Weiguo,
I guess I wasn’t clear. I think you draft, for the reasons I have
detailed, is a non-solution to a non-problem with tremendous control
plane cost.
Yours Irrespectively,
John
*From:*Haoweiguo [mailto:[email protected]]
*Sent:* Thursday, March 26, 2015 6:17 PM
*To:* John E Drake; Patrice Brissette (pbrisset)
*Cc:* Ali Sajassi (sajassi); [email protected]
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
Pls see below.
Thanks,
weiguo
------------------------------------------------------------------------
*From:*John E Drake [[email protected]]
*Sent:* Friday, March 27, 2015 6:00
*To:* Haoweiguo; Patrice Brissette (pbrisset)
*Cc:* Ali Sajassi (sajassi); [email protected] <mailto:[email protected]>
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
To recap,
We have established that your proposal is untenable because of its
control plane load.
We have established that your proposal is based upon a flawed
understanding of the DF election in RFC 7432.
[weiguo]: In ethernet world, traffic loop is serious than short timer
traffic disruption. If you want to implement transiet traffic loop
process, i will modify my draft to solve your issue.
If i am the developer, i will prefer short timer traffic disruption
based on current EVPN protocol.
What you are now arguing is that your draft prevents two or more PEs
from being DF simultaneously. This is clearly nonsense.
[weiguo]: I will modify the draft problem statements, and use the same
handshaking solution to solve it.
Furthermore, we have established that having two or more DFs for what
even you admit is a brief transient leads to duplicate traffic, which
is acceptable, but not loops, your assertion to the contrary.
[weiguo]: It is transient loop and traffic duplication issue.
Yours Irrespectively,
John
*From:*Haoweiguo [mailto:[email protected]]
*Sent:* Thursday, March 26, 2015 5:37 PM
*To:* John E Drake; Patrice Brissette (pbrisset)
*Cc:* Ali Sajassi (sajassi); [email protected] <mailto:[email protected]>
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
John,
As your understanding of the EVPN draft, the DF election mechanism has
more serious side effect, it will have short time traffic loop,i.e.,
dual DF PEs will exist for a short time. I think dual DF PEs is
absolutely not tolerated, because native ethernet header has no TTL,
up to several hundred ms traffic loop normally not tolerated in
commertial networks.
As your understanding, the PEs should do as following:
1. Accurate timer sync. NTP accuracy is bad, 1588v2 is good but have
rarely deployment.
Assuming PE1,PE2 and PE3 have consistent timer clock, when PE3 joins
ESI and trigger DF re-election. When reception timer expires:
PE1 upgrades to DF PE.
After reception timer+ ES route transmission timer:
PE2 downloads to non-DF PE.
So in timer clock sync case, dual DF PEs will exist at least
transmission timer.
If NTP is used for timer sync, because it has bad accuracy, dual DF
PEs will exist more longer timer.
So as your understanding for DF election, the drawback is more clear.
Thanks,
weiguo
------------------------------------------------------------------------
*From:*John E Drake [[email protected]]
*Sent:* Friday, March 27, 2015 4:41
*To:* Haoweiguo; Patrice Brissette (pbrisset)
*Cc:* Ali Sajassi (sajassi); [email protected] <mailto:[email protected]>
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
Weiguo,
We have already established that your proposal is untenable because of
its control plane load.
What we are now discussing is that your proposal is based upon a
misunderstanding of the algorithm in RFC 7432. You are assuming that
PE1 will advertise an ES route and then wait for the configured
interval before performing the DF election while PE2 and PE3 will
perform the DF election as soon as they receive the ES route from PE1.
This is not what RFC 7432 says.
Rather, what is says is that the advertisement of the ES route by PE1
and its receipt by PE2 and PE3 causes all three PEs to start the
configured interval timer - “3. When the timer expires, each PE
builds an ordered list of the IP addresses of all the PE nodes
connected to the Ethernet segment (including itself), in increasing
numeric value.”
Yours Irrespectively,
John
*From:*Haoweiguo [mailto:[email protected]]
*Sent:* Thursday, March 26, 2015 3:26 PM
*To:* John E Drake; Patrice Brissette (pbrisset)
*Cc:* Ali Sajassi (sajassi); [email protected] <mailto:[email protected]>
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
Pls read my detail replies to Satya. If you still can't catch it, pls
read my draft and EVPN base protocol, thanks
weiguo
------------------------------------------------------------------------
*From:*John E Drake [[email protected]]
*Sent:* Friday, March 27, 2015 1:28
*To:* Patrice Brissette (pbrisset)
*Cc:* Haoweiguo; Ali Sajassi (sajassi); [email protected]
<mailto:[email protected]>
*Subject:* Re: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
I think Patrice is correct. Your proposal doesn't solve the problem
and it does so at huge cost.
Sent from my iPhone
On Mar 26, 2015, at 10:34 AM, Patrice Brissette (pbrisset)
<[email protected] <mailto:[email protected]>> wrote:
Weiguo,
I’m not sure I’m following here.
Don’t you have the same issue with your handshaking mechanism?
If you don’t know your peer, how can you handshake?
Regards,
Patrice
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*Patrice Brissette*
TECHNICAL LEADER.ENGINEERING
[email protected] <mailto:[email protected]>
Phone: *+1 613 254 3336*
*Cisco Systems Canada Co. / Les Systemes Cisco Canada CIE*
Canada
Cisco.com <http://www.cisco.com/global/CA/>
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*From: *Haoweiguo <[email protected] <mailto:[email protected]>>
*Date: *Thursday, March 26, 2015 at 10:24 AM
*To: *Patrice Brissette <[email protected]
<mailto:[email protected]>>, John E Drake <[email protected]
<mailto:[email protected]>>, Ali Sajassi <[email protected]
<mailto:[email protected]>>, "[email protected]
<mailto:[email protected]>" <[email protected] <mailto:[email protected]>>
*Subject: *RE: [bess] Handshaking among PEs in an EVPN ES based on
Paxos algorithm
Hi Patrice,
Up to reception timer traffic disruption in transient phase is
one of the issues.
Thanks,
weiguo
------------------------------------------------------------------------
*From:*Patrice Brissette (pbrisset) [[email protected]
<mailto:[email protected]>]
*Sent:* Thursday, March 26, 2015 20:54
*To:* Haoweiguo; John E Drake; Ali Sajassi (sajassi);
[email protected] <mailto:[email protected]>
*Subject:* Re: [bess] Handshaking among PEs in an EVPN ES
based on Paxos algorithm
Weiguo,
You mention "But if your draft have not solved all issues”,
Can you explain what Satya’s draft is not solving?
Regards,
Patrice
Image removed by sender.
*Patrice Brissette*
TECHNICAL LEADER.ENGINEERING
[email protected] <mailto:[email protected]>
Phone: *+1 613 254 3336*
*Cisco Systems Canada Co. / Les Systemes Cisco Canada CIE*
Canada
Cisco.com <http://www.cisco.com/global/CA/>
Image removed by sender.Think before you print.
This email may contain confidential and privileged material
for the sole use of the intended recipient. Any review, use,
distribution or disclosure by others is strictly prohibited.
If you are not the intended recipient (or authorized to
receive for the recipient), please contact the sender by reply
email and delete all copies of this message.
Please click here
<http://www.cisco.com/web/about/doing_business/legal/cri/index.html>
for Company Registration Information.
*From: *Haoweiguo <[email protected]
<mailto:[email protected]>>
*Date: *Wednesday, March 25, 2015 at 10:38 PM
*To: *John E Drake <[email protected]
<mailto:[email protected]>>, Ali Sajassi <[email protected]
<mailto:[email protected]>>, "[email protected]
<mailto:[email protected]>" <[email protected] <mailto:[email protected]>>
*Subject: *Re: [bess] Handshaking among PEs in an EVPN ES
based on Paxos algorithm
Hi John,
Firstly i think EVPN community should reach consensus on
the issues of current DF election mechanism. All these
issues should be resolved in a single new DF election
draft,rather than in multiple separate drafts. If your
draft can solve all these issues and stable, i have no
question for its progressing. But if your draft have not
solved all issues, i think it had better combine with
other drafts to provide a comprehensive solution. I think
the issues listed in draft-rabadan-bess-evpn-ac-df-01 and
draft-hao-bess-evpn-df-handshaking-00 is valid, it should
be resolved. So i think although your new Hash algorithm
for DF election is good, it only includes partial
enhancements, maybe it still needs some time for consensus.
Thanks,
weiguo
------------------------------------------------------------------------
*From:*John E Drake [[email protected]
<mailto:[email protected]>]
*Sent:* Thursday, March 26, 2015 7:16
*To:* Haoweiguo; Ali Sajassi (sajassi); [email protected]
<mailto:[email protected]>
*Subject:* RE: [bess] Handshaking among PEs in an EVPN ES
based on Paxos algorithm
Weiguo,
Your proposal introduces a control plane processing load
that is O(#EVIs * PEs) per DF election and given that
there can be 4K EVIs per ES, this looks like a
**substantial** load. Furthermore,
you can’t use the ES route to co-ordinate DF election
because you would need to carry your new extended
community for each EVI and they would not all fit. You
also can’t use the Per EVI Ethernet AD route because that
is processed by all PEs in the EVI.
I think that from a practical perspective the new DF
election proposed in Satya’s draft is sufficiently stable
that it renders your draft moot, even if it could be made
to work.
Yours Irrespectively,
John
*From:*BESS [mailto:[email protected]] *On Behalf Of
*Haoweiguo
*Sent:* Wednesday, March 25, 2015 5:34 PM
*To:* Ali Sajassi (sajassi); [email protected]
<mailto:[email protected]>
*Subject:* Re: [bess] Handshaking among PEs in an EVPN ES
based on Paxos algorithm
Hi Ali,
Thanks for your information. I scanned through this draft,
it really introduces inter-chassis message for DF election
handshaking, the requirements in this draft is to
eliminate transiet Loop and traffic duplication. Current
EVPN DF election mechanism already eliminated loop and
traffic duplication by configuring long reception timer on
each multi-homed PE, but up to reception timer traffic
disruption issue still exist. EVPN for DCI is an important
use case for EVPN, up to reception timer traffic
disruption can't be tolerated for service providers, it
should be improved.
Also for accuracy, i think handshaking state machine on
each multi-homed PE is also needed. From solution
perspective, in my draft, no inter-chassis message is
introduced, only one new extended community is introduced,
i think the process is comparatively simple than your
following draft.
Current EVPN DF election has some drawbacks, so there are
three new drafts about DF election emerged. I think BESS
WG can consider these three drafts in global view, a
single,comprehensive new DF election draft is hoped.
thanks.
Thanks,
weiguo
------------------------------------------------------------------------
*From:*BESS [[email protected]
<mailto:[email protected]>] on behalf of Ali Sajassi
(sajassi) [[email protected] <mailto:[email protected]>]
*Sent:* Thursday, March 26, 2015 0:21
*To:* [email protected] <mailto:[email protected]>
*Subject:* [bess] Handshaking among PEs in an EVPN ES
based on Paxos algorithm
FYI- First published July 4, 2011
https://datatracker.ietf.org/doc/draft-sajassi-l2vpn-evpn-segment-route/
-Ali
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