Re: Does the debian kernel sends the gratuitous arp ?
On Mon, Oct 09, 2023 at 10:15:38PM +0200, Geert Stappers wrote:
> On Mon, Oct 09, 2023 at 08:39:02PM +0530, Balaji G wrote:
> > Hi Geert,
>
> Hello mailinglist (archive )readers of debian-user@lists.debian.org
>
Hello again,
>
> > >>> During `ip link set down dev eno5np0` and `ip link set up dev eno5np0`
> > >>> are NO IP-addresses involved.
> >
> > This interface eno5np0 is configured with the ip addresses(10.45.10.4 ).
> >
> > # ifconfig
> } ( mismatch between `ifconfig` command expected `ifconfig` output )
> > eno5np0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
> > inet 10.45.10.4 netmask 255.255.255.0 broadcast 10.45.10.255
> > ether 88:e9:a4:49:18:48 txqueuelen 1000 (Ethernet)
> > RX packets 2967346895 bytes 4417546189260 (4.0 TiB)
> > RX errors 0 dropped 1 overruns 0 frame 0
> > TX packets 1634521866 bytes 2220475762246 (2.0 TiB)
> > TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
>
>
> I did missed "LOWER_UP", then I noticed that `ifconfig` is used. More
> on that later. Back to 'Subject: Re: Does the debian kernel sends the
> gratuitous arp ?'
>
> To me is the answer "Yes, Debian kernel sends gratuitous ARP when it
> supposed to do". But we, this mailinglist, have this discussion because
> somewhere is the gratuitous ARP missing. What triggered the "I wonder
> why there is no gratuitous ARP?" is yet unknown.
>
> Let me try to capture a gratuitous ARP. I will be using only one
> interface (it is OK if the computer has many other network interfaces)
> Using two logins as root, one for "tcpdump", the other "set address".
>
> In "tcpdump session"
>
> tcpdump -n -i eth0 arp
>
>
> In "set address session"
>
> sudo ip address add 198.51.100.23/24 dev eth0
>
>
> Back to "tcpdump session".
>
> And to my surprise: **no** gratuitous ARP !
>
> It should be there. I even tried after:
>
> $ cat /proc/sys/net/ipv4/conf/eth0/arp_notify
> 0
> $ echo 1 | sudo tee -a /proc/sys/net/ipv4/conf/eth0/arp_notify
> 1
> $ cat /proc/sys/net/ipv4/conf/eth0/arp_notify
> 1
> $
>
>
> I'm gonna sleep about it. Expect me back over 48 hours.
:-)
> > Thanks,
>
> Yeah, thanks for the good question.
>
It did learn me that things have changes.
I hope it is the improvement that was aimed for.
No, I have no idea if the H.A., High Available, setup I did build
for a previous employer are effected.
> > Balaji
>
> Groeten
> Geert Stappers
>
>
> About ifconfig :
> https://serverfault.com/questions/633087/where-is-the-statement-of-deprecation-of-ifconfig-on-linux
>
a.k.a. use `ip addres`, `ip a` for short.
Groeten
Geert Stappers
--
Silence is hard to parse
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