Subject: Re: [PATCH 2/2] bridge: allow forwarding some link local frames

From: Ross Brattain <[email-masked]>
Date: Mon, 17 Oct 2011 13:53:23 -0700

On Mon, 17 Oct 2011 07:35:53 -0700
Ed Swierk <[email-masked]> wrote:

> Why is forwarding LLDP (01-80-C2-00-00-0E) frames forbidden? I'm
> testing LLDP in a virtual topology and need the bridge to forward
> them.
> 
> If we're worried about standards, there is justification for allowing
> forwarding of LLDP frames. 802.1d-2005 specifies two classes of
> bridge, customer (C-VLAN) and provider (S-VLAN). Customer bridge is
> just new terminology for what was previously just called an
> 802.1d-compliant bridge, while provider bridge is a new class that
> transparently forwards certain control frames.

01-80-C2-00-00-0E should not pass the physical link.  If it does it will affect PFC 802.1Qbb and ETS 802.1Qaz.

802.1AB-2009 is more specific.  See Table 7-1 Group MAC addresses used by LLDP:

Nearest bridge: 01-80-C2-00-00-0E
Propagation constrained to a single physical link; stopped by all types of bridge

Nearest non-TPMR bridge: 01-80-C2-00-00-03
Propagation constrained by all bridges other than TPMRs; intended for use within provider bridged networks

Nearest Customer Bridge: 01-80-C2-00-00-00
Propagation constrained by customer bridges; this gives the same coverage as a customer-customer MACSec connection

--
Ross