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

From: Stephen Hemminger <[email-masked]>
Date: Thu, 3 May 2007 14:38:32 -0700

On Thu, 3 May 2007 22:53:46 +0200
Sam Ravnborg <[email-masked]> 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
> > [email-masked]

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

-- 
Stephen Hemminger <[email-masked]>