Re: Routing 600+ vlan's via linux problems (looks like arp problems)

Stephen Hemminger
2007-05-03T21:38:49Z

On Thu, 3 May 2007 22:53:46 +0200
Sam Ravnborg <sam@ravnborg.org> wrote:

> On Thu, May 03, 2007 at 10:25:48PM +0200, Øyvind Vågen Jægtnes wrote:
> > Hi,
> Hi Øyvind.
>
> Forwarding your mail to netdev where the networking people are
> hanging out. Maybe they can help you.
>
> Sam
>
> >
> > We have a one gigabit internet connection that is normally
> > routed by a hardware juniper router. The drive in this is down
> > and we need to use a linux machine (Pentium D 3 ghz) as a
> > temporary router.
> > Now setting up all the 600 vlans and assigning ip addresses
> > is no problem. We have testet all by using a laptop, setting up
> > 600 vlan interfaces on this and running dhcpclient on all.
> > This worked just fine, all the interfaces got address.
> >
> > Now for the real setup.
> > We closed the mac of the juniper to the network card that
> > would be connected to the internal LAN, set up the interfaces,
> > and swapped cables. This worked fine for approximately 100
> > of the computers that are connected, but the rest would not
> > get IP. The connected 100 computers were routed just fine.
> >
> > What we think the problem is, is that the arp cache on the
> > linux router seems strange. It can resolve the MAC for the
> > 100 clients that actually got through.
> > For the rest all we see in the arp cache is (incomplete)
> >
> > Here is some of the listing for arp -n:
> > 193.239.155.118 ether 00:0A:E4:59:75:66 C
> > eth1.1087
> > 193.239.154.74 (incomplete)
> > eth1.1016
> > 193.239.155.7 ether 00:11:95:D2:3F:FD C
> > eth1.2002
> > 83.143.114.222 (incomplete)
> > eth1.1305
> > 83.143.113.246 ether 00:0B:5D:4B:B8:77 C
> > eth1.1247
> > 83.143.116.126 (incomplete)
> > eth1.1409
> > 83.143.118.114 (incomplete)
> > eth1.1534
> > 193.239.154.210 ether 00:03:0D:2F:1B:7F C
> > eth1.1050
> > 169.254.69.247 ether 00:15:C5:C2:31:6C C
> > eth1.1262
> > 83.143.112.38 (incomplete)
> > eth1.1131
> > 83.143.118.18 (incomplete)
> > eth1.1510
> > 83.143.112.118 ether 00:11:95:CE:BF:72 C
> > eth1.1151
> > 192.168.1.2 ether 00:0D:88:78:C0:00 C
> > eth1.2050
> > 83.143.117.138 (incomplete)
> > eth1.1476
> > 83.143.116.18 (incomplete)
> > eth1.1382
> > 83.143.118.26 (incomplete)
> > eth1.1512
> > 83.143.112.6 (incomplete)
> > eth1.1123
> > 193.239.155.62 (incomplete)
> > eth1.1073
> >
> > `arp -n|wc -l` returns around 350, which is the number of active ports on
> > the
> > edge switches...
> > this number is confirmed by snmp
> >
> > I have looked through the source for arp.c but i can't see any immediate
> > problems. There is no messages in dmesg, kern.log og messages (except for
> > eth1.vlanid up * 600).
> >
> > If anyone know what the problem can be, if this is a bug, or if PSBKC i
> > would
> > much appreciate it.
> >
> > regards
> > Øyvind Vågen Jægtnes
> > +47 96 22 03 08
> > lorrides@gmail.com

What kernel version? Are you on a recent 2.6 kernel or stuck on some
old "vendor stable" 2.4 kernel?

--
Stephen Hemminger <shemminger@linux-foundation.org>