Hello World

The header is not creative I know. However, is it not the best ever? Just two words says so much. I am not a programmer, nor a coder. I’ve dabbled, haven’t we all played with it in some form or another? There are few things that I get excited about:

1. Networking – the ability of hundreds and thousands of machines to talk to one another in so many forms sending and receiving data across thousands of miles,and for the receiver to get it exactly as the sender wanted to send it.

2. Innovation – the ability to have an idea, formulate it, create it, and broadcast it. We complain daily, if not hourly ūüėČ Come on be honest: is there a day that has gone by where you haven’t said, “There has got to be a better way to do this”. Whether its at work, at school, going through the drive thru, or just simply while driving during rush hour, but there IS a better way, someone just hasn’t come up with it……yet.

3. How does it work? The internet is the best thing that has happen to me. If I had this when I was growing up, I would have been genius!!! Okay not really, however, there isn’t anything you cannot find on the internet. And I have dug for some truly amazing things. Need a class on how SPF works? There is a youtube video of¬† MIT professor explaining just that to his class. And in case that one video doesn’t clear it all up, there are hundreds of videos and thousands of websites explaining it in multiple ways.¬† Pretty cool, eh?

 

I have lots to say, who will listen? I don’t expect anyone.

There are two reasons for me to start this blog::

1. I was lucky enough between my junior and senior year in high school to attend Arkansas Governor’s School. One day in a class, the instructor gave us a piece of paper. He instructed us to close our eyes, clear our minds for a minute. Then he said, write everything that pops into your mind, it doesn’t have to make sense, it doesn’t have to be in order, it doesn’t even have to be grammatically correct. Just write everything that you are thinking of. Not sure how long this lasted, maybe a minute or two? Or even 5. But when I went back and read all that I wrote, I was amazed at all the information flying through my head.

This is what my blog is for me, to get everything that is flying around in my head down “on paper”.

2. I believe that in order to really know something, you should be able to teach it to another. I am currently¬† working towards my Cisco Certifications, to include the CCIE in Routing and Switching. To get there, I want to know it. This goal of mine is deeply rooted in something I’ve always wanted. What’s the value of having it or not? Is it as valuable today as it was decades ago? That is not the why I am doing it. There are plenty of posts and articles out discussing it. Simply for me, because its something I’ve always wanted.

Now the caveat to this last reason is if I can help someone that would be ideal, but also that I don’t know everything, I am still learning as well, so hopefully those who do know can teach me, correct me, enlighten me, I would be grateful.

 

Is that enough for the first post? Ahhh, so much to say….

 

 

Thanks for stopping by,

Ha

 

 

More about RIPv1 and RIPv2

In the previous two blogs I went into the basic information regarding this protocol. Enabling RIP is not unlike the enabling other protocols. In my head, I don’t feel it is necessary to present the commands for enabling RIP. So I’ll write about some other commands, deep dive let’s just say:

Unicast Updates:

RIPv1 uses broadcast for updates and RIPv2 uses Multicast. What about unicast updates? Scenarios where we would need that is in NBMA links, or we just would prefer not to have the extra overhead on our links.

Two commands to know:

Passive-interface command will disable the designated interfaces from sending multicast/broadcast updates. Key word here is sending, it will still receive any updates, whether its unicast, multicast or broadcast updates.

Neighbor xxx.xxx.xxx.xxx will enable unicast updates.

Figure 1-7

As you can see from the figure above, the L2 and L3 destination has now changed from what we saw earlier for RIPv1 and RIPv2, broadcast and multicast respectively, and we see unicast packet. The RIP command shows it’s a response message, one of the 30 sec updates.

The config below:

Figure 1-8

Important notes: if you only configure the Neighbor command without the passive-interface command, the RIP enable interface will send both multicast and unicast. Also the neighbor command does not build a RIP relationship with the neighbor to allow RIP, it simply defines that unicast updates be sent rather than multicast/broadcast. The network command will still need to be used in order to enable RIP on that interface.

Offset List:

The offset command is a fairly easy concept. But I understand things better when I can see a scenario where it would be necessary. I have found a few scenarios but none that I feel like I can hang my hat on. So let’s just talk about the offset list command. Basically, it allows the admin to alter the metrics by increasing or decreasing the metric count, for either incoming or outgoing on an interface.

So for now, unless anyone can provide a real life scenario, please feel free to comment.

The following two figures show the configuration of the off-set and the results of the configuration, normal metric would have been (120/1) but after the addition of the offset list, it is (120/4)

Figure 1-9

Figure 1-10

What I haven’t discussed but the offset list can be configured with an access list as well:

As you can see, in my configuration I did not use an access-list and therefore used 0 to apply for all networks.

 

Adjusting Timers:

I had discussed the timers for both RIP versions in the previous blogs. I know what each timer does, but here adjustments can be made on them if ever there is a need, such as a faster convergence.

Note: This should be done on all the routers which are participating in RIP, not doing this will cause network instability.

For configuration this is the order with the defaults noted below them:

timers basic
update invalid holddown flush

timers basic
30 180 180 240


Figure 1-11

 

 

 

 

 

 

All About RIPv2-D√©j√† vu?

?

You will see below that the information is the same, and what I did was highlight what was in v1 and added the change for v2 in red:

 

So let me wrap my head around the basic information about RIPv1         v2

Administrative Distance:                  120

Metric used:                                       Hop Count

Port it uses:                                       UDP 520

Method of communication:             Broadcast 255.255.255.255     Multicast 224.0.0.9

Type of Routing Protocol:               Distance Vector

Addressing:                                      Classful                                     Classless

100 words or less:

These items are what you can say, it is what it is. But we can add on a little more about Hop Count. The Hop Count values are 1-16, with 1 being directly connected, and 16 being unreachable. Legitimate routes will have a value between 1-15.

Authentication:                               none                                            MD5

Types of Messages sent:

Request Message    a request by router broadcasted for information

Respond Message    a response to the request with the update requested.

Additionally this is sent every 30 secs in conjunction with the Update timer below.

 

Now on to the Timers that RIP uses, with its respective defaults:

Update Timers:         30secs     Interval at which a Respond message is sent

Note: There is a specific random variable used by Cisco IOS, RIP_JITTER, subtracts up to 15% of the update timer (of 30 secs=4.5 secs) from the update time. This variable is to prevent table synchronization. So an update can be sent anywhere between 25.5-30 secs. (Reference: Routing TCP/IP, Doyle, J., Carroll, Jennifer, 2006, Cisco Press page170)

Invalid Timers:        180secs

Note: Also called expiration or timeout timer. This timer limits the amount of time a route can be in the routing table without an update (6x Update timer=180 secs). If an update has not been heard for a route and the invalid timer runs out, the route is marked as unreachable (hop count: 16)

Flush Timers:        240secs

Note: Once a route has been set to unreachable (hop count: 16) in the routing table it has an addition 60 secs before it is flushed from the routing table. During those 60 secs, it will be advertised as unreachable (Invalid timer + 60secs=240 secs)

Hold down Timers:    180secs

Note: Not noted in RFC1058, but used in CISCO. When a update (respond message) with a route with a higher hop count (metric) than is recorded in the route table, the new route is marked as unreachable for the hold down period. If the neighbor is still advertising the higher hop count, the new metric will be accepted.

 

These timers can be seen when the command “sh ip protocol” is used:

Figure 1-4

So with the show command above, note the difference in the version type.

So let’s now take a Wireshark capture from R2 and see what information we can glean from it for RIPv2:

Figure 1-5

Starting at the top, with the Ethernet header, we see the destination as the RIPv2 is now an IPv4mcast_09 and the IP Header with the Multicast IP,224.0.0.9. Next in the UDP header, still using the UDP port 520. Under Routing Information Protocol, command, the message request is (1) for request and this packet is for RIPv2

The next capture will be from a response from R1 to R2’s request above:

So, notice the difference between RIPv1 vs RIPv2?

The main difference would be the following:

  1. Allows for VLSM
  2. Allows for authentication
  3. Does not Broadcast, rather uses Multicasts

I will dig into the VLSM and authentication in the RIP configurations at a later date.

 

All About That RIP

So let me wrap my head around the basic information about RIPv1

Administrative Distance:             120

Metric used:                                  Hop Count

Port it uses:                                   UDP 520

Method of communication:         Broadcast 255.255.255.255

Type of Routing Protocol:            Distance Vector

Addressing:                                  Classful

100 words or less:

These items are what you can say, it is what it is. But we can add on a little more about Hop Count. The Hop Count values are 1-16, with 1 being directly connected, and 16 being unreachable. Legitimate routes will have a value between 1-15. In other words, the longest path in a network using RIP should be 15 hops.

Authentication:                           none

Types of Messages sent:

Request Message    a request by router broadcasted for information

Respond Message    a response to the request with the update requested.

Additionally this is sent every 30 secs in conjunction with the Update timer below.

 

Now on to the Timers that RIP uses, with its respective defaults:

Update Timers:         30secs     Interval at which a Respond message is sent

Note: There is a specific random variable used by Cisco IOS, RIP_JITTER, subtracts up to 15% of the update timer (of 30 secs=4.5 secs) from the update time. This variable is to prevent table synchronization. So an update can be sent anywhere between 25.5-30 secs. (Reference: Routing TCP/IP, Doyle, J., Carroll, Jennifer, 2006, Cisco Press page170)

Invalid Timers:        180secs

Note: Also called expiration or timeout timer. This timer limits the amount of time a route can be in the routing table without an update (6x Update timer=180 secs). If an update has not been heard for a route and the invalid timer runs out, the route is marked as unreachable (hop count: 16)

Flush Timers:        240secs

Note: Once a route has been set to unreachable (hop count: 16) in the routing table it has an addition 60 secs before it is flushed from the routing table. During those 60 secs, it will be advertised as unreachable (Invalid timer + 60secs=240 secs)

Hold down Timers:    180secs

Note: Not noted in RFC1058, but used in CISCO. When a update (respond message) with a route with a higher hop count (metric) than is recorded in the route table, the new route is marked as unreachable for the hold down period. If the neighbor is still advertising the higher hop count, the new metric will be accepted.

 

These timers can be seen when the command “sh ip protocol” is used:

Figure 1-1

In addition, you can also see the RIP version under Default Version Control

So let’s now take a Wireshark capture from R2 and see what information we can glean from it:

Figure 1-2

Starting at the top, with the Ethernet header, we see the destination as the RIPv1 Broadcast MAC and the IP Header with the Broadcast IP. Next in the UDP header, using the RIPv1 port 520. Under Routing Information Protocol, command, the message request is (1) for request and this packet is for RIPv1.

The next capture will be from a response from R1 to R2’srequest above:

Figure 1-3

Information really hasn’t changed, except for the Routing Information Protocol header: Command is now type 2 for Response and this packet carries the IP addresses updates for 10.0.0.0 and 172.16.0.0 with a hop count of 1.

Next we will look at the routing table of R2, where we see R2 has updated it’s routing table with the information it received from R1:

R2#sh ip route

R 172.16.0.0/16 [120/1] via 192.168.100.1, 00:00:20, FastEthernet0/0

R 10.0.0.0/8 [120/1] via 192.168.100.1, 00:00:20, FastEthernet0/0

192.168.100.0/30 is subnetted, 1 subnets

C 192.168.100.0 is directly connected, FastEthernet0/0

There are a few more things to note but I want to get the basics out of the way with the various RIP versions.

Change of Study Plans

Its been 11 days since I had passed the final exam for my CCNP. I spent a few days reviewing the blue print and coming up with a study plan for the CCIE written. There were plenty of information out there for the CCIE Lab, but there is less so for the Written itself. With the exception of this past weekend, I have spent the “study” days watching the CBT Nuggets “Cisco CCIE R&S v5 All-In-One: 1.0 Network Principles and 2.0 Layer 2 Technologies” which accounted for a total of approximately 11hrs. I also spent my time reading the first two chapters of the CCIE Routing and Switching v5.0: Ethernet Basics and Virtual LANs and VLAN Trunking and taking notes using XMind.

I’m not happy with my progress, though I feel I am learning stuff. So today, after sleeping in a bit I decided to read the CCIE Professional Development Routing TCP/IP vol I by Jeff Doyle as well as the MPLS for Cisco Network by Stuart Fordham. I am breaking it up a bit, because by jumping back and forth it breaks the monotony of one particular subject. I’ve got a ton of reading to do, but I feel I need to get through this in this manner. We’ll see. I’ll provide an update end of this week to see how I am coming along.

I don’t feel too pressured since I am technically ahead of schedule. Remember I allotted Nov-Jan for studying the CCIE Written. So I’m about to play around and see how I am going to tackle all of this information in the blueprint.

Happy Studying!!

Started studying for the CCIE R&S

So, I had passed my final¬† exam last week on Tuesday, Oct 7th for my CCNP. Spent the rest of the week kind of relaxing but kind of not, I just was so excited to get into this part of my studying I couldn’t stop thinking about it.¬† Even when I was studying for my other exams, I kept thinking about the CCIE.¬† It was hard to keep focus on the task at hand, and try not to get caught up thinking about the CCIE. But I don’t know if it helped me or hurt me. I know that at times it did motivate me to keep going.

I have the books, at least some of them anyway. My line of thought is if I can’t get through the books I have now, why spend the money now on the books if for whatever reason I don’t get that far?

I have the subscriptions to CBT Nuggets,  INE and to CLN. I purchased INE when it was discounted so was about to get a good deal on the Ultimate package of the AAP.

And lastly, I still have my GNS3 as well as physical switches: 2-3560s, 4-3550s and an access server.

My official start date to study for the CCIE written was this past Monday, so I’m officially 4 days into it. I have to admit, I’ve printed out the blueprint for the written and the lab months ago when I was trying to decide if I wanted to go as far as CCIE. And I’ve looked at it multiple times, but for whatever reason, looking at it more closely, I am overwhelmed with the amount of information.

Oh yeah, it is laid out great, tells you exactly what you need to know. But my frustration is how much? I have this bad habit of going down the rabbit hole, because its just there. I’ll dig and dig and dig cause I just want to know more.

Now, four days later, I look back and see what have I done? Typically on all the other exams, I look at the blueprint and pull the subject which has the most value and study that first. Well, for this exam its 40% on Layer 3. I’m not ready to tackle that big horse just yet. So I have been reading up and watching videos on¬† 1.0 Network Principles and 2.0 Layer 2 Technologies.

The goal here(and when I say this in these posts, these are all tentative of course, I’m lucky to have all the time in the world to do this, but I want to be efficient), is to be complete with 1.0 and 2.0 by next Wednesday. I do believe I am on pace.

The additional task I have given myself is that if I can write about here in my blog, than I can move on. So expect a lot of post come next Wednesday regarding all things for Network Technologies and Layer 2.

Have a good night!

Oh btw, did you see who was going to the World Series? Any thoughts???

When I passed the CCNP…

Yesterday, I walked in to Pearson VUE in downtown LA to take the final exam of the CCNP R&S. About an hour and a half later, I walked out having completed the TSHOOT successfully, thereby becoming CCNP certified. For the next couple of hours, I was riding on cloud 9 and ready to jump into studying for the CCIE written. I don’t even know if I can begin to describe how exciting it is to learn this stuff and the craving for more.

It has always amazed me from the time I was in AIT(Army Individual Training) for the Army to now, that it still intrigues me how all this communicating that we do is done so fast and without seldom glitches. Of course, there are problems, what electronic device doesn’t give us headaches from time to time.

After the initial high, I crashed pretty fast. I was extremely tired and I don’t know that it was from a lack of sleep or over study. I felt I was studying enough, not too much, but not too little. I think though it was the unknown stress that we have.

What stress?? We all have them. Realizing it, figuring out its source, and lessen it as much as you can. Some of us strive for me, we live to be stressed to motivate us. I’m one of those people.

I like to set the expectation high cause it motivates me to get it down. I will also tell you that I deep down in side, I like the high expectations of my superiors as well, if they believe that I can do it, I do all I can to ensure I don’t let them down. Whether its in the Army or in the Telco business, I don’t like to fail.

So here I am, almost 24hrs later from becoming certified, and I’m not gonna lie, I’ve been looking at the information for the CCIE. I’ve watched some CBT Nuggets videos.¬† I’ve searched the INE forums and the classes to see what will work best for me. And I’ve trolled the CLN discussions.

I’ve got a plan formulating in my head on how to tackle the CCIE written. Just not ready to put it down on paper and commit to it yet. I have to take into consideration, family and friends over the next few months. The holiday season will be upon us soon and as much as I’d like to just study away, I also want to spend time with loved ones.

The great news is I am 3 weeks ahead of schedule, since the goal was to have the CCNP completed by the end of Oct, and its only Oct 12, I have nearly 3 weeks more to dedicate towards the CCIE. How about that? That’s even with me having to retake the ROUTE exam once.

I will officially start studying for the CCIE written tomorrow. Today I am just going to relax, hoping the Giants to beat the Cardinals, and wrap my head around how I will be studying for the next 3 months.

Oh btw, I have gone ahead and schedule the exam date: Dec 22, 2014.

Let’s do this!!

CCNP Completed, Onward to the CCIE v5 Written

Yesterday, I walked in to Pearson VUE in downtown LA to take the final exam of the CCNP R&S. About an hour and a half later, I walked out having completed the TSHOOT successfully, thereby becoming CCNP certified. For the next couple of hours, I was riding on cloud 9 and ready to jump into studying for the CCIE written. I don’t even know if I can begin to describe how exciting it is to learn this stuff and the craving for more.

It has always amazed me from the time I was in AIT(Army Individual Training) for the Army to now, that it still intrigues me how all this communicating that we do is done so fast and without seldom glitches. Of course, there are problems, what electronic device doesn’t give us headaches from time to time.

After the initial high, I crashed pretty fast. I was extremely tired and I don’t know that it was from a lack of sleep or over study. I felt I was studying enough, not too much, but not too little. I think though it was the unknown stress that we have.

What stress?? We all have them. Realizing it, figuring out its source, and lessen it as much as you can. Some of us strive for me, we live to be stressed to motivate us. I’m one of those people.

I like to set the expectation high cause it motivates me to get it down. I will also tell you that I deep down in side, I like the high expectations of my superiors as well, if they believe that I can do it, I do all I can to ensure I don’t let them down. Whether its in the Army or in the Telco business, I don’t like to fail.

So here I am, almost 24hrs later from becoming certified, and I’m not gonna lie, I’ve been looking at the information for the CCIE. I’ve watched some CBT Nuggets videos.¬† I’ve searched the INE forums and the classes to see what will work best for me. And I’ve trolled the CLN discussions.

I’ve got a plan formulating in my head on how to tackle the CCIE written. Just not ready to put it down on paper and commit to it yet. I have to take into consideration, family and friends over the next few months. The holiday season will be upon us soon and as much as I’d like to just study away, I also want to spend time with loved ones.

The great news is I am 3 weeks ahead of schedule, since the goal was to have the CCNP completed by the end of Oct, and its only Oct 12, I have nearly 3 weeks more to dedicate towards the CCIE. How about that? That’s even with me having to retake the ROUTE exam once.

I will officially start studying for the CCIE written tomorrow. Today I am just going to relax, hoping the Giants to beat the Cardinals, and wrap my head around how I will be studying for the next 3 months.

Oh btw, I have gone ahead and schedule the exam date: Dec 22, 2014.

Let’s do this!!