OSPF Stubby & Totally Stubby, explained

OSPF (Open Shortest Path First) has many configurable topologies. One of being the  Stubby Area,  as if that didn’t confuse you enough they introduced  the Totally Stubby Area when this was first explain to me, I couldn’t grasp the concept of what the instructor was talking about, at least not until I drew the network out and configured it out in GNS3, it was then I was able to seen it for myself.

FYI OSPF overview, stubby networks only used for a small area that need to block all the external routes in their routing table.   Routing will show a default internal route pointing to their ABR. Generally in the OSPF world all things must connect to Area 0, the ISP link would normally flow out Area 0 ASBR  I think of Area 0 as the OSPF body and other area as limbs (the analogy works for me). Click topology for larger pic.

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Avaya’s System Platform

Many AVAYA products have already moved to the System Platform base (and the rest of them except CMS will move to SP by end of year).  System Platform is a “virtual server” environment… there is one VERY CRITICAL “feature” that everyone who potentially works on an AVAYA SP based product needs to know.  In the past, you could go into most products and make a change to the time (CM, AES, MM, etc) and the system would restart it’s time service or NTP service and you were good to go.

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EIGRP query messages, the good the bad the ugly.

If a network goes down, EIGRP will send out query messages to its neighbors to find an alternate route.  EIGRP will do this for 180 seconds (three minutes) it will keep sending the query messages even if a path is reported within that time frame, the path will simply set in queue until all queries have been answered.   While this message waits the link can become “stuck in active” and after the 3 minute period all neighbor relations will be torn down and the link will become active, afterward the rest of the neighbor relations are restored.

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My preliminary Cisco router setup

As a potential engineer one of the many basic skills you’ll need to master in your career is setting up a newly purchased router. Surprisingly I know a lot of Engineers that have worked in NOC’s (Network Operations Centers) for years, troubleshooting all sorts Cisco devices and various issues and never really having to configure anything. This is truly one of the down sizes of working in a large company; you tend to get pigeon-toed into doing on particular thing all the time.

Two skills are needed to know from memory.

• Basic setup a router or switch

• Basic password recovery for a router or switch Continue reading

Custom Cisco menu configuration

A while ago I stumbled upon a great piece of code that could make your Cisco router a little less intimidating for your tier one tech support staff.   The tier one team is useless the first ones that the customer engages when calling in a trouble. 

Most of the time tier one is responsible for taking the customer information, creating a ticket and performing some basic trouble shooting steps,  i.e. verify links and change passwords or provide application assistance, anything more in depth is forwarded to the tie 2 or 3  group.

With a simple menu configured on a Cisco router you can perform  basic show  commands that any tier 1 or 2 can use without the fear causing any intrusive down time to the production network, and the person performing the commands does not need to know the  proper command syntax .

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Config Bytes Elearning Pod Casts

It’s been a busy six weeks for me.  I got the crazy idea of putting together some short five to ten minute how-to ConfigBytes video casts,   I’m just polishing up the last frames of my video podcast debut.  I decided to create these from watching several others that ether fall short or are out dated.

There is nothing more frustrating than watching a configuration video that someone placed on YouTube with NO sound or at least a commentary of what they are doing.  What I found is that these are freaking hard to make, trying not to stutter and remember to look up at the camera ever now and then were the hard parts then threes video and sound editing along with fact checking (making sure that the config you type is correct)

I hope to have the first video in the can by the end of this month.  My  goal to create one a month based on the amount of feedback I get I can see me doing one a week.

ASA 5505 board repair and recovery

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I received a faulty ASA 5505 from a customer the other day.  Customer has already been shipped a replacement and now I asked what should I do with this one, sitting on my desk. The problem with this device is that the power plug had become loose, periodically causing the ASA to reload and causing havoc on the customer’s network. It clearly had to be replaced

Normally I would send a refurbished non smart net covered Cisco item out for repair, if the cost was justified. ASA 5505 can be purchased from Bay for around 375 bucks used and 600 new; cost to repair this plus shipping would have been close to $200.  In this case it was better to simply replace it.    I decided to crack this box open and take a peek inside. I feel comfortable doing this because my previous career was an electronics bench tech.  Continue reading

Network Address Translation

Network Address Translation, sometimes called Network Address Translator (NAT), was originally outlined in RFC 1631 in 1994. This was to allow devices on the inside network the use of private IP addresses that are presently defined in RFC 1918. NAT makes it possible to have a very big internal network with thousands of local addresses represented by a handful of global addresses or possibly a single global address.

basicnat

We will setup a basic static and dynamic NAT configuration.

To the left we have a basic example of how NAT operates.  Starting from the bottom we have our …

  • Inside Local Addresses
  • Outside Local Address
  • Inside Global Address
  • Outside Global Address
Our ISP has given us the following IP range.  189.45.23.56/29, looking at this subnet we can tell that our network starts on the 8th subnet range and this will give us 6 usable addresses

(For simplicity we will not be using subnet-zero)

  • Network ID: 189.45.23.56 (Will always be even)
  • First usable address: 189.45.23.57 (Will always be odd)
  • Last usable address: 189.45.23.62 (Will always be even)
  • Broadcast address: 189.45.23.63 (Remember BrODDcast, always odd)
  • Netmask of: 255.255.255.248

For more subnet information refer to The Last Subnet Doc

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