Support for Test Gap Fill Requests via UDP on TOPS v1.5

IEX Trading Alert #2016 - 059

Overview

On Monday, October 31, IEX will begin to support the ability to send test Gap Fill Requests via UDP ("UDP Gap Fill Test Request") using the IEX Transport Protocol (IEX-TP) on TOPS v1.5. Participants may send a UDP Gap Fill Test Request to test the availability of a Gap Fill Server, even before any data is published on the multicast feed.

IEX will also begin enforcing the validations on Gap Fill Requests, as currently specified in the Transport Specification and noted below.

Please be advised that recipients of TOPS v1.4 must migrate to TOPS v1.5 by December 16, 2016. TOPS v1.4 will be terminated at the close of business on December 16, 2016.

UDP Gap Fill Test Request

Participants may send a UDP Gap Fill Request with no request ranges specified (Request Range Count = 0) to test the availability of a Gap Fill Server. The response to a valid UDP Gap Fill Test Request is one Outbound Segment with no Payload unicast back to the source address of the UDP Gap Fill Test Request ("Gap Fill Test Response").

Gap Fill Test Responses are sent by the server in response to a valid UDP Gap Fill Test Request. A Gap Fill Test Response contains the next byte within the stream for the Stream Offset, the sequence number of the next message for First Message Sequence Number, and 0 (zero) for both Payload Length and Message Count.

An example UDP Gap Fill Test Request and Response may be found in the latest IEX-TP Specification.

Gap Fill Request Validation

All Request Range Blocks in a Gap Fill Request must use the same Request Type, not overlap, and monotonically increase. These same restrictions apply over multiple TCP Gap Fill Requests sent using the same TCP/IP socket connection. Invalid Gap Fill Requests are ignored by Gap Fill Servers and, in the case of a request sent via TCP, the session will be terminated by the Gap Fill Server.

TOPS v1.4 Decommission on December 16, 2016

As previously announced in IEX Trading Alert #2016-047 distributed on August 31, 2016, TOPS v1.4 will be decommissioned on December 16, 2016. All Data Recipients must migrate to TOPS v1.5 prior to such date.

More Information

Please contact IEX Market Operations or Sales with any questions:

About IEX

IEX is on a mission to build fairer markets. Founded in 2012 and headquartered in New York City, IEX introduced its first trading venue in 2013 and launched as a U.S. stock exchange in 2016. IEX is the stock exchange that believes that every investor has the right to trade on equal and fair terms, on every trade. Learn more at: iextrading.com.