Re: [bess] VXLAN BGP EVPN Question

[Gyan Mishra <[e-mail]>]

Hi Jeff

Yes - Cisco has a draft for multi site for use cases capability of inter
pod or inter site segmented path between desperate POD fabrics intra DC or
as DCI option inter DC without MPLS.  The segmentation localizes BUM
traffic and has border gateway DF election for BUM traffic that is
segmented stitched between PODs as I mentioned similar to inter-as L3 vpn
opt b.  There is a extra load as you said on the BGW border gateway
performing the network vtep dencap from leaf and then again encap towards
the egress border gateway.  Due to that extra load on the border gateway
it’s not recommended to have spine function on BGW thus an extra layer for
multi site to be scalable.  Definitely requires proprietary asic and not
merchant silicon or white box solution.  The BUM traffic is much reduced as
you stated from multi fabric connected super spine or single fabric spine
that contains all leafs.  That decoupling sounds like incongruent control
and data plane with Mac only Type 2 routes which would result in more BUM
traffic  but it sounds like that maybe trade off of conversation learning
only active flows versus entire data center wide Mac VRF being learned
everywhere.  I wonder if their is an option to have that real decoupling of
EVPN control plane and vxlan data plane overlay that does not impact
convergence but adds stability and only active flow Type 2 Mac learner
across the fabric.

https://datatracker.ietf.org/doc/draft-sharma-multi-site-evpn/

Kind regards

Gyan

On Thu, Apr 23, 2020 at 6:04 PM Jeff Tantsura <[e-mail]>
wrote:

> Gyan,
>
> "Multi site” is not really an IETF terminology, this is a solution
> implement by NX-OS, there’s a draft though. Its main functionality is to
> localize VxLAN tunnels and provide segmented path vs end2end full mesh of
> VxLAN tunnels (participating in the same EVI). We are talking HER here.
> The feature is heavily HW dependent as it requires BUM re-encapsulation at
> the boundaries (leaf1->BGW1-BGW2->leaf2..n). So good luck seeing it soon on
> low end silicon.
> It doesn’t eliminate BUM traffic but significantly reduces the span of
> “broadcast domain” and reduces the need for large flood domains (modern HW
> gives you ~512 large flood groups, obviously depending on HW)
>
> Wrt your question about Mac conversation learning - this is an
> implementation issue, nothing in EVPN specifications precludes you of doing
> so, moreover in the implementation I was designing (in my previous life) we
> indeed decoupled data plane learning from control plane advertisement so
> control plane was aware of “Active” flows.  Needless to say - this creates
>  an additional layer of complexity and all kinds of funky states in the
> system ;-).
>
> Hope this helps
>
> Cheers,
> Jeff
> On Apr 23, 2020, 8:30 AM -0700, Gyan Mishra <[e-mail]>,
> wrote:
>
>
>
> Slight clarification with the arp traffic.  What I meant was broadcast
> traffic translated into BUM traffic with the EVPN architecture is there any
> way to reduce the amount of BUM traffic with a data center design
> requirement with vlan anywhere sprawl with 1000s of type 2 Mac mobility
> routes being learned between all the leaf VTEPs.
>
> The elimination of broadcast is a tremendous gain and with broadcast
> suppression of multicast that does help but it would be nice to not have
> such massive Mac tables type 2 route churn chatter with a conversation
> learning where only active flows are are in the type 2 rib.
>
> Kind regards
>
> Gyan
>
> On Wed, Apr 22, 2020 at 6:47 PM Gyan Mishra <[e-mail]> wrote:
>
>>
>> In the description of the vxlan BGP evpn scenario has a typo on the
>> multisite feature segmented LSP inter pod with the RT auto rewrite which is
>> similar to MPLS inter-as option b not a.
>>
>> Kind regards
>>
>> Gyan
>>
>> On Wed, Apr 22, 2020 at 5:57 PM Gyan Mishra <[e-mail]>
>> wrote:
>>
>>>
>>> All
>>>
>>> Had a question related to vxlan BGP EVPN architecture specifications
>>> defined in BGP EVPN NVO3 overlay RFC 8365 and VXLAN data plane RFC 7348.
>>>
>>> In a Data Center environment where you have a multiple PODs individual
>>> fabrics per POD connected via a super spine extension using a Multi site
>>> feature doing auto rewrite of RTs to stitch the NVE tunnel between pods
>>> similar to inter-as option A.
>>>
>>> So in this scenario where you have vlan sprawl everywhere with L2 and L3
>>> VNIs everywhere as if it were a a single L2 domain.  The topology is a
>>> typical vxlan spine leaf topology where the L3 leafs are the TOR switch so
>>> very small physical  L2 fault domain. So I was wondering if with the vxlan
>>> architecture if this feature below is possible or if their is a way to do
>>> so in the current specification.
>>>
>>> Cisco use to have a DC product called “fabric path” which was based on
>>> conversation learning.
>>>
>>> Is there any way with existing vxlan BGP evpn specification or maybe
>>> future enhancement to have a Mac conversation learning capability so that
>>> only the active mac’s that are part of a conversations flow are the mac
>>> that are flooded throughout the vxlan fabric.  That would really help
>>> tremendously with arp storms so if new arp entries are generated locally on
>>> a leaf they are not flooded through the fabric unless their are active
>>> flows between leafs.
>>>
>>> Also is there a way to filter type 2 Mac mobility routes between leaf
>>> switches at the control plane level based on remote vtep or maybe other
>>> parameters..  That would also reduce arp storms BUM traffic.
>>>
>>> Kind regards
>>>
>>> Gyan
>>> --
>>>
>>> Gyan  Mishra
>>>
>>> Network Engineering & Technology
>>>
>>> Verizon
>>>
>>> Silver Spring, MD 20904
>>>
>>> Phone: [phone]
>>>
>>> Email: [e-mail]
>>>
>>>
>>>
>>> --
>>
>> Gyan  Mishra
>>
>> Network Engineering & Technology
>>
>> Verizon
>>
>> Silver Spring, MD 20904
>>
>> Phone: [phone]
>>
>> Email: [e-mail]
>>
>>
>>
>> --
>
> Gyan  Mishra
>
> Network Engineering & Technology
>
> Verizon
>
> Silver Spring, MD 20904
>
> Phone: [phone]
>
> Email: [e-mail]
>
>
>
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> --

Gyan  Mishra

Network Engineering & Technology

Verizon

Silver Spring, MD 20904

Phone: [phone]

Email: [e-mail]