[bess] EVPN VPWS BDF forwarding behavior at MH site

gangadhara reddy chavva <meetgangadhara@gmail.com> Fri, 09 August 2019 13:31 UTC

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From: gangadhara reddy chavva <meetgangadhara@gmail.com>
Date: Fri, 09 Aug 2019 19:01:02 +0530
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Subject: [bess] EVPN VPWS BDF forwarding behavior at MH site
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HI All,

i have one question on EVPN VPWS BDF forwarding behavior at MH site.
when PE is selected as BDF, it will communicate the EAD EVI route with B
bit set to remote PE. so remote PE will install the FRR route with primary
path towards DF PE and secondary path towards BDF.
when ever primary path get disconnected it will switch the path to
secondary path quickly at remote PE. because of this data from the remote
PE will reach to BDF very quickly, but if BDF is not programmed its path
towards multi homed segment then traffic will be get dropped until control
plane convergence and it will be elected as DF.

for faster convergence if we can install the route such that BDF can allow
the traffic from remote PE towards to multi homed segment, we can forward
the traffic received from the remote PE.

at the same time we shouldn't allow the traffic from multi homed site this
leads to duplicate traffic on the remote PE. to achieve this we should not
program the path from multi home site towards remote PE until this PE
elected as DF for that VPWS instance.

can you please let me know if there are any problems with this kind of
approach.

[image: image.png]

Regards,
Gangadhar