Filtering traffic with vlan access list

Topology Lab setup Linux 2 belongs to vlan 10. Linux 3 and 4 belong to vlan 20. Router is the dhcp server for vlan 10 and 20. A default route goes from Router to the internet where the web application DVWA resides. VLAN 10 subnet 10.10.10.0/24 and VLAN 20 subnet 10.20.20.0/24. Damn Vulnerable Web Application … Continue reading Filtering traffic with vlan access list →

Stackwise

Stack master election criteria The criteria is in order, if the first criteria does not meet the second criteria will be the tie breaker. 1. The switch that is configured with the highest stack priority. 2. The switch that is not using the default configuration. 3. The switch that is using a higher priority IOS, … Continue reading Stackwise →

IOS installation for Catalyst 3750 switch

Precaution 1. When adding an additional switch to the current switch stack always check the new switch IOS version first. 2. If the new switch is added to the current stack and if the IOS is mismatched the stack knows and the master of the stack will attempt to synchronize its own IOS with the … Continue reading IOS installation for Catalyst 3750 switch →

Multiple Spanning Tree Protocol (802.1s)

This protocol is inspired by Cisco proprietary Per-Vlan Spanning tree plus (PVST+). Cisco PVST+ creates an STP instance for each Vlan. MSTP has more flexibility than PVST+, MSTP instances can map unlimited number of Vlans. MSTP supports 16 STP instances. When MSTP is enabled, RSTP is essentially enabled as well. The disadvantage of PVST+ is … Continue reading Multiple Spanning Tree Protocol (802.1s) →

Rapid Spanning Tree Protocol (802.1w)

Port roles 1. Root port - STP path that is "shortest" to root bridge. 2. Designated port - Port that is forwarding and is not a root port. 3. Alternate port - Backup root port. Present the alternate path to the root bridge. 4. Backup port - Backup designated port. Bridge Protocol Data Unit 1. … Continue reading Rapid Spanning Tree Protocol (802.1w) →

Spanning Tree Protocol (802.1D)

This protocol prevents bridging loop created by redundant links within switch network. STP calculation will make switch/es block its own port so that the switch path is one straight line and not a loop. This is perhaps the most confusing concept in switch, it is not extremely difficult but many terminologies and the method on … Continue reading Spanning Tree Protocol (802.1D) →

VLAN Trunking Protocol

This is a Cisco proprietary protocol that is designed to ease Vlan database management, it has nothing to do with trunking. The concept is that a switch with a VTP server mode will propagate VLAN database down to all switches with VTP client mode. Sw2-3560 vlan database before a new vlan is added (VTP client) … Continue reading VLAN Trunking Protocol →

Catalyst Switch: Turn off trunking negotiation

To turn off dynamic trunking protocol (DTP) and use dot1q standard. It is recommended to turn off trunking protocol and put vtp to transparent mode, this is because a newly introduced Catalyst switch may form undesired switch topology and if the newly introduced Catalyst switch has a vtp revision number higher than the current switch … Continue reading Catalyst Switch: Turn off trunking negotiation →

Catalyst Switch: No trunks is formed

I have connected two Cisco Catalyst 3560 switches together by a pair of fibre cables. No trunk was formed. The default interface configuration for Catalyst 3560 is dynamic auto, in Catalyst 3550 the default was dynamic desirable. Dynamic desirable is actively negotiating a trunk with another cisco catalyst switch, whereas dynamic auto is passively waiting … Continue reading Catalyst Switch: No trunks is formed →

Cisco IE3000: Resilient Redundancy Protocol

IE3000 is a din-rail mount switch with eight fast ethernet copper ports and two gigabit ethernet combo ports. People who worked for datacentre, enterprise, and ISP might not have seen or used this kind of switch before. The IE3000 is designed for used in Industrial network, most of the control systems like PLCs are mounted … Continue reading Cisco IE3000: Resilient Redundancy Protocol →