Re: [bess] Some questions regarding draft-ietf-bess-evpn-inter-subnet-forwarding-05

"Ali Sajassi (sajassi)" <sajassi@cisco.com> Thu, 31 January 2019 02:19 UTC

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From: "Ali Sajassi (sajassi)" <sajassi@cisco.com>
To: Zhuangshunwan <zhuangshunwan@huawei.com>, "draft-ietf-bess-evpn-inter-subnet-forwarding@ietf.org" <draft-ietf-bess-evpn-inter-subnet-forwarding@ietf.org>
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Thread-Topic: [bess] Some questions regarding draft-ietf-bess-evpn-inter-subnet-forwarding-05
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Subject: Re: [bess] Some questions regarding draft-ietf-bess-evpn-inter-subnet-forwarding-05
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Please refer to my reply inline marked with “AS>”

From: BESS <bess-bounces@ietf.org> on behalf of Zhuangshunwan <zhuangshunwan@huawei.com>
Date: Thursday, September 13, 2018 at 1:00 AM
To: "draft-ietf-bess-evpn-inter-subnet-forwarding@ietf.org" <draft-ietf-bess-evpn-inter-subnet-forwarding@ietf.org>
Cc: "bess@ietf.org" <bess@ietf.org>
Subject: [bess] Some questions regarding draft-ietf-bess-evpn-inter-subnet-forwarding-05

Dear authors,

I have some questions regarding draft-ietf-bess-evpn-inter-subnet-forwarding-05.

The last paragraph of https://tools.ietf.org/html/draft-ietf-bess-evpn-inter-subnet-forwarding-05#section-4.1.2<https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dbess-2Devpn-2Dinter-2Dsubnet-2Dforwarding-2D05-23section-2D4.1.2&d=DwMFbw&c=HAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoCI&r=f7wsLGcfzAWDNS6XNTBZwj_OLAOsZZqdrR2IDAzeZqE&m=0IvlO-HEBllNV94YGKHqwBXn0tXwm4ewl0m1NgqEKBE&s=sY6nMHomcrBcYyfUaGw-D6CN6yH6pCF1s-w6Xzy_0WE&e=> (Page 21) said:
   If EVPN-IRB NVEs are configured not to advertise MAC-only routes,
   then upon receiving the first data packet, it learns the MAC address
   of the TS and updates the MAC entry in the corresponding MAC-VRF
   table with the local adjacency information (e.g., local interface).
   It also realizes that there has been a MAC move because the same MAC
   address has been learned remotely from the source NVE. It then sends
   an unicast ARP request to the host and when receiving an ARP
   response, it follows the procedure outlined in section 4.1.1<https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dbess-2Devpn-2Dinter-2Dsubnet-2Dforwarding-2D05-23section-2D4.1.1&d=DwMFbw&c=HAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoCI&r=f7wsLGcfzAWDNS6XNTBZwj_OLAOsZZqdrR2IDAzeZqE&m=0IvlO-HEBllNV94YGKHqwBXn0tXwm4ewl0m1NgqEKBE&s=Xk1XmUZDuYMFzFEwbeDAb0bPJvdjVZJFHmynSmsJrmQ&e=>JvdjVZJFHmynSmsJrmQ&e=>..

Question 1:
“… it follows the procedure outlined in section 4.1.1<https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dbess-2Devpn-2Dinter-2Dsubnet-2Dforwarding-2D05-23section-2D4.1.1&d=DwMFbw&c=HAkYuh63rsuhr6Scbfh0UjBXeMK-ndb3voDTXcWzoCI&r=f7wsLGcfzAWDNS6XNTBZwj_OLAOsZZqdrR2IDAzeZqE&m=0IvlO-HEBllNV94YGKHqwBXn0tXwm4ewl0m1NgqEKBE&s=Xk1XmUZDuYMFzFEwbeDAb0bPJvdjVZJFHmynSmsJrmQ&e=>..”jVZJFHmynSmsJrmQ&e=>..”,
Which specific paragraph of section 4.1.1 is followed?
IMO, It follows the procedure that starts from the second paragraph of the section 4.1.1:
“
   The target NVE upon receiving this ARP request, updates its MAC-VRF,
   IP-VRF, and ARP table with the host MAC, IP, and local adjacency
   information (e.g., local interface).
…
“
Is my understanding correct?

AS> It is both 2nd and 3rd paragraphs of section 4.1.1.

Question 2:
“It then sends an unicast ARP request to the host and when receiving an ARP response”.
I think this sentence means: The target NVE sends an unicast ARP request to the moved host (TS) and the target NVE receives an ARP response from the moved host (TS). Then, per the ARP response, the target NVE can recognize that the moved host (TS) has been migrated to the target NVE.
Is my understanding correct?

AS> That’s correct.

Thanks,
Shunwan