IPv6 Header Format Explained
The IPv6 header byte by byte: 40 bytes fixed, 8 fields, extension headers, Next Header chaining, comparison to IPv4, and what it looks like in Wireshark.
Networking
Core networking tutorials covering protocols, addressing, infrastructure design, and foundational concepts for network engineers and certification candidates.
Latest posts
IPv6 Configuration on Cisco IOS XE
IPv6 configuration on Cisco IOS XE: enabling IPv6, static and SLAAC addresses, RA options, OSPFv3, BGP for IPv6, EIGRP for IPv6, VRRPv3, dual-stack, and first-hop security.
IPv6 Address Types: Link-Local, Global, Unique Local
The six IPv6 address types: global unicast, link-local, ULA, multicast, anycast, and special. Prefixes, scope, when to use which, and design implications.
IPv4 vs IPv6: The Real Differences
IPv4 vs IPv6 in 2026. Header differences, ARP vs Neighbor Discovery, SLAAC vs DHCP, NAT vs end-to-end, and dual-stack as the migration reality.
IPv6 Address Format Explained Byte by Byte
IPv6 addresses are 128 bits as eight groups of four hex digits. The two compression rules, prefix notation, EUI-64 interface IDs, special addresses, and worked examples.
GLBP for Active/Active Load Balancing
GLBP (Gateway Load Balancing Protocol) is Cisco's load-balancing FHRP. AVG, AVFs, three load balancing methods, configuration, and when GLBP is actually the right answer.
VRRP Explained: The Vendor-Neutral FHRP
VRRP (Virtual Router Redundancy Protocol, RFC 5798) is the vendor-neutral FHRP. How it works, master election, IP address owner trap, vs HSRP, Cisco IOS XE configuration, and tracking.
Cisco MPLS Configuration on IOS XE
Cisco MPLS configuration on IOS XE: enabling MPLS forwarding, LDP, LDP-IGP sync, VRFs for L3VPN, and MP-BGP between PEs. With a complete PE config example.
LDP and MPLS Label Distribution
LDP (Label Distribution Protocol) distributes MPLS labels across the network. Discovery, session establishment, distribution and retention modes, LDP-IGP sync, and Cisco IOS XE configuration.
MPLS Labels Explained: Format, Stacking, and Penultimate Hop Popping
MPLS labels byte-by-byte: 20-bit label, EXP/TC, S bit, TTL. The label stack model, reserved labels, Penultimate Hop Popping, TTL handling, and what labels look like in Wireshark.
QoS Queueing, Policing, and Shaping Compared
LLQ, CBWFQ, policing, and shaping each do something different. The three primitives, when to use which, hierarchical shaping for sub-rate WAN handoffs, and the production patterns.
QoS Classification, Marking, and Trust Boundaries
Classification and marking at the trust boundary are the foundation of every QoS deployment. The patterns (untrusted access ports, conditional trust for IP phones, explicit MQC marking) and the discipline that makes them work.