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RE: One question on draft "draft-vgovindan-l2vpn-evpn-bfd-01"

"Vengada Prasad Govindan (venggovi)" <venggovi@cisco.com> Fri, 28 March 2014 07:15 UTC

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From: "Vengada Prasad Govindan (venggovi)" <venggovi@cisco.com>
To: "Xialiang (Frank)" <frank.xialiang@huawei.com>, "Samer Salam (ssalam)" <ssalam@cisco.com>, "Ali Sajassi (sajassi)" <sajassi@cisco.com>
Subject: RE: One question on draft "draft-vgovindan-l2vpn-evpn-bfd-01"
Thread-Topic: One question on draft "draft-vgovindan-l2vpn-evpn-bfd-01"
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Date: Fri, 28 Mar 2014 07:15:16 +0000
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Hello Frank,
  Sorry for the delay in my response. The reason why IP encapsulation is not preferred is that the BFD packet may go out-of-band since the DIP of the packet inside the MPLS-BFD is 127/8 (different from the IP a data packet may use). Any node hashing on the DIP may cause it take an out-of-band path especially when the packet does not carry an entropy label in the MPLS label stack. Since this issue is not present in the GAL/ G-Ach case the draft recommends that option.
Thanks
Prasad

From: Xialiang (Frank) [mailto:frank.xialiang@huawei.com]
Sent: Thursday, March 27, 2014 9:18 AM
To: Vengada Prasad Govindan (venggovi); Samer Salam (ssalam); Ali Sajassi (sajassi)
Cc: l2vpn@ietf.org
Subject: RE: One question on draft "draft-vgovindan-l2vpn-evpn-bfd-01"

Hi authors, ping your echo.

From: Xialiang (Frank)
Sent: Thursday, March 20, 2014 3:02 PM
To: 'venggovi@cisco.com'.com'; 'ssalam@cisco.com'.com'; 'sajassi@cisco.com'
Cc: l2vpn@ietf.org<mailto:l2vpn@ietf.org>
Subject: One question on draft "draft-vgovindan-l2vpn-evpn-bfd-01"

Hi authors,
I have one question about BFD packet encapsulation: you point out 2 ways: by GAL/G-ACH, or by IP. And you think that the way by IP is not suitable because BFD packets will follow a different path than that of data packets when they use different destination IP address.
Can you clarify the specific reason? And why can the way by GAL/G-ACH avoid this problem of different path?
Thanks!

B.R.
Frank

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