Data compression negotiation in a telecommunication system

Constructing method of this invention relates to data line, the end-to-end ring with error correction protocol different branch comprises at least two (402 and 403). The two power of with different physical layer is or, wherein error correction protocol (V.120, RLP) can be different. The two power (402 and 403) between the laser chip according to the invention interconnect function IWF, wherein the two branches is connected on the table is of channels service flow channel each other to corresponding, a data exchange compressed parameter. IWF to the end-to-end data compression to consult, a transmission from branch to the branch message and protocol converting; and need, and is compressed of fast in a consult retard, wherein which are in each other to synchronize; and need, wherein change the compressed parameter of the two in a manner; and end-to-end data compression consultation failure, which can IWF is provided with a data compression on branch.