Cisco Simple GRE with IPSEC Tunnels
GRE with IPSEC KB ID 0000951 Problem I’ve spent years setting up VPN tunnels between firewalls. The only time I’ve ever dealt with GRE is for letting VPN client software though firewalls. GRE’s job is to ‘encapsulate’ other protocols and transport those protocols inside a virtual point to point link. Below is the topology, I’m going to use. The tunnel will run form Router R1 to Router R3, once...
Cisco IOS – An interface whose trunk encapsulation is “Auto” can not be configured to “trunk” mode.
KB ID0001167 Problem If you try and change a ports status, to make it a trunk port, you may see this error; Petes-Switch(config-if)#switchport mode trunk Command rejected: An interface whose trunk encapsulation is “Auto” can not be configured to “trunk” mode. Trunk Settings I don’t know if this is a throwback to when we had ISL trunking and 802.1q, but you need to specify the encapsulation before you can...
Cisco ASA 5500 – Sub Interfaces and VLANS
KB ID 0001085 Problem You can take the physical interface of a Cisco ASA firewall, (or an ether channel) and split it down into further sub-interfaces. This way you can set multiple VLANs to use this interface as a gateway at the same time whilst still separating the traffic. In this scenario I’m going to have two VLANs, one for my wired clients, and one for a ‘Guest WiFi’ that I’m setting up. I want the guest...