Re: [MBONED] Continued Review of multicast-yang-model

[[e-mail]]

Hi Gyan, 


Thank you! We will update the model as soon as possible. 


Best regards,


Sandy














原始邮件



发件人：GyanMishra
收件人：张征00007940;
抄送人：Holland, Jake;MBONED WG;
日 期 ：2021年05月12日 12:42
主 题 ：Re: [MBONED] Continued Review of multicast-yang-model





Hi Sandy

Most welcome.  Happy to help out and provide guidance on the major undertaking with the Yang model.  Again, excellent work by the authors.


Let me know when you have the draft updated with the hierarchy and I would be happy to provide some further feedback. 


Kind Regards


Gyan




On Tue, May 11, 2021 at 11:08 PM <[e-mail]> wrote:


Hi Gyan, 


Thank you very much for your review! The suggestion is great! 


We'll consider how to improve the draft and model.


Please find my answer inline with Sandy>.







原始邮件


发件人：GyanMishra
收件人：张征00007940;
抄送人：[e-mail];[e-mail];
日 期 ：2021年05月09日 02:01
主 题 ：Re: [MBONED] Continued Review of multicast-yang-model


Hi Sandy & Authors 


Excellent work capturing all the complexity and nuances of all the scenarios related to multicast deployments in the Yang model.



I just reviewed the Multicast Yang model and as this should capture I believe existing and future PTA tunnels types I noticed a few missing.


The Yang framework diagram is quite complicated and maybe we can setup a call to go over it below is confusing.


3.1 Diagram 


This diagram provides a really nice flow chart for the overall multicast Yang model.  Few comments 


Multicast model has 3 categories underlay, transport and overlay.  


The layering horizontally is a bit hard to follow in the diagram and here are some ideas.


So there are two main cases fork in the road


1. Underlay-only  netwok

2. Underlay/Overlay network
Sandy> These categories are from the protocol perspective. Do I understand right? Yes, some of the protocols, for example PIM, can be used as transport and overlay as well. 

Because there is no explicit layer concept before. Now we can find that the layered architecture is more beneficial for current and future multicast depolyment. 

So the model is classified for three layers.





The difficulty is how do you represent it all together in a homogeneous Yang model hierarchy 
Sandy> Yes. It's difficult. But it may help more multicast deployment work after it's improved.





Underlay/Overlay network - “BGP free” core with PIM option for MVPN Rosen PTA

BGP is part of MVPN SAFI 129 so I don’t think we have to call our BGP in overlay 

Sandy> It sounds reasonable, we will consider the modification about it.


MLD / MLD snooping is v6 underlay - Underlay only IP transport related 

Sandy> Because MLD/IGMP is a single hop protocol, it can not be used as multiple hop transport protocol, but it can be used as overlay protocol to collect the receiver information. 

MLD/IGMP snooping is analogous though it can transport more hops.



So here am showing both together as you have it in the diagram 


Overlay 


MVPN SAFI 129( RFC 6513 6514 procedures)


FEC TLV - Type, Root, Opaque


Ingress - FEC Root  Type 1-5

Egress  Type 6 7



Egress  triggered-mLDP



Ingress triggered- RSVP-TE /BIER Type 4 leaf-ad
Sandy> Yes. A set of keys needs to be used for make relationship between this model and MVPN YANG model. And further IMO the specific information about types may not need to be defined in this model but in MVPN YANG model.





Transport 


IP - could be v4 or v6 and would be for Underlay only scenario 
Sandy> Yes. We will consider add some description.





MPLS  / SR-MPLS


PTA = mLDP P2P MP2MP, P2MP TE, IR, BIER, Replication SID

PIM GRE - ASM, SSM, BIDIR
Sandy> Good catch. We will consider to add some or all of them. 





SRv6 

PTA - Replication SID

BIER
Sandy> Good suggestion. We will think about to add the segment routing technology as transport technology.





Underlay v4 v6 dual stacked 


L3


OSPF PIM or no PIM for non MVPN Rosen PTA

ISIS PIM no PIM for non MVPN Rosen PTA

BGP PIM no PIM for non MVPN Rosen PTA

BABEL PIM


L2 


Snooping v4 


MLD Snooping v6
Sandy> I am not much sure if we need to split to L3 and L2. But we will consider about it.
Much appreciate for your review and suggestion!

Best regards,

Sandy



Kind Regards 



Gyan



On Sat, May 8, 2021 at 4:49 AM <[e-mail]> wrote:


Hi Jake, 


Thank you very much for your review! And sorry for the late response. 


Please find my answer with Sandy> inline.







原始邮件


发件人：Holland,Jake
收件人：MBONED WG;张征00007940;
日 期 ：2021年03月20日 11:01
主 题 ：Continued Review of multicast-yang-model

Hi Sandy,
 
During the mboned meeting I think you said you were waiting on a review from
me, but I thought I had sent one here the day after IETF 109, so I didn't
realize you were waiting:
https://mailarchive.ietf.org/arch/msg/mboned/cjVQ_qM2yeboxY0i3vvjSe9g3Xo/
 Sandy> Appreciate for your review again! :-)




Also, after a quick review of what I said during 109, I think I was expecting
you to send something to the list detailing which parts of the model were
well-proven with its use in production, and which parts of the model needed
a closer look since nobody has used it yet:
https://www.youtube.com/watch?v=K1FS3XqqWTw&t=3371s
 Sandy> Because we verified this model in ODL BIER project, so some other parts included in this model, such as mldp or p2mp-te, has not been verified yet. 

So experience with these protocols may do good help for the model review.




Anyway, I see from my last review that there's parts of the document I didn't
cover, so I guess I'll try to do that now:
 
0.
I'm struggling with the high-level expectations of what happens in a
network if I configure something with this model.  In Appendix A, a
helpful example is given, but what happens when you set that data
instance in a netconf instance?  Does it make the forwarding get
configured, so this is mostly a transport path signaling mechanism?
 Sandy> The model can be used by netconf, but it won't affect the netconf running. When this model configured, some other model may be also configured. For example, when BIER is configured as transport, BIER model may also be configured if you have any parameter needs to be set in BIER model.




What happens if the underlay does not match?  (For example, what if
the underlay in the setting says ospf, but it's in fact the network
between ingress and egress was running isis?)
 Sandy> Yes. The underlay may not match. So the nofitication can be used to report this situation to controller. But what the controller needs to do is out of scope of this draft.




1.
There are errors in the yang rules validation, as reported on the datatracker
page:
https://datatracker.ietf.org/doc/draft-ietf-mboned-multicast-yang-model/
 
[e-mail]:252: error: RFC 8407: 4.14: statement "grouping" must have a "description" substatement
[e-mail]:363: error: RFC 8407: 4.14: statement "grouping" must have a "description" substatement
[e-mail]:364: error: RFC 8407: 4.14: statement "choice" must have a "description" substatement
 
These seem to need a fix.

Sandy> Thank you very much for your reminder, I'll fix it.


2.
In 3.2/3.3, the multicast-keys list seems to be a problem, especially with
respect to vni-type and vni-value, because there's only 3 possibilities for
virtual-type (vxlan, nvgre, and geneve), but a value is required in order
to have it as a key.  Likewise, I'm not sure the vpn-rd and vni-value make
sense for all (S,G)s, do these have a value?  (What about in a traditional
PIM network?)
 
Would it make sense to use a type that permits these to be blank where
appropriate?
 Sandy> Yes. If these keys are not used, it can be set to blank or zero.




3.
I'm confused about the multicast-underlay/ospf/ospf/toplogy location.  What
is that, and why don't the other underlays have anythin analogous?
 Sandy> Thank you for your pointing out it. OSPF and ISIS support multi-topoloty feature, so the underlay can map to a specific topology. I'll also add it in ISIS underlay.





4.
In section 3.3, there are a lot of grammar problems.  I'll list some of
them here, do you need text suggestions for these?
 Sandy> Much appreciate if you make some suggestion for these. :-)












4.a.
 
    ... Multicast keys include the features of multicast flow,
   such as(vpnid, multicast source and multicast group) information.  In
   data center network, for fine-grained to gather the nodes belonging
   to the same virtual network, there may need VNI-related information
   to assist.
 
4.b.
 
    ... there may define BIER
   information including (Subdomain, ingress-node BFR-id, egress-nodes
   BFR-id).  If no (ingress-node, egress-nodes) information are defined
   directly, there may need overlay multicast signaling technology, such
   as MLD or MVPN, to collect these nodes information.
 
 
5.
In section 3.3, I was confused by this bit:
 
   ... One or
   several transport technologies could be defined at the same time.
 
What does it mean if several transport technologies are defined at
the same time, are those for redundant paths or something?
 
Likewise this about the underlay:
 
    ... One or several underlay
   technologies could be defined at the same time if there is protective
   requirement.
 
By "protective environment" do you mean a redundant setup that can
forward the traffic through multiple paths?  (And if so, what if the
redundant paths use the same type of underlay?  Or if not, what does
it mean?)








Sandy> Yes. But I am not sure if these usage is existed actually. Do you think it's better to only keep one for it?
 
6.
As an overview comment:
 
I still feel like I'm missing something when I read through this
spec--am I understanding correctly that the whole purpose is to
set up the forwarding for each of the given (S,G)s through the
network?  If so, I'm confused about what the underlay and overlay
properties are for, exactly.  How does the controller use the
information that there's an OSPF underlay, when it has that info?
 Sandy> For example, if the OSPF topology is configured, the associated OSPF YANG should also be configured in the controller. And the controller will push the multicast model and OSPF model to the device. But as you said, the description needs to be updated. It's great if you have any suggestion for it.
 
I hope that's helpful, and please let me know if you're expecting
anything else from me on this revision.
 Sandy> Thank you very much again for your help!

Best regards,

Sandy




Best regards,
Jake
 
 









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Gyan Mishra


Network Solutions Architect 


Email [e-mail]



M 301 502-1347

























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Gyan Mishra


Network Solutions Architect 


Email [e-mail]



M 301 502-1347