This is the first post in a 6 part series covering various interior gateway protocols(IGP). Over the next 6 posts we will touch on the most used routing protocols and their pros and cons. The goal is to help you better understand routing and allow you to pick the protocol that is best suited to your network.

First of all, what is an interior gateway protocol(IGP)?

IGP is a routing protocol used to exchange data between nodes within an autonomous system.

Interior gateway protocols fall under 2 categories. Distance-vector routing protocol and Link-state routing protocol.

Distance-vector routing protocol

In distance-vector routing protocols, routers do not have information about a network topology in it’s entirety. Routers only have the details of the neighboring routers and they rely on those routers to route packets efficiently based on their neighbors. Distance-vector protocols use the Bellman-Ford algorithm to determine the best route.

The 3 distance-vector routing protocols we will be going over the next few posts are as follows:

• Routing Information Protocol (RIP)
• Interior Gateway Routing Protocol (IGRP)
• Enhanced Interior Gateway Routing Protocol (EIGRP)

Link-state routing protocol

Opposite of distance-vector protocols, link-state protocols contain information about the entire network topology. Each individual router is able to calculate the best route using the information contained in their local routing table.

The 2 link-state protocols we will look at are as follows:

• Open Shortest Path First (OSPF)
• Intermediate System to Intermediate System (IS-IS)

One of the best things you can do with your money is to invest in YOU.

My preferred method of investing in yourself is through education. Take classes, work towards a college degree, buy tech books, and earn certifications.

I believe that getting a great job has a lot to do with luck as well as qualifications and personality. While gaining more knowledge isn’t a guarantee that you will get a better job it would likely increase your chances.

Don’t further your education for the sole reason of improving your job. Do it for yourself. Be proud of it once you completed it. Set goals. Reward yourself. Have a passion to learn everything you can.

Wasting money on material possessions is exactly that. A WASTE. Those objects will come and go. Knowledge will always be with you. Once you earn a degree it never gets old and thrown away. You never get tired of it. It can’t get tossed aside and forgotten.

Don’t tell yourself you don’t have time for school. Stop making excuses. MAKE TIME. Get your priorities straight. Myself, I am going to school full time while working full time and supporting a family. I didn’t think I had time when I first started, but I made time. Sure I’m tired, but it will pass.

It’s never too late to invest in your own education. Learning is a life experience.

These 10 tips will probably translate over to basically any field. I think these are a great way to boost your career and put you on the right track to be successful.

It may be hard to start doing all of these things at once so I suggest you take it a little at a time. I’m actually still working to become this person. Set small goals that lead up to the big goal. No one eats a meal in one bite, you take smaller bites until you finish.

1. Educate yourself. Constantly. I can’t stress this one enough. Part of our job is to integrate, introduce, maintain, and support new technology in the businesses we take care of. Set aside some time to read white papers, books, blogs, watch talks, listen to podcasts, and take courses in your particular specialty. If you don’t have a hunger for learning the latest and greatest in your field you will quickly fall behind. This industry is constantly changing and as technologies get more and more advanced the learning curve gets a little higher. Having a good foundation in the basics will give you a great advantage. Learn the basics inside and out. Make this a habit. An obsession.

2. Find solutions. Never bring up any faults unless you have a solution to propose. No one wants to hear you tell them about their issues. It’s simply not constructive. Try to come up with ways that you could improve the system. People love problem solvers. If you can make some one’s job a little easier they will remember you for it. The respect you will gain will be priceless.

3. Be approachable. There is confidence and then there is over confidence. Don’t be the overly confident jerk in the IT department that belittles non-technical staff. This is really demeaning and will cause employees to respect you less. I understand that there will be times where you get pushed to the edge of sanity. I’ve been there. Work is not the place to cut loose. Tell someone outside of work about what made you angry. They may not be able to help you, but just by telling someone you will feel better about the situation. Your job is to take the friction of technology off of your users. You are the expert, they aren’t.

4. Make yourself available. Don’t hide from from issues. If you get an alert during your off hours that the Exchange server has crashed, don’t try to avoid the situation by making excuses to not take care of business. Your company depends on you in order to operate. You need to take ownership of your network. Make it yours. If your car were to break down you would probably get it fixed immediately because you need it. Do the same with your network. If it fails, you fail.

5. Socialize. Get to know your users. By just shooting the breeze with your users you can get an idea of how satisfied they are with the network you take care of. You will also get a sense of who is somewhat tech savvy and who’s not. This can play to your advantage, especially in the case of troubleshooting issues at a remote branch office. If you know who is tech savvy, you may have a pair of eyes and hands on site.

6. Teach others. Show your users how to do simple tasks on their own. This will take some burden off of you if you teach the right people. Some people just aren’t able to be taught, but if you can show some of your users solutions to simple issues they may be able to help others. I take care of 4 branch offices alone, but I have at least one tech savvy person at each site I can teach and depend on to make small changes or fixes that require physical hands.

7. Document everything. Keep drawings and notes of everything. This is very important to yourself as well as the company. In the case that something were to happen to you or you left for another position your documentation would provide a blueprint for your successor. Keep notes about how you fixed certain issues that are likely to pop up again in the future. When I start a new position I look at existing documentation and then I either improve it or create new ones as soon as I learn the network. Document any projects you work on as well. These will be good when it comes time to negotiate salary raises and also demonstrate responsibility.

8. Take fault. Take responsibility for your ‘Ah, ha’ moments. If you accidentally crash a server during business hours tell the truth and fix it. Don’t lie about how you just logged in and it went down. If you are caught in a lie you will lose points and your job could possibly be at risk. Everyone makes mistakes. Fix them and move on. Have integrity.

9. Don’t say ‘I don’t know’. No one is expected to know everything. If you don’t know the answer, find it. There is a wealth of information out there that is easily obtained. Knowing how to find the correct answer is better than being a know it all. If you can be relied upon to figure things out when it counts you will be a great asset to any employer. Don’t fear to tread where others haven’t.

10. Stay upbeat. Always show enthusiasm. This is better than being an angry genius. Be passionate about your field of work. Strive to become an expert. Be easy going. People enjoying being around people like this. Why? Because they are inspiring. No one wants to be around a grouchy person. Also, surround yourself with people like this. It’s contagious. It will rub off on you and your enthusiasm will rub off on others. Find a mentor or mentor someone else. Some times people like this are hard to find, but when you do meet one stay in touch. They offer a wealth of information and knowing them can be very beneficial.

These 10 tips will probably translate over to just about any field. I think these are great to boost your career and put you on the right track to be successful.

Hopefully I’ve helped someone with this post. If I have, just send me some money in a brown paper bag.

If you have anything to add or argue, please feel free to do so in the comments.

A brief inspection of the running services on the newly upgraded Windows 2008 primary domain controller showed that the ‘Computer Browser’ service was disabled. Apparently, this service is disabled by default in Windows 2008 Server. Setting the service to run automatically and then starting it resolved the browsing issues.

If you are having similar issues after upgrading your domain controllers, we recommend checking the ‘Computer Browser’ service. Ideally, you would probably want this service running on all of your domain controllers to ensure NetBIOS browsing is possible from any of the subnets on your network.

The ideal solution would be setting up a complete MPLS network using another service provider. This is probably the most costly solution however will give you the greatest results.

Another solution is to have point to point connections to the branch offices. This can be costly as well depending on how many branch offices there are and what other offices they need to have connectivity to.

The most cost effect solution will only give marginal performance depending on the load. You can set up an IPSEC VPN between offices using your typical broadband connections (cable, DSL). I’m actually currently in the process of setting this up for a small office that needs connectivity to a main office in the event that their MPLS link goes down.

Automating the fail-over process for these solutions should be no different than doing it for a dedicated circuit. There are multiple ways of going about it. Dynamic routing, load balancing, and setting different metrics for the 2 different routes are a few ways to do it.

This was just to give you an idea of what types of solutions are out there. In a later post, I will go into detail about the equipment that can be used and some example configurations of the scenarios given the different equipment.

The Open Systems Interconnection (OSI) model consists of seven layers of network architecture. These layers are the Application, Presentation, Session, Transport, Network, Data-Link, and Physical layers. For the most part if you’re a network administrator, like me, most of your work will be concerned with the first three layers, Physical, Data-Link, and Network.

Now let’s break down the different OSI model layers and what they do:

Layer 7 – Application Layer

The Application layer is generally the closest to the end user. This is where the end user will interact with software in order to communicate across a network. General examples of this layer are telnet,  HTTP, FTP, SMTP.

Layer 6 – Presentation Layer

The Presentation layer is where the data from the Application layer is taken and encapsulated into a form of data that can be used for travel across a network. This layer converts data for use in the Application layer or the Session layer for use in the opposing layer.

Layer 5 – Session Layer

The Session Layer maintains communications or connections between nodes on a network. It establishes, maintains, and terminates. It can operate in full-duplex, half-duplex, or simplex operating modes. Any checkpointing or recovery operations in TCP usually happen on this layer. An example of this layer in action would be an application that uses RPC to execute actions in another address space remotely.

Layer 4 – Transport Layer

The Transport layer is where reliability is controlled through flow control, (de)segmentation, and error control. This is where all data is transfered between end users. Error checking happens on this layer and it can retransmit any failures. Examples of this implementations of this layer are TCP and UDP.

Layer 3 – Network Layer

The Network layer, my favorite, is where all routing happens on a network. This is where data is transferred to it’s destination across one or more networks. This is where routers operate. Data travels across this layer alot like traveling the highway system. Data flows between different routers (hops) to finally make it to it’s destination. The most known implementation of the Network layer is Internet Protocol or IP, as it is most called.

Layer 2 – Data-Link Layer

The Data-Link layer is where data is transfered between nodes on a network. This layer has the capability to detect and correct errors that might have occured on the Physical layer. One of the most well known implementations of this layer is Ethernet. You will find most network switches on this layer. The Data-Link layer provides a connection across the physical link by using vendor assigned hardware MAC address verses assigned IP addresses, like the Network layer does.

Layer 1 – Physical Layer

The Physical layer is where all electrical and physical connections are made. On this layer you will find cabling, hubs, and, network adapters to name a few. Where the Data-Link layer connects multiple nodes, the Physical layer is mostly concerned with connected a single device to the network medium.

That’s a rough introduction to the OSI model. There is a lot more theory of it, but I just wanted to give a quick overview.

All your troubleshooting efforts should start at layer 1, what I like to call ‘checking the basics’. Bypassing layer 1 can cost you alot of time in troubleshooting. I generally make sure cables are plugged in and all devices are powered on. A lot of times you may find a simple easy to correct issue here and save yourself alot of grief in troubleshooting the higher level layers. From there you can just work your way up the layers. This will provide good coverage of possible failures or misconfigurations across the network.

Some network administrators, including my self, talk of a ‘Layer 8′. This is the actual end user themself. I like to call this ‘operator head space and timing’. You should be able to judge and categorize your end users by level of knowledge if you’ve been working with them for some period of time. You can usually skip to ‘Layer 8′ if you’re able to identify the issue with the end user from their complaint. This of course is not part of the Cisco certification process and has more to do with experience in dealing with end users, which you will learn on the job.

We are going to assume you have a Cisco router already setup and in service on your network.

First thing you will want to do is login to your router and go into config mode. Once in config mode you will want to setup a DHCP pool.

Router(config)# ip dhcp pool newpool

You can replace ‘newpool’ with whatever you choose to name your DHCP pool. Next thing we want to do is tell the router the network and subnet.

Router(dhcp-config)# network x.x.x.x y.y.y.y

Replace x.x.x.x with the network address and y.y.y.y with the subnet mask. Next we will tell the router what DNS domain name the clients will use.

Router(dhcp-config)# domain-name domain.com

Obviously, you will replace ‘domain.com’ with your domain. Now we need to tell the router the primary and secondary DNS server IP addresses to be used in the DHCP scope.

Router(dhcp-config)# dns-server 1.1.1.1 2.2.2.2

Replace 1.1.1.1 with your primary DNS server and 2.2.2.2 with your secondary DNS server. We need to specify the default gateway or router.

Router(dhcp-config)# default-router x.x.x.x

Replace x.x.x.x with your default gateway or router IP address. Next we want to specify the length of the lease of the addresses assigned by the DHCP server.

Router(dhcp-config)# lease 7

Here I have set the lease time to expire in 7 days. Alternatively, you can use the syntax ‘lease DAYS HOURS MINUTES’, replacing those variables with the obvious requirements. You can even go as far as setting it for an infinite perios of time using ‘lease infinite’.

This pretty much sums up setting up DHCP on a Cisco router with IOS. I do want to show you one more thing. Suppose you want to exclude some IP address that you want to reserve for static devices. The following command needs to be performed in the the global configuration mode, so type ‘exit’ and perform the following if you are still at the last step.

Router(config)# ip dhcp excluded-address x.x.x.x y.y.y.y

You will want to replace y.y.y.y with the start address of the range you want to exclude and replace y.y.y.y with the end address. Example: ‘ip dhcp excluded-address 192.168.100.0 192.168.100.100. This will exclude addresses all the way up to 192.168.100.100. Therefore, DHCP will start assigning IP address leases at 192.168.100.101.

Now that we have setup our DHCP scope we can enable to DHCP service.

Router(config)# service dhcp

Now you should be able to grab an IP address via DHCP. Don’t forget to save your configuration.

Any how let’s get started.

This assumes you have already logged in to your Cisco router and are in enable mode.

First, you want to check whether SSH has already been enabled.

Router# show ip ssh
%SSH has not been enabled

If you see the result above it obviously means that SSH has not already been enabled on this device.

On with the configuration:

You will want to configure a hostname on your router. This will be performed in configuration mode. (note the prompt)

Router(config)# hostname Router1

The hostname has been set. Now we will configure a domain name for the device.

Router1(config)# ip domain-name Domain1

The domain name has been set. Now we want to generate a RSA key pair.

Router1(config)# crypto key generate rsa modulus 1024

Next we will set a timeout interval.

Router1(config)# ip ssh time-out 120

This will set a time limit of 120 seconds for the SSH session to negotiate.
You can also set a maximum number of retry attempts incase of a failed negotiation.

Router1(config)# ip ssh authentication-retries 3

This will set the maximum amount of retries to 3.
The next thing we will do is change the default port for SSH from 22 to 8855. This is not necessary, however I do recommend it for an added level of security.

Router1(config)# ip ssh port 8855

At this time you can log off of the Cisco device and test the connection with a terminal client. In Windows I like to use PuTTY and in Linux or OSX I use the ssh command in the terminal.

Once you’ve logged in and verified the connection is good you can disable telnet access.

Router1(config)# line vty 0 4
Router1(config)# transport input ssh

Now the only way you will be able to remotely access your Cisco device is via SSH on the port you specified earlier, if you opted to change the default port.

Now to save your configuration changes to the Cisco device, you want to save the running-config to the startup config. There are 2 ways of performing this. I will show you both ways, but you should already know this by now.

Option 1

Router1# wr mem

Option 2

Router1# copy running-config startup-config

Now your new configuration should be saved. One last thing we can do to verify SSH configuration is repeat the first command in this tutorial.

Router1# show ip ssh
SSH Enabled - version x.x
Authentication timeout: 120 secs; Authentication retries; 3

We should see the above result with the configuration that we performed.

That concludes setting up SSH access on your Cisco router or switch. I highly recommend using SSH over telnet especially if you will be managing your device remotely. Telnet will give you absolutely no protection from sniffing.

Many of you might know that this is business as usual. Volume licensing users have long had the ability to use their licenses to install a version back. Normally this was restricted to one version back, but for a limited time Microsoft OEM’s will allow customers to downgrade 2 Windows versions prior. This will allow customers to select versions of Windows as old as XP.

Since Windows 7 is just a refresh of the mixed reviewed Windows Vista operating system we at illcommunications thought this was inevitable. We do however feel that Windows 7 is a major improvement over the Windows Vista platform.

As with prior versions of the Windows operating system some business users will probably elect to continue utilizing Windows XP in their business environments for some time. We don’t believe that Microsoft’s offering of downgradability to be any judgement of what Windows 7 will be, but more of a convenience and hopefully continued support of the Windows XP platform for those that are less likely to be early adopters the new operating system.

Google has apparently opened their new voice service, Google Voice, to GrandCentral users. According to Google this service will provide a one number for life solution for free. With this service you will be able to use one number for all of your voice and SMS needs otherwising eliminating the issue of having multiple phone numbers or even changing numbers.

You can see a more detailed list of the features they will be offering with this free service on the Google Voice website.

This looks like a great service that will be offered for free. We are really excited about giving it a try.

For right now it is only available to existing GrandCentral users. You can sign up for an invite at the Google Voice website.

We would be interested in trying this service out and possibly reviewing it. Hint: Hey Google, hook us up with an invite!