Luke Judge

Ayal,

In the case of ETH carried over MPLS LSP both the shared MEG and independent MEG cases are present. The difference between the two cases is determined by the supported transparency (preservation) of the VLAN Tag.

Example 1: C-VLAN Tag not preserved
In this case the MEG levels of the ETH connection (VLAN) are shared between the customer and network.

ETH signal is identified on the UNI by a C-VLAN ID. In the network the ETH signal is carried by the LSP and is then identified by the PW Label.

In the UNI-N port, the C-VLAN Tag is removed, the ETH signal is passed through an ETH MIP function and then it is passed through an ETH Tandem Connection Monitoring MEP function (in G.8021 terms: ETH/ETH_A + ETH_FT + ETHD/ETH_A + ETHDe_FT atomic functions). AFter that the ETH signals is applied at the input of a LSP to ETH adaptation function (LSP/ETH_A) which adds the PW label stack entry header, including the PW label.

Example 2: S-VLAN Tag preserved
In this case the MEG levels of the ETH connection (VLAN) are independent; customer has 8 MEG levels and network has another 8 MEG levels.

ETH signal is identified on the UNI by a S-VLAN ID. In the network the ETH signal is carried by a server ETH signal and this server ETH signal is carried by the LSP and is then identified by the PW Label.

In the UNI-N port, the S-VLAN Tag is “functionally removed”, the ETH signal is passed through an ETH MIP function and then it is passed through an ETH Network Connection Monitoring MEP function (in G.8021 terms: ETH/ETH-m_A + ETH_FT + ETHD/ETH_A + ETHDe_FT atomic functions), which puts back the S-VLAN Tag with the same S-VID, S-PCP and S-DEI. After that the server ETH signals is applied at the input of a LSP to ETH adaptation function (LSP/ETH_A) which adds the PW label stack entry header, including the PW label.

Example 3: Port based service
In this case there are multiple C-Tagged VLANs carried over a link VLAN. The link VLAN is untagged or Priority-S-Tagged.

There are now several subcases to consider:
3A) Priority-S-Tag preserved ==> same as example 2 above
3B) Priority-S-Tag not preserved ==> same as example 1 above
3C) Untagged, shared MEG levels ==> ETH signal is passed through ETH MIP at UNI-N port and then passed through an ETH Tandem Connection Monitoring MEP function (as in example 1)
3D) Untagged, independent MEG levels ==> ETH signals is passed through ETH MIP at UNI-N port and then passed through an ETH Network Connection Monitoring MEP function as in example 2).

Similar considerations apply to I-Tagged and B-Tagged ETH UNI signals.

Then for case of E-Tree or E-LAN services, it is strongly recommended to insert an additional MAC header (TYPE=89-10, SA, DA) in the ETH frames arriving over the UNI to enhance MAC scalability in the transport network. The insertion of such MAC header will always result in two independent sets of MEG levels.

Regards,
Maarten

10 Mbps & Slower adaptation, independent customer, mpls, priority, signals, vlan id