Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 312)

282 Multi-Service IronWare Switching Configuration Guide
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Backbone Edge Bridge (BEB) operation
11
IB-Tagged Endpoint with S-VLAN Keep mode
The system can be configured with S-VLAN keep mode which indicates that packets received at the
IB-Tagged endpoint from the PBB network will contain an S-Tag after the I-Tag field (see
Figure 44 ).
When such a packet is destined to a local endpoint, in addition to stripping the PBB header the
S-Tag is also removed.
Example 1:
If the packet is destined to a C-Tagged endpoint with C-VID 100, the original PBB header and
the S-Tag is stripped and a C-Tag with C-VID 100 is inserted as the packet exit the C-tagged
endpoint. The TPID value will be what is configured for the exiting port's Ethernet type value.
Example 2:
If the packet is destined to an S-Tagged endpoint with S-VID 300, the original PBB header and
the S-Tag is stripped and an S-Tag with S-VID 300 is inserted as the packet exit the S-tagged
endpoint. The TPID value will be what was configured for the exiting port's Ethernet type value.
The S-VID of the S-Tag in the original PBB frame is “translated” into the S-VID of the destination
S-Tagged endpoint. The PCP/DEI is preserved or modified depends on the PCP encode and
decode setting of the receiving/destination ports.
Example 3:
If the packet is destined to another IB-Tagged endpoint with the same B-VID and ISID value of
the received PBB frame, the original PBB frame is NOT touched (the PBB header and S-Tag
remains unchanged) and will be send out towards the specified outgoing interface as
determined by the BEB’s switching logic.
S-VLAN VID Value setting when packet exit IB-Tagged Endpoint
with S-VLAN Keep mode
If a packet is received from a C-Tagged or S-Tagged endpoint destined towards an IB-Tagged
endpoint under S-VLAN keep mode, the S-VLAN VID value will depend on the original VLAN ID
received. If the packet was received from an untagged endpoint, then the untagged VLAN value
of the port will be used as the S-VLAN VID as it goes out of the IB-Tagged endpoint.
Example 1
If the packet is received from a C-Tagged endpoint with C-VID 100 and destined to an IB-tagged
endpoint, the original tag that contains the C-VID of 100 is stripped and a PBB header
(contains the B-MACs, B-Tag, I-Tag, and S-Tag) is inserted when the packet exits through the
IB-Tagged endpoint. The S-Tag S-VLAN VID in the PBB header will have a value of 100.
Example 2
If the packet is received from a S-Tagged endpoint with S-VID 200 and destined to an IB-tagged
endpoint, the original tag that contains the S-VID of 200 is stripped and a PBB header
(contains the B-Macs, B-Tag, I-Tag, and S-Tag) is inserted when the packet exits through the
IB-Tagged endpoint. The S-Tag S-VLAN VID in the PBB header will have a value of 200.
Example 3
If the packet is received from an Untagged endpoint with default port VLAN set as 150 and
destined to a IB-tagged endpoint, a PBB header (contains the B-Macs, B-Tag, I-Tag, and S-Tag)
is inserted when the packet exits through the IB-Tagged endpoint. The S-Tag S-VLAN VID in the
PBB header will have a value of 150.