Upstream:

C-TagÆ(User port)-----(Uplink port)ÆS-Tag

Downstream:

S-TagÆ(Uplink port)-----(User port)ÆC-Tag

3.Stacking

In this mode, the system will add S-TAG before user port’s C-TAG. Note that the mapping from C-Tag to S-Tag+C-Tag is still one to one. So a user port’s C-Tag can’t be used for another translation rule, as well as an uplink port’s S-Tag+C-Tag.

Upstream:

C-TagÆ(User port)-------(Uplink port)ÆS-Tag+C-Tag

Downstream:

S-Tag+C-TagÆ(Uplink port)--------(User port)ÆC-Tag

4.Stacking and Replaced

In this mode, the system will replace the user port’s C-Tag to C’-Tag and add S-Tag before C’-Tag. Note that the mapping from C-Tag to S-Tag+C’-Tag is still one to one. So a user port’s C-Tag can’t be used for another translation rule, as well as an uplink port’s S-Tag+C’-Tag.

Upstream:

C-TagÆ(User port)-------(Uplink port)ÆS-Tag+C’-Tag

Downstream:

S-Tag+C’-TagÆ(Uplink port)--------(User port)ÆC-Tag

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