February 2011

My Top 5 Networking Reads of the Week 2/13/11 – 2/19/11

Here are my top 5 Networking Reads of the week. The first link is something worth watching. Many of us in the IT field lack the work-life balance. Another important topic is the Cisco Petition that Greg Ferro has going on his blog. I’ve signed up, have you? I hope you enjoyed your week and hope you have a great weekend!

Here are the blog posts that I’ve published this week:

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Open Letter to Cisco – Can We Get an Educational License?

How can one truly validate their skills without a fully working emulator or up-to-date hardware worth thousands of dollars? As we continue down our career paths we find obstacles to acquiring the right skills and knowledge. The path gets beaten and we’re forced to make tough decisions.

Many of us do not have service contracts that allow us to download IOS images. Even then, it is against Cisco’s terms to use them with GNS3.

So how will you allow future engineers to move forward in their careers and acquire Cisco certifications? How can we recommend Cisco technology when we haven’t worked with them. We can only do so much when forced to use non-Cisco emulators.

Many of us are looking for ways to learn how to use YOUR technology. Help us learn the right way by building an emulator that fits within each of the certification blueprints.

Getting educated in Cisco technology is now in danger with the introduction of new feature activations and license keys.

Cisco must take the lead and fix this educational crutch. There must be an alternative to spending thousands of dollars to build our own lab equipment. What we’re looking for is a way to load a fully featured Cisco emulator that meets the objectives of each Cisco certification blueprint. This can even be released on every Cisco Press book, on the CD’s that are provided.

There have been some great suggestions out there to help kick start this project. One example is how Microsoft allows users to use their software for a trial period. We’re open-minded, anxious and excited for Cisco.

The community is uniting to ask of you, Cisco, to create a version of IOS for educational purposes at a free or low cost value.

Regards,

Rowell Dionicio

To the Cisco network community: Please sign up for the Cisco IOS Educational License Petition on Etherealmind’s blog. Help us send this message to Cisco and please do share with your colleagues.

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Part III: OSPF Link-State Advertisements

Moving from Part II OSPF Packets, we have the link-state advertisements (LSAs). Every router in an AS creates one or more link-state advertisements which, collectively, form the link-state database.

LSAs contain state information of routers and the links between routers. They are reliable, flooded throughout the area and periodically refresh before aging out of the LSDB.

Each of the LSAs have specific functions which will be described below.

Type 1 LSA – Router

Every router advertises a Type 1 Router LSA for itself. This LSA describes the states of the router’s directly attached links. The Router LSA gets flooded throughout the area which the router resides.

The Router LSA advertises the type of connections attached, such as it’s type and link ID:

Type 1
Describes: Point-to-Point
Link ID: Neighbor Router ID

Type 2
Describes: Link to transit network
Link ID: Interface address of designated router

Type 3
Describes: Link to stub network
Link ID: IP network number

Type 4
Describes: Virtual link
Link ID: Neighbor router ID

Type 2 LSA – Network

This LSA is generated for every transit broadcast or NBMA network in the area. It lists each of the attached routers that make up the transit network.

The link state ID will be the IP address of the designated router for that network.

Type 3 and 4 LSA – Summary

Type 3 Summary LSAs are generated by ABRs that contain networks owned by an area to the rest of the areas in the OSPF autonomous system. Only intra-area and inter-area routes will be advertised into other areas.

Type 4 Summary LSAs are generated if an ASBR exists in an area. This LSA identifies the ASBR and provides a route to the ASBR.

Type 5 LSA – External

This LSA is generated and flooded throughout the entire autonomous system by ASBRs of an area that describes routes to networks outside of the OSPF autonomous system.

External LSAs do not get flooded into stub areas.

Type 6 LSA – Multicast

This type is not supported on Cisco devices.

Type 7 LSA – NSSA

Generated by an NSSA, Not-so-stubby-area, ASBR. This LSA is generated because Type 5 LSAs are not allowed in NSSA areas.

Part I, Getting to Know OSPF of a series on OSPF Operation
Part II, OSPF Packets
Part III, OSPF Link-state Advertisements
Part IV, OSPF Network Types
Part V, OSPF Frame-Relay
Part VI, OSPF Route Summarization
Part VII, OSPF Stub Areas
Part VIII, OSPF Authentication
Part IX, Putting it All Together
Part X, Verification

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