Subject: Enhancing 802.1ad bridge module in VPLS capable PEs (draft-ietf-l2vpn-vpls-bridge-interop)

From: Maarten Vissers <[email-masked]>
Date: Sun, 05 Oct 2008 21:21:56 +0200

Dinesh, Ali,

draft-ietf-l2vpn-vpls-bridge-interop identifies in section 5.3 the
possibility to encapsulate customers' MAC addresses within the provider MAC
header such that the number of MAC addressed learned will be significantly
reduced within the provider network for H-VPLS with MPLS access. One of the
means to do this is via the use of a "802.1ah bridge module" in a VPLS
capable PE as introduced in my email "add 802.1ah I-BEB Bridge Module to
draft-ietf-l2vpn-vpls-bridge-interop". 

The use of an 802.1ah bridge module supports the following services
1) port-based service
2) S-Tagged service (one-to-one, bundling, all-to-one bundling)
but does not support the 
3) C-Tagged services (individual, bundling).

To reduce the number of MAC addresses learned within H-VPLS networks for
C-VLAN services it is necessary to enhance the 802.1ad Bridge Module with a
MAC Header insertion/extraction function as indicated in the figure below. 

For interworking with the existing 802.1ad Bridge Modules it is important to
make the use of the MAC header insertion/extraction function optional. This
MAC Header insertion/extraction function must only be activated when all
ports of a VPLS instance support this function.

             U-LAN |                     ------------                | 
        +---+P-LAN |  +------+           | +------+ | +-----------+  | 
        |CE |---------|C-VLAN|-------------|  MAC |---|           |  | 
        +---+C-LAN |  |bridge|             |Header|   |           |  | 
                   |  |      |             +------+   |           |  |
                   |  |      |                        |           |  |
                   |  |      |                        |           |  |
                   |  |      |           ------------ |           |  |
                   |  |      |  +------+ | +------+ | |   VLAN    |  |
             U-LAN |  |      |--|C-VLAN|---|  MAC |---|           |  |
        +---+P-LAN |  |      |--|(d)mux|   |Header|   |  Bridge   |  | 
        |CE |---------|      |  +------+   +------+   |           |  | 
        +---+C-LAN |  |      |                        |           |  | 
                   |  +------+                        |           |  |

       Figure - Enhanced 802.1ad Bridge Module supporting reduced MAC
                address learning for C-VLAN services

The frame formats after the MAC Header insertion function will then be as
follows:

  1-to-1         bundling
 C-Tagged        C-Tagged
  service         service 
   frame:          frame:

    B-DA            B-DA
    B-SA            B-SA
    TYPE:89-10      TYPE:89-10
    C-DA            C-DA
    C-SA            C-SA            
    MSDU            C-Tag     
                    MSDU

My proposal is to add this enhanced 802.1ad Bridge Module to the next
version of draft-ietf-l2vpn-vpls-bridge-interop.

Regards,
Maarten