP header:
UDP header is set as defined in Section 4 of [RFC5881]
BFD Packet:
BFD packet SHOULD be constructed as defined in Section 4 of
[RFC5880].
6. Reception of BFD Packet:
Once a packet is received VTEP MUST validate packet as described in
Section 4.1 of [RFC7348]. Since inner IP TTL is set to 1 packet
SHOULD be consumed by VTEP and should not be forwarded further to VM.
It is recommended that BFD packets should not be throttled with TTL
1. Implementation MAY have a check to relax throttling if the inner
IP address is 127/8 range for IPv4 and 0:0:0:0:0:FFFF:7F00/104 for
IPv6 then UDP destination port is 3784.
6.1. Demux of BFD Packet:
Demux of IP BFD packet has been defined in Section 3 of [RFC5881].
BFD demultiplexing for VXLAN is going to be different as destination
IP is same for all sessions and underlay is layer 3 and may have
ECMP. Source address and VNI should identify a BFD session on VTEP,
initially when BFD packets are sent with with your discriminator set
to 0 BFD packets MUST be demultiplexed with source address and VNI as
the key. If BFD packet is received with non-zero your discriminator
then BFD session should be demultiplexed only with your discriminator
as the key.
7. Echo BFD:
Support for echo BFD is outside the scope of this document.
8. S-BFD:
S-BFD can also be used for connectivity check as defined in
[I-D.ietf-bfd-seamless-base]
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8.1. Transmission of S-BFD:
VTEP MUST encapsulate S-BFD packet as defined in Section 5. For
S-BFD however your Discriminator will be set to VNI from the VXLAN
header.
8.2. Reception of S-BFD:
VTEP MUST decapsulate S-BFD packet as defined in above section
"reception of BFD packet". Reflector MUST validate if your
Discriminator belongs any one of the VNI on that VTEP.
9. IANA Considerations
This document has no actions for IANA.
10. 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.
11. Acknowledgements
Authors would like to thank Jeff Hass of Juniper Networks for his
reviews and feedback on this material.
12. Normative References
[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-04 (work in
progress), January 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.
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[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
Sudarsan Paragiri
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, California 94089-1206
USA
Email: sparagiri@juniper.net
Basil Saji
Juniper Networks
Embassy Business Park
Bangalore, KA 560093
India
Email: sbasil@juniper.net
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