Iain's Learning Path

Hi Everyone,  Today I'm gonna learn more about switch security, I think today's session will be focused more on protecting and limiting the physical ports themselves so I dont think there will be to much ground that needs to be covered today, after I've went through the notes I'm going to do some labbing and take last lesson and this lesson and put the theory into practice just to build the muscle memory - I think last lesson all the things discussed we're relatively straightforward so hopefully this lesson will be to.  In a regular switched environment when a device connects into a switchport the MAC address of that device gets stored onto the switches CAM table and the device gets allocated into the network along with any specific vlan that it may have been assigned to, but what if a rouge device connects into a switchport that is designated for a manager? they now have complete access into the companies network. By configuring port security each port can be desig

Hi Everyone!  Today ill be learning about switch security, I have vaguely covered man in the middle attacks in my university when I done my dissertation so that section should be okay but the rest of this is all new information which im looking forward to learning! Feel like all my topics are really starting to come together, always feels nice to be making progress! I'll smash the CCNA in two in no time! DHCP Snooping -  When using a router because routers dont forward broadcasts the ip helper command is used to direct a clients dhcp request from one subnet to another one to be able to provide the client with an IP address, why is this important I hear you asking? What if a rouge DHCP server is connected onto the switch where the client is? The client would be handed wrong information, this would kick clients off the network making them unusable. To avoid this whole scenario DHCP snooping is configured, when DHCP snooping is used DHCP requests that aren't from ports that are se

Hi Everyone!  After my day of labbing yesterday I feel I understand STP more than enough now, I think I'm understanding the concepts generally okay but just remembering every bit of the theory - mostly the election processes of these protocols is quite difficult not to get one protocol muddled up with another! I know that this will come to me with time so im not worried about it at all.  Anyways, enough waffling! today i'm going to learn about EtherChannel. When talking about EtherChannel it needs to be known that the reason that it exists is due to spanning tree, when configuring EtherChannel essentially what is happening is two interfaces are getting bundled into one interface, why is this useful? In spanning tree ports that aren't being used are set into a blocking state, when this happens that port is no longer sending/receiving data, in a packet tracer this is fine but in a real world environment this could leave loads of ports unused wasting bandwidth and available po

Hi Everyone!  Today will be a quiet day theory wise, just gonna spend the day doing some labs on STP as I think I have the theory down anyway, hoping the labs will help me cement in a lot of the show commands as theirs a few that I want to just memorize the output of just for the exam knowledge as I'm required to configure and verify STP. Anyways thats it today. I have labbed everyday so far so I've kept on top of the theory!

Hi Everyone!  Today I decided that I would brush up on Spanning-tree, I was originally going to spend the day with HSRP but the concept of it was actually a lot easier than what I thought it was going to be - to keep use updated over the past few days I've done OSPF and lots of labbing then HSRP yesterday, I've configured and verified spanning-tree before - both PVST+ and RSTP so I believe this session will be more of a remembering lesson than a learning one.  Spanning tree is used to provide redundancy to a network. STP uses BPDU's (Bridge protocol data units) and sends these out every few seconds to let the other switches on the network know the sending switches state that way if a link goes down the other switch will know and will set a port that has been put in a blocked state to unblocked.  Spanning tree is enabled by default on switches.  Layer 3 devices (routers) have a TTL within the packets that are sent out this prevents looping, in a Layer 2 environment the switc

Hi Everyone!  Today I decided to learn about HSRP, this is a new concept for me so you'll have to bare with me if I get anything wrong! So anyways - From what I've learned so far two routers are configured with a crossover cable to each other to provide redundancy, from here HSRP is configured at the interface-level when this happens a virtual IP address is created and this will be used as the default gateway of the PC's, one router will be assigned as the active router and the other will be standby  when the standby doesn't receive any hello messages the standby router takes over and becomes the active router (the protocol name really suits whats happening here!). To configure a router to be an active  router the router priority is manually changed (the default priority is 100), the higher priority is considered the better one, if both routers have the same priority it then uses the highest IP address to decide what router will be active and what router will be standby

Hi Everyone!  Today will be spent labbing and using ospf, just want to really cement the concepts of it into my brain and I always believe the best way to remember something is to practice, practice, practice! I've also started to use cheat sheets for topics, I'm finding them alot more readable as the information is condensed into what you need to know about the topic rather than overloading on every inch of the topic. As it is just now the current study method that I'm following is a three-step process of - learn, practice, teach (In my case I have no one to teach so my dog will be a master of ospf by the end of this ;p), so far this three step process is working just struggling to remember all the in's and outs of OSPF, regardless after today I'm moving onto a different topic as I've spent the past 3-4 days just on this and I really need to be getting on, if I still dont properly remember everything ill just re-visit it when I study for the exam. 

Hi Everyone,  These are some notes I've taken for myself from doing Neil Anderson's OSPF lab, the things have been discussed in my previous blogs but I'm just writing these down for my own memory purposes - hopefully doing this will also reinforce the muscle memory of it all, can't believe theirs so much to OSPF but I love it!  Remember the router id (also referred to as Neighbor ID) in ospf is a device identifier it is NOT an interface IP address. Process numbers do NOT need to be the same across routers BUT areas need to be identical.  Wildcard mask is just -255 so say for a subnet of 255.255.255.192 the wildcard would be 255 - 192 = 63. Configuring ospf on interface just requires going into interface and using ip ospf *process id* area *number*  Rules to make Neighbor Adjacency -      Same Subnet     Same OSPF area     Same Timer (Hello Interval)     Same Authentication  For OSPF to converge this has to be identical to become neighbors . Point to point -  When using

Hi Everyone!  Today I wont be updating my blog as I'm going to revise some of the topics I've discussed, I've also purchased the BosonEx-Sim so ill attempt that even though I am lacking in quite a bit of knowledge but ill use it as revision material to learn some topics more in depth, it'll also give me a good grasp of how the CCNA exam will be when I actually take it.  Anyways thats it from me today, thanks for reading.  

Hi Everyone!  Today's subject is the biggy of the CCNA routing protocols - OSPF! I've left this to its own topic as I intend to put more time into this specific topic rather than the other two (RIP & EIGRP), by the end of this we'll both understand how to configure and verify OSPF! and if we dont...dont sue me ;p anyways lets get into it!  OSPF shares a few of the same attributes as EIGRP - its a link state protocol with fast convergence times that uses multicast (224.0.0.5) to send out updates. Uses Dijkstra algorithm to determine what path is considered the best path. Why use OSPF in comparison to EIGRP if there both similar? OSPF is an open standard!  because of this any networking device form any vendor can use OSPF whereas in comparison the EIGRP protocol is a  Cisco protocol meaning its not always supported on other vendors. The updates sent from OSPF send out all the information it knows of the network that its connected to and the interfaces it has, this provide

Hi Everyone! Today I'm going to go into more depth about RIP and EIGRP, in the last study session that consisted of these two topics the depth I went into about each topic wasn't as much as it needed to be, I figured ill cover the areas that were missed in this section of the blog.  So!  For RIP - there is two versions, the first is a legacy edition thats very outdated and not used anymore, the reason that this is the case is that with version 1 the router would use broadcast (255.255.255.255)  update messages, this essentially would slow down the network as devices would receive updates that they didn't need! This lead to version 2 of RIP, to try avoid the broadcast problem version 2 uses the multicast (224) address by doing this only the devices that needed to know updates received them, version 2 also supports authentication unlike version 1. Version one of RIP supports no auto summerisation, because of this subnet masking & vlsm are unavailable as the subnet mask ge

Hi Everyone!  Today I decided that I was going to brush up on my routing protocols - RIP, EIGRP, OSPF, IS-IS. RIP used distance vector, so does EIGRP although its better its not ideally suited for businesses. OSPF is the most widely used protocol as its vendor neutral and is link state. IS-IS is a protocol aimed at more at ISP's.  Interior Gateway routing protocols - RIP, EIGRP, OSPF, IS-IS. Exterior Gateway routing protocols - External BGP. Link state - Makes decisions based on the cost of the link (internet speed). Distance Vector - Based on how many hops to X devices.  Administrative Distance - Lowest AD to route wins. AD is how much that link is trusted. AD Measurements -  Connected - 0  Static Route - 1 External BGP - 20 EIGRP - 90 OSPF - 110 IS-IS - 115 RIP -120 Metric -  When multiple paths are learned through a routing protocol the metric will be used to decide what path is the best along with the AD. Router looks at AD first, then uses metric to decide what path to use.  [

Hi Everyone,  This blog post will consist of what I am currently using as flashcards (Questions & Answers), this is for personal reference.  What are runts? - Ethernet Frames less than 64 Bytes. Jumbo (Giant) Frame - >1500 bytes ( With bad FCS ) Baby Giant Frame - Slightly Bigger than 1500 bytes Babbles -The number of transmitted frames greater than 1518 bytes in size. What technology does CDP rely on? - Layer 2  What heavily relies on CDP? - VoIP lldp commands?   lldp run lldp transmit  lldp receive  what does ARP do? - maps IP Addresses (Layer 3) to MAC Addresses (Layer 2), keep getting these muddled up!. New TCP/IP Stack - Application (App,Pres,Ses), Transport (Trans), Network (Network), Data Link (DataLink), Physical (Physical)   TCP Handshake -  SYN: The client sends a SYN to the server. SYN-ACK: In response, the server replies with a SYN-ACK. ACK: Finally, the client sends an ACK back to the server. Protocol Number/Type  - 21 TCP FTP control 22 TCP SSH 23 TCP Telnet 25

Hi Everyone,  These are the commands that I have built up over studying, obviously I wont name every command in the entire CCNA BUT I will name the ones that I believe may appear on the exam. show commands in general will be used in labing for verifying interfaces or errors. show controllers - this will be used to check the serial cable. Look out for DCE/DTE in output.  show run show version - check ios of switch/router show cdp - show cdp neighbor - show cdp neighbor detail show lldp - show lldp neighbor - show lldp neighbor detail show interface  show run interface *interface* show ip route show ip route static show ip protocols   show ip rip database - basically a routing table of rip received addresses show ip ospf database  copy running-config startup-config ip route *destination network IP* *subnet* *IP of next hop to get to network* (static route) ip route  0.0.0.0 0.0.0.0 *IP of next hop to get to network* (default route) ip route *destination network IP* *subnet* *IP of next h

Hi Everyone!  The three layer model can be split into three manageable sections (Duh!) -  Access - The lowest level, this is providing users with a connection to the network so its very basic. Distribution - Middle level, policy based connection, connects to the top and bottom levels. Core (or backbone) - The core layer is essentially used to provide fast data transfer between areas. I remember this by the acronym ADC (makes me think of LoL, if you know what that is ;) ) To better understand the layers, understanding what functions that each layer can do helps - the access layer does Layer 2 switching, PoE, ARP Inspection, VACL's (Virtual Access Control Lists), an easy way to remember what the access layer does is to just think of an access layer switch and the functions the switch provides. The distribution layer handles ACL's, Routing (for LAN & VLANS), Link Aggregation of LAN's and WAN's. The core layer is what I said it was, fast data transfer! that and reliab

Hi Everyone! Today I'm going to talk about Cisco DNA (Digital Network Architecture) Center's and WLAN Controller's, this is building on the previous session I had! After discussing these two topics this will cover 1.1 of the Exam Objectives! Woohoo!  Figure 1  As this is my study notes I've only discussed the topics that I needed to learn/re - study (c, d, e in Figure 1), after this section I will spend some time reviewing all the topics just to build the muscle memory as I believe this section has been mostly just facts and how devices operate, anyways lets get it into it!  When automation is used in Cisco what manages it? The Cisco DNA Controller - its used as a way to manage networks along with the ability to be able to deploy a network in seconds, this is also a good technology to provide third party integration. The DNA controller is managed through a GUI web interface (This is similar to a MaaS server, if anyone has configured that!), in summary a DNA controller i