Alcatel 1660SM Technical Handbook page 547

Although "VCG management block" can transport several type of layer 2 or 3 formats, foreseeable
applications of ISA ES16 only calls for transport of Ethernet and MPLS frames.
Extracted frames are sent for further processing to "ETHERNET Mapper" block the function of which are:
– Serial link alignment
– frame delineation
– storing of frames entering from SPI3 and access card and forwarding to AD FPGA
– reassembling of ethernet frames received from AD FPGA and forwarding to Access card
– format adaptation of segments coming from AD directed to Calla48
ISA ES16 UNIT is connected to FE or GE "access card" directly by "ETHERNET Mapper" block.
"Ethernet Mapper" block interfaces to "Layer 2 processing" block through 2 monodirectional 13 LVDS links
bus at 450 Mbps.
In Rx direction full packet are transferred across the interface. Each packet is prepended with a control
word carrying indications of input port, length and other service information.
In Tx direction, segments of up to 128 bytes are transferred across the interface: "Ethernet Mapper" block
dispatches data to Ethernet reassembling circuitry or to "VCG management" block.
Ethernet packets are processed by "Layer 2 processing" block to:
– decode protocol header, up to eight nested protocols or MPLS labels can be extracted
– search flow and session to which the packet belong
– policing the streams according to session parameters
– monitor the traffic with inflow and outflow counters
– schedule forwarding of packets
– encapsulation of outgoing packets
Output port, encapsulation and assigned quality of service of outgoing packets depend on a subset of
input port, VLAN tags, MAC address and MPLS labels. "Layer 2 processing" block and the local
microprocessor cooperates in dynamically learning and obsoleting MAC addresses.
Local Microprocessor
It controls and supports the Ethernet functionalities (Ethernet Physical Interface, Ethernet Switch Module
and Ethernet Mapper): configuration, alarms and states collections, performances monitoring,
communications with the OS (SNMP).
The microprocessor is provided with relevant devices SDRAM (for data memory), Flash EPROM (for
program memory) and Compact Flash.
External Shelf Controller (SC) controls SDH related circuits by ISPB bus.
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