[ovs-dev] TOS for BFD packets

Venkatesan Pradeep venkatesan.pradeep at ericsson.com
Tue Oct 17 09:12:38 UTC 2017

Hi Ben,

The implementations I've worked on have used tos=0xC0 (DSCP CS6). Given that DSCP CS6 is recommended for network control traffic, and is used by OSPF, BGP etc., I think it is likely that many implementations do that for BFD too. Since BFD flaps have significant impact, marking BFD packets with the right DSCP value will allow the network to apply the right QoS for those packets and prevent BFD flaps due to network congestion.



-----Original Message-----
From: Ben Pfaff [mailto:blp at ovn.org] 
Sent: Monday, October 16, 2017 11:13 PM
To: Venkatesan Pradeep <venkatesan.pradeep at ericsson.com>
Cc: ovs-dev at openvswitch.org
Subject: Re: [ovs-dev] TOS for BFD packets

On Mon, Oct 16, 2017 at 04:32:45PM +0000, Venkatesan Pradeep wrote:
> BFD packets are being sent with tos = IPTOS_LOWDELAY | 
> IPTOS_THROUGHPUT which would put them in the best-effort class. It 
> would be better if we send with tos = IPTOS_PREC_INTERNETCONTROL so 
> that they can be appropriately prioritized in the network.

Is that common practice for other BFD implementations?  If so, then I agree that OVS should follow it also.

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