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Showing posts from June, 2013

Understanding STP Ports States

Hello! Frens, here is another article about STP, in this article I try to explain switch port status and how we  recognize ports status as well as Root ID and Bridge ID, What MAC address STP take to elect the Root Bridge. Hope this article is useful to understand Spanning Tree Protocol and at last I try to explain why we need RSTP. I'll post another article about RSTP in coming days. As I already explain in my previous article about STP Root Bridge election, now we can see S1 have lowest MAC address wins the Root Bridge, let’s verified and check the status of the switches ports. Look at the picture above we can see, from the VLAN001, which have Root ID and Bridge ID, Root ID have all information about the Root Bridge, that mean S2 knows that is the Root Bridge and out port is Fa1/1, which is Root Port and directly connected to the RB. Root Bridge has priority of 32769, MAC is 000D.BD2D.6BD9, and cost is 19 to reach the Root. Bridge ID is information about

Script for mikrotik router

Here is some script of Mikrotik router to add IP address and make queue list on top. Adding such a huge IP Address one by one is very difficult and time consuming task. So here a script to add IP Address in Mikrotik router. Tested on MT OS verson 5.x Make sure you already open the MT with Winbox, in my case I already done. Click on System Menu on the left and choose Script from popup menu, see below Now on  Script list window.  click Plus( + ) , then copy paste below script on source field. Like in picture :for i from=2 to=51 do={/queue simple add name="192.168.20.$i" target-address="192.168.20.$i/32" max-limit="64000/128000" parent=Night-User time=19h-7h,sun,mon,tue,wed,thu,fri} (Modified it with our requirement) To view the queue list, which we have just add Click on Queues on the left pane, you can see look like this. This Script make your queue list at top of the list.  /queue simple move [find name=(y

Per VLAN Spanning Tree

All modern Cisco switch support PVST. As name indicates what per VLAN Spanning Tree does is add a VLAN number to the priority of the BPDU headers. e.g., the default priority is 32768; if you run VLAN 10 on your switch then new priority would be 32778. The result of this is you have one Root Bridge per VLAN. If your network has multiple VLAN then you have multiple Root Bridge per VLAN. In that case if you don't change anything, by default same switch will elected as Root Bridge for every single VLAN number. From the diagram above we have VLAN 10 and 20 running on Switches which are trunked each other. We have two VLAN here that means we have two completely separate network of Spanning Tree running. Now the trunk link has run both VLAN 10 & 20. We already discuss by default priority is 32678, and then new priority would be 326778 for VLAN 10 and 32688 for VLAN 20. If that so then it’s all tied and VLAN 10 only communicate with VLAN 10 and VLAN 20 only Communicated it

Spanning Tree Electing Root Bridge

Per-VLAN Spanning Tree Concepts Let’s began with how Spanning tree work in enterprise network. From the figure we can identified who will be the root bridge and config to choose who will be the root bridge in our network. Let’s start with default state of Spanning tree. A real world Spanning tree example. We have 3 tiered network structure of enterprise network. Top of Switch is Access, which is directly connected with the user and middle is Distribution then core switch, at bottom server FARM switches. We don't change anything priority and mac address are the same; now guess who will be the Root Bridge. Obviously switch0, because it has the lowest mac address. That access layer switch became the Root Bridge. Now do we want that switch became Root Bridge in our network? No we didn't want it to be Root Bridge. That isn't the center of the network. Remember that all switch finds best way to reach Root Bridge and block all other redundant links. Switches th