Login without TAP - Direct Connection FAQs


Exchange had announced introduction of “Login without TAP i.e. Direct Connection functionality” vide circular Ref. No. NSE/FAOP/31548 and NSE/CD/31549 dated January 12, 2016 in Futures & Options (FO) and Currency Derivatives (CD) Segment circular Ref. No. NSE/CMTR/31663 dated February 1, 2016 in Capital Market (CM) Segment and NSE/SLBS/45260 dated August 06, 2020 in Securities Lending and Borrowing Market (SLBM) for Non-Neat Frontend (NNF) Applications.

All Non-Neat Frontend (NNF) applications are required to mandatorily connect via “Direct Connection” using the Trimmed Protocol w.e.f. November 07, 2020.

Members have been provided with “NEAT Adaptor” which shall support login for Exchange provided NEAT or NEAT Plus applications.

Accordingly, members currently have the following options to connect to the Exchange trading system in the CM, FO, CD and CO segments and SLBM.

Protocol Mode of Connection Can be used for
  NEAT Adaptor For "NEAT" or "NEAT +” Only.
Trimmed Direct Connection For Non Neat Frontend (NNF) applications

The member queries on Direct Connection functionality have been summarized in the form of an FAQ.

Exchange has provided “NEAT Adaptor” application for login using NEAT or NEAT Plus applications.

The “NEAT Adaptor” will not support login via NNF.

(Note: MPLS shall be discontinued w.e.f March 31, 2021. Kindly refer to Download Ref. No. NSE/MSD/45173 dated July 30, 2020 for details).

Yes, NEAT Adaptor is to be used for login using NEAT/NEAT Plus application and Direct Connection with Trimmed Protocol for NNF users

In Direct Connection, members need to connect directly to Exchange without using any middleware application provided by the Exchange. Member systems must initiate a TCP socket connection to the Gateway Router (GR) and the Gateway addresses (IP and Port details) given by the Exchange. For further details regarding direct connection feature, members can refer to the Trimmed Protocol documents.

The process of allocating gateway servers is Exchange determined and highly simplified for the member. The Gateway Router (GR) Functionality has been implemented as follows:

Members have to first connect to a gateway router server in the respective segment (Details mentioned in consolidated circular ref. no. 45703 dated September 15, 2020 of and as updated from by the Exchange from time to time.)

The gateway router server will decide which gateway server is available for the member and will accordingly provide the details of the allocated gateway server to the member through the response message.

After getting the response message the member will need to connect to the allocated gateway server. Thus, the gateway router will decide the gateway server for the member for each trading day in the following manner:

The gateway router will maintain the used capacity of each gateway server. The gateway router will allocate least used gateway server (according to capacity). The capacity is based on the no. of messages allotted for each Box Id.

If all gateway servers have similar used capacity then a gateway server will be randomly allocated by the gateway router server.

Once a member has been provided session key with gateway server details by gateway router server, the member is expected to connect and login to the allocated gateway server at any time during rest of the trading day.

If the member gets logged off from the allocated gateway server, then the member has to request the gateway router server for getting new session key and gateway server details.

A member will be directed to the same gateway server by the gateway router server, once it has been allocated for the trading day.

Though the user will get directed to the same gateway, the user must ask the gateway router for getting the gateway details and session key as the old session key will be unique for that particular session and is cleaned up from the gateway once the user gets logged off.

Also, if the gateway has a failure during the day, the user will be allocated a new gateway server. This will be done transparently for the user by the gateway router server.

At the end of each trading day the gateway router server will clean up the used capacity, and will have the same capacity (full capacity) available for all gateway servers for the next day.

Exchange has already introduced “Multi User Login Facility through DC” in the CM, FO, CD and COM segments, SLBM of the Exchange. This facility allows multiple users to connect from the same IP in a segment.

For NEAT Application the NEAT adaptor continues to support multi user login.

Members need to note the following:

Member can either connect through NEAT or through NNF from an IP in the segment. NEAT and NNF application cannot simultaneously connect through same IP in the segment. Member if logged in from NEAT will require separate IP for “Direct Connection”.

Accordingly, following options are available for members who wish to login via NEAT as well as NNF Applications

Option 1: NEAT and NNF on separate physical line with individual IP (Apply for separate connectivity scenarios)

Option 2: NEAT and NNF on same physical line but different IPs (Parent – Child).

Members can apply for child IP on the Existing IP. Exchange will issue additional (child) IPs in the same subnet that of main (parent) IP. There is no change in process for message allocation across Parent – Child IP and/or across segment.

Members can shift their NEAT / NNF User ids on the child IP / alternate IP as per their requirement.

Existing message rate and user limits as applicable according to scenario would remain. Member will be required to bifurcate the message rate and user rate across IP and Segments so that the total message rate and user rate does not exceed the total allotted capacity for the said scenario i.e. in this case being 100 m.p.s and 50 users.

For E.g. B scenario IP with all 100 messages per second allotted for CM segment only

IP Type IP address Box ID in CM Message Rate set in CM User Rate set in CM
Parent 123 50 26
Child 1 456 25 12
Child 2 789 25 12
Total 100 50


Members need to take care while allocating messages to respective segments on an IP in such manner that the overall rate applicable for that connectivity is not breached to avoid disconnection by the Exchange. (For details, kindly refer the Trimmed Protocol documents)

Member can apply for maximum 9 child IP’s on a parent IP in Non-Colocation connectivity scenarios. There is no concept of child IP allotment in the colocation facility of the Exchange.

Members can apply for Child IPs under their Parent TAP IP under below path in ENIT:

NEW –ENIT > Membership > TCP IP Scenario Activation > Direct Connection

Members need to take care while allocating messages to respective segments on an IP in such manner that the overall rate applicable for that connectivity is not breached to avoid disconnection by the Exchange. (For details, kindly refer the Trimmed Protocol documents)

Exchange trading system will control the Order message rate per second for each connected BOX id. Member systems must count the number of messages sent in a second and not exceed the message rate allocated by the member. (Member systems must maintain the message rate per second which the member has subscribed for). If there is breach, members shall experience disconnection from Exchange Trading System as the Exchange shall logoff the Box id. Effectively all user ids connected to the Box id shall also be disconnected.

The message flow control mechanism as applicable irrespective of “NEAT Adaptor” or “Direct Connection” mode of connecting to the Exchange is as follows:

For Members connecting on LAN i.e. through Colocation IP’s:

The message threshold is currently set at “configured message rate per second +10%”. Accordingly, the messages received beyond subscribed rate up and to 110% of subscribed rate are rejected by the Exchange. Further the Box id is disconnected if the messages exceed 110% of the subscribed rate for the respective segments.

For Members connecting on WAN i.e. through Non-Colocation IP’s:

The message threshold is currently set at “configured message rate per second * X factor”. Accordingly, the Box id is disconnected if the messages exceed the threshold calculated as mentioned above of the

Subscribed rate for the respective segments. The X factor is internally decided by the Exchange in order to account for the network propagation delay faced by the members for connection via non-colocation facility.

Also “NEAT Adaptor” and “Direct Connection” both will continue to follow the existing logic of Gateway router functionality and will share common nets as currently done.

For effective message rate control, member systems can test their implementations in test market environment.

For e.g., if the order rate decided is 100 msgs/second, and the order rate is being counted separately by the trading system and the exchange host, it may happen sometimes that the order rate as seen by the exchange host exceeds 100 msgs/second, due to different time window calculations at both ends.

Clock time is not to be considered for message-rate. Member systems are expected to control their message rate per second (the ‘second’ is not of the clock, but of running time, i.e. sliding window). I.e. when an order is being sent, check how many messages are already sent in t-minus- 1000 milliseconds or t-minus-1000000 microseconds.

Yes. All the business functionalities including COL will work with Direct Connection as with TAP/NEAT Adaptor.

Each multi-leg order (Spread/ 2L/3L) message will be counted as 1.

Members can multiple lock their user id across maximum 4 IP. The IPs can be any i.e. Parent IP as well as child IP. There is no change in the existing rules of Multi-locking due to this change.

No, there will be no invitation message or counts.

No. There is no change in Market Data dissemination mechanism and in the Tick-by-tick price-feed.

Download FAQ’S on Login without TAP- Direct Connection (.pdf)

Disclaimer :

This document/FAQ has been drafted in order to ease Member’s/reader’s understanding of the subject matter. The information and/ or content (collectively ‘Information’) provided herein is general information only and NSE has issued detailed circulars to that effect from time to time, While reasonable care has been exercised to ensure that the information is adequate and reliable, no representation is made by NSE as to its accuracy or completeness and NSE, its affiliates and subsidiaries accept no liability of whatsoever nature for any direct or consequential loss, including without limitation any loss of profits, arising from reliance on this information. The readers are expected to undertake their own diligence and are advised not to solely rely on this document. Any such reliance shall be at the reader’s own risk. Nothing stated herein shall bind NSE, in any manner whatsoever.”

Updated on: 19/03/2021
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