Table of Contents
Advertisement
The following standards apply to ETH physical ports:
•
IEEE 802.3 10BASE–T Ethernet (twisted–pair copper)
•
IEEE 802.3u 100BASE–TX Fast Ethernet (twisted–pair copper)
•
IEEE 802.1z (Gigabit Ethernet)
•
ANSI/IEEE 802.3 Auto–negotiation
•
IEEE 802.3x Flow Control
•
Data transfer rate from client equipment is limited in accordance with the specified traffic
characteristics by the standard IEEE 802.3x flow control mechanism.
Flow control frames are used to prevent congestion of the network that may cause packet discarding at
the egress of the network; the flow control mechanism stops the client source until the bandwidth allocated
to the service is able to absorb the extra traffic.
The result is that no packets are lost even in case of congestion. Flow control can be disabled according
to the operator's choice.
The following standards apply to the ETH over SDH ports:
•
ITU–T G.7041 GFP (Generic Framing Procedure)
•
ITU–T G.7042 LCAS (Link Connection Adjustment Scheme)
•
G.707 (SDH VC Virtual Concatenation at Low and High Order VC–12, VC–3 and VC–4 nv)
The Ethernet mapping scheme on the trunk ports adheres to the Generic Framing Procedure (ITU–T G.
7041).
The Ethernet traffic, opportunely mapped in the SDH transport structures, is then sent by the trunk ports
toward the SDH matrix from the back–plane and than to the corresponding SDH port.
A trunk port is realized by a bundle of SDH VCs (VC–12, VC–3, VC–4) grouped together according to
ITU–T G.707 (Virtual Conc) and ITU–T G.7042 (LCAS).
The bandwidth of the trunk port in normal operational mode corresponds to the available bandwidth of the
grouped VCs (e.g. 5xVC–12 equals 10 Mbps).
ED
02
3AL 91669 AA AA
674
287
/
674
Advertisement
Table of Contents
