Fig. 5.2 shows the basic functional structure of SURPASS hiT 7060.
MS OH
HOCC/LOCC MS Overhead Process RS Overhead Process
VC Mapping
System Controller Timing controller Maintenance Panel
TNMS-M/
On the line side, the send/receive modules (SDH) carry out the conversion to optical/electrical signals. The SDH cards can be equipped with various transceiver modules (SFP modules) in several distance variants up to 2.5 Gbps.
On the tributary side, SURPASS hiT 7060 supports various Plesiochronous Digital Hierarchy (PDH), Ethernet and STM-N interfaces.
The central element of SURPASS hiT 7060 includes SC, CC, timing controller, and maintenance panel.
5.2.1 User Data Interfaces
SURPASS hiT 7060 can be equipped with the following interfaces (line and tributary signals):
Interface Type Bit Rate Connection Ports per Card SDH 2.5 Gbps (STM-16) optical 1 (bidirectional) SDH 622 Mbps (STM-4) optical 4 (bidirectional) SDH 155 Mbps (STM-1) optical/electrical 2 or 4 (bidirectional) PDH 34 Mbps or 45 Mbps electrical 3 (bidirectional)
PDH 2 Mbps electrical 63 (bidirectional)
Ethernet 1000 Base-X optical 2 (full duplex) Ethernet 10/100 Base-Tx electrical 6 or 8 (full duplex or
half duplex)
Tab. 5.1 User Interfaces
5.2.2 Switch Fabric Functions
The switching device provides the HO and LO switching at the same time.
Capacity of the CC Fabric
SURPASS hiT 7060 has the following CC capacity:
• High Order Cross-Connection (HOCC): 25 Gbps (160 × 160 VC-4s)
• Low Order Cross-Connection (LOCC): 10 Gbps (4032 × 4032 VC-12s) Cross-Connection
All types of cross-connections are possible. The switch fabric is a non-blocking square structured fabric for point-to-point and point-to-multipoint connections.
Granularity
The configurable and simultaneously usable switching hierarchies of the fabric are VC-4, VC-3 and VC-12.
HO and LO VC-n Connectivity
The switching fabric allows the following connections:
• Unidirectional connections
• Unidirectional point-to-multipoint (including 1 + 1 SNCP head end)
• Bidirectional connections
• Broadcasting (HOCC 1 : 4, LOCC 1 : 63)
• Drop and continue (broadcast 1 to 2 + SNCP tail end)
• Selector 2 to 1 (protected tail end for 1 + 1 SNCP) Concatenation
Virtual concatenated VC-12, VC-3 and VC-4 signals are supported. Protection switching for virtual concatenated signals VC-4, VC-3 and VC-12 is also supported. The group of constituent paths that belong to a concatenated signal is determined by the Telecommunication Network Management (TNM) and written to an internal configuration table. Using this information, the
SURPASS hiT 7060 software is able to set signal fail or signal degrade alarms for all paths of a concatenated signal channel. In order to keep the (differential) delay of the signals low, all constituent paths of a concatenated signal must be on the same optical trail. It results in a bundling rule for the TNM.
5.2.3 Multiplex and Mapping Functions
SURPASS hiT 7060 transmits SDH and PDH signals.
Fig. 5.3 shows the organization and relationship of SDH and PDH multiplex structures.
Chapter 9.1 summarizes the possible user data interfaces for the SURPASS hiT 7060 NEs.
VC-4
5.2.3.1 SDH HO/LO Multiplexer and Mapping Functions
SURPASS hiT 7060 implements the following HO/LO multiplexing and mapping methods:
• VC-4 containers are aligned (with frame offset information) with an AU-4, according to ITU-T G.707. The AU-4 may further be mapped via AUG-1 into STM-1, or further via AUG-4 into STM-4. STM-16 follows the same pattern.
• VC-3 containers are aligned (with frame offset information) with a TU-3, according to ITU-T G.707. The TU-3 is further mapped via TUG-3 into VC-4.
• VC-12 containers are aligned (with frame offset information) with a TU-12, according to ITU-T G.707. The TU-12 is further mapped via TUG-2 and TUG-3 into VC-4.
5.2.3.2 PDH Mapping into SDH Containers
SURPASS hiT 7060 implements the following mapping of PDH signals on SDH containers:
• 2 Mbps signals are mapped into a VC-12 asynchronously, according to ITU-T G.707. The VC-12 is further mapped on a VC-4, via TU-12, TUG-2 and TUG-3.
• 34 Mbps and 45 Mbps signals are mapped into a VC-3 asynchronously, according to ITU-T G.707. The VC-3 is further mapped on a VC-4, via TU-3 and TUG-3.
5.2.3.3 Ethernet Packet Multiplexer and Mapping Functions
SURPASS hiT 7060 supports Ethernet frame mapping into SDH containers.
So LAN traffic can be transported over different SDH payload sizes (requires encapsulation by using an appropriate protocol and mapping of the resulting frame into an SDH container).
For encapsulation, the GFP (GFP-F according to ITU-T G.7041) is used. The encapsulated protocol frames can be mapped into different SDH containers using the virtual concatenation technique.
Ethernet Mapping into SDH Containers
SURPASS hiT 7060 supports a flexible mapping scheme:
• Ethernet Mapping into HO virtually concatenated containers
Encapsulated GFP-F frames can be mapped into different HO container sizes providing a scalable solution that can cover network applications with very different transport capacity requirements.
Mapping into VC-4, VC-4-Xv (x = 1 to 7)
The GE interface cards support this mapping function.
• Ethernet Mapping into LO virtually concatenated containers
Encapsulated GFP-F frames can be mapped into different LO container sizes providing a scalable solution that can cover network applications with very different transport capacity requirements.
Mapping into:
− VC3, VC-3-Xv (x=1 to 3 for FE or x=1 to 21 for GE)
− VC12, VC-12-Xv (x = 1 to 46)
The virtual concatenation for VC-3 supports both FE and GE.
GFP-F Mapping
GFP is supported by the FE interfaces.
GFP provides a generic mechanism to adapt traffic from higher-layer client signals over an octet synchronous transport network. This is a simple and robust encapsulation method for packet traffic. All of the relevant MAC layer information, from destination address through Frame Check Sequence (FCS) inclusive, is preserved intact by the mapping.
SURPASS hiT 7060 uses a Protocol Data Unit (PDU) oriented, frame-mapped adaptation mode (GFP-F) for the client signal adaptation.
GFP-F does not rely on flag characters, and associated control escape octet, for frame delineation purposes as High level Data Link Control (HDLC) does.
Instead, GFP-F uses a variation of the Header Error Control (HEC) based frame delineation mechanism defined for Asynchronous Transfer Mode (ATM).
This avoids non-deterministic expansion of the client signal due to insertion of control escape characters.