Virtual Leased Line Services
7750 SR OS Services Guide Page 187
Circuit Emulation Services
Two modes of circuit emulation are supported, unstructured and structured. Unstructured mode is
supported for DS1 and E1 channels per RFC 4553, Structure-Agnostic Time Division Multiplexing
(TDM) over Packet (SAToP). Structured mode is supported for n*64 kbps circuits as per RFC
5086, Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet
Switched Network (CESoPSN). In addition, DS1, E1 and n*64 kbps circuits are supported (per
MEF8). TDM circuits are optionally encapsulated in MPLS or Ethernet as per the referenced
standards in the following figures.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
| MPLS Label Stack |
| ... |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| SAToP Control Word |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| OPTIONAL |
+-- --+
| |
+-- --+
| Fixed RTP Header (see [RFC3550]) |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| Packetized TDM data (Payload) |
| ... |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 34: RFC 4553 [SAToP] MPLS PSN Encapsulation
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
| MPLS Label Stack |
| ... |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| CESoPSN Control Word |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| OPTIONAL |
+-- --+
| |
+-- --+
| Fixed RTP Header (see [RFC3550]) |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| Packetized TDM data (Payload) |
| ... |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 35: CESoPSN Packet Format for an MPLS PSN
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