IKEv2 is not IKEv1 with a bigger version number. It is a different protocol, defined in a different RFC, with a different exchange, different state machine, different show commands, and a completely different philosophy about defaults. If you learned IPsec
You have a site-to-site VPN in production. It works. It has worked for years. It uses a crypto map, an ISAKMP policy, a pre-shared key, and a transform set, and the last time anybody touched it was
If you are building a brand new site-to-site tunnel in 2026, this is the one you should build: IKEv2 for the control plane, AES-GCM-256 for the data plane, and a static VTI for the forwarding plane.
Sooner or later someone hands you two routers, two sites, and "encrypt the traffic between them." On Cisco IOS XE you have two mainstream ways to do it: a crypto map or a virtual tunnel interface (VTI). Same
If you are still building site-to-site VPNs with crypto maps in 2026, you are configuring a router the way it was done in 1999. The Static Virtual Tunnel Interface (SVTI) is the modern answer, and the whole idea
Every error message in this article came off a real router. Not a textbook, not a vendor doc, not a forum post from 2011. We built a live IPsec lab in CML (two cat8000v edge routers, an ISP router, a
Every IPsec engineer eventually hits the same wall. The tunnel worked perfectly in the lab, you shipped the branch router, and now the site is behind a broadband modem doing PAT. Phase 1 comes up. Phase 2 does not. Nothing
Configure GRE over IPsec on Cisco IOS XE with IKEv2 and IPsec profiles. Modern and legacy configs, MTU planning, OSPF over the tunnel, and gotchas.
Almost everything written about IPsec starts with a config snippet. That is backwards. If you do not know what an SA is, why IKE runs in two phases, or which bytes of your packet actually get encrypted, then a crypto
A site-to-site VPN built with crypto maps is still the config the CCIE Security lab expects you to type from memory, and it is still the one that teaches you the most, because crypto maps make every moving