Jan
24

Just ahead of our brand new CCNA Voice live online bootcamp beginning this Monday, I thought it might be nice to provide an easy-to-follow graphic for those starting out in Voice (or on any other Cisco networking track). This graphic was from last year, but remains quite easy to follow for each and every Cisco track.

Be sure you have a high resolution set if you wish to see the entire thing, otherwise scrolling may be necessary.

Click here for the Cisco Career Certification Path poster

Jan
23

Cisco had promised us Christmas 2010 editions of these new exams. Those dates have slipped again.

The new Cisco CCDA 640-864 DESGN and CCDP 642-874 ARCH exams are now scheduled to hit by January 31, 2011.

Both exams promise to test new material regarding virtualization and data centers. Stay tuned to see if these new exams do actually materialize. For those tracking such things - this is the third new date for these exams. :-)

Jan
03

Continuing my review of titles from Petr’s excellent CCDE reading list for his upcoming LIVE and ONLINE CCDE Bootcamps, here are further notes to keep in mind regarding EIGRP.

About the Protocol

  • The algorithm used for this advanced Distance Vector protocol is the Diffusing Update Algorithm.
  • As we discussed at length in this post, the metric is based upon Bandwidth and Delay values.
  • For updates, EIGRP uses Update and Query packets that are sent to a multicast address.
  • Split horizon and DUAL form the basis of loop prevention for EIGRP.
  • EIGRP is a classless routing protocol that is capable of Variable Length Subnet Masking.
  • Automatic summarization is on by default, but summarization and filtering can be accomplished anywhere inside the network.

Neighbor Adjacencies

EIGRP forms "neighbor relationships" as a key part of its operation. Hello packets are used to help maintain the relationship. A hold time dictates the assumption that a neighbor is no longer accessible and causes the removal of topology information learned from that neighbor. This hold timer value is reset when any packet is received from the neighbor, not just a Hello packet.

EIGRP uses the network type in order to dictate default Hello and Hold Time values:

  • For all point-to-point types - the default Hello is 5 seconds and the default Hold is 15
  • For all links with a bandwidth over 1 MB - the default is also 5 and 15 seconds respectively
  • For all multi-point links with a bandwidth less than 1 MB - the default Hello is 60 seconds and the default Hold is 180 seconds

Interestingly, these values are carried in the Hello packets themselves and do not need to match in order for an adjacency to form (unlike OSPF).

Reliable Transport

By default, EIGRP sends updates and other information to multicast 224.0.0.10 and the associated multicast MAC address of 01-00-5E-00-00-0A.

For multicast packets that need to be reliably delivered, EIGRP waits until a RTO (retransmission timeout) before beginning a recovery action. This RTO value is based off of the SRTT (smooth round-trip time) for the neighbor. These values can be seen in the show ip eigrp neighbor command.

If the router sends out a reliable packet and does not receive an Acknowledgement from a neighbor, the router informs that neighbor to no longer listen to multicast until it is told to once again. The local router then begins unicasting the update information. Once the router begins unicasting, it will try for 16 times or the expiration of the Hold timer, whichever is greater. It will then reset the neighbor and declare a Retransmission Limit Exceeded error.

Note that not all EIGRP packets follow this reliable routine - just Updates and Queries. Hellos and acknowledgements are examples of packets that are not sent reliably.

Dec
30

To start my reading from Petr's excellent CCDE reading list for his upcoming LIVE and ONLINE CCDE Bootcamps, I decided to start with:
EIGRP for IP: Basic Operation and Configuration by Russ White and Alvaro Retana
I was able to grab an Amazon Kindle version for about $9, and EIGRP has always been one of my favorite protocols.
The text dives right in to none other than the composite metric of EIGRP and it brought a smile to my face as I thought about all of the misconceptions I had regarding this topic from early on in my Cisco studies. Let us review some key points regarding this metric and hopefully put some of your own misconceptions to rest.

  • While we are taught since CCNA days that the EIGRP metric consists of 5 possible components - BW, Delay, Load, Reliability, and MTU; we realize when we look at the actual formula for the metric computation, MTU is actually not part of the metric. Why have we been taught this then? Cisco indicates that MTU is used as a tie-breaker in a situation that might require it. To review the actual formula that is used to compute the metric, click here.
  • Notice from the formula that the K (constant values) impact which components of the metric are actually considered. By default K1 is set to 1 and K3 is set to 1 to ensure that Bandwidth and Delay are utilized in the calculation. If you wanted to make Bandwidth twice as significant in the calculation, you could set K1 to 2, as an example. The metric weights command is used for this manipulation. Note that it starts with a TOS parameter that should always be set to 0. Cisco never did fully implement this functionality.
  • The Bandwidth that effects the metric is taken from the bandwidth command used in interface configuration mode. Obviously, if you do not provide this value - the Cisco router will select a default based on the interface type.
  • The Delay value that effects the metric is taken from the delay command used in interface configuration mode. This value depends on the interface hardware type, e.g. it is lower for Ethernet but higher for Serial interfaces. Note how the Delay parameter allows you to influence EIGRP pathing decisions without the manipulation of the Bandwidth value. This is nice since other mechanisms could be relying heavily on the bandwidth setting, e.g. EIGRP bandwidth pacing or absolute QoS reservation values for CBWFQ.
  • The actual metric value for a prefix is derived from the SUM of the delay values in the path, and the LOWEST bandwidth value along the path. This is yet another reason to use more predictive Delay manipulations to change EIGRP path preference.

In the next post on the EIGRP metric, we will examine this at the actual command line, and discuss EIGRP load balancing options. Thanks for reading!

Nov
28

Just as with the CCDP, Cisco has delayed the release of the new DESGN exam. The DESGN exam (640-864) is expected to be available on December 16, 2010.

Here are the topics promised fro the new exam:

Describe the Methodology used to design a network
Describe developing business trends
Identify Network Requirements to Support the Organization
Describe the tools/process to characterize an existing network
Describe the top down approach to network design
Describe Network Management Protocols and Features
Describe network structure and modularity
Describe the Network Hierarchy
Describe the Modular Approach in Network Design
Describe network architecture for the enterprise
Design Basic Enterprise Campus Networks
Describe Campus Design considerations
Design the Enterprise Campus Network
Design the enterprise data center
Describe enterprise network virtualization tools
Design Enterprise Edge and Remote Network Modules
Describe the Enterprise Edge, branch, and Teleworker design characteristics
Describe physical and logical WAN connectivity
Design the branch office WAN solutions
Describe Access Network solutions for a remote worker
Design the WAN to support selected redundancy methodologies
Identify Design Considerations for a Remote Data Center
Design IP Addressing and Routing Protocols
Describe IPv4 Addressing
Describe IPv6 Addressing
Identify Routing Protocol Considerations in an Enterprise Network
Design a Routing Protocol Deployment
Design network services
Describe the security lifecycle
Identify Cisco technologies to mitigate security vulnerabilities
Select appropriate Cisco security solutions and deployment placement
Describe high level voice and video architectures
Identify the design considerations for voice/video services
Describe Cisco Unified Wireless Network Architectures and Features
Design wireless network using controllers

Describe the Methodology used to design a network

  • Describe developing business trends
  • Identify Network Requirements to Support the Organization
  • Describe the tools/process to characterize an existing network
  • Describe the top down approach to network design
  • Describe Network Management Protocols and Features

Describe network structure and modularity

  • Describe the Network Hierarchy
  • Describe the Modular Approach in Network Design
  • Describe network architecture for the enterprise

Design Basic Enterprise Campus Networks

  • Describe Campus Design considerations
  • Design the Enterprise Campus Network
  • Design the enterprise data center
  • Describe enterprise network virtualization tools

Design Enterprise Edge and Remote Network Modules

  • Describe the Enterprise Edge, branch, and Teleworker design characteristics
  • Describe physical and logical WAN connectivity
  • Design the branch office WAN solutions
  • Describe Access Network solutions for a remote worker
  • Design the WAN to support selected redundancy methodologies
  • Identify Design Considerations for a Remote Data Center

Design IP Addressing and Routing Protocols

  • Describe IPv4 Addressing
  • Describe IPv6 Addressing
  • Identify Routing Protocol Considerations in an Enterprise Network
  • Design a Routing Protocol Deployment

Design network services

  • Describe the security lifecycle
  • Identify Cisco technologies to mitigate security vulnerabilities
  • Select appropriate Cisco security solutions and deployment placement
  • Describe high level voice and video architectures
  • Identify the design considerations for voice/video services
  • Describe Cisco Unified Wireless Network Architectures and Features
  • Design wireless network using controllers
Nov
06

Just a quick reminder that the CCDA and CCDP exams are updating to version 2.1 on November 8, 2010.

Our upcoming CCDP Bootcamp will reflect the new 2.1 exam, and we will be updating our CCDA Bootcamp in November/December 2010 as well. As always, customers that had previously purchased the CCDA Bootcamp will receive the updates free of charge.

Thank you so much for choosing INE, and enjoy your studies!

Jul
25

So many students have written me excited for the upcoming Cisco Certified Design Associate (CCDA) 5 day online bootcamp. In this blog post I want to provide everyone with a preview of some of the hugely valuable content in this course.

Early in the week of the event, we review a network health checklist from Cisco Systems. We take this one step further during the bootcamp  and show you how to actually obtain these measurements without breaking your budget:

  • Ethernet segments should not feature a sustained utilization of 40% or higher
  • All Ethernet segments should be switched - no shared segments (hub-based)
  • No WAN links should feature a sustained utilization of 70% or higher
  • Response times should be generally less than 100 ms
  • LAN response times should generally be 2 ms

No segments have more than one cyclic redundancy check (CRC) error per million bytes of
data.
  • No segments should have more than one CRC (cyclic redundancy check) error per million bytes of data
  • No segments should have more than 20 percent multicast or broadcast traffic
  • For Ethernet segments, there should be less than .1 percent collisions
  • Over 5 minute intervals, CPU utilization should not exceed 75%
  • The number of output queue drops should not exceed 100 in an hour
  • The number of input queue drops should not exceed 50 in an hour
  • The number of buffer misses should not exceed 25 in an hour
  • The number of ignored packets should not exceed 10 in an hour
Jul
24

Are you wondering what the month of August 2010 will bring for INE fans?

Try all new, online bootcamps in the following disciplines:

  • MPLS
  • BGP
  • CCNA
  • CCNP
  • CCDA

Watch the blog and your email for all of the exciting new details.

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