Re: [bess] About draft-wang-bess-l3-accessible-evpn

[Wei Wang <[e-mail]>]

Hi Gyan,


Thanks for your reply. Please see in-line [WW].


Best Regards,
Wei
------------------ Original ------------------
From:                                                                                                                        "Gyan Mishra"                                                                                    <[e-mail]&gt;;
Date:&nbsp;Thu, Mar 18, 2021 09:27 AM
To:&nbsp;"Wei Wang"<[e-mail]&gt;;
Cc:&nbsp;"Patrice Brissette (pbrisset)"<pbrisset=[e-mail]&gt;;"jorge.rabadan"<[e-mail]&gt;;"[e-mail]"<[e-mail]&gt;;"Fomin, Sergey (Nokia - US/Mountain View)"<[e-mail]&gt;;
Subject:&nbsp;Re: [bess] About draft-wang-bess-l3-accessible-evpn





Hi Wei 


If you are stretching EVPN DCI over SR or MPLS core and not doing any IP VPN to EVPN gateway translation function, then you don’t need define any VRFs on the PEs unless the PE is terminating the NVO3 overlay which usually is not the case. &nbsp;


The DCI core box border spine / border leaf / shared border box would terminate the NVO3 tunnel within the DC.
[WW] Do you mean to build NVO3 tunnel directly between MSEs in different MANs? It obviously works, but it requires VNIs in MAN1-3 to be globally unique, and the scenario we are considering does not meet this requirement (VNIs in MAN1-3 are independently allocated, which may lead to the overlap of VNI in different customer sites).


Kind Regards 


Gyan 
&nbsp;
On Tue, Mar 16, 2021 at 2:25 AM Wei Wang <[e-mail]&gt; wrote:

Hi Gyan, Sergey, Patrice and Jorge,


In fact, we are considering the following scenario:



where Backbone is EVPN domain, and MAN1-3 are Layer-3 network. VNIs in MAN1-3 are independently allocated, which may lead to the overlap of VNI in different customer sites.


If there are 3 customers who need cross domain networking: A, B, C.
In general, we allocate 3 VNIs for the 3 customers in each MAN, and configure 3 VRFs on each PE to maintain the VPN routes of them. 
In our solution, we allocate one VNI for all customers in each MAN, and configure only one VRF on each PE, which can simplify the configuration work during deployment. On PEs, the VRF can be divided into 3 sub-tables according to LSI information to maintain the VPN routes of customers.


To Gyan: in the two documents you mentioned, a device (Interworking PE / GW) is needed for routing conversion and redistribution, which is not needed in our solution.


Best Regards,
Wei
China Telecom


------------------ Original ------------------
From:                                                                                                                        "Gyan Mishra"                                                                                    <[e-mail]&gt;;
Date:&nbsp;Sun, Mar 14, 2021 10:18 AM
To:&nbsp;"Fomin, Sergey (Nokia - US/Mountain View)"<[e-mail]&gt;;
Cc:&nbsp;"Wei Wang"<[e-mail]&gt;;"bess"<[e-mail]&gt;;
Subject:&nbsp;Re: [bess] About draft-wang-bess-l3-accessible-evpn





Dear Authors


I am trying to understand the purpose of this document.


Is the goal for EVPN to be L3 accessible?


The way this has been done the past in a DC fabric environment using EVPN ESI single or all active multi home is from the DC fabric &nbsp;from the Border leaf or Border spine that terminates the NVO3 overlay vxlan/vxlan-gpe/Geneve the DC core L3 box for DCI inter connect can act as a “fusion” router and terminate both tenant VRF and underlay peer and fuse the VRF overlay and global table underlay routing to provide access between overlay and underlay as well as external L3 reachability out of the fabric.&nbsp; All the Type-2 Mac-IP and Type-5 prefix can be converted imported as IPv4 AFI SAFI-1 so the Type-2 in SAFI-1 BGP RIB as host route and Type-5 shows as subnet prefix. 


I am not sure if that is what you are trying to accomplish?




If you are trying to achieve EVPN to IPVPN interworking see draft below:


https://tools.ietf.org/html/draft-ietf-bess-evpn-ipvpn-interworking-02


DCI EVPN overlay 


https://tools.ietf.org/html/draft-ietf-bess-dci-evpn-overlay-10




Kind Regards 


Gyan


On Fri, Mar 12, 2021 at 5:06 PM Fomin, Sergey (Nokia - US/Mountain View) <[e-mail]&gt; wrote:

   
Hi Wei,
 
&nbsp;
 
This draft presents a peculiar way of bringing something similar to bridge-domain/bridge-table concepts into IP-VRFs..
 
&nbsp;
 
One significant problem, in my opinion, is that you not only introduce a new dataplane dependency; but also propose to _redefine_ VXLAN-GPE header semantics (instead of just using it, or GENEVE). I would assume you have to go to  nvo3 WG for the proposed VXLAN-GPE format changes (either with the full draft or splitting it into 2 parts (control &amp; data plane)).
 
&nbsp;
 
Additionally, I would like to see more text on the motivation of the proposed solution. In the abstract you make a point that “This draft … proposes a new solution which can simplify the deployment of layer-3 accessible EVPN service.”  -&gt; this simplicity is not obvious at all, and one may argue that this solution is more complex compared to the existing ones (such as draft inter-subnet-forwarding with multiple IP-VRFs)
 
&nbsp;
 
--
 
Sergey
 
&nbsp;
  
From: BESS <[e-mail]&gt; On Behalf Of  Wei Wang
 







Sent: Friday, March 12, 2021 12:14 AM
 To: linda.dunbar <[e-mail]&gt;; jorge.rabadan <[e-mail]&gt;
 Cc: bess <[e-mail]&gt;
 Subject: [bess] About draft-wang-bess-l3-accessible-evpn








 
 
&nbsp;
  
Hi Linda and Jorge,
 





  
&nbsp; &nbsp; Thanks for your comments at IETF110 meeting, and I think I need to explain our considerations for the newly defined LSI (Logical Session Identifier) concept.
 
  
&nbsp;
 
   
Question 1, from Linda Dunbar, "Is the usage of LSI same as the RD for VPN route distinguish?"
 
  
Answer: LSI(Logical Session Identifier) is mainly used for distinguishing the different logical sessions between CE and PE device. Such session can be established via Vxlan, IPsec, or other tunnel technologies that can span layer 3 network. 
 
  
The LSI information should be transferred via the control plane and forwarding plane. In control plane, we try to use Ethernet Tag ID/newly defined ESI type to transfer, its purpose is to further distinguish the cusomer routes within one  provider VRF. In forwarding plane, this information should be inserted into some place of the exising VxLAN encoding, as proposed in our draft:https://datatracker.ietf.org/doc/html/draft-wang-bess-l3-accessible-evpn-04#section-6.1
 
  
&nbsp;
 
  
Question 2, from Jorge Rabadan. "The ESI shouldn't be used to distinguish the route-type 5, it is mainly used for multi-homing purpose"
 
  
Answer: Currently, we are considering using two methods to identify the routes that associated different LSI:
 
  
&nbsp; &nbsp; &nbsp; &nbsp;Method 1: Ethernet Tag ID, which is similar with its usage in layer 2 vlan environment.
 
  
&nbsp; &nbsp; &nbsp; &nbsp;Method 2: Newly defined ESI type(type 6)
 
  
&nbsp;
 
  
&nbsp; &nbsp; We think both methods are approachable:
 
  
&nbsp; &nbsp; Method 1 requires also the update of  https://tools.ietf.org/html/draft-ietf-bess-evpn-prefix-advertisement-11(Ethernet Tag ID is set to 0 for route type 5), may arises some confuse with its original defintion.
 
  
&nbsp; &nbsp; Method 2 requires the extension of ESI type (as described in:  https://datatracker.ietf.org/doc/html/draft-wang-bess-l3-accessible-evpn-04#section-6.2). The original purpose of ESI (mulit-homing) can also be preserved.
 
 
  
&nbsp;
 
  
&nbsp; &nbsp; I hope the above explanations help.
 
  
&nbsp; &nbsp; Comments and questions are always welcome.
 
  
&nbsp;
 
  
Best Regards,
 
  
Wei
 
  
China Telecom
 
 
 
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Gyan Mishra

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Gyan Mishra

Network Solutions Architect 

M 301 502-1347
13101 Columbia Pike 
Silver Spring, MD















Wei Wang
China Telecom