CCNA,CCNP,CCIE Blogs

The process to upgrade a Cisco Wireless Lan Controller is quite straightforward but there are a few things you need to be aware of which can minimise the downtime for your wireless network. This guide will go through the process to upgrade a pair of 5508 WLC’s configured in HA setup and connected back to back with RP port. Here is the Topology: Upgrade Software on Cisco 5508/5520 WLC – Steps The first step is to upload the new image to the controller. This process does nothing to your live network and only uploads the image to the controller. Download the image from  cisco.com  and store in a known location on your laptop. For the purpose of this guide I am using 8.0.121.0 .Don't forget to check compatible matrix for your AP Models.  You will need a TFTP server running, I am using TFTPD32 running locally on my laptop. You can also use FTP or SFTP server to transfer the image.  Copy the new image into your tftp directory and go to the GUI on ...

1) What is Routing? Routing is the process of finding a path on which data can pass from source to destination. Routing is done by a device called routers, which are network layer devices. 2) What is the purpose of the Data Link? The job of the Data Link layer is to check messages are sent to the right device. Another function of this layer is framing. 3) What is the key advantage of using switches? When a switch receives a signal, it creates a frame out of the bits that was extracted from that signal. With this process, it gains access and reads the destination address, after which it forwards that frame to the appropriate port. This is a very efficient means of data transmission, instead of broadcasting it on all ports. 4) When does network congestion occur? Network congestion occurs when too many users are trying to use the same bandwidth. This is especially true in big networks that do not resort to network segmentation. 5) What is a Window in networking terms? ...

What are the Port Roles in RSTP? 1. Root port - It is the port on the switch that has the best root path cost to the root bridge. This is identical to 802.1D. 2. Designated port - The switch port on a network segment that has the best root path cost to the root. 3. Alternate port - A port that has an alternative path to the root, different from the path the root port takes. This path is less desirable than that of the root port. 4. Backup port - A port that provides a redundant (but less desirable) connection to a segment where another switch port already connects. If that common segment is lost, the switch might or might not have a path back to the root. What are different port states in RSTP? 1. Discarding - Incoming frames simply are dropped; no MAC addresses are learned.This state combines the 802.1D Disabled, Blocking, and Listening states. 2. Learning - Incoming frames are dropped, but MAC addresses are learned. 3. Forwarding - Incoming frames are forwa...

What is STP & Redundant Links? Spanning Tree Protocol (STP) is a protocol which prevents layer 2 loops. STP enables switches to become aware of each other so that they can negotiate a Loop-Free path through network. In practical Scenario, Redundant links are created to avoid complete network failure in an event of failure of one link. How STP works? STP chooses a Reference point (Root Bridge) in the network and calculates all the redundant paths to that reference point. Than it picks one path by which to forward frames and blocks other redundant paths. What are the different port states? 1. Disabled - A port in the disabled state does not participate in the STP. 2. Blocking - A blocked port does not forward frames. It only listens to BPDUs. The purpose of the blocking state is to prevent the use of looped paths. 3. Listening - A port in listening state prepares to forward data frames without populating the MAC address table. The port also sends and listens t...

Explain Border Gateway Protocol (BGP) ? Border Gateway Protocol advertises, learns and chooses the best paths inside the global Internet. When two ISPs connect, they typically use BGP to exchange routing information. Enterprises also sometimes uses BGP to exchange routing information with ISPs, allowing the Enterprise routers to learn Internet routes. when we have multiple Internet connections and we want to influence some packets to take one path and some packets to take another we use BGP. Can Routers on different subnet become BGP neighbors? BGP does not require neighbors to be attached to the same subnet. Instead, BGP routers use a TCP connection between the routers to pass BGP messages allowing neighboring routers to be on the same or different subnet. What TCP port number BGP use for connection? BGP uses TCP port 179 for the connection. Difference between eBGP and iBGP neighbor? In iBGP, neighborship is formed between routers within the same AS (autonom...

What is OSPF Routing Protocol? Open shortest path first is an Open Standard Link State routing protocol which works by using Dijkastra algorithm to initially construct the shortest paths and follows that by populating the routing table with resulting best paths. What are the steps required to change Neighborship into adjacency? 1.Two-way communication (using Hello Protocol). 2.Database Synchronization which means exchange of Database Description (DD) packets, Link State Request (LSR) packets, Link State Update (LSU) packets. After Database synchronization is complete, the two routers are considered adjacent. Explain LSA (Link-State Advertisement), LSU (Link State Update) and LSR (Link State Request)? The LSAs (Link-State Advertisements) are used by OSPF routers to exchange routing and topology information. When two neighbors decide to exchange routes, they send each other a list of all LSAs in their respective topology database. Each router then checks its topolog...