Zhone Technologies ZTI-PG - Manual (Page 7)

A C C E S S F O R A C O N V E R G I N G W O R L D 
The EFM standard supports on-the-fly adaptation of bond groups, allowing the bonding of pairs with unequal
rates, as well as hitless adds or drops of individual pairs from the group. This resiliency translates into higher value
for EFM services in mission-critical business or public-sector applications where high link reliability and stability is
of utmost importance.
The performance of the EFM standard represents a nearly 10x improvement over legacy T1/E1-based services.
Rates for links without repeaters stay very robust over the typical “in town” distances required to serve SMOs. The
addition of repeaters can carry multi-megabit speeds over copper at the greater distances required for cell site
backhaul.
Frame
Fragments
Fro
m Di
st’n
n x
SHD
SL
PHY
Ethernet
MAC
How EFM Wo
rks
EFM Aggrega
tion
Platf
orm
Ethernet
Access
Device
n x
Twisted
Pair
Copper
Loops
Ethernet F
rame
Reassembled
Frame
Theoretical Best-Case EFM Rate vs. Reach
(Zero-Noise Environment)
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
11,000
12,000
13,000
14,000
15,000
16,000
0
0 1 2 3 4 5 mi.
T1 reference
Up to 4 repeaters can be
used, on 6 kft. spacing
1 2 3 4 5 6 7 8 km
C
o
n
n
e
ct
R
a
te
,
k
b
p
s
TC-PAM-128 Modulation
...-64
...-16
…-32
...-8
TC-PAM-4
0.4mm / 26AWG Loop Length