05
Thu, Dec
6 New Articles

TechTip: Fixing PC5250 Connecting or Reconnecting Problems

Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times
Every time I talk with customers, it's not long before they mention one of two problems. Either they cannot make a connection when using PC5250 in a remote environment (e.g., accessing their iSeries from the Internet), or they can't reconnect their PC5250 session after being dropped while in a local environment (e.g., accessing their iSeries from a local LAN). In the second case, this seems to be caused by server jobs hanging around after the PC5250 session has dropped. These jobs need to be manually cancelled in order to reconnect. If you've run into either of these problems, then read on; this article is for you.

One Telnet Parameter Does All

Believe it or not, both of these problems can be solved using the same parameter on the Change Telnet Attribute (CHGTELNA) command. The parameter is called Session Keep Alive Timeout (TIMMRKTIMO). So what does the Session Keep Alive Timeout do? According to the IBM Help documentation, "It sets the amount of idle time that the TCP/IP protocol will allow before sending a probe to test an inactive session." Got that? No? Then, let's step back a bit.

TCP/IP Keepalive

When you start up a PC5250 session, your PC and your iSeries communicate back and forth. While you are actively using the PC5250 session, PC5250 is sending data to and receiving data from the iSeries when you press interrupt keys, such as Enter or Function keys. In this case, the iSeries knows the PC5250 session is active because it is receiving data from the PC. However, when that activity stops, the iSeries needs to know if the PC5250 session is still there or if it has been dropped. So it sends what is called in TCP/IP architecture a "keepalive"--or what I like to call an "Are you there?" request. If the PC5250 is still there but just waiting for someone to press an interrupt key, it responds to the "keepalive" request with an "I'm still here" response. The iSeries will continue to periodically send "Are you there?" queries as long as it keeps getting the "I'm here" responses and there is no active communication (i.e., interrupt data) being sent from the PC5250 session.

When the iSeries sends a keepalive (Are you there?) query, it waits for a period of time, and if it does not receive a response from the PC5250 session, it ends the PC5250 session. For specifically named PC5250 sessions (i.e., not QPADEVnnnn), it performs the action set in the Device Recovery Action (QDEVRCYACN) system value such as end or disconnect the interactive job running "in" the PC5250 session. For QPADEVnnnn, TCP/IP will always end the job.

Session Keep Alive (TIMMRKTIMO)

The TIMMRKTIMO parameter on the CHGTELNA command sets the amount of time the iSeries waits to query the status of the PC5250 session. You will need to end and restart the TCP/IP server in order for a change to the TIMMRKTIMO to take effect. The larger you make this value, the longer it will take to detect that a PC5250 session has dropped, thus the longer it will be before the iSeries will clean up the disconnected job. The length of time you could wait for this cleanup to occur could be up to twice the TIMMRKTIMO value. The smaller you make it, the more network traffic you will have and the shorter time a remote user (i.e., PC5250 connection via the Internet) has to make a connection. The default is 600 seconds (10 minutes). A value of zero (0) means there is no timeout, which means cleanup will never occur.

So what value should you use for TIMMRKTIMO? First, find out what your current TIMMRKTIMO is. If you are having trouble connecting, increase the value. If you are having trouble getting reconnected, decrease the value. You will need to find your comfort level between how much traffic you want to tolerate (lower setting means more network traffic) versus how fast you need to have your lost PC5250 session detected.

Help Spread the News

I hope this will help many of you who have experienced these problems. And if so, please spread the word. There is no need to be frustrated by connection problems. The solution is just a TIMMRKTIMO away.

Becky Schmieding is an IBM Certified Senior Project Manager at IBM Rochester. She is a noted speaker and author on PC5250, iSeries Navigator, and the iSeries Access family of products. She can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it..







Becky Schmieding is an IBM Certified Executive Project Manager at IBM Rochester on the Product Definition Team (PDT) responsible for the E2E upgrade process. She is a noted speaker and author on PC5250, iSeries Navigator, and the iSeries Access family of products.
BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: