One document matched: draft-spallagatti-bfd-vxlan-03.xml
<?xml version="1.0" encoding="US-ASCII"?>
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<rfc category="std" docName="draft-spallagatti-bfd-vxlan-03" ipr="trust200902">
<!-- category values: std, bcp, info, exp, and historic
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<!-- ***** FRONT MATTER ***** -->
<front>
<title abbrev="BFD for VXLAN">
BFD for VXLAN
</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<!-- Another author who claims to be an editor -->
<author fullname="Santosh Pallagatti" initials="S." role="editor"
surname="Pallagatti">
<organization>Independent Contributor</organization>
<address>
<email>santoshpk@juniper.net</email>
</address>
</author>
<author fullname="Basil Saji" initials="B."
surname="Saji">
<organization>Juniper Networks</organization>
<address>
<postal>
<street>Embassy Business Park</street>
<city>Bangalore</city>
<region>KA</region>
<code>560093</code>
<country>India</country>
</postal>
<email>sbasil@juniper.net</email>
</address>
</author>
<author fullname="Sudarsan Paragiri " initials="S."
surname="Paragiri">
<organization>Juniper Networks</organization>
<address>
<postal>
<street> 1194 N. Mathilda Ave.</street>
<city>Sunnyvale</city>
<region>California</region>
<code> 94089-1206</code>
<country>USA</country>
</postal>
<email>sparagiri@juniper.net</email>
</address>
</author>
<author fullname="Vengada Prasad Govindan" initials="V." role="editor"
surname="Govindan">
<organization>Cisco</organization>
<address>
<email>venggovi@cisco.com</email>
</address>
</author>
<author fullname="Mallik Mudigonda" initials="M."
surname="Mudigonda">
<organization>Cisco</organization>
<address>
<email>mmudigon@cisco.com</email>
</address>
</author>
<author fullname="Greg Mirsky" initials="G."
surname="Mirsky">
<organization>Ericsson</organization>
<address>
<email>gregory.mirsky@ericsson.com</email>
</address>
</author>
<date year="2016" />
<area>Nov3 Working Group</area>
<workgroup>Internet Engineering Task Force</workgroup>
<!-- WG name at the upperleft corner of the doc,
IETF is fine for individual submissions.
If this element is not present, the default is "Network Working Group",
which is used by the RFC Editor as a nod to the history of the IETF. -->
<keyword>BFD</keyword>
<keyword>BFD for VXLAN</keyword>
<!-- Keywords will be incorporated into HTML output
files in a meta tag but they have no effect on text or nroff
output. If you submit your draft to the RFC Editor, the
keywords will be used for the search engine. -->
<abstract>
<t>This document describes use of Bidirectional Forwarding Detection (BFD) protocol for VXLAN .</t>
</abstract>
<note title="Requirements Language">
<t>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 <xref target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section title="Introduction" anchor="Intro">
<t>"Virtual eXtensible Local Area Network (VXLAN)" has been defined in <xref target="RFC7348"/> that provides an
encapsulation scheme which allows VM's to communicate in data center network. </t>
<t>VXLAN is typically deployed in data centers interconnecting virtualized hosts,
which may be spread across multiple racks. The individual racks may
be part 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.</t>
<t>A virtual machine (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 is terminated on VXLAN Tunnel End Point(VTEP) (hypervisor/TOR).
VTEPs (hypervisor/TOR) are responsible for encapsulating and decapsulating frames exchanged among
VM's. </t>
<t>Since underlay is a L3 network, continuity check for these tunnels becomes important.
BFD as defined in <xref target="RFC5880"/> can be used to monitor the VXLAN tunnels. Use of
<xref target="I-D.ietf-bfd-multipoint"/> is for future study. </t>
<t> This draft addresses requirements outlined in <xref target="I-D.ashwood-nvo3-operational-requirement"/>.
Specifically with reference to the OAM model to Figure 3 of <xref target="I-D.ashwood-nvo3-operational-requirement"/>,
this draft outlines proposal to implement the OAM mechanism between the NV Edges using BFD.
</t>
</section>
<section title="Use cases" anchor="usecase">
<t>Main use case of BFD for VXLAN is for tunnel continuity check. BFD packets between VTEPs will exercise the VXLAN path in underlay/overlay
ensuring the VXLAN path reachability. BFD failure detection can be used for maintenance. There are other use cases such as
<list style="empty">
<t>Layer 2 VM's:
<list style="empty">
<t>Most deployments will have VM's with only L2 capabilities that may not support L3.
BFD being a L3 protocol can be used as tunnel CC mechanism, where BFD will
start and terminate at the Network Virtualization (NV) Edge (VTEPs).</t>
<t>It is possible to aggregate the CC sessions 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. </t>
</list>
</t>
<t>Fault localization:
<list style="empty">
<t>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 among VM's for CC. In addition
BFD sessions can be established among VTEPs for tunnel CC. Having a hierarchical
OAM model helps localize faults though requires additional consideration.</t>
</list>
</t>
<t>Service node reachability:
<list style="empty">
<t>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. BFD session between TOR/hypervisor and service node can be used to monitor service node reachability.</t>
</list>
</t>
</list>
</t>
</section>
<section title="Deployment">
<figure anchor="Fig" align="left"><preamble></preamble><artwork align="left"><![CDATA[
+------------+-------------+
| 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 |
+--------------------------+
]]></artwork></figure>
<t><xref target="Fig"/> illustrates the 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 packets intended to Hypervisor VTEP should be forwarded to a VM as VM may drop BFD packets
leading to false negative. This method is applicable whether VTEP is a software or a physical device. </t>
</section>
<section title="BFD Packet Transmission">
<t>BFD packet MUST be encapsulated and sent to remote VTEP as explained in <xref target="encap" />.
Implementations SHOULD ensure that the BFD packets follow the same lookup path of VXLAN packets within the sender system.</t>
<section title="BFD Packet Encapsulation" anchor="encap">
<t>VXLAN packet format has been defined in Section 5 of <xref target="RFC7348"/>. The Outer IP/UDP and VXLAN headers MUST
be encoded by the sender as per <xref target="RFC7348"/>.</t>
<t> If VTEP is equipped with Generic Protocol Extension (GPE) header capabilities and decides to use GPE instead of VXLAN then
GPE header MUST be encoded as per Section 3.3 of <xref target="I-D.quinn-vxlan-gpe"/>. Next Protocol Field in
GPE header MUST be set to IPv4 or IPv6. </t>
<t>Details of how VTEP decides to use VXLAN or GPE header are outside the scope of this document.</t>
<t>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:
<list>
<t> Ethernet Header:
<list>
<t> 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 are outside the scope of this document.</t>
<t> Source MAC: MAC address of the originating VTEP </t>
</list>
</t>
<t>IP header:
<list>
<t>Source IP: IP address of the originating VTEP.</t>
<t>Destination IP: IP address of the terminating VTEP.</t>
<t>TTL: This MUST be set to 1. This is to ensure that the BFD packet is not routed within the L3 underlay network.</t>
<t>[Ed.Note]:Use of inner source and destination IP addresses needs more discussion by the WG.</t>
</list>
</t>
<t> The fields of the UDP header and the BFD control packet are encoded as specified in RFC 5881 for p2p VXLAN tunnels.</t>
</list></t>
</section>
</section>
<section title="Reception of BFD packet">
<t>Once a packet is received, VTEP MUST validate the packet as described in Section 4.1 of <xref target="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. </t>
<t> 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.</t>
<t> To ensure BFD detects the proper configuration of VXLAN Network Identifier(VNI) in a remote VTEP, a lookup SHOULD be performed with the MAC-DA and VNI as key in the
Virtual Forwarding Instance(VFI) table of the originating/ terminating VTEP in order to exercise the VFI associated with the VNI.</t>
<section title="Demultiplexing of the BFD packet">
<t>Demultiplexing of IP BFD packet has been defined in Section 3 of <xref target="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 <xref target="RFC5880"/>. For such packets, the BFD session MUST be identified using the
inner headers, i.e. the source IP and the destination IP present in the IP header carried by the payload of
the VXLAN encapsulated packet. The VNI of the packet SHOULD be used to derive interface related information
for demultiplexing 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.</t>
</section>
</section>
<section title="Use of reserved VNI">
<t> BFD session MAY be established for the reserved VNI 0. One way to aggregate BFD sessions between VTEP's
is to establish a BFD session with VNI 0. A VTEP MAY also use VNI 0 to establish a BFD session with a service node.</t>
</section>
<section title="Echo BFD">
<t>Support for echo BFD is outside the scope of this document.</t>
</section>
<section title="IANA Considerations">
<t>The well-known MAC to be used for the Destination MAC address of the inner MAC frame needs to be defined </t>
</section>
<section title="Security Considerations">
<t>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.</t>
<t> 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.</t>
</section>
<section title="Contributors">
<t>
<figure>
<artwork><![CDATA[
Reshad Rahman
rrahman@cisco.com
Cisco]]></artwork>
</figure>
</t>
</section>
<section title="Acknowledgements">
<t>Authors would like to thank Jeff Hass of Juniper Networks for his reviews and feedback on this material.</t>
<t>Authors would also like to thank Nobo Akiya, Marc Binderberger and Shahram Davari for the extensive review.</t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
<references title="Normative References">
<?rfc include="reference.RFC.5880"?>
<?rfc include="reference.RFC.5881"?>
<?rfc include="reference.RFC.7348"?>
<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.I-D.ashwood-nvo3-operational-requirement"?>
<?rfc include="reference.I-D.quinn-vxlan-gpe"?>
<?rfc include="reference.I-D.ietf-bfd-multipoint"?>
</references>
</back>
</rfc>
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