Spanning-Tree between HP Comware and Cisco

In the past, I had many problems with a heterogene infrastructure containing HPE 5000 Comware devices and Cisco Catalyst switches. I couldn’t get Multiple Spanning-Tree (MSTP) on the run (same revision number, same case-sensitive region-name). So we decided to go on with Per VLAN Rapid Spanning-Tree. But this also didn’t work, also no other VLANs that … Read more

Cisco Telnet hack available :)

Ok… cracking is bad… but enabling telnet is worse! “Cisco is warning of a new critical zero-day IOS / IOS XE vulnerability that affects more than 300 of its switch models. The company identified this highest level of vulnerability in its product while analyzing “Vault 7” — a roughly 8,761 documents and files leaked by … Read more

Cisco switch “inline power denied”

I had a curios problem with the new Cisco Aironet access points “AIR-AP2702I-UXK9”. This are universal (country-independent) APs. After several seconds, the access points from this series (connected directly to the PoE switches) made a power reset. Powering this APs with PoE-Injector solved the problem. The Cisco switches used in the environment are 3550 series. The installed firmware … Read more

StackWise configuration with Cisco Catalyst 3750-X Series

Today I will open the box of pandora of switch virtualization 🙂 Switch virtualization is needed for configure etherchannels or LACP over two or more devices, configuration-redundancy, single-configuration and easy network expansion. In this example I will show you how to configure a stackwise cluster with Cisco Catalyst 3750-X switches:   with Cisco StackWise you can … Read more

Spanning Tree Protocol and PXE Boot

Most of us is using STP (Spanning Tree Protocol) within switched networks. In the last days I had problems on one location of a customer. We distribute new Cisco Catalyst 3750-X switches to the location and didn’t understand why desktop clients can’t boot via DHCP/PXE (Preboot Execution Environment). With globally activated STP/RTSP on the switches, every … Read more