Hi Muthu,

This is what my understanding also.

Thanks,
Chalapathi.

From: Muthu Arul Mozhi Perumal [mailto:[email protected]]
Sent: Thursday, March 07, 2019 12:23 PM
To: Luc Andre Burdet (lburdet) <[email protected]>
Cc: chalapathi andhe <[email protected]>; [email protected]; Jaikumar 
Somasundaram <[email protected]>; Sean Wu 
<[email protected]>; Chalapathi Andhe <[email protected]>
Subject: Re: [bess] FW: Regarding the Alias label usage in EVPN Multihoming

My understanding:

For the single-active case in the diagram below, when PE4 receives the A-D per 
ES route withdraw it won't know whether PE2 or PE3 will become the new 
primary/DF for the <ES, VLAN>, so it will start flooding the traffic destined 
to MAC1. Then either PE2 or PE3 will become the new primary/DF for the <ES, 
VLAN> and advertise the MAC/IP route for MAC1. PE4 will then start sending the 
traffic destined to MAC1 to the new primary.

For the all-active case, when PE4 receives the A-D per ES route withdraw it 
will update the nexthop list for MAC1 by removing PE1 from that list. PE4 will 
then load balance the traffic destined to MAC1 by send it to PE2 and PE3 using 
alias label.

Regards,
Muthu

On Wed, Mar 6, 2019 at 7:51 PM Luc Andre Burdet (lburdet) 
<[email protected]<mailto:[email protected]>> wrote:
Hi Chalu,

Please read 7432 s.8.4: in single-active it is not an aliasing label/procedure 
but a backup-path procedure.
It will answer your questions (both, actually).

There is no flooding once the MAC is learnt & distributed: cf. that’s the point.


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Luc André Burdet
[email protected]<mailto:[email protected]>
Tel: +1 613 254 4814






Cisco Systems Canada Co. / Les Systemes Cisco Canada CIE
Cisco.com<http://www.cisco.com/web/CA/>







From: BESS <[email protected]<mailto:[email protected]>> on behalf of 
chalapathi andhe <[email protected]<mailto:[email protected]>>
Date: Wednesday, March 6, 2019 at 04:15
To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Cc: Sean Wu <[email protected]<mailto:[email protected]>>, Jaikumar 
Somasundaram 
<[email protected]<mailto:[email protected]>>,
 "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>
Subject: Re: [bess] FW: Regarding the Alias label usage in EVPN Multihoming



Hi All,

Can you please help us on the following issue.
In the following diagram, PE1, PE2, PE3 are connected to the same ES [ES1] in 
Single active mode, and PE4 is a remote PE.
Let’s say PE1 is advertising the MAC1 route, PE4 will install the MAC1 with the 
PE1 as primary path with MAC Label,
and PE2, PE3 as backup with the Alias Label. Now if the PE1 to CE1 link goes 
down, then PE1 withdraw the EAD/ES route
which will be processed by PE4.
Now what should the forwarding state at PE4 ?, PE4 should update the forwarding 
state of MAC1 with the PE2, PE3 Alias label
and any traffic destined to MAC1 should be flooded to PE2, PE3 with the Alias 
labels ?
Or packet should be flooded to PE2, PE3 with the Flood labels ? Or should it be 
some other method ?

In similar if the ES is operating in all active mode, what should be the 
forwarding state at PE4 ?
PE4 should update the forwarding state of MAC1 with the PE2, PE3 Alias label
and any traffic destined to MAC1 should be sent to either PE2 or PE3 with the 
Alias labels [ not flood to both] ?
Or packet should be flooded to PE2, PE3 with the Flood labels  or Alias Label ?
Or should it be some other method ?


[cid:1695247dcc04ce8e91]


Thanks,
Chalapathi.
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