VPN Blocks — build an IPsec tunnel from blocks

What to look at: (1) nesting: the tunnel contains its IPsec profile, which contains the transform set and the IKEv2 profile, just as IOS references them by name. (2) The coloured lines link fields that must agree between the peers: solid green = agree, red = mismatch, dashed amber = works but falls back or isn't recommended. (3) The checklist follows the order of the IKEv2 handshake. Hover an item to highlight its lines. (4) Apply sends the generated IOS to the real v3 simulator and shows whether the tunnel comes up. (5) In the IKEv2 proposal, click the chips to choose each router's preferences (the number is the order). The line between the two lists turns green only when they overlap and shows the agreed value; red = no overlap and the tunnel fails; grey = not configured yet or a non-fatal mismatch. (6) Learning aids: the four steps 1 Reach → 2 Agree → 3 Trust → 4 Protect (click one to focus on it); Complete the peer mode (R1 is locked, you build R3); Feedback: After Apply hides the lines until you test; Predict first asks for your prediction before each Apply. Try the Concepts view and the scenarios at the top.