PM7340-PI datasheet(92/334 Pages) PMC

92 / 334 page

PRELIMINARY

INVERSE MULTIPLEXING OVER ATM

PM7340 S/UNI-IMA-8

DATA SHEET

PMC-2001723

ISSUE 3

INVERSE MULTIPLEXING OVER ATM

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

If sufficient links are not accepted, the group will not become operational. Note

that within any collection of links that are targeted to form an IMA group the group

may not become operational even though there are combinations of Prx links that

meet the programmed maximum DCB threshold. This would occur in situations

where the internal algorithm used to determine link order may not select the

combination or “tightest” grouping of links that would otherwise meet the

programmed maximum DCB threshold. In this case, the relative delays of the

links are available to the plane management (.i.e. microprocessor) using the

read_delay command. The microprocessor can then analyze this information,

remove the offending link or links and restart the group.

10.2.5.2

Link Addition and Differential Delay

Once a group is started, the delay profile for the group is determined. In order to

add links, the delay on the new links must be compatible with the existing links in

the group and be able to be synchronized with the existing links within the DCB

constraints.

There are two mechanisms regarding delay that can be used.

The first method uses the guardband capability. At group start-up, a guardband is

added to the link with the longest transport delay. This guardband results in

additional delay to be queued in the DCBs for each link in the group. The

guardband allows for links with a longer transport delay to be added in the future

without introducing any additional CDV.

The second method allows the delay accumulated per link to be increased

dynamically. This method will introduce additional delay to all of the links within

the group when a link with a larger transport delay is added to the group. The

process of adding additional delay to the links within a group will cause additional

CDV to be introduced when the playout of data is stopped while the delay is

accumulated.

The RIPP determines the delay of the links that are being added and performs

the appropriate action to either include the link in the group or to reject the link if

the link cannot be synchronized within the DCB constraints If a link is rejected

due to delay, a LODS defect will be reported on the link.

When links are deleted from the group, the delay of the remaining links is not

adjusted.

See 10.2.4.2 for more details on the management of the DCB buffers.

PM7340-PI Datasheet(PDF) 92 Page - PMC-Sierra, Inc

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