Networking · Cluster
Network Virtualization
Overlays, tunnels, and software dataplanes.
- 01 The Overlay and Underlay Split in Virtual Networks How a virtual network carries its own addresses inside an ordinary routed network, what the mapping between the two layers costs, and where the separation leaks.
- 02 VXLAN Header Layout and the Scope of the VNI A byte-level reading of the eight-byte VXLAN header, why the tenant identifier is twenty-four bits, and what the reserved fields constrain.
- 03 Tunnel Encapsulation Overhead and Path MTU Discovery How many bytes each overlay scheme adds, why ICMP-based path MTU discovery breaks across a tunnel, and the options for keeping an inner frame inside the underlay MTU.
- 04 Flood and Learn Versus a BGP EVPN Control Plane How a tunnel endpoint discovers the remote endpoint for a MAC address by flooding and learning from the reply, what that costs at scale, and how a routing protocol replaces the guesswork.
- 05 Overlay Endpoint Resolution and Its Caches How a host maps an inner destination to the tunnel endpoint that hosts it, what the per-flow and per-prefix caches hold, and why a stale mapping is worse than a missing one.
- 06 UDP Source Port Entropy and Underlay ECMP Why a tunnel collapses many flows onto one underlay path, how deriving the outer source port from an inner-header hash restores path diversity, and when the hash runs out of entropy.
- 07 Network Namespaces and veth Pairs as Virtual Routers How a Linux network namespace holds an independent forwarding table, how veth pairs connect two of them, and what a packet crossing between namespaces actually costs.
- 08 Match-Action Pipelines and Flow Caching in Software Switches How a packet is classified by a sequence of table lookups, why the first packet of every flow takes a slow path, and how a wildcard cache shortens the common case without breaking correctness.
- 09 XDP and eBPF in the Receive Path Where an XDP program runs relative to the socket layer, what the three attach modes give up, and which packet-processing decisions can be made before a socket buffer exists.
- 10 SRv6 Segment Lists as a Source-Routed Overlay How a 128-bit IPv6 address doubles as a forwarding instruction, what the segment list in the routing header encodes, and why path state moves from the core to the edge.