SDWAN Shus Down an interface every few minutes

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SDWAN Shus Down an interface every few minutes

L1 Bithead

SDWAN.1 is Xfinity comcast no issue ( cable modem 500 down 30 up)

SDWAN PROFILE. set to ethernet even though it is a cable modem circuit with an ethernet handoff


SDWAN.1 TIER 1 ISP.   Bouncing every few minutes based on SDWAN probing.



Tried ETHERNET  vs Fiber link.


The Tier1 carrier and I have verified evrything with the circuit and see no issues.

MTR on the TIER1 network of course limits icmp so observed packet loss is not relevant since it is at only 1 hop where the policers are applied


Maybe there is a better way or something I am missing for SDWAN circuit health



L2 Linker

Look for TCP retransmissions in pcaps as windows ramp up during transmits.  Might be a MTU issue.  set your MTU down to low 1430 to test if currently at 1500. 

Douglas Elliott
Security Implementation Engineer

this is a Direct Internet Access / ISP circuit not a tunnel

If the underlay is the issue and not the overlay SDWAN interfaces, I would look for layer 2 channel issues or seek help from Comcast support to remediate a MAC ghosting issue. 

Douglas Elliott
Security Implementation Engineer
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