# F5 LTM Module 3 Virtual Servers & pools Source: https://ai.techclick.in/blog_f5_ltm_module_3_virtual_servers_pools Markdown: https://ai.techclick.in/blog_f5_ltm_module_3_virtual_servers_pools.md Publisher: Techclick Infosec Pvt Ltd Configure BIG-IP nodes, pools, and Standard Virtual Servers. Choose Round Robin, Least Connections, and Priority Groups, then prove with curl and tmsh. Lessons · F5 LTM series · Module 3 F5 LTM recorded course · 7 modules Same lab numbers on every page: client 198.51.100.50 , VIP 192.0.2.100 , Self IPs 192.0.2.10 / 10.20.20.10 , members 10.20.20.101–103 . - Hub · Course map - M1 · Fundamentals & admin - M2 · Networking & traffic flow - M3 · Virtual Servers & pools ← you are here - M4 · Profiles, SNAT, SSL - M5 · Monitors, iRules, policies - M6 · High availability - M7 · Troubleshooting Next → M4 · Profiles, SNAT, SSL Recorded course + workbooks: My Courses · syllabus F5 LTM / GTM / ASM ## Publishing the application Module 2 made the box reachable. Module 3 publishes an application: Node → Pool Member → Pool → Virtual Server. Ticket: “VIP is up, pool is empty, users get a reset.” Someone created a Virtual Server without a pool, or named the VIP and thought that was load balancing. Hero · VIP to pool The VIP is only a listener. The pool is the set of IP:port services. Confusing those two words in a bridge call wastes an hour. Quick answer A node is an IP. A pool member is IP:port. A pool is the group plus algorithm plus monitor. A Virtual Server matches destination IP + port + protocol (and VLAN) and then uses that pool. Standard VS = full proxy, two TCP sessions. ## Object hierarchy Flow 1 · objects Flow 1 · objects - Node 10.20.20.101 Member 101:443 Pool WEB_POOL VS 192.0.2.100:443 Build bottom-up: nodes/members, then pool, then VS. Deleting a node still in a pool will refuse. Say this out loud Clients send to the Virtual Server destination. BIG-IP does not “become” 10.20.20.101. It selects a member and builds a server-side connection. ## Load-balancing methods Method Picks Use when Round Robin Next member in order Equal servers, easy lab proof Ratio Weighted members Unequal capacity Least Connections Member with fewest live connections Long-lived sessions, mixed object sizes Priority Group Higher group first until min-members N+M: keep backups idle until primaries die Fastest / Observed / Predictive Dynamic samples Only after you understand the metric — Module 3 PDF flags these as advanced Decision · Path A vs Path B Round Robin is the lab default. Least Connections is the usual production HTTP default when members are equal. Do not mix them in one sentence in an interview. Also set Slow Ramp Time so a member just marked up does not eat every new connection, and connection limits so one server cannot be drowned. Priority Group Activation needs a minimum-active-members number or the backup group never engages. ## Runbook — first HTTPS (or HTTP lab) Virtual Server ### Side A · node and pool #### Create or confirm nodes GUI: Local Traffic → Nodes → Node List. A node can exist without being in a pool; a member cannot. - #### Create the pool Local Traffic → Pools → Pool List → Create. Name WEB_POOL. Add 10.20.20.101–103 with the real service port. - #### Attach a monitor later Module 5 builds the HTTP monitor. For this module a TCP monitor is enough to prove L4. Do not pretend ICMP means the app works. TMSH · pool from Module 3 PDF tmsh create ltm pool WEB_POOL monitor tcp load-balancing-mode round-robin members add { 10.20.20.101:80 10.20.20.102:80 10.20.20.103:80 } tmsh list ltm pool WEB_POOL tmsh show ltm pool WEB_POOL members https://192.168.100.10/tmui/Control/jspmap/tmui/locallb/pool/create Training mock · not live Local Traffic > Pools > Pool List > Create ### New Pool Name WEB_POOL Health Monitor tcp (upgrade to HTTP in Module 5) Load Balancing Method Round Robin New Members 10.20.20.101:80, 10.20.20.102:80, 10.20.20.103:80 Cancel Finished Source: F5-BIG-IP-LTM-Module-3.pdf and F5 cert Lab 1. ### Side B · Virtual Server https://192.168.100.10/tmui/Control/jspmap/tmui/locallb/virtual_server/create Training mock · not live Local Traffic > Virtual Servers > Virtual Server List > Create ### New Virtual Server Name vs_web_http Type Standard Destination Address/Mask 192.0.2.100 / 32 Service Port 80 Protocol TCP Default Pool WEB_POOL Source Address Translation Auto Map (if return path needs it — Module 4) Cancel Finished More-specific VS wins: longer mask, explicit port, explicit VLAN. A :443 VS will not catch :8443. TMSH · Virtual Server tmsh create ltm virtual vs_web_http destination 192.0.2.100:80 ip-protocol tcp pool WEB_POOL source-address-translation { type automap } tmsh list ltm virtual vs_web_http tmsh show ltm virtual vs_web_http ### Side C · verify without lying to yourself Browser refresh is not a load-balancing test — it reuses the TCP connection. Open a new connection per request (curl in a loop, or disable keep-alive). Proof curl -sv --http1.0 http://192.0.2.100/ | head tmsh show ltm virtual vs_web_http tmsh show ltm pool WEB_POOL members tcpdump -nni 0.0 host 192.0.2.100 Ops · pool health tiles One red member is not a down VIP. A down VIP is no VS match, empty pool, or no listener on that port. ## Runtime after VS match Flow 2 · client to member Flow 2 · client to member - Match IP+port+proto Profiles later M4 LB pick algorithm Member new TCP Standard VS = two sessions. FastL4 is a different type — do not mix the mental model. ## Traps + proof Failure Symptom Fix Said 'the VIP' meaning the pool Wrong object in the change window Name VS, pool, member separately Port mismatch Client 443, VS 8443, no stats tmsh list ltm virtual destination No pool attached VS enabled, RST or timeout Default pool field Browser keep-alive Always hits one member curl --http1.0 in a loop Member :80 vs app :443 Monitor up, HTTP garbage Member port is the service port, not the VIP port You are done with Module 3 when You can draw Node vs Member vs Pool vs VS from memory. - tmsh show ltm virtual increments on each new curl. - You know when to use Priority Groups vs Least Connections. ## Knowledge check Object words matter on a bridge call. Q1 A pool member is: Only a hostname IP + service port A Self IP A UCS file Correct: b . Hierarchy in Module 3. Q2 Standard Virtual Server is: A bump-in-the-wire L2 forward only A full proxy with two TCP sessions Always FastL4 Always SNAT Correct: b . FastL4 is a different type. Q3 Priority Groups are for: Encrypting cookies Using backups only after primaries fall below min members Port Lockdown NTP Correct: b . Set minimum active members. Q4 Client hits :443 but VS is :8443: HTTP profile fixes it No VS match Automap fixes it Monitor marks up Correct: b . Match is IP+port+protocol. Q5 Best lab proof of Round Robin: Press F5 in the browser curl --http1.0 in a loop and watch member stats Ping the VIP Reboot TMM Correct: b . Keep-alive reuses one server. Q6 GUI path to create the pool: System > License Network > Routes Local Traffic → Pools → Pool List → Create Device Management → Devices Correct: c . PDF runbook. Check answers Reset ## Sources - Techclick PDF: F5-BIG-IP-LTM-Module-3.pdf (from OneDrive_1_8-26-2026.zip, 26 Aug 2026) - Companion deck: F5-Ltm-Training-Ppt (1).pptx.pdf - Official lab paths: F5 cert Lab 1 — VLANs, Self IPs, pools, virtual servers - TMSH virtual server reference: ltm virtual - Related deep dives on this site: SSL modes · SNAT · Persistence · VS/pools · VIP down / tcpdump Related: Course hub · Syllabus · My Courses · F5 LTM interview --- Cite this Techclick lesson with the source URL. Do not invent fees, batch dates, or job guarantees. Browse all lessons: https://ai.techclick.in/blogs AI index: https://ai.techclick.in/llms.txt