Hi Adrian:
>
> Is there any difference (from the point of view of the
> network) between a VLAN with just two sites, and an LSP that
> uses the (same along the whole
> path) VLAN tag to route data?
If by two sites you mean a link between two NEs, yes there is a difference.
If by two sites you mean a very simple VLAN in the context of a larger network that may have many other VLANs, I beleive the answer is also yes.
My understanding (and I welcome correction) is that currently any specified intermediate device that queues and steers traffic on the basis of an Ethernet VLAN tag is by definition a bridge and it will do P2P and MP2P fan in exclusively on the basis of VLAN tag, and only inspects the mac address when there is a choice of more than one output port.
Further that as specified bridges do not generally provide unique treatment per VLAN tag, as the number of spanning trees permitted does not correspond to the entire VLAN range.
There are also OAM implications etc. associated with such a device being an Ethernet device. It would be desirable that such a device implemented MIP (maintenance intermediate point) functionality.
cheers
Dave
>
> Clearly there is a difference in hardware with respect to the
> way that the hardware is programmed from the control plane.)
>
> Adrian
> ----- Original Message -----
> From: "David Allan" <dallan@nortelnetworks.com>
> To: "'Adrian Farrel'" <adrian@olddog.co.uk>; "'Shahram
> Davari'" <Shahram_Davari@pmc-sierra.com>
> Cc: <ccamp@ops.ietf.org>
> Sent: Thursday, January 27, 2005 9:37 PM
> Subject: RE: Layer 2 Switching Caps LSPs
>
>
> > Hi Adrian:
> >
> > Your suggestion is in a way reasonable but with the caveat that in
> > IEEE terms, a bridging topology is currently all VLANs
> (802.1Q single
> spanning
> > tree) or partitioned into specific ranges (I believe 64 in 802.1s
> although I
> > do not claim to be an expert).
> >
> > If the PEs were to implement a bridge function and we were
> using GMPLS
> to
> > interconnect them, then the control plane should be
> identifying either
> all
> > VLANs (single spanning tree, which I beleive the draft covers by
> referring
> > simply to Ethernet port) or a VLAN range to be associated
> with the LSP
> > consistent with 802.1s if it is to operate to interconnect bridges
> defined
> > by the IEEE...
> >
> > I suspect assuming any other behavior (e.g. LSP for single VLAN tag)
> would
> > go outside the boundary of what is currently defined...so alignment
> > with 802.1s IMO would be a minimum requirement if we are to
> consider
> > carrying VLAN information in GMPLS signalling....
> >
> > cheers
> > Dave
> >
> > You wrote....
> > > Hi,
> > >
> > > The authors of the draft might like to clarify for the
> list exactly
> > > what data plane operations they are suggesting. To me it seems
> > > possible that the draft is proposing VLAN ID *swapping*. But an
> > > alternative is that the VLAN ID is used as a label, but that the
> > > same label is used for the full length of the LSP.
> > >
> > > Adrian
> >
> >
> >
>
>
>