-------- -------- | | | | | | | | | X11 | | X21 | | | | | | | | | -------- -------- . . . . . . . . . . -------- -------- -------- -------- -------- -------- | | | | | | | | | | | | | | | |.....| | | |.....| | | | | Y11 |..| Sw1 |.....| PE1 |=============| PE2 |.....| TDM |....| Y21 | | | | | | | | | | (MUX) | | | | | | | | | | | | | | | -------- -------- -------- -------- -------- -------- . . . . . . . . . . -------- -------- | | | | | | | | | Z11 | | Z21 | | | | | | | | | -------- -------- PE1 and PE2 are M Series Routers Sw1 is a distribution switch that terminates in a gig ethernet interface on PE1.