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Technical Specifications
10-8 Issue 3 June 2001
— Receive MAC packets discarded.
In addition, to monitor the efficiency of the IMA link the following
parameters are supported:
— Transmit ATM cells total
— Transmit ATM idle cells
— Receive ATM cells total
— Received ATM cells Idle.
LAN Interface (BBF10) 10
■ Electrical Specification:
The BBF10 LAN circuit pack provides a single 100BaseFX, IEEE 802.3
compliant interface. The LAN port performs protocol transparent filtering
and bridging of incoming MAC frames. MAC frames with a destination
address on the local bus are filtered by the BBF10 to prevent unnecessary
transmission of frames over the wide area network (WAN). The LAN
interface autonegotiates mode (full/half duplex) and speed (100 Mb/s)
when interfacing with other 802.3 compliant devices over twisted pair
media. The circuit pack occupies two adjacent low-speed slots and
converts an optical signal to from one to 8 DS1 signals to provide native
mode LAN transport through a SONET WAN.
■ LAN port:
— 100BaseFX IEEE 802.3 compliant
— SC optical connector
— 1300 nm nominal center wavelength
— 62.5 micron multimode fiber
— Buffering .5 MByte for each direction
— See Table 10-2 for optical characteristics.
■ Format Specification:
The LAN interface converts incoming MAC frames to an ATM cell format
using ATM adaptation layer 5 (AAL5) encapsulation as specified in IETF
RFC-1483. ATM cells are distributed in round robin order on 1 to 8 ESF
formatted DS1 signals using the ATM forum IMA Specification Version 1.1
for inverse multiplexing. The DS1 signals are mapped into asynchronous
VT1.5 signals for transport through a SONET network. The circuit pack can
compensate for up to 50 ms of differential delay among the 8 DS1s and
uses a single IMA group with one ATM virtual channel (VC). The following
provisioning options are provided:
— AAL5 Protocol - VC multiplex or LLC encapsulation (Bridged)
— MAC Frame Check Sequence (FCS) Preservation - enable or
disable
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