Classification:Internal

 

Hi Mark,

 

Thanks for the update. You have any backhauls, that is running over an L2 xconnect  ? I’m facing issue only on the backhaul link over a l2vpn ckt.  

 

Ta,

 

 

From: NANOG <nanog-bounces+harivishnu.abhilash=mannai.com.qa@nanog.org> On Behalf Of Mark Tinka
Sent: Thursday, July 16, 2020 8:35 PM
To: nanog@nanog.org
Subject: Re: BFD for long haul circuit

 

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On 16/Jul/20 05:51, Harivishnu Abhilash wrote:

Classification:Public

 

Guys, I’m looking for recommendation regarding BFD timers that we can use for long haul circuit. RTT is roughly around 110 ms. In fact this is a l2vpn ckt provided by a telco.

Can you please advise the factors we can consider when setting the BFD timers (or any recommended values)? I have set 10 ms dead time but this is causing BFD to go down occasionally.


We run different intervals and multipliers depending on whether the connection is LAN or WAN.

For LAN (so within the same data centre), intervals are set to 150ms and multipliers are set to 3.

For WAN (any backbone regardless of latency), intervals are set to 250ms and multipliers are set to 5.

Since our network spans multiple countries and continents, we wanted a uniform value for the WAN side of things, so we don't have too many customized configurations. We found these settings to work well in mixed environments where implementations vary between CPU and line card processing, and also to strike a balance between accuracy and false positives.

We've been running this on IOS XE, IOS XR and Junos platforms since 2014. The only issues we found were:

Our longest circuit point-to-point is 140ms (Cape Town - London). These settings have been running fine on there since Day 1 (IOS XR-to-IOS XR), and overall detection and re-convergence of IS-IS + LFA leaves us happy and sleeping well at night.

Mark.

 

This email is classified as Internal by Harivishnu Abhilash

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