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Re: Continued Poll for Adoption of Ethernet I-Ds



Hi Attila,

Please, see in line.

----- Original Message ----
From: Attila Takacs <Attila.Takacs@ericsson.com>
To: Igor Bryskin <i_bryskin@yahoo.com>; Don Fedyk <dwfedyk@nortel.com>; neil.2.harrison@bt.com; adrian@olddog.co.uk; ccamp@ops.ietf.org
Sent: Thursday, April 10, 2008 2:54:21 AM
Subject: RE: Continued Poll for Adoption of Ethernet I-Ds

Hi Igor,
 
But how the separation of VLAN ID space would help in this case? If PBB packets are leaked into PBB-TE they will be immediately dropped because there will be no PBB-TE connections configured for such packets. If PBB-TE packets are leaked into PBB, than, since, PBB knows nothing about PBB-TE anyway the packets will be flooded across the PBB domain.  
 
Unfortunately, leaking from PBB to PBB-TE does not necessarily means immediate discarding of PBB frames. Due to the VLAN separation between PBB and PBB-TE, there is no clear layering here. Hence leaking can essentially mean that the VID of a bridged (PBB) frame is changed to a VID used for explicitly routed connections (PBB-TE). This does not necessarily means that the frame will be dropped. It is a valid assumption that the MAC address of the PBB frame is configured in the PBB-TE region as well and as such leakig PBB traffic will be forwarded as if it would belong to an explicitly routed connection.

IB>> In order for a packet, leaking from PBB to PBB_TE not be dropped, it is necessary for the triplet from PBB MAC header (SA-DA-VID) to match one of configured on the node PBB-TE connections. Even if one assumes that this is possible, it is highly unlikely to be the case on the next along the connection PBB-TE node. Hence the packet will be dropped either immediately or on the next PBB-TE node.

Cheers,
Igor
Note that what I just wrote is true regardless whether PBB-TE uses specially allocated ranges of VLANIDs or all VLANIDs. Hence there is no architectural need for the VLANID space separation.
  
I think this is not necessary true, if one allocates the whole VLAN space to PBB-TE then there will be no bridged traffic in the network. As a consequence no leaking and no other cross effects is to be expected.
 
Best regards,
Attila


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