Thanks Jorge.
I think that this optimization is not mentioned in the RFC 7432.
Section 8.5 of RFC 7432:
In the case of link or port failure, the affected PE withdraws its
Ethernet Segment route. This will re-trigger the service carving
procedures on all the PEs in the redundancy group. For PE node
failure, or upon PE commissioning or decommissioning, the PEs
re-trigger the service carving.
Section 13.2.1 of RFC 7432:
- If the PE is not the designated forwarder on any of the ESIs for
the Ethernet tag, the default behavior is for it to drop the
packet.
Section 14.1.1 of RFC 7432:
If there is more than one backup PE for a given ES, the remote PE
MUST use the primary PE's withdrawal of its set of Ethernet A-D per
ES routes as a trigger to start flooding traffic for the associated
MAC addresses (as long as flooding of unknown unicast packets is
administratively allowed), as it is not possible to select a single
backup PE.
Thanks & Regards
Jaikumar S
From: Rabadan, Jorge (Nokia - US/Mountain View) <[email protected]>
Sent: Thursday, October 4, 2018 10:11 PM
To: Jaikumar Somasundaram <[email protected]>; [email protected]
Cc: Jiang He <[email protected]>; P Muthu Arul Mozhi
<[email protected]>
Subject: Re: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Hi Jai,
Yes, but see my other email.. if you only have two PEs in the ES, you may
optimize things.
Thanks.
Jorge
From: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>
Date: Thursday, October 4, 2018 at 5:39 PM
To: "Rabadan, Jorge (Nokia - US/Mountain View)"
<[email protected]<mailto:[email protected]>>,
"[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Cc: Jiang He <[email protected]<mailto:[email protected]>>, P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: RE: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Hi Jorge,
Yes, new DF will be identified after the new election.
Election process will need to wait for DF election timer period, say 3s or the
configured timer period.
Until this DF election timer expiry and new DF is identified, the traffic
towards CE coming to the node this PE
will get dropped. Please let me know if my understanding is right?
Thanks & Regards
Jaikumar S
From: Rabadan, Jorge (Nokia - US/Mountain View)
<[email protected]<mailto:[email protected]>>
Sent: Thursday, October 4, 2018 8:06 PM
To: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
Cc: Jiang He <[email protected]<mailto:[email protected]>>; P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: Re: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Jai,
The new DF becomes DF because it re-runs DF election.
Thx
Jorge
From: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>
Date: Thursday, October 4, 2018 at 12:23 PM
To: "Rabadan, Jorge (Nokia - US/Mountain View)"
<[email protected]<mailto:[email protected]>>,
"[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Cc: Jiang He <[email protected]<mailto:[email protected]>>, P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: RE: [bess] EVPN MH: Backup node behavior in Primary Path Failure
In-line.
From: Rabadan, Jorge (Nokia - US/Mountain View)
<[email protected]<mailto:[email protected]>>
Sent: Thursday, October 4, 2018 3:33 PM
To: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
Cc: Jiang He <[email protected]<mailto:[email protected]>>; P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: Re: [bess] EVPN MH: Backup node behavior in Primary Path Failure
In-line.
Thx
Jorge
From: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>
Date: Thursday, October 4, 2018 at 11:28 AM
To: "Rabadan, Jorge (Nokia - US/Mountain View)"
<[email protected]<mailto:[email protected]>>,
"[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Cc: Jiang He <[email protected]<mailto:[email protected]>>, P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: RE: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Thanks Jorge for the quick reply.
Please find further question below.
From: Rabadan, Jorge (Nokia - US/Mountain View)
<[email protected]<mailto:[email protected]>>
Sent: Thursday, October 4, 2018 1:52 PM
To: Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
Cc: Jiang He <[email protected]<mailto:[email protected]>>; P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: Re: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Hi,
Questions:
1. Will the node in backup mode forward the packet to CE?
[JORGE] as soon as it becomes DF it can forward packets to the CE. The backup
node will have to run DF election upon the ES route withdrawal from the
primary. If AC-DF is enabled, it can also react to the withdrawal of AD routes
from the primary PE.
[Jai] Does that mean if any packet comes to a node that is still in the backup
mode will get dropped, before the new DF election is complete? Why cant this be
used as FRR? Or what is the use case of having backup node(s)?
[JORGE2] when the primary node fails, ES and AD routes are withdrawn. The AD
route withdrawal is an indication for remote nodes that they have to send
traffic to the backup (for a given MAC) or to flush the MACs if there are more
than 2 PEs in the ES. Around the same time or maybe earlier, the ES route
withdrawal will make the backup PE take over as DF
[Jai] will it become DF without DF election? What if there is more than one PE
in backup mode?
. So the overall convergence time will depend on how/when those two things
happen in time. Only the DF PE can forward traffic. A non-DF can never forward
traffic or there will be risk of duplicate packets.
2. Will all the nodes in backup mode forward the packet before DF election?
[JORGE] Only the new DF can forward.
3. If they forward, how is duplicate packets handled, in this case?
[JORGE] see above.
My two cents..
Thanks.
Jorge
From: BESS <[email protected]<mailto:[email protected]>> on behalf of
Jaikumar Somasundaram
<[email protected]<mailto:[email protected]>>
Date: Thursday, October 4, 2018 at 10:03 AM
To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>
Cc: Jiang He <[email protected]<mailto:[email protected]>>, P Muthu
Arul Mozhi
<[email protected]<mailto:[email protected]>>
Subject: [bess] EVPN MH: Backup node behavior in Primary Path Failure
Hello Everyone,
Sorry if it is a duplicate. I repost this query as I did not receive any
response yet.
(I was wondering if this mail already reached the group or not)
I have a question on Primary PE encountering a failure in EVPN multihoming
in single active mode.
RFC7432, section 14.1.1:
<snip>
If there is more than one backup PE for a given ES, the remote PE
MUST use the primary PE's withdrawal of its set of Ethernet A-D per
ES routes as a trigger to start flooding traffic for the associated
MAC addresses (as long as flooding of unknown unicast packets is
administratively allowed), as it is not possible to select a single
backup PE.
</snip>
Questions:
1. Will the node in backup mode forward the packet to CE?
2. Will all the nodes in backup mode forward the packet before DF election?
3. If they forward, how is duplicate packets handled, in this case?
Please help me anwere these questions.
Thanks & Regards
Jaikumar S
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