Ping Labz (Page 9)

Troubleshooting Inter-VLAN Routing: SVIs, Router-on-a-Stick, and ARP Issues

Inter-VLAN routing failures are usually caused by SVIs in down state, missing routes, DHCP misconfiguration, or ARP timeouts. Learn to diagnose and fix them systematically.

10 min read Apr 1, 2026

VLAN public

Troubleshooting VLAN and Trunk Problems on Cisco Switches

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Most VLAN outages stem from ports in the wrong VLAN, trunks not allowing required VLAN, or native VLAN mismatches. Here's how to diagnose and fix them systematically.

7 min read Apr 1, 2026

VLAN public

Private VLANs on Cisco Catalyst Switches: Isolated and Community Ports

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Private VLANs let you enforce micro-segmentation within a single VLAN—isolating hosts completely or grouping them into communities while keeping them behind a single gateway IP.

5 min read Apr 1, 2026

VLAN public

Configuring Voice VLANs on Cisco Switches for IP Phones

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Voice VLANs let a single access port carry both data traffic from a PC and voice traffic from an IP phone — each in its own VLAN with its own QoS treatment.

7 min read Apr 1, 2026

VLAN public

Inter-VLAN Routing on a Layer 3 Switch: SVI-Based Routing on Catalyst 9000

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Layer 3 switches route between VLANs in hardware at wire speed — no external router bottleneck. Here is how to configure SVI-based inter-VLAN routing on a Catalyst 9300.

8 min read Apr 1, 2026

VLAN public

Inter-VLAN Routing with Router-on-a-Stick on Cisco IOS XE

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When you don't have a Layer 3 switch, router-on-a-stick provides inter-VLAN routing via a single physical link split into subinterfaces. Learn when this design is appropriate, how to configure subinterfaces, and why it's a bandwidth bottleneck.

10 min read Apr 1, 2026

VLAN public

DTP (Dynamic Trunking Protocol): How It Works and Why You Should Disable It

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DTP lets switches negotiate trunk formation automatically—but this convenience comes with security risks that make disabling it a best practice in production networks.

8 min read Apr 1, 2026

VLAN public

VLAN Access Ports and Switchport Modes: Access, Trunk, and Dynamic

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Learn the differences between access mode, trunk mode, and dynamic trunking protocol negotiation on Cisco Catalyst switches, and why static configuration is the production standard.

7 min read Apr 1, 2026

VLAN public

How VLANs Work: Tagging, Broadcast Domains, and Frame Forwarding

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VLANs are more than a configuration checkbox — they change how every frame is tagged, forwarded, and filtered inside the switch. Here's the mechanics.

7 min read Apr 1, 2026

VLAN public

What Is a VLAN? Virtual LANs Explained for Network Engineers

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VLANs let you carve one physical switch into multiple isolated broadcast domains — without buying more hardware. Here's how they work and why every network uses them.

6 min read Apr 1, 2026

BGP public

BGP Path Attributes Explained: Well-Known vs Optional

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BGP path attributes are the foundation of every traffic engineering technique: local preference, MED, AS-path prepending, communities. Understand the well-known vs optional attribute matrix before touching policy.

4 min read Mar 28, 2026

BGP public

BGP Message Types: OPEN, UPDATE, KEEPALIVE, and NOTIFICATION

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BGP uses just four message types: OPEN, UPDATE, KEEPALIVE, and NOTIFICATION. Understanding the field-level format of each makes debug output and packet captures far more readable for anyone troubleshooting BGP.

4 min read Mar 28, 2026