Hey Dirk, Ohhhhh that is REALLY helpful, thankyou!! Ok I will keep playing with it tonight and see if there's some way to get more debugging info from both the Tik and Nexus sides, and also get more captures the working from ROS6<>Nexus pair, and see what the differences might be! Thanks, Damien On Thu, 22 Aug 2024 at 17:17, TFM Cloud - Dirk Bermingham <dirk@tfmcloud.au> wrote:
Hi guys,
Its not a bug, it's a required behaviour of the protocol re: the RFC https://datatracker.ietf.org/doc/html/rfc5880#section-6.8.2
"When bfd.SessionState is not Up, the system MUST set bfd.DesiredMinTxInterval to a value of not less than one second (1,000,000 microseconds). This is intended to ensure that the bandwidth consumed by BFD sessions that are not Up is negligible, particularly in the case where a neighbor may not be running BFD."
There has to be something else going on there Damien...
Regards,
DB
-----Original Message----- From: Public <public-bounces@talk.mikrotik.com.au> On Behalf Of Roger Plant via Public Sent: Wednesday, August 21, 2024 1:33 PM To: MikroTik Australia Public List <public@talk.mikrotik.com.au>; Damien Gardner Jnr <rendrag@rendrag.net> Cc: Roger Plant <rplant@melbpc.org.au> Subject: Re: [MT-AU Public] Soooo, how does one get BFD to come up on ROS 7? :)
Hi Again,
I did some more testing over a pppoe link, and it would normally connect immediately when rejigging the bfd, but if I downed the pppoe link and then restored it a short time (10S or so) later it would sometimes take a long time before bfd would come back up.
And while it was down, it was sending bfd packets with an incorrect value of 1000ms for the min_tx interval. The first seen reply packet also had a Min tx interval of 1000ms.
Once the other end started replying they would both then send the correct 200ms (in this case) value.
It was only sending BFD packets a bit under every second or so until the BFD link was up. Then it started sending quickly. This rate sort of makes sense while not connected, but perhaps it shouldn't be in the actual packet??
Seems likely a bug.
Some packets
Frame 5: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00) Internet Protocol Version 4, Src: 192.168.97.1, Dst: 192.168.97.244 User Datagram Protocol, Src Port: 49174, Dst Port: 3784 BFD Control message 001. .... = Protocol Version: 1 ...0 0000 = Diagnostic Code: No Diagnostic (0x00) 01.. .... = Session State: Down (0x1) Message Flags: 0x40 Detect Time Multiplier: 5 (= 5000 ms Detection time) Message Length: 24 bytes My Discriminator: 0x45839bbb Your Discriminator: 0x00000000 Desired Min TX Interval: 1000 ms (1000000 us) Required Min RX Interval: 200 ms (200000 us) Required Min Echo Interval: 0 ms (0 us)
First seen reply packet
Frame 15: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00) Internet Protocol Version 4, Src: 192.168.97.244, Dst: 192.168.97.1 User Datagram Protocol, Src Port: 49158, Dst Port: 3784 BFD Control message 001. .... = Protocol Version: 1 ...0 0000 = Diagnostic Code: No Diagnostic (0x00) 01.. .... = Session State: Down (0x1) Message Flags: 0x40 Detect Time Multiplier: 5 (= 5000 ms Detection time) Message Length: 24 bytes My Discriminator: 0x11f867b3 Your Discriminator: 0x00000000 Desired Min TX Interval: 1000 ms (1000000 us) Required Min RX Interval: 200 ms (200000 us) Required Min Echo Interval: 0 ms (0 us)
2nd BFD reply packet
Frame 29: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00) Internet Protocol Version 4, Src: 192.168.97.244, Dst: 192.168.97.1 User Datagram Protocol, Src Port: 49158, Dst Port: 3784 BFD Control message 001. .... = Protocol Version: 1 ...0 0000 = Diagnostic Code: No Diagnostic (0x00) 11.. .... = Session State: Up (0x3) Message Flags: 0xc0 Detect Time Multiplier: 5 (= 1000 ms Detection time) Message Length: 24 bytes My Discriminator: 0x11f867b3 Your Discriminator: 0x45839bbb Desired Min TX Interval: 200 ms (200000 us) Required Min RX Interval: 200 ms (200000 us) Required Min Echo Interval: 0 ms (0 us)
From: Damien Gardner Jnr <rendrag@rendrag.net> Date sent: Wed, 21 Aug 2024 11:17:44 +1000 Subject: Re: [MT-AU Public] Soooo, how does one get BFD to come up on ROS 7? :) To: MikroTik Australia Public List <public@talk.mikrotik.com.au> Copies to: Roger Plant <rplant@melbpc.org.au>
To: TFM Cloud - Dirk Bermingham <<a href="mailto:dirk@tfmcloud.au" target="_blank">dirk@tfmcloud.au </a>><br> Subject: Re: [MT-AU Public] Soooo,<br> From: Damien Gardner Jnr via Public <<a href="mailto:public@talk.mikrotik.com.au" target="_blank"> public@talk.mikrotik.com.au</a>><br>
Oooh really? Can I ask what settings you have in /routing/bfd ?
---------------------------- Roger Plant
_______________________________________________ Public mailing list Public@talk.mikrotik.com.au http://talk.mikrotik.com.au/mailman/listinfo/public_talk.mikrotik.com.au
-- Damien Gardner Jnr VK2TDG. Dip EE. GradIEAust rendrag@rendrag.net - http://www.rendrag.net/ -- We rode on the winds of the rising storm, We ran to the sounds of thunder. We danced among the lightning bolts, and tore the world asunder