Welcome, This will be my last post here in Uptweet and I am moving to a blogging site specifically for Fiber Nexus. So let's make this blog a good one! Let's start off with setting up your home lab. Imagine when you first heard Fedex or UPS knock on your door and you see your boxes arrive. Love that feeling. I had a lab before but it was old and very problematic. I have 3 Cisco 3750 switches and 4 2811 routers now. They work like a charm and the switches are Layer 3 switches, which means that you can use routing protocols to route traffic instead of STP. STP can still be used when you attach more access layer switches to it but for now STP will not be used. I would highly recommend everyone to buy 3550s and better L3 switches because beginner students usually buy the 2950 or 2960 switches and they are too old and don't have the better capabilities as the Layer 3 switches. Since I only have 3 switches, I will need to buy a few more to copy the same design that Cisco recommends in a network. There are 3 layers, Core, Distribution, and Access. For now I have Core routers and Distribution/Access switches. Here is a picture of that design:The first thing I did after booting up the devices was to give them a host name and a username and password. Now remember, this is all basic configuration to get you started. router(config)#hostname NexusEdge1.1NexusEdge1.1(config)#username fibernexus privilege 15 secret [password]NexusEdge1.1(config)#line vty 0 15 NexusEdge1.1(config-line)#login localNexusEdge1.1(config)#line console 0NexusEdge1.1(config-line)#login localAfter I am done securing my router, I want to connect my router with my cable modem to any port with a crossover ethernet cable. Then I go to the CLI and instead of adding an ip address to the interface connected to the cable modem, I make it request for an ip address using the ip address dhcp command as noted:NexusEdge1.1(config)#in f0/0NexusEdge1.1(config-if)#description Connected_CablemodemNexusEdge1.1(config-if)#ip address dhcpYou will see a prompt that it received an ip address from the cable modem. If you login to the cable modem configuration portal, you can actually configure it to where it will a provide a static ip so it won't change every week and you dont have to constantly figure out what is the new ip address. If you do add that static ip , you need to disable then enable the router's interface to get the new ip address. If your cable modem is wireless, you can telnet to your router with the ip address that it has assigned on the cisco router's interface without the console cable. Now that you can telnet and ping your router and cable modem with each other, you need to set up a default route and access list to your router to reach the internet. To do that you need to do the following: NexusEdge1.1(config)#access-list 101 permit ip 188.8.131.52 0.0.255.255 anyNexusEdge1.1(config)#ip nat inside source list 101 interface FastEthernet0/0 overloadNexusEdge1.1(config)#ip route 0.0.0.0 0.0.0.0 10.0.0.1 (cable modem ip address) NexusEdge1.1(config)#ip route 184.108.40.206 (switch network) 255.255.0.0 220.127.116.11 (switch next hop ip address)The second ip route has the switch network range and it is pointing to the switch's ip address. I will explain later. Now once you created your default route, you need to enable NAT on both interfaces connected to the cable modem and the switch and add an ip address to the interface connected to the switch. NexusEdge1.1(config)#interface FastEthernet0/0 (connected to cable modem)NexusEdge1.1(config-if)#ip nat outNexusEdge1.1(config)#interface FastEthernet0/1 (connected to switch)NexusEdge1.1(config-if)#description Connected_NexusSwitch1.1_P24NexusEdge1.1(config-if)#ip address 18.104.22.168 255.255.255.0NexusEdge1.1(config-if)#ip nat insideTo make sure this works, ping google.com from your Cisco router and see if it works. If not you need to add a dns server that the cable modem provides through their configuration page or add the public dns server of 22.214.171.124NexusEdge1.1(config)#ip name-server 126.96.36.199If you can ping google.com then you have to add a routing protocol to communicate with your Layer3 switch:NexusEdge1.1(config)#router eigrp 65NexusEdge1.1(config-router)#passive-interface defaultNexusEdge1.1(config-router)#no passive-interface FastEthernet0/1NexusEdge1.1(config-router)#network 10.0.0.0 0.0.0.255NexusEdge1.1(config-router)#network 188.8.131.52 0.0.255.255NexusEdge1.1(config-router)#no auto-summaryNexusEdge1.1(config-router)#exitNow console into your switch and add the same username and password that we did in the beginning. Make the port connected to your Cisco router into a layer 3 routed port then add the ip address in the same subnet:NexusSwitch1.2(config)#ip routingNexusSwitch1.2(config)#in f0/24NexusSwitch1.2(config-if)#no switchportNexusSwitch1.2(config-if)#ip address 184.108.40.206 255.255.255.0Now add the same routing protocol you used in your Cisco router to your switch and add a default route pointing to your router interface and also add the dns server.NexusSwitch1.2(config)#router eigrp 65NexusSwitch1.2(config-router)#network 220.127.116.11 0.0.255.255NexusSwitch1.2(config-router)#passive-interface defaultNexusSwitch1.2(config-router)#no passive-interface f0/24NexusSwitch1.2(config-router)#no auto-summaryNexusSwitch1.2(config-router)#exitNexusSwitch1.2(config)#ip route 0.0.0.0 0.0.0.0 18.104.22.168 (Router's interface ip connected to switch)NexusSwitch1.2(config)#ip name-server 22.214.171.124Ping google.com and it should work. You now have a switch and router connected with each other and also to the public internet. You can also telnet into your router and switch wirelessly. If you are having trouble with connectivity you can use the following commands to verify your connected neighbors and if there is a valid route in your routing table.show ip routeshow ip int briefShow cdp neighbors (find Device ID) Show cdp entry ( then look for device IP address)* *Telnet [ip address]Show ip route eigrp show run If you have any issues with this please let me know and I will be able to assist you in the process either by Instagram @fiber_nexus or by email at firstname.lastname@example.org. Thanks and I hope you have fun setting up your lab.
Welcome,I am here thinking of that one time I posted a video on Instagram about Virtual-Links but I did not post an explanation about it. Well today I wanted to give you an idea of what it is and how easy it is to implement. Also, I am throwing in here some Point-to-Point OSPF connections and how they are useful. I see many Point-to-Point OSPF links here at work so I wondered what the benefits are. Let's start off with what is a Virtual-Link. In OSPF, Area 0 is the backbone area of your network and every area must somehow connect to it directly. But what can you do if you add another OSPF area to an area that is not Area 0? Tricking OSPF. You have to make it think that it is directly connected to Area 0 so you must create a tunnel that skips the area between Area 0 and your foreign area. In the topology below, you see that I marked a "blue dotted tunnel" from Area 3, through Area 1, and connecting into Area 0. The way to do that is by adding a simple command to point to each others loopback address in the OSPF process. In this case, I used the command area 1 virtual-link 126.96.36.199 on R2 and area 1 virtual-link 188.8.131.52 on R3. I also added OSPF authentication as you can see. To make sure it works, you must see this notification: %OSPF-5-ADJCHG: Process 555, Nbr 184.108.40.206 on OSPF_VL2 from LOADING to FULL, Loading Done. Once you see this adjacency you will be able to advertise traffic from Area 3 across Area 1 into Area 0. In this topology I added 2 Virtual-Links and made sure you can ping from R1 to R6 through several OSPF areas. This would happen if you have too many routers in OSPF Area 0 and Area 1. That is rare but it is good to know this command for your Cisco studies.Now let's talk about Point-to-Point OSPF links. The normal OSPF network you would probably learn from CCENT or CCNA is broadcast OSPF, which means you will have a Dedicated Router and Backup Dedicated Router, DR/BDR. If you see this topology, you might just want to not have a DR/BDR so you force OSPF to point to one direction only. You add the ip ospf network point-to-point command under the interface using OSPF. Now there are more differences between broadcast and point-to-point OSPF networks. Broadcast networks establish an adjacency much slower than point-to-point and generates around 50% more LSAs. This causes slow convergence as you can see in this chart:BROADCASTPOINT-TO-POINTNetwork: Hello: DeadInterval: Adjacency time:Broadcast 10s 40s 40sPoint-to-Point 30s 120s 2sAs you can see, the Hello & Dead Intervals for an OSPF Broadcast network is much faster! but it is much slower to make an adjacency. So how can you tweak that? Well you add the ip ospf network point-to-point command and also ip ospf hello-interval 10 & ip ospf dead-interval 40 commands under the interface. That way you will have the same Hello/DeadInterval time as a Broadcast network and an even better adjacency time than a broadcast network. Tweaking the times would make a Point-to-Point link really fast in all areas. You can see all the in the configs that I posted below regarding Virtual-Links and a Point-to-Point OSPF network. Well hopefully you learned something today and I will see you soon!###ROUTER 1###config t!hostname nexusrouter1!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 555 area 3!interface GigabitEthernet1/0 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 3 ip ospf hello-interval 10 ip ospf dead-interval 40!router ospf 555 router-id 22.214.171.124 log-adjacency-changes area 3 authentication message-digest passive-interface default no passive-interface GigabitEthernet1/0 network 126.96.36.199 0.0.0.0 area 3 maximum-paths 32 endwr####ROUTER 2####config thostname nexusrouter2!interface Loopback0 ip address 188.8.131.52 255.255.255.255 ip ospf 555 area 1!interface GigabitEthernet1/0 ip address 184.108.40.206 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 3 ip ospf hello-interval 10 ip ospf dead-interval 40!interface GigabitEthernet2/0 ip address 220.127.116.11 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 1 ip ospf hello-interval 10 ip ospf dead-interval 40!router ospf 555 router-id 18.104.22.168 log-adjacency-changes area 1 authentication message-digest area 1 virtual-link 22.214.171.124 authentication message-digest area 3 authentication message-digest network 126.96.36.199 0.0.0.0 area 3 network 188.8.131.52 0.0.0.0 area 1 end wr###ROUTER3###config thostname nexusrouter3!interface Loopback0 ip address 184.108.40.206 255.255.255.255 ip ospf 555 area 0!!interface gigabitethernet3/0 ip address 220.127.116.11 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 0 ip ospf hello-interval 10 ip ospf dead-interval 40!interface gigabitethernet2/0 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 1 ip ospf hello-interval 10 ip ospf dead-interval 40!router ospf 555 router-id 22.214.171.124 log-adjacency-changes area 0 authentication message-digest area 1 authentication message-digest area 1 virtual-link 126.96.36.199 network 188.8.131.52 0.0.0.0 area 1 network 184.108.40.206 0.0.0.0 area 0 endwr###ROUTER4###config thostname nexusrouter4!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 555 area 0!interface gigabitethernet3/0 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 0 ip ospf hello-interval 10 ip ospf dead-interval 40!!interface gigabitethernet4/0 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 2 ip ospf hello-interval 10 ip ospf dead-interval 40!router ospf 555 router-id 126.96.36.199 log-adjacency-changes area 0 authentication message-digest area 2 authentication message-digest area 2 virtual-link 188.8.131.52 network 184.108.40.206 0.0.0.0 area 2 network 220.127.116.11 0.0.0.0 area 0 endwr####ROUTER5####config thostname nexusrouter5!!interface Loopback0 ip address 18.104.22.168 255.255.255.255 ip ospf 555 area 2!!interface gigabitethernet5/0 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 4 ip ospf hello-interval 10 ip ospf dead-interval 40!interface gigabitethernet4/0 ip address 126.96.36.199 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 2 ip ospf hello-interval 10 ip ospf dead-interval 40!router ospf 555 router-id 188.8.131.52 log-adjacency-changes area 2 authentication message-digest area 2 virtual-link 184.108.40.206 authentication message-digest area 4 authentication message-digest network 220.127.116.11 0.0.0.0 area 2 network 18.104.22.168 0.0.0.0 area 4 endwr###ROUTER6####config thostname nexusrouter6!interface Loopback0 ip address 22.214.171.124 255.255.255.255 ip ospf 555 area 4!!interface GigabitEthernet5/0 ip address 126.96.36.199 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco ip ospf network point-to-point ip ospf 555 area 4 ip ospf hello-interval 10 ip ospf dead-interval 40!!router ospf 555 router-id 188.8.131.52 log-adjacency-changes passive-interface default no passive-interface GigabitEthernet5/0 network 184.108.40.206 0.0.0.0 area 4 maximum-paths 32 endwr
Welcome,I am glad you are here ready to learn a bit more today. I can honestly say learning and remembering all these networking protocols and commands are not easy. The biggest challenge in the real world is time. When you are hired for your first networking job whether its an entry level engineer job or an administrator, quick and timely decisions are very important! When there is an outage and your customers, clients, or even co-workers have no internet or voice service, time is your biggest challenge. You won't have much time to go over your notes to check and find what the issue might be before you have your customers asking for an update and requesting the network to be restored immediately. But at the end of the day, trial and error is the best teacher. With that being said, I wanted to talk about two very important protocols that many ISPs use, MPLS and OSPF. OSPF is the most popular routing protocol because it is not proprietary and it is very flexible. Just to remind new students, these protocols are just "rules" of how you want to route traffic within your network. The same way the streets and highways are designed with off-ramps, traffic lights, left turns, right turns, merges, and you have to follow the law or "rules" according to your city, that is the same way routing protocols are designed. The routers use highways of traffic with rules set in place so traffic can be routed smoothly, safely, and to it's destination. At the end of the day, it's up to you and the company to decide what " rules" you want to implement into your network. The same with MPLS, instead of making the routers verify each packet, it already knows what is the next destination based on its labels. I made this small lab so you can have an idea of how it works and how you can troubleshoot it in real life. Cell Backhaul has a similar setup although it is more advanced and I will add the rest of the configs with VRFs and mBGP next time. It is not the best design of course but at least you have an idea of how it is set up and what the commands look like. My best advice is to create a lab of your own changing the configs so you can practice the CLI commands better. Also, you would need to study and learn basic MPLS and OSPF if you haven't done so through Cisco's book and videos. Youtube and CBT Nuggets also have a lot of videos. In the picture below, that is the way the network is setup in GNS3 using the 7200 Cisco image. You would have to copy and paste each SMOP depending on the ###ROUTER### name and interface. If you are able to use the 7200 image with Gigabit interfaces, this should work smoothly. If not you can edit the SMOP based on what you have. Here are some basic show commands to use. Enjoy this lab!show mpls ldp neighbor show mpls ldp bindings show ip route ospfshow ip ospf int briefshow ip ospf neighborsshow ip ospf int#####ROUTER 1######!hostname nexusR1!ip cef!no ip domain-lookup!!mpls ldp router-id lo 0mpls label range 100 199mpls ip!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 60 area 0!!interface gigabitEthernet 1/0 description Connected_nexusR3 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut!interface gigabitEthernet 3/0 description Connected_nexusR4 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut !router ospf 60 router-id 126.96.36.199 passive-interface default no passive-interface gigabitEthernet 2/0 no passive-interface gigabitEthernet 3/0 mpls ldp sync mpls ldp autoconfig area 0 log-adjacency-changes area 0 authentication message-digest network 188.8.131.52 0.0.0.0 area 0 network 184.108.40.206 0.0.0.0 area 0 end wr######ROUTER 2######!hostname nexusR2!ip cef!no ip domain-lookup!!mpls ldp router-id lo 0mpls label range 200 299mpls ip!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 60 area 0!!interface gigabitEthernet 2/0 description Connected_nexusR3 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut!interface gigabitEthernet 4/0 description Connected_nexusR4 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut !router ospf 60 router-id 126.96.36.199 passive-interface default no passive-interface gigabitEthernet 2/0 no passive-interface gigabitEthernet 4/0 mpls ldp sync mpls ldp autoconfig area 0 log-adjacency-changes area 0 authentication message-digest network 188.8.131.52 0.0.0.0 area 0 network 184.108.40.206 0.0.0.0 area 0 end wr#####ROUTER 3#####!hostname nexusR3!ip cef!no ip domain-lookup!!mpls ldp router-id lo 0mpls label range 300 399mpls ip!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 60 area 0!!interface gigabitEthernet 2/0 description Connected_nexusR2 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut!interface gigabitEthernet 1/0 description Connected_nexusR1 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut !router ospf 60 router-id 126.96.36.199 passive-interface default no passive-interface gigabitEthernet 2/0 no passive-interface gigabitEthernet 1/0 mpls ldp sync mpls ldp autoconfig area 0 log-adjacency-changes area 0 authentication message-digest network 188.8.131.52 0.0.0.0 area 0 network 184.108.40.206 0.0.0.0 area 0 end wr######ROUTER 4##########!hostname nexusR4!ip cef!no ip domain-lookup!!mpls ldp router-id lo 0mpls label range 400 499mpls ip!interface Loopback0 ip address 220.127.116.11 255.255.255.255 ip ospf 60 area 0!!interface gigabitEthernet 3/0 description Connected_nexusR1 ip address 18.104.22.168 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut!interface gigabitEthernet 4/0 description Connected_nexusR2 ip address 22.214.171.124 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 n3xu5 ip ospf hello-interval 5 ip ospf dead-interval 30 ip ospf 60 area 0 mpls ip no shut !router ospf 60 router-id 126.96.36.199 passive-interface default no passive-interface gigabitEthernet 4/0 no passive-interface gigabitEthernet 3/0 mpls ldp sync mpls ldp autoconfig area 0 log-adjacency-changes area 0 authentication message-digest network 188.8.131.52 0.0.0.0 area 0 network 184.108.40.206 0.0.0.0 area 0 end wr
Welcome back to my networking blog. I am extremely motivated and happy for having viewers and readers here and that is why I want to continue providing short but valuable information, for example the RFC 2544 Test. I think this topic is very real world and very important for people that are interested in the networking world. At my job there are a lot of RFC tests done during the month. The reason why is because the RFC test is a standard made by the IETF to measure and provide performance data according to the SLAs. First lets start with what is a SLA. Here is a description by Palo Alto Networks: "A service level agreement (SLA) is a contract between a service provider (either internal or external) and the end user that defines the level of service expected from the service provider. SLAs are output-based in that their purpose is specifically to define what the customer will receive. SLAs do not define how the service itself is provided or delivered. The SLA an Internet Service Provider (ISP) will provide its customers is a basic example of an SLA from an external service provider. The metrics that define levels of service for an ISP should aim to guarantee:A description of the service being provided – maintenance of areas such as network connectivity, domain name servers, dynamic host configuration protocol servers Reliability – when the service is available (percentage uptime) and the limits outages can be expected to stay withinResponsiveness – the punctuality of services to be performed in response to requests and scheduled service datesProcedure for reporting problems - who can be contacted, how problems will be reported, procedure for escalation, and what other steps are taken to resolve the problem efficientlyMonitoring and reporting service level – who will monitor performance, what data will be collected and how often as well as how much access the customer is given to performance statisticsConsequences for not meeting service obligations – may include credit or reimbursement to customers, or enabling the customer to terminate the relationship. Escape clauses or constraints – circumstances under which the level of service promised does not apply. An example could be an exemption from meeting uptime requirements in circumstance that floods, fires or other hazardous situations damage the ISP’s equipment.In covering these areas, the document aims to establish a mutual understanding of services, areas prioritized, responsibilities, guarantees, and warranties provided by the service provider." Now that is when the RFC test comes into play. For example, if Verizon decides to run an RFC test through their network from end-to-end, and it fails, the ISP has to check their SLA, test the network, look for the problem, and if the problem is not found, run the RFC test with the Verizon technician at the same time. The RFC test will measure several things like Throughput, Frame Loss, Burstability, Latency, and Jitter (optional but recommended.) It uses frame sizes minimum of 64 bytes and up to 1518 bytes to stress the network. Usually the Test and Turn up team will run the RFC test before making the site live but in many cases the customers test their networks again to ensure the ISP is meeting the SLA requirements. By the way, Test and Turn up is a department where they test, modify, and ensure that your enterprise internet service will be fully functional and then make your site live and allow the network to pass traffic. The RFC test is very real world and anyone starting from CCENT and up should know the basics of what is involved with a RFC 2544 Test because they will definitely come across it while working as a Network Admin or Network Engineer. So today you now gained valuable real world knowledge, knowing what a RFC 2544 Test is, what a SLA is, and what is Test and Turn up. These 3 things come together in an enterprise environment and knowing the basics will definitely help you in the long run. Thanks for reading and you can email me at email@example.com or DM me on my Instagram account called fiber_nexus.
Welcome, It is 2:24 AM on a Tuesday morning and I'm here at work not doing much. Yea I am slacking off a little... So what comes to mind at this time? The new lab I just bought!!! Yes, I sold my old one and bought a better one. I now have 4 2811 Cisco routers, and 3 3750 switches and I also upgraded the modules to 16FE interfaces so I can do some heavy bundling between the routers and switches. This will be my CCIE lab and I am planning to maybe get 1 more switch but that will be later. I am also considering getting a full blown Juniper lab as well, so soon I am going to have 2 decent lab kits from 2 different vendors to get them to work together. Juniper and Cisco, to me, provide the best equipment and certifications in this market and both have a very high demand. With that being said, I wanted to talk about my CCNA experience. I honestly didn't know much about networking. I had some knowledge but definitely not on a CCNA or CCNP level. The real reason that interested me was because it was available for self studies and it was cheap. I never thought the potential that it had until I really got involved. I had bought a decent lab 4 2600 routers and 4 2950 switches. But do you really need 8 devices you might ask? The answer is no. You can definitely have a decent lab by just having 2 routers and 2 switches both the 2600 and 2950 models if money is tight. A website that is good to buy CAT5 cables straight and crossovers is in Monoprice.com. They have very cheap cabling if you dont have the tools to make them. So the equipment was in an ok condition when I bought them but after a while they started failing, which to me was great. I learned to replaced the fans, modules, RAM memory, Flash card, and even the serial cables and interfaces which I had to change the clock rates to get it to work. I also learned how to set it up with my cable modem as the gateway. Everyday I studied for a few hours and on the weekend it was time to hit the lab. The downfall was how loud those routers are and how much power it eats up so beware! I also used Microsoft One Note to take notes. You can take that free app anywhere including your phone and have nice and clean organized notes. You MUST take A LOT of notes when studying this, trust me it can be hard to remember all these protocols. Anyways I wanted to share a subnetting trick that I had posted on my IG account. Once you master that chart, subnetting will come in easy and that will be the least of your worries while taking the test. Remember time will NOT be in your favor while taking the test so you have to really check your time and not spend so much time in one question. I actually failed my first test, the ICND1. I was soooo mad and I hated Cisco for it, but after my second attempt, I passed it fine. So here it is and hopefully you enjoy it....ATTACKING A SUBNET Many students nowadays have questions and difficulty understanding what subnetting is. I have made an easy explanation on how to solve subnetting questions to ace the test and to use it in the real world. I will be honest, more than likely you will not subnet a network by memory when you get hired for a networking job. The entire network is already designed. Calculators and programs have been made to ease the pain. But, the purpose of this tactic is for you to attack it on the day you won’t have a calculator in hand, like your test day. Hey maybe you forgot how to subnet because you have been so used to using a calculator like me. Before you continue, you must have some understanding of what subnet masks are and their purposes. If you don’t, then you must go back and hit the books. First thing is first, having a visual chart will help you tremendously when subnetting a network. So let’s first start with this chart. When the day comes that you have to take your CCNA test, I would HIGHLY recommend writing out this simple chart quickly before the test starts. The test does not have enough time for you to spare. 128 64 32 16 8 4 2 1 192 224 240 248 252 254 255 So what do you do when you have 192.168.1.0 /25 mask? Well you must know that a subnet mask is composed by 8 bits for every decimal. 255.255.255.255 = 8bits.8bits.8bits.8bits = 32bits So what happens when you have a /25 mask? You just add the first 3 decimals equal to 24 bits. Then you only have 1 left right? 255.255.255.? = 255.255.255. (Add the first one from the graph horizontally which is 128) 255.255.255.128 is your subnet mask What about a /26 mask? 255.255.255.? = 255.255.255. (Add 2 from the graph horizontally which is 128 + 64 = 192) 128 64 32 16 8 4 2 1 192 224 240 248 252 254 255 One more example, what about a /27 mask? = 255.255.255. (Add 3 from the graph horizontally 128+64+32= 224) 128 64 32 16 8 4 2 1 192 224 240 248 252 254 255 As you can see, your answers are already in the graph. You just need to add the same amount of bits that you used horizontally to vertically. Now, what do you do when you have the subnet mask? You subtract 256 from whatever you have left on the subnet mask. Using a 192.168.1.0 /25 mask, you subtract 256 from 128 and that leaves you with a 128 subnet block. This means that you only have 2 subnets to use. Remember to subtract 2 for the subnet ip address and broadcast ip address. EASY RIGHT?!!!! 256-128 = 128 subnet block 192.168.1.0 ß 192.168.1.128 192.168.1.256 SUBNET IP MASK 192.168.1.0 255.255.255.128 USABLE IP ADDRESSES BROADCAST IP 192.168.1.1 to 192.168.1.126 192.168.1.127 After attacking this /25 subnet, now you know that you can have 2 subnets and 126 hosts in your network. Ok one more that is not a common one. What is the subnet mask and usable IP addresses for 220.127.116.11 /28? = We already know the first 3 decimals are 24 bits. Add 4 bits to make it 28. 128 64 32 16 8 4 2 1 192 224 240 248 252 254 255 256-240= 16 subnet block 18.104.22.168 22.214.171.124 ß 126.96.36.199 Subnet IP 188.8.131.52 Mask 255.255.255.240 Usable IP Broadcast IP 184.108.40.206 to 220.127.116.11 18.104.22.168
Welcome, Today's blog will be about HFC (Hybrid Fiber Coax). I have 6 years of experience in HFC troubleshooting and installation and one thing I can say is that it is very interesting! HFC is the combination of a Fiber and Coax network that some ISPs like Time Warner, Comcast, Charter, Cox, etc use. It is very interesting because it has a lot of different types of equipment used to provide TV, Internet, and Voice services. The way it is designed is by having most of the networking and transport equipment at a local Headend. It is like the "brains" of the network. There it will receive TV content via satellite dishes or via IP streaming. The networking routers and CMTS would be located there to provide the WAN internet connection and the PSTNs would be there for the voice services. The modulators and demodulators are there to encode TV RF (Radio Frequency) signal throughout the entire HFC network. From the Headend, it will travel and connect to a Node via fiber cables. The node is located in the field to convert it from fiber to coax, hence the word HFC, and the coax trunk cables that are running across the poles or underground go through amplifiers to amplify the signal until it reaches a tap. The tap is the connection at the pole or at an underground pedestal by your home. Remember back when people would steal cable and they had a guy do it for them on the side? Well they would connect the RG6 cable to the tap where it grabs the RF signal. Once the cable reaches the inside of your home, the signal would be split through a device called a RF Splitter and the cable would connect directly to your cable modem or cable box. The biggest issue with cable is weather. The heat, cold, cracks, kinks, bends, or connector suck-outs would cause intermittent internet issues and tiling on your TV signal. My best advice is always make sure your coax cabling is no more than 6 years old. It can definitely last longer but if you move in to a home older than 6 years, its better to replace it and be sure your wiring is up to date. Also, the best cable to use for the inside of your home is RG6! Always replace RG59 cabling. That type of cable is very old and definitely not strong enough to carry the amount of RF signal and bandwidth nowadays. Today I wanted to post something different. I wanted to take a break from networking because it can get frustrating sometimes when you are studying a lot, but next blog I will come back to talk about another routing protocol whether its EIGRP or BGP. I still haven't had someone request an explanation for a particular topic or routing protocols so I will just post whatever comes to mind. You guys can always ask me anything even lab examples! I enjoy doing this. Anyways, I hope you learned something today and if you have any questions let me know! Here is a really good and simple picture that Wikipedia posted regarding HFC.