User`s guide

DC 900-1339H 27

Chapter

FMP Protocol Summary

2.1 Message Formats

Although the text message format of each primary market feed is unique, the protocols

used to frame the text fall into three general categories: bisynchronous, asynchronous,

and isochronous. This chapter describes these three protocol categories. Information

regarding the protocol framing of your feed can be found in the digital feed speciﬁca-

tion document supplied by the stock exchange or feed provider. This information is

usually a one-page description called “line characteristics” located near the front of the

speciﬁcation.

The line mode option of the FMP product is used to conﬁgure communication links on

the FMP ICP for different protocol categories. The line mode option (described in

Section 4.18 on page 92) allows the FMP software to receive a large number of the

world’s primary digital feeds. Refer to your feed speciﬁcation to determine what general

protocol category it ﬁts into. Next, read the following sections to determine what line

mode option setting to use. Finally, refer to Chapter 4 for any additional options

required for your feed.

All of the feeds described in this chapter are simplex; that is, they are one-way digital

broadcasts. There are no protocol-level acknowledges for received blocks. Retransmis-

sion of data blocks for some feeds may be accomplished by telephone. The subscriber

tells the exchange which block was missed (by sequence number) and the exchange

retransmits the block when there is time on the link. Since the repeated block is trans-

mitted to all subscribers, it is usually marked with a retransmission ﬂag so that it will be

ignored by the subscribers who don’t need it.