Re:[nvo3] BFD over VXLAN: Trapping BFD Control packet at VTEP

<xiao.min2@zte.com.cn> Fri, 27 September 2019 02:50 UTC

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Hi Anoop,






Due to the fact that a variety of Tunnels could be used under the NVO3 architecture, as an example, below figure illustrates the format of MPLS packet over Geneve Tunnel.




 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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | |
 ~ Outer Ethernet Header ~
 | |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | |
 ~ Outer IPvX Header ~
 | |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | |
 ~ Outer UDP Header ~
 | |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | |
 ~ Geneve Header ~
 | |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
 | | |
 ~ MPLS Label Stack ~ M
 | | P
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L
 | | S
 | |
 ~ Payload ~ P
 | | K
 | | T
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
 | FCS |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





Note that in NVO3 working group Greg and I have submitted an individual draft draft-xiao-nvo3-bfd-geneve, which is used to address BFD over Geneve.

The intention is to make the two drafts draft-ietf-bfd-vxlan and draft-xiao-nvo3-bfd-geneve aligned, that is to say, we try to define the identical mechanism for the common part of BFD over VxLAN Tunnel and BFD over Geneve Tunnel. For the common part, draft-xiao-nvo3-bfd-geneve would reference to draft-ietf-bfd-vxlan, and for the other part specific to Geneve, we'll define the specific mechanism in draft-xiao-nvo3-bfd-geneve.




Hope that clarifies.




Best Regards,

Xiao Min



原始邮件



发件人:AnoopGhanwani <anoop@alumni.duke.edu>
收件人:肖敏10093570;
抄送人:Greg Mirsky <gregimirsky@gmail.com>;didutt@gmail.com <didutt@gmail.com>;draft-ietf-bfd-vxlan@ietf.org <draft-ietf-bfd-vxlan@ietf.org>;nvo3@ietf.org <nvo3@ietf.org>;santosh.pallagatti@gmail.com <santosh.pallagatti@gmail.com>;rtg-bfd WG <rtg-bfd@ietf.org>;Joel M. Halpern <jmh@joelhalpern.com>;tsridhar@vmware.com <tsridhar@vmware.com>;bfd-chairs@ietf.org <bfd-chairs@ietf.org>rg>;
日 期 :2019年09月26日 23:16
主 题 :Re: [nvo3] BFD over VXLAN: Trapping BFD Control packet at VTEP




Hi Xiao Min,
I think we would need more detail around the use case below.  What does the MPLS packet over Tunnel look like?

Thanks,
Anoop




On Wed, Sep 25, 2019 at 11:37 PM <xiao.min2@zte.com.cn> wrote:



Hi Anoop,






Thanks for your comments.


Considering a scenario where TS1 has an MPLS access (i.e. MPLS-Packet over Tunnel between NVEs) to VNI1, TS3 has an Ethernet access (i.e. MAC-Frame over Tunnel between NVEs) to VNI1, then how can TS1 and TS3 share one VAP?






Best Regards,


Xiao Min



原始邮件



发件人:AnoopGhanwani <anoop@alumni.duke.edu>
收件人:肖敏10093570;
抄送人:Greg Mirsky <gregimirsky@gmail.com>;didutt@gmail.com <didutt@gmail.com>;draft-ietf-bfd-vxlan@ietf.org <draft-ietf-bfd-vxlan@ietf.org>;nvo3@ietf.org <nvo3@ietf.org>;santosh.pallagatti@gmail.com <santosh.pallagatti@gmail.com>;rtg-bfd WG <rtg-bfd@ietf.org>;Joel M. Halpern <jmh@joelhalpern.com>;tsridhar@vmware.com <tsridhar@vmware.com>;bfd-chairs@ietf.org <bfd-chairs@ietf.org>rg>;
日 期 :2019年09月26日 08:36
主 题 :Re: [nvo3] BFD over VXLAN: Trapping BFD Control packet at VTEP


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>>>

Some people may argue that all Tenant Systems connecting to the same Virtual Network MUST share one VAP, if that's true, then VAP1 and VAP3 should merge into one VAP and my explanation doesn't work. Copying to NVO3 WG to involve more experts, hope for your clarifications and comments.  


>>>

I would be one of those that would argue that they MUST share on VAP if they connect to the same Virtual Network.  IMO, the NVO3 arch doc should have been clearer about this.

Thanks,
Anoop



On Tue, Sep 24, 2019 at 7:40 PM <xiao.min2@zte.com.cn> wrote:



Hi Santosh,






With regard to the question whether we should allow multiple BFD sessions for the same VNI or not, IMHO we should allow it, more explanation as follows...


Below is a figure derived from figure 2 of RFC8014 (An Architecture for Data-Center Network Virtualization over Layer 3 (NVO3)).




 | Data Center Network (IP) |
 | |
 +-----------------------------------------+
 | |
 | Tunnel Overlay |
 +------------+---------+ +---------+------------+
 | +----------+-------+ | | +-------+----------+ |
 | | Overlay Module | | | | Overlay Module | |
 | +---------+--------+ | | +---------+--------+ |
 | | | | | |
 NVE1 | | | | | | NVE2
 | +--------+-------+ | | +--------+-------+ |
 | |VNI1 VNI2 VNI1 | | | | VNI1 VNI2 VNI1 | |
 | +-+-----+----+---+ | | +-+-----+-----+--+ |
 |VAP1| VAP2| | VAP3 | |VAP1| VAP2| | VAP3|
 +----+-----+----+------+ +----+-----+-----+-----+
 | | | | | |
 | | | | | |
 | | | | | |
 -------+-----+----+-------------------+-----+-----+-------
 | | | Tenant | | |
 TSI1 | TSI2| | TSI3 TSI1| TSI2| |TSI3
 +---+ +---+ +---+ +---+ +---+ +---+
 |TS1| |TS2| |TS3| |TS4| |TS5| |TS6|
 +---+ +---+ +---+ +---+ +---+ +---+
To my understanding, the BFD sessions between NVE1 and NVE2 are actually initiated and terminated at VAP of NVE.


If the network operator want to set up one BFD session between VAP1 of NVE1 and VAP1of NVE2, at the same time another BFD session between VAP3 of NVE1 and VAP3 of NVE2, although the two BFD sessions are for the same VNI1, I believe it's reasonable, so that's why I think we should allow it.






Of course, in RFC8014 it also says:

"Note that two different Tenant Systems (and TSIs) attached to a common NVE can share a VAP (e.g., TS1 and TS2 in Figure 2) so long as they connect to the same Virtual Network."
Some people may argue that all Tenant Systems connecting to the same Virtual Network MUST share one VAP, if that's true, then VAP1 and VAP3 should merge into one VAP and my explanation doesn't work. Copying to NVO3 WG to involve more experts, hope for your clarifications and comments.






Best Regards,


Xiao Min