Monthly Archives: January 2014

Log 4: …..Read, Read, Read

Week: 5

Hours: 61.25

Did I mention I am still reading? Week 5 is still all about going through TCP/IP Volume I. Again the book is a really good read and the Case Studies are really helpful. I wish more books would take that approach to teaching/writing. I am currently on Chapter 10: IS-IS. This is the first time I have ever learned anything about IS-IS so it is definitely a learning curve. I know that IS-IS has been brought back into the CCIEv5 Written exam so I think a general overview on the chapter will help me out. I am not sure yet if I am going to read the whole chapter. The reason I say this is because the IS-IS chapter is just about the longest chapters in the book. And since this topic is only on the written portion of the exam, I feel that I don’t need to be super fluent in it. So we will see what happens with that.

I really want to get back into labbing so I decided once I am done with Volume I I am going to start on Narbik labs that correspond to Volume I. This includes RIP, EIGRP, OSPF, Redistrubution, and some others that I am sure I’m missing. After that I’ll start on Volume II and do the same process. If I get stumped on anything Ill either read up on it or watch the corresponding INE Advanced Technologies video.

On another note, my new job has been going great. Everyday I am working/configuring something new which is great experience. However the hours can be really long and at times stressful. In my opinion though this is good and it is teaching me skills that will take me a long way. My current environment consists of mostly Cisco, Arista, and some Juniper gear. I must say that I am really impressed by the Arista switch line. I really think they are going to be the next big thing in Networking. If you have never heard of Arista Networks, I highly recommend you check it out.

 

P.S. If you have an Arista device in your network try typing the command “show donkys”. You’re Welcome :)

Log 3: Read, Read, Read

Week: 4

Hours: 45.75

Week 4 was filled with finishing up the rest of the INE Written Bootcamp videos and then starting on Routing TCP/IP Volume I. As I mentioned in my last log I really was not impressed with the INE Written video series. I would not recommend it. However I do recommend Routing TCP/IP! I am not a huge fan of reading, however this book is actually written very well. I’ll be honest I was very intimidated about starting it because I thought it was going to be very dull and boring. So far though it has been the complete opposite. Most of the chapters are written in “Case Studies” which basically is a scenario and then it walks you through how the routers would act in such a scenario. I am really enjoying it so I decided I am going to read both Volumes cover to cover, only skipping topics not covered in CCIEv5.

Some have asked what I have been using to do labs. My main lab resource at this time has been GNS3. I have always sworn by my physical lab, however with CCIEv5 being announced to run in a virtual environment I figured it would not be very smart of me to purchase an entire v4 lab. For some labs I have been using my 3560s since they cannot be simulated in GNS3. Surprisingly though I have not ran into any issues using GNS3 through the  Narbik Foundation Workbooks. Hopefully Cisco VIRL will be released soon and I can get my hands on that.

Trouble Finding Good Network Engineers

This is going to be a rant so I just want to apologize beforehand. I want to express my concern with the current state of network engineering applicants. I have had the displeasure in trying to find a few more guys to fill our team of network engineers. At first I thought, “Oh this will be fun!” But wow I was wrong. The applicants we have had so far has really made me realize that there is a serious problem in our industry. That problem being PAPER NETWORK ENGINEERS! If you have read my blog at all your know that I am a huge supporter in getting certified. But c’mon some of these guys we interviewed are CCNPs and can’t even answer simple subnetting questions! WTF! Oh its gets even better when we have someone that claims to be a CCIE candidate. Jesus Christ I just facepalm every time. The questions we ask are not even difficult. Were not looking for a superstar, just someone that loves networking and also can back up what they write on their resume. Simple VTP questions stump some of these guys. VTP the protocol we all learn about in CCNA stumps CCNPs….somethings gotta give.

Either we have been very unlucky or we are just getting braindump’d network engineers.  This is why most companies only take referral candidates. All these people that can’t back up their certs ruin the job market for the rest of us when we apply without a referral. My company goes through a lot of network engineer applicants since we are always looking for talent. We get FLOODED with resumes daily. It’s not wonder that most of the people we actually hire are people that were referred to us. One word of advice to the people applying for network engineering positions. BE HONEST. Really that’s it, be honest on your resume and don’t claim to know something that you’ve worked with once. Don’t be the CCIE candidate that we interviewed who claimed to know Nexus yet couldn’t explain VPCs or VDCs. Literally these applicants give me a headache, it’s so hard to keep my cool and not burst out at them and say “STOP BRAINDUMPING AND LEARN YOUR SHIT!!!” lol

/end rant

Log 2: Building a CCIE Foundation

Week: 3

Hours: 36.5

Week 3 was dedicated to finishing Volume 2 of the Narbik Foundation series, which I completed on Wednesday night. All in all the Foundation workbooks from NArbik were a great refresher on all the CCNP topics as well as added topics that are found in the CCIE. The workbooks really held my hand through the labs and gave great detailed explanations on all the commands. I was very impressed by them and you can tell Narbik put a lot of effort into them. I give them two thumbs up! I can’t wait to start on the Narbik Advanced R&S workbooks.

The rest of Week 3 was focused on going through the INE Written Bootcamp. Personally I think the Written Bootcamp is lacking in sooooo many areas. Not only are there a handful of videos but they are also very short. I’m sorry but you can not have only one video on BGP and have it be 50 minutes. I guess that’s why they push the Advanced Technologies video series as well. I have about 5 more videos to go so they will be finished in Week 4.

I still need to read through Routing TCP/IP Vol 1 and 2 so my plan is also to start on that come Week 4. Any free time during work I am also going through Cisco Docs as well as RFCs. One cool feature I found on the Cisco website is the Q and A section of the different technologies. I highly recommend checking it out.

“Listen to me: don’t quit, don’t give up. If it get’s hard tie a knot around yourself, you double tie it if you have to, but you hold on”

Weekend motivation! Stay focused! Keep reaching, keep climbing!

Introduction to IP Multicasting

Introduction to IP Multicasting

Basic Definition: “Sending a message from a single source to a selected multiple destinations across a Layer 3 network in one data stream”

Problem with Unicast and Broadcast Networks

  • Unicast would send one copy of each packet to every group member’s unicast address. With a few receivers this isn’t an issue, but try scaling to 1000′s of users. Your bandwidth connections would quickly become oversaturated
  • Broadcast requires the transmission of the data only once, but it has some serious issues! First, if receivers are in different broadcast domains from the sender, routers will need to forward the broadcasts. However this can lead to wasted bandwidth as well as an increase in processing load on all the network devices. Obviously this is not ideal if only a small group of hosts needs to receive that broadcast packet.

Although Multicast offers many advantages , it also has some disadvantages. Multicast is UDP based and hence unreliable. Lack of TCP windowing can result in network congestion. Some multicast multicast protocol mechanisms occasionally generate duplicate packets and deliver packets out of order.

Requirements for supporting multicast across a routed network

Multicast IP Addresses

A multicast address used as destination address on an IP packet signifies that the packet is carrying  traffic for a specific multicast application. A multicast address is never used as a source address.

Multicast Address Ranges

  • Permanent Groups: 224.0.0.0 – 224.0.1.255
    • There are two ranges in permanent multicast addresses. 224.0.0.0 through 224.0.0.255 is used for local  (not routed) purposes. Think routing protocol multicasts. The other range 224.0.1.0 through 224.0.1.255 is used when the packets should be routed.
  • Source-Specific Multicast (SSM): 232.0.0.0 – 232.255.255.255
  • GLOP Addressing: 233.0.0.0 – 233.255.255.255
    • Can be used by anyone who owns a registered ASN to create 256 global multicast addresses that can be owned and used by the entity
  • Private Multicast addresses: 239.0.0.0 – 239.255.255.255
    • Allowed for use in private multicast domains.
  • Transient Multicast Addresses
    • Remaining multicast addresses are referred to as this. These address are not permanently assigned to any application. Any enterprise can use these multicast addresses without requiring any registration or permission from IANA, but the enterprise is expected to release these multicast addresses after their use.

Manage Distribution of Multicast Traffic with IGMP

When a router receives a multicast packet it needs to make a decision about where to forward that multicast. A mechanism is required for hosts and a local router to communicate with eachother. IGMP was designed to enable communication between a router and connected hosts.

Switches also need to know on which ports they should forward traffic. By default, a switch will flood a multicast throughout the VLAN. The reason for this is because a switch will never find a multicast MAC in its CAM table. This is because a multicast MAC is never used as a source address.  This of course defeats the purpose of using multicast.

CGMP, IGMP snooping/IGMP, and RGMP are tools used to optimize multicast forwarding logic by solving the above issues.

***RGMP has been removed from the CCIEv5 blueprint***

Joining a Group

Before a host can receive any multicast traffic, a multicast application must be installed and running on that host. The process of installing and running a multicast application is referred to as launching an application or joining a multicast group. After a host joins a group, the host software calculates the multicast MAC address, and its NIC then starts listening to the multicast MAC address, in addition to its BIA.

Internet Group Management Protocol

IGMP packets pass only over LAN and are not forwarded by routers, due to their TTL values. IGMP messages are sent in IP datagrams with IP protocol number 2, with the IP TTL set to 1.

Two Goals of IGMP

  • To inform a local multicast router that a host wants to receive multicast traffic for a specific group
  • To inform local multicast routers that a host wants to leave a multicast group

IGMP Version 2

Features:

  • Host Membership Queries – these messages are sent out LAN interfaces to determine whether a multicast group member is on any interface. Routers send this message every Query Interval, by default 60 seconds.
  • Host Membership Reports – these messages are send by hosts in response to IGMP queries and communicate to a local router for which multicast group they want to receive traffic.
  • Leave Group and Group Specific Query Messages -  when a host leaves a group, it sends an IGMPv2 Leave message. When an IGMPv2 router receives a Leave message, it immediately sends a Group-Specific Query for that group. The Group-Specific Query asks only whether any remaining hosts still want to receive packets for that single multicast group. As a result, the router quickly knows whether to continue to forward traffic for that multicast group.

IGMPv2 Querier:

  • When IGMPv2 routers start, they each send an IGMPv2 General Query message to the well-known All Hosts group 224.0.0.1. When an IGMPv2 router receives a General Query message, it compares the source IP address of the General Query message with its own interface address. The router with the lowest IP address on the subnet is elected as the IGMP querier. The nonquerier routers do not send queries but monitor how frequently the querier is sending general IGMPv2 Queries. When the elected querier does not send a query for two consecutive Query Intervals plus one half of one Query Response Interval, it is considered to be dead, and a new querier is elected.

IGMPv2 Timers

  • Query Interval – 125 seconds – time between General Queries sent by a router
  • Query Response Interval – 10 seconds – maximum response time for hosts to respond to the periodic general queries.
  • Group Membership Interval – 260 seconds – if a router does not receive an IGMP Report, the router concludes that there are no more members of the group on the subnet
  • Other Querier Present Interval – 255 seconds – time period during which, if the IGMPv2 nonquerier routers do not receive an IGMP Query from the querier router, the nonquerier routers conclude that the querier is dead.
  • Last Member Query Interval – 1 second – maximum response time inserted by IGMPv2 routers into the Group-Specific Queries and the time period between two consecutive Group-Specific Queries sent for the same group.

IGMP Version 3

  • To use the new features of IGMPv3, last-hop routers have to be updated, host operating systems have to be modified, and applications have to be specially designed and written.
  • IGMPv3 allows a host to filter incoming traffic based on the source IP addresses from which it is willing to receive packets, through a feature called Source-Specific Multicast (SSM).

Log 1: The CCIE Journey Begins

Week: 1-2

Hours: 0-23.5

So some of you may be thinking “How could you already have two weeks of studying for the CCIE under your belt if you only just finished CCNP yesterday?”. Good question. My Tshoot studies encompassed starting my CCIE studies. For the past two weeks I have gone through Narbik’s CCIE Foundation Volume 1 and am currently about halfway done Volume 2. 

So far the workbooks have been mostly a review but it is nice to finally start labbing routing topics again. Currently I am working on the BGP labs which is already teaching me a ton that wasn’t covered in the Route exam. The current breakdown of the Narbik Foundation Volumes goes like this.

Volume 1:

  • 3560 Switching
  • Frame-Relay (I skipped this since it won’t be in CCIEv5)
  • RIPv2
  • EIGRP

Volume 2:

  • OSPF
  • BGP
  • Redistribution
  • IPv6
  • QoS

My plan from the start was to skip over topics completely that will not be in the CCIE v5. This includes:

  • Flexlinks
  • ISL
  • Layer 2 Protocol Tunneling
  • Frame-Relay
  • WCCP
  • IOS Firewall
  • IOS IPS
  • RITE
  • RMON
  • RGMP
  • RSVP QoS
  • WRR/SRR

After completing Volume 2 this week my plan is to go through the INE Written Bootcamp videos and start reading TCP/IP Vol 1 & 2

I am now CCNP!

Oh man does it feel good! My 1-year CCNP journey finally comes to an end! All in all Tshoot was a breeze and the only reason I held off on taking it for so long was because of my new job.

Next up for me is to start studying CCIE topics. With v5 right around the corner I figured this is the best time to start studying. I am not giving myself a time frame to pass but I do hope to at least make an attempt in the next two years. This journey is sure to be long and very stressful but I feel that pass or fail it will make me a better network engineer. So join me in my journey to CCIE! I’m sure it will be a bumpy ride.

And for those that are curious what I used to prepare for Tshoot. I started on Narbik’s CCIE Foundation Labs.

Sorry for keeping this so short but I am taking no breaks! I am actually in the middle of doing BGP Narbik labs :). So far these Narbik labs have been great, I highly recommend them.

 

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