auto-negotiation-(nway) secure-remote-access ah-yes-20-millionen-cisco-sachen dual-stack-topology router switching-concepts vlans inter-vlan-routing stp-spanning-tree-protocol etherchannel-(lag) dhcpv4 auto-ip-bereich-apipa ip-v6 ipv6-discovery slaac test prac first-hop-redundancy-protocols layer-2-lan-security-concepts wlan