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RE: Frameformat in a l2cs gmpls rnvironment.
Dear Juergen, Par and all,
The proposed framework of L2SC was not intended to suggest
any specific solution. It is still an open question.
As Adrian noted, it only aims to present requirements
as in scenarios that may drive people toward next step in many
viable solutions.
In fact, there are other options we may also consider for L2 label encoding.
IEEE 802.1 Ethernet bridges forward frames based on 48bits of MAC address,
and additionally using VLAN tag.
When the purpose of GMPLS control over Ethernet is not to create new dataplane
but to utilize IEEE 802.1 bridge architecture, we may consider using
one of the two forwarding methods, MAC forwarding or VLAN forwarding.
(and perhaps any other combination of fields in MAC, but I'll not discuss it)
Use of VLAN ID for label encoding may automate VLAN configuration
using IP protocols. However, GMPLS protocol cannot use the field exclusively
because public/private operators already use VLAN for various purpose.
There is a potential conflict with existing use of VLAN and GMPLS use of VLAN label.
Furthermore, scalability of VLAN ID has been frequently noted as weakness
because the size of VLAN ID is at most 4096 (12bit).
The scalability may be improved if the scope of VLAN label is confined to
link-local, and some additional swapping function of VLAN ID is introduced in
Internal Sublayer [802.1D] of GMPLS implemented switch.
However, this will only be effective when the configuration of network
is mesh structure that multiple LSP paths exist. If the configuration of network
is star or tree shape, as normal configuration of access network,
LSPs concentrate in root node and total number of
LSPs that the network can hold still be limited by available label space
at a few root links.
For these reasons, I do not think any form of VLAN ID label is
an appropriate choice for layer-2 label encoding.
There are some other proposals assuming new assignment of Ethernet
Length/Type value (e.g. new TPID in VLAN tag) and re-definition of
information fields placed between 802.3 MAC header and IP packet.
In this case, only the format of VLAN tag or extended VLAN tag
is borrowed, however, inside the switching hardware, the filter and relay,
etc. are totally different new dataplane switch.
I do not see such approach is a GMPLS implementation for Ethernet
because the core switching technique is not 802.1 Ethernet bridge at all.
The other option we may consider is using MAC address filed as below.
+-------+-------+-------+-------+-------+-------+
| 1byte | 2byte | 3byte | 4byte | 5byte | 6byte |
+-------+-------+-------+-------+-------+-------+
+-----------------------+-----------------------+
| OUI Prefix (=GMPLS) | DA-label (24bit) |
+-----------------------+-----------------------+
| OUI Prefix (=GMPLS) | SA-label (24bit) |
+---------------+-------+-----------------------+
| Length/Type |
+---------------+
IEEE is designated by the ISO Council to act as the registration authority
for the higher three-octet of OUI number in the MAC address
to be used by manufacturer. Ethernet manufacturer may generate
global unique MAC address using the OUI prefix and address block of
lower three-octet (24bit). Taking advantage of the addressing scheme,
GMPLS may use the lower three-octet exclusively if a unique OUI number
is reserved for the protocol. With this labeling scheme, GMPLS will
control MAC forwarding entry, not VLAN table.
All Ethernet frames controlled by GMPLS will have identical OUI number
that they can easily be distinguished from other Ethernet frames.
In principle, the label lookup hardware is identical to MAC lookup
hardware in this labeling scheme. Therefore GMPLS implemented
switch may still function as normal Ethernet bridge to the frames
that OUI number is not GMPLS. This also facilitates GMPLS implemented
switches being deployed in operating Ethernet with minimum service disruption.
Note also that above proposed label encoding method is transparent
to the use of Ethernet Length/Type field. End-user device may use
the Length/Type field as defined in IEEE 802.3 protocol.
It also allows network operators configure VLAN for their own purpose.
When IEEE 802.1p is used in conjunction with L2-LSP, the priority
field of VLAN tag can also be used for imposing consistent TE policy in
legacy switches and GMPLS switches.
Any way, my conclusion is, there are other options we may consider,
and this issue is still open to discuss.
Thanks,
Sincerely,
Jaihyung
-----?? ???-----
?? ??: "Heiles Juergen" <juergen.heiles@siemens.com>
?? ??: 2005-07-22 ?? 10:23:43
?? ??: "Loa Andersson" <loa@pi.se>, "richard.spencer@bt.com" <richard.spencer@bt.com>
??: "per@defero.se" <per@defero.se>, "ccamp@ops.ietf.org" <ccamp@ops.ietf.org>
??: RE: Frameformat in a l2cs gmpls rnvironment.
Loa,
I interpret the ID as a proposal to use GMPLS for VLAN setup. So GMPLS and VLAN to not compete. The VLAN is at the data plane and GMPLS at the control plane. The question is how and should different control plane techniques like GMPLS and (GVRP and STB) work together?
Regards
Juergen
> -----Original Message-----
> From: owner-ccamp@ops.ietf.org
> [mailto:owner-ccamp@ops.ietf.org] On Behalf Of Loa Andersson
> Sent: Friday, July 22, 2005 2:53 PM
> To: richard.spencer@bt.com
> Cc: per@defero.se; ccamp@ops.ietf.org
> Subject: Re: Frameformat in a l2cs gmpls rnvironment.
>
> Richard,
>
> I agree to most of this. Since we have doubts about the viability
> of taking GMPLS all the way to end-user or enterprise I think it
> would be good, from a wg perspective, if we agreed to solve the
> core network problems first.
>
> Do you have any comment on the requirement to run both VLANs and
> GMPLS on the same switch?
>
> /Loa
>
> richard.spencer@bt.com wrote:
> > Regardless of whether or not a switch is directly connected
> > to hosts, it must be able to forward packets using the
> connectionless
> > Ethernet data plane. This is due to the fundamental
> requirement that
> > for GMPLS switches to be able to exchange control information with
> > each other, a data plane for control traffic must be present.
> > This is akin to using the IP data plane for MPLS signalling in an
> > IP/MPLS network. An alternative would be to use a static reserved
> > L2-LSP for control traffic in the same way that reserved VPI/VCIs
> > are used for PNNI signalling in ATM.
> >
> > Regarding connecting hosts to GMPLS switches, I personally don't
> > think extending L2-LSPs into the enterprise/home network is
> > commercially viable. However, if you do want to use GMPLS switches
> > in the home/enterprise network and for some reason don't want to
> > extend L2-LSPs down to the host then you will not be performing
> > normal Ethernet Mac address switching anyway. Instead you will
> > need some kind of policy on the switch that maps connectionless
> > Ethernet packets (e.g. based on MAC src/dest, 802.1p, VLAN) to a
> > L2-LSP. This is because multiple L2-LSPs to the same destination
> > (e.g. a gateway router) may exist for different services/flows
> > (e.g. video download, VoIP call, etc.).
> >
> > Regards,
> > Richard
> >
> >
> >>-----Original Message-----
> >>From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org]On
> >>Behalf Of Par Mattsson
> >>Sent: 22 July 2005 11:42
> >>To: Loa Andersson
> >>Cc: ccamp@ops.ietf.org
> >>Subject: Re: Frameformat in a l2cs gmpls rnvironment.
> >>
> >>
> >>
> >>>Per and Dimitri,
> >>>
> >>>I would like to come down stronger than that, for me it is
> >>>a very strong requirement that the same switch can handle
> >>>both VLANs and GMPLs trafic correctly. I can't dsee how that
> >>>could be done if using the VLAN tpid to indicate GMPLS
> >>>traffic.
> >>
> >>If you ever want that same switch to handle traffic for a directly
> >>connected host (not to uncommen) you would want that to use normal
> >>ethernet macaddress switching. So of course you do not want
> to have to
> >>choose between vlan and gmpls, you would want both at the same time.
> >>
> >>/per
> >>
> >>
> >>
> >>>/Loa
> >>>
> >>>Par Mattsson wrote:
> >>>
> >>>>>hi par, one of the possibilities that has been considered
> >>
> >>to cope with
> >>
> >>>>>this requirement is to use a dedicated TPID for the
> >>
> >>Ethernet labeled
> >>
> >>>>>frames; this would allow differentiated processing with
> non-labeled
> >>>>>framesthanks.
> >>>>
> >>>>
> >>>>That seems to make more sence. If that frame is to be sized like a
> >>>>802.1q
> >>>>frame. There is not that much space left to a label. Or is
> >>
> >>the demand to
> >>
> >>>>use jumboframes ?
> >>>>Has there been any discussion on labelstacking, and
> mainly where to
> >>>>place
> >>>>the information?
> >>>>
> >>>>Regards.
> >>>>Per
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>--
> >>>Loa Andersson
> >>>
> >>>Principal Networking Architect
> >>>Acreo AB phone: +46 8 632 77 14
> >>>Isafjordsgatan 22 mobile: +46 739 81 21 64
> >>>Kista, Sweden email: loa.andersson@acreo.se
> >>> loa@pi.se
> >>>
> >>
> >>
> >>
> >
>
>
> --
> Loa Andersson
>
> Principal Networking Architect
> Acreo AB phone: +46 8 632 77 14
> Isafjordsgatan 22 mobile: +46 739 81 21 64
> Kista, Sweden email: loa.andersson@acreo.se
> loa@pi.se
>