NetworkPuzzles

recent posts

    • WFQ, CBWFQ and LLQ Explained in a Practical Way

      When multiple traffic flows pass through a router, the default behavior is usually very simple. Packets are processed in the order they arrive, without any awareness of the type of traffic or its importance. This behavior works fine until the network becomes busy. If one application starts sending a large amount of traffic, it can…

    • How Traffic is Classified, Marked, and Queued

      When we design networks, we usually assume that all traffic is treated equally. Routers forward packets as fast as possible, without considering the type of application or its requirements. But what happens when the network becomes congested? In real networks, not all traffic is equal. Some applications are very sensitive to delay and packet loss.…

    • NAT

      Network Address Translation is one of the most fundamental technologies in networking. It allows us to modify IP addresses as packets pass through a router. 1) Static NAT One-to-one mapping between a private and public IP. Used for: devices that must always be reachable. Config (on R2): 192.168.1.10 is always translated to 200.1.1.10 (Fixed mapping).…

    • Proxy ARP

      When we design networks, we usually expect hosts to communicate with devices in other subnets through a default gateway. Each subnet is a separate broadcast domain, and ARP is only used for local communication. But what happens if hosts are misconfigured and don’t have a proper default gateway? This is where Proxy ARP comes into…

    • DNS and HTTP GET with IP SLA

      When engineers first learn IP SLA, they often start with ICMP echo, because it is simple and useful for checking basic reachability. But in production networks, just knowing that a device is reachable is often not enough. A server may still answer ping, while the actual service users need is already broken. That is where…