Date: Mon, 07 Aug 2000 11:42:20 -0500 From: Bob Van Valzah <Bob@WhiteBarn.Com> To: "Pedro J. Lobo" <pjlobo@euitt.upm.es> Cc: freebsd-net@FreeBSD.ORG Subject: Re: VLAN Config Advice Message-ID: <398EE6EC.26646EE9@WhiteBarn.Com> References: <Pine.BSF.4.21.0008071016390.302-100000@deneb.euitt.upm.es>
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I found my problem in misconfiguration between my Cisco FreeBSD. Details below.
"Pedro J. Lobo" wrote:
> > If I do ifconfig fxp0 first and then ifconfig vlan0 on top of it, I get
> > a booted system. However, arp issues lots of warning messages about
> > packets arriving on fxp0 when they should be on vlan0 and I can't ping
> > the box.
>
> Hmmm, I've been using simultaneously fxp0 (i.e., without tag) and vlan0
> (tagged, hooked on fxp0) without any problems. Are you sure you are
> configuring fxp1 and vlan0 with addresses that are on different subnets?
I've learned that 802.1q has this notion of a "native VLAN." On Ciscos (at least)
that defaults to VLAN 1. My problem was that I had my FreeBSD vlan0 interface
configured on an IP network that was on VLAN 1. My cisco wasn't tagging packets for
VLAN 1 so they appeared to arp as if they were arriving on fxp0 (the physical
interface) even though the arp request went out on vlan0.
There are two simple fixes. 1) On the cisco side: "switchport trunk native vlan 999"
or some other VLAN you're not using. This has the effect of forcing the Cisco to tag
traffic for all VLANs in use. 2) Configure the physical interface for the IP network
on VLAN 1. This is probably a little cleaner in that it doesn't depend on the
VLAN code working at all to have at least one working IP address.
Does anybody with experience on other switches know if VLAN 1 is always the default
native VLAN? Either way, this quirk should be mentioned in the Handbook in the VLAN
section (still to be written).
Thanks,
Bob
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