Arista Switch BFD issue - custom port
Hi, I'm running BIRD on Arista which allows access to Linux bash. I'm having issue with running multihop BFD session on it and I believe it's related to port being already binded.
bash-4.3# netstat -tulpen | grep 4784
udp6 0 0 :::4784 :::*
0 4269 -
Above is netstat output from bash on Arista (there is no BFD configured on switch). When I try to run *nc -ul4 4784* I'm getting
Ncat: bind to 0.0.0.0:4784: Address already in use. QUITTING.
I couldn't find any configuration option for BFD to change port being used, but maybe there is one? Perhaps anyone run into similar issue and have a workaround? -- Kuba Nowacki Senior NetOps M: +(48) 605 508 118 E: jnowacki@greywizard.com GreyWizard Sp. z o.o. ul. Palacza 113 60-273 Poznań, Poland NIP: 779-24-22-423 Regon: 302744400 KRS: 0000512326 greywizard.com support@greywizard.com +48 22 201 33 13 Sąd Rejonowy w Poznaniu, VIII Wydział Gospodarczy Krajowego Rejestru Sądowego. Kapitał zakładowy 10000 PLN.
On Mon, Aug 13, 2018 at 03:14:10PM +0200, Jakub Nowacki wrote:
Hi,
I'm running BIRD on Arista which allows access to Linux bash. I'm having issue with running multihop BFD session on it and I believe it's related to port being already binded.
bash-4.3# netstat -tulpen | grep 4784
udp6 0 0 :::4784 :::*
0 4269 -
Hi I thing 4269 here is PID, what is the process? netcat should return the process name, which is not here, but perhaps it is some limited variant of netcat. Maybe BFD is implemented in control plane on Arista, so it collides on kernel level? Also, there should be an error message in the BIRD log related to bind errors.
I couldn't find any configuration option for BFD to change port being used, but maybe there is one?
There is no such option. Perhaps we should add it, as BGP and RIP also have port option.
Perhaps anyone run into similar issue and have a workaround?
As a workaround you can recompile BIRD with changed BFD_MULTI_CTL_PORT in proto/bfd/bfd.h file. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."
On Tue, Aug 14, 2018 at 2:27 PM Ondrej Zajicek <santiago@crfreenet.org> wrote:
On Mon, Aug 13, 2018 at 03:14:10PM +0200, Jakub Nowacki wrote:
Hi,
I'm running BIRD on Arista which allows access to Linux bash. I'm having issue with running multihop BFD session on it and I believe it's related to port being already binded.
bash-4.3# netstat -tulpen | grep 4784
udp6 0 0 :::4784 :::*
0 4269 -
Hi
I thing 4269 here is PID, what is the process? netcat should return the process name, which is not here, but perhaps it is some limited variant of netcat. Maybe BFD is implemented in control plane on Arista, so it collides on kernel level?
4269 is Inode, netstat for some reason doesn't show PID/process name for ports related to BFD on Arista. This seems to be Arista thing not Bird, so probably that's not a place to investigate this here. Also, there should be an error message in the BIRD log related to bind
errors.
I haven't seen any error messages in log, perhaps logging level were not set for it. I'll double check it.
I couldn't find any configuration option for BFD to change port being used, but maybe there is one?
There is no such option. Perhaps we should add it, as BGP and RIP also have port option.
That would be super helpful. I could create Pull Request for it, but I've only written in C++ years ago, never actually touched plain C, it can take me some time.
Perhaps anyone run into similar issue and have a workaround?
As a workaround you can recompile BIRD with changed BFD_MULTI_CTL_PORT in proto/bfd/bfd.h file.
That's what I did. After changing port to arbitrary value, which is not taken on Arista it started to work. So it seems that BFD is failing due to Arista OS.
-- Elen sila lumenn' omentielvo
Ondrej 'Santiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."
-- Kuba Nowacki Senior NetOps M: +(48) 605 508 118 E: jnowacki@greywizard.com GreyWizard Sp. z o.o. ul. Palacza 113 60-273 Poznań, Poland NIP: 779-24-22-423 Regon: 302744400 KRS: 0000512326 greywizard.com support@greywizard.com +48 22 201 33 13 Sąd Rejonowy w Poznaniu, VIII Wydział Gospodarczy Krajowego Rejestru Sądowego. Kapitał zakładowy 10000 PLN.
participants (2)
-
Jakub Nowacki -
Ondrej Zajicek