Hello,I've got a router at a customer's site that uses ISDN as a backup line. For some reason, I was able to successfully make a call this morning, but then trying again right after that call, I get the following error message when I try to make an i...

Hello,please refer to the attached diagram.Our network doesn't follow the Cisco-recommended mesh topology with redundant connections everywhere.  Basically, we have a star-topology that doesn't really use STP at all. (Core switch is in the center and...

Hey everyone,Our current network is comprised of about 50 Cisco switches, all C2950s or C2960s, with a C6500 and C3750 stack at the core.Because our network had components from another vendor, the previous network administrator decided to use VLAN 1 ...