M28529G-12 Mindspeed Technologies, M28529G-12 Datasheet - Page 17

• Manufacturer Part Number: M28529G-12
• Description: ATM IMA 8.192Mbps 1.8V/3.3V 484-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of M28529G-12

• Package: 484BGA
• Utopia Type: Level 2
• Typical Operating Supply Voltage: 1.8|3.3 V
• Minimum Operating Supply Voltage: 1.71|3.135 V
• Maximum Operating Supply Voltage: 1.89|3.465 V
• Maximum Output Rate: 8.192 Mbps

IMA solves this problem by allowing users to purchase bandwidth in smaller increments and combine these smaller
'pipes' into one high speed connection. An example is given in
4.6 Mbps data link.
At first glance, the concept of IMA is deceptively simple: spread the ATM cells out evenly over the available
individual lines. However, many serious technical issues must be dealt with and a wide range of functions must be
supported. These include IMA framing, differential delay accommodation, link/group state machines, IMA clocking,
and maintenance. Several terms must be defined:
Figure 1-2.
1.1.2.1
The IMA protocol employs a simple frame structure as shown in
cell (ICP) and M – 1 ATM layer cells, where M is the IMA frame length. Valid frame lengths are 32, 64, 128 (default),
or 256. This example shows a group composed of three links and an IMA frame length of 16. (An invalid frame
length of 16 is used for brevity, the default frame length is 128.)
28529-DSH-001-K
IMA Engine
Link
Group
Group State Machine
Link State Machine
IMA Overview
IMA Framing
The logic that performs the actual IMA function. This sits between the ATM layer and the individual links (see
Figure
Refers to an individual physical connection such as a T1 or DSL line. Each link has an individual UTOPIA address or
serial connection to the IMA engine.
An IMA group is composed of links. A group appears as a single UTOPIA address to the ATM layer. Thus an IMA-4
group would have 4 individual links.
The operation of the IMA group is governed by the Group State Machine (GSM), the Group Traffic State Machine
(GTSM), and the Link Addition and Slow Recovery (LASR) procedure. These three processes ensure reliable
transmission and reception of ATM layer cells across all links in the Active state. This includes the negotiation of
group parameters (i.e., symmetry and M values), the bringing up of the IMA group, and the graceful addition/
recovery and deletion of links to and from the group. For the M28529, this function is performed in the host software.
The software itself is available from Mindspeed.
A Link State Machine (LSM) is defined for the transmit and receive directions of each IMA link. The IMA protocol is
defined to allow symmetric or asymmetric cell rate transfer over the IMA virtual link. It allows for smooth
introduction of each link in the group. It also allows graceful handling of error conditions and removal of a link. This
function is performed internally by the M28529.
1-2). An IMA engine can control multiple independent groups.
4.5 Mb/s
3
2
Mindspeed Proprietary and Confidential
Mindspeed Technologies
1
3 - T1 1.544 Mb/s
3
2
1
Figure 1-2
Figure
®
1-3. It consists of a single IMA overhead
where 3 T1 lines are combined into one
3
4.5 Mb/s
2
1
Functional Description
500027_053
2