For success designing and implementing Cisco Wireless solutions, a CCNA Wireless student needs to be familiar with the options for various wireless topologies. Two were defined by the 802.11 committees, while others were made possible thanks to excellent developments by wireless vendors like Cisco Systems.

The 802.11 Topologies

Ad Hoc Mode

While not popular, it is possible to have wireless devices communicate directly with no central device managing the communications. This is called the Ad Hoc network topology and is one of the two topologies defined by the 802.11 committees. In the Ad Hoc type topology, one device sets a group name and radio parameters, and another device uses this information to connect to the wireless network.

This type of wireless network topology is referred to as an Independent Basic Service Set (IBSS). This is easy to remember as we know the devices are working independently of an access point (AP).

Network Infrastructure Mode

When an access point is used to create the network, the official term is network infrastructure mode for the network. There is a Basic Service Set (BSS) setup that uses a single access point, or the Extended Service Set (ESS) that uses multiple access points in order to extend the reach of the wireless network.

Access points running in the network infrastructure mode are often described as a cross between hubs and bridges. The APs act like hubs in that they service a single collision domain and must operate in a half duplex fashion. Fortunately for the AP, it does possess intelligence beyond a simple hub, however, and processes frames and forwards these based on MAC address information.

Vendor-Specific Topology Extensions

Workgroup Bridge

Perhaps your network contains clients that you want to connect to the wired infrastructure but these devices are in a location where it is difficult to extend actual physical wires. This is the perfect time to have the access point function as a workgroup bridge. The access point extends the wired LAN out to these wireless devices.

Repeater

In this case, the job of the access point is to strengthen the wireless signal from another access point. Perhaps it is strengthening the signal of an access point acting in the workgroup bridge role. When repeaters are used, there must be overlap in the access point cell coverage. In order to provide optimal performance, the overlap needs to be 50%.

Outdoor Wireless Bridge

These access points are typically used within a few miles of each other and are used to connect two or more LANs. The Cisco technology allows the configuration of point-to-point or point-to-multipoint topologies.

Outdoor Mesh Networks

The outdoor mesh network features an access point acting as a root device. This AP has an Ethernet connection to a distribution network and it associates with a Wireless LAN Controller (WLC). The other access points in the design act as mesh APs. All these devices need is power and can act as repeaters as required in order to allow all devices to reach the root access point. While the IEEE is working on a mesh standard called 802.11s, the Cisco solution features Adaptive Wireless Path Protocol (AWPP). AWPP promotes the mesh devices finding the best path back to the root AP.

One of the features students love in the INE 5-Day CCNP bootcamp is the frequent Exam Challenges that are presented to students. Have fun with this sample from SWITCH.

Q1: Examine the configurations shown and the topology. Identify three errors in the configurations.

Exhibit 1

SW1
interface range fa0/16 – 17
switchport trunk encapsulation dot1q
switchport mode dynamic desirable
no shutdown
channel-group 1 mode on

SW3
interface range fa0/16 – 17
switchport trunk encapsulation dot1q
switchport mode dynamic auto
shutdown
channel-group 3 mode active 

In the first part of this series, we subdivided the processes of EIGRP into four discrete steps, and detailed troubleshooting the first two. This is taken from the 5-Day CCNP bootcamp:

• Discovery of neighbors
• Exchange of topology information
• Best path selection
• Neighbor and topology table maintenance

Let us now discuss path selection and maintenance troubleshooting.

We should all remember that we can view the topology table of EIGRP with the command show ip eigrp topology. Here we can see the successor routes (these are the best routes that are placed in the routing table) and we can see the second best routes, the feasible successor routes. These feasible successor routes are the key to the lightening fast convergence that EIGRP can offer us. When a speaker loses its successor, it can quickly install a feasible successor route in its place.

We need to remember the important rule of feasible successors. The advertised distance of the proposed feasible successor must be less than the feasible distance of the current successor route. This is actually a loop prevention mechanism.

Another big gotcha when it comes to path selection in EIGRP is the configuration of variance to unequal cost load balance. I can remember fighting with this in an INE practice lab long ago when I was preparing for the exam. Something I had no idea of back then…in order to be considered for the unequal load balancing, the alternate paths must be feasible successors! Older editions of CCNP courses never thought to tell us that little nugget!

We should be careful when modifying bandwidth to effect path selection. Cisco gave us delay for this purpose. Modifying the bandwidth can starve EIGRP updates of bandwidth to use. Remember, by default, EIGRP will only use 50% of an interface’s bandwidth. We can control this with the command ip bandwidth percent eigrp.

For table maintenance, show ip eigrp topology is critical. Note that in this table, passive is what we want to see. Active indicates there is not a feasible successor and neighbors are being queried for an alternative path. SIA log messages indicate a Stuck in Active issue. Here the router is not receiving a reply to queries. The most common reasons this can occur:

• Bad link
• Congested link
• The query scope if too big (too many routers involved)
• Excessive redundancy is built into the network
• The router CPU is overloaded
• There is a shortage of memory on the router
• There are software defects

When it comes to table maintenance, another excellent troubleshooting command is show ip eigrp topology summary. This command displays the total number of routes in the topology table and the total number of queries the router is waiting on responses for. It also shows a quiescent interface field that shows which interface have no outstanding packets to be sent or acknowledged.

Some of our favorite EIGRP verification commands:

• show ip route eigrp
• show ip protocol
• show ip eigrp neighbor
• show ip eigrp topology
• show ip eigrp topology all-links
• show ip eigrp topology summary
• debug eigrp packet hello
• debug eigrp packet query reply

We are so excited here at INE for the live, online 5-Day CCNP bootcamp that starts Monday, August 16, 2010 . I look forward to seeing many of our aspiring CCIE candidates in this course. These students realize that they really need to improve their foundation Tier 1 knowledge as they seek to conquer the Lab Exam beast.

In this blog post, we are going to provide a sneak peek into some of the awesome information shared in the TSHOOT section of the bootcamp regarding the Troubleshooting of EIGRP. This can prove critical in the Troubleshooting and Configuration sections of the CCIE R&S Lab Exam, as well as the TSHOOT CCNP exam (duh!).

Where Is My Neighbor!?!?!?

The first thing that you want to master when it comes to troubleshooting EIGRP is the ‘workflow” that EIGRP follows in its operation. We can subdivide the processes of this exciting protocol into four discrete steps:

• Discovery of neighbors
• Exchange of topology information
• Best path selection
• Neighbor and topology table maintaince

Discovery of Neighbors

Remember that EIGRP discovers neighbors through bi-directional multicast by default. IP protocol 88 and 224.0.0.10 are the key parameters we need to watch out for here. Could there be issues with NBMA pseudo-broadcast support or filtering causing neighbor discovery to fail? Certainly things to examine in the topology. Also, watch out for the neighbor command under the EIGRP routing process. This feature causes the use of unicast packets for neighbor creation exclusively and must be agreed upon by BOTH neighbors.

Another area we need to be aware of is the attributes that must match in order for neighbors to form. Sure this list is nowhere near as lengthy as the parameters that we have to watch out for in OSPF networks, but the list is just as critical:

• Common Subnet (Must be the primary address – not a secondary)
• Autonomous System Number
• Authentication
• K values (metric weights)

Exchange of Topology Information

When it comes to the exchange of topology information, this is done with unicast. Notice that connectivity for neighborship still requires mutlicast communications (unless you are using the neighbor command).

Remember that EIGRP will only advertise those prefixes that it installs in the routing table. This is an excellent time to review the difference from the Topology Table to the Routing Table.

Important troubleshooting considerations for the exchange of topology information include:

• Automatic summarization in use?
• Split horizon settings
• The use of duplicate router IDs preventing external route introduction
• No seed metric set for external prefixes
• Filtering through the use of distribute lists

Please consider these troubleshooting aspects for these two phases of EIGRP’s operation. We will cover more in the next installment coming soon…

The author and poet Maya Angelou said “Words mean more than what is set down on paper. It takes the human voice to infuse them with deeper meaning.”. Well that is certainly what we have attempted to do with the CCIE Voice Deep Dive self-paced Class on Demand series – that is to bring the human instructional voice element to infuse deeper meaning to what is already fantastic Cisco Documentation. Anyone that has set out and determined to undertake the task of studying for and ultimately passing any CCIE Lab exam, knows that at some point during your studies, the words on paper (Cisco Docs, RFCs, books) – while a absolute phenomenal source of information – can at times seem to loose their impact. Perhaps you have been studying too long, read one too many docs, have the time pressure of your family and friends waiting for you to return to be a part of their life, or perhaps you are just starting out on your adventure and don’t know where to begin. Whatever stage you are at or whatever the case may be, it is certainly helpful to have a tutor and mentor there beside you at times, assisting you in understanding what each complex technology’s documentation is trying to teach you, in possibly a deeper and more insightful way than you can manage on your own.

Wait no longer for such help to arrive! INE is happy to announce that each Live-Online Deep Dive course that we have taught has been recorded, and you have the ability to access these extensive repositories of knowledge at any time.

Here are a couple of great demo’s of just a portion of the latest Deep Dive session we held on Globalization & Localization in order to whet your appetite:

Demo 1: Globalization Prezi – Theory and Reasons

Demo 2: Inbound Calling Party Localization

For each complex topic we have held — or will soon hold (listings to follow below) — a separate online class where we dive down deep and explore all the concepts, practical application and troubleshooting associated with each technology topic. We then allow you to purchase each module individually (if you like) so that you can either try small sections of the product, or so that those who only need to plug in small gaps of knowledge can do so at a very deep, intense level – either one without committing to purchase the entire product series.

The general format for each Class-on-Demand Deep Dive module spends between 4-7 hours on the given topic for that day, and during that time follows this outlined training methodology:

• Collectively discuss and teach all concepts involved in the technology
• Whiteboard concepts to further deepen every participant’s understanding
• Define a specific set of tasks to be accomplished
• Demonstrate how the tasks and concepts are implemented and properly configured
• Test the configuration thoroughly
• Vary the configuration to understand how different permutations effect the outcome
• Debug and trace the working configuration to understand what should be seen
• Break the configuration and troubleshoot with debugs and traces to contrast from the working set

Thus far, we have held 10 online sessions – each with a median recorded runtime of 6 hours. We have almost 60 hours of Class on Demand content, and we’ve only just begun! We conservatively estimate that by the time we complete our more than 30 planned modules, that we will have at over 200 hours of Deep Dive recordings.

Below is a detailed index from the 10 currently available sessions:

Module 1 :: Network Infrastructure with LAN Quality of Service

• Catalyst 3560/3750 Classification and Marking
• Catalyst 3560/3750 Conditional Trust
• Catalyst 3560/3750 Ingress Interface Mapping
• Catalyst 3560/3750 Ingress Interface Queuing
• Catalyst 3560/3750 Ingress Interface Expedite Queue
• Catalyst 3560/3750 L2 CoS to L3 DSCP Mapping
• Catalyst 3560/3750 Egress Interface Mapping
• Catalyst 3560/3750 Egress Interface Queuing
• Catalyst 3560/3750 Interface Queue Memory Allocation
• Catalyst 3560/3750 Egress Queue-Set Templates
• Catalyst 3560/3750 Weighted Tail Drop (WTD) Buffer Allocation
• Catalyst 3560/3750 Egress Interface Expedite Queue
• Catalyst 3560/3750 Egress Interface Sharing
• Catalyst 3560/3750 Egress Interface Shaping
• Catalyst 3560/3750 Scavenger Traffic Policing

Module 02 :: CUOS GUI and CLI Admin

• CUCM WebUI: Service Activation and Stop/Start/Reset
• CUCM WebUI: Bulk Administration Tool (Import/Export, Phone Reports, etc)
• CUCM WebUI: DB Replication Status
• CUCM WebUI: Trace Files
• CUOS CLU: TFTP Files Management
• CUOS CLU: Status and Hostname
• CUOS CLU: DB Replication Assurance
• CUOS CLU: DB Replication Repair and Cluster Reset
• CUOS CLU: Trace Files
• CUOS CLU: RIS DB Search
• CUOS CLU: Performance Monitor (PerfMon)
• RTMT: Trace Files
• RTMT: Performance Monitor (PerfMon)

Module 03 :: CUCM System and Phone – SCCP and SIP Fundamentals

• CUCM Services
• UC Servers and Groups
• Date/Time with NTP Reference
• Regions and Codecs
• Location-Based Call Admission Control
• SRST References
• Device Pools
• System Parameters
• Enterprise Parameters
• Phone Button Templates
• Softkey Templates
• SCCP Phone Basics
• SIP Phone Basics

Module 04 :: Users, Credentials, Multi-Level Roles and LDAP Internetworking

• CUCM User Credentials and Policies
• LDAP Synchronization for CUCM and Unity Connection
• LDAP Authentication for CUCM and Unity Connection
• CUCM End Users
• CUCM User Roles
• CUCM Multi-Level Administration
• CUCM Device/Phone/Line User Association
• UCCX and CUP Basic Users

Module 05 :: Call Features – In-Depth

• SCCP and SIP Phone Display
• Phone Firmware
• Phone Logging
• Ring Settings
• Basic and Advanced Call Forwarding Display
• Auto-Answer Options
• CallBack (Camp-On)
• Intercom
• Advanced Call Hold Options
• Call Park
• Directed Call Park
• Advanced Call Park Settings
• Call Pickup
• Group Call Pickup
• Other Call Pickup
• Directed Call Pickup
• Call Pickup Attributes
• Shared Line
• Barge and cBarge (Conference Barge)
• Privacy
• Built-In IP Phone Bridge

Module 06 :: Media Resources – MTPs, Conf Bridges, Annunciator and Music on Hold

• IOS Software MTP
• IOS Conference Bridge
• IOS Transcoding
• Media Preference and Redundancy
• Meet-Me Conferencing
• Ad-Hoc Conferencing
• Annunciator
• Unicast Music on Hold
• Traditional Multicast Music on Hold
• Alternate Multicast Music on Hold

Module 07 :: Expert Gateways & Trunks

• ISDN Switch Types and Advanced CNAM options
• ISDN Information Elements
• SIP Trunks – Fundamental and Advanced Options
• H.323 Gateways – Fundamental and Advanced Options
• MGCP Gateways – Fundamental and Advanced Options

Module 08 :: Expert H.323 Gatekeeper

• Provisioning IOS H.323 Gatekeeper
• Registering CUCM with H.323 Gatekeeper
• Registering CUCME with H.323 Gatekeeper
• Routing Calls from CUCME to CUCM via Gatekeeper in Multiple Zones with Dynamic E.164 Aliases
• Routing Calls from CUCM to CUCME via Gatekeeper in Multiple Zones with Multiple Tech Prefixes
• Routing Calls from CUCME to CUCM via Gatekeeper in Multiple Zones with Multiple Tech Prefixes
• Routing Calls from CUCME to CUCM via Gatekeeper in Multiple Zones with Static E.164 Aliases
• Routing Calls from CUCM to CUCME and Back via Gatekeeper in One Zone with One Tech Prefix
• Gatekeeper Call Admission Control
• Routing Calls from CUCM to CUCME and Back via Alternate Gatekeeper Clustering in Multiple Zones with Multiple Tech Prefixes using GUP

Module 09 :: Dial Plan – Line Device Approach and the Not-So-Basic Fundamentals

• Class of Service: Calling Search Spaces and Partitions
• Gateways, Route Groups, Local Route Groups/Device Pools
• Route Lists and Standard Local Route Groups
• Route Patterns and Translation Patterns
• Digit Manipulation: Calling & Called Party Transformations and IOS Dial Peers
• Private Line Automatic Ringdown (PLAR)

Module 10 :: Dial Plan – Globalization & Localization of both the Calling and the Called Numbers, and with Mapping the Global Number to the Local Variant

• Inbound PSTN Calls (Ingress from PSTN, Egress to Phones): Calling Party Globalization :: GW Incoming Calling Party Settings
• Inbound PSTN Calls (Ingress from PSTN, Egress to Phones): Calling Party Localization :: Phone Calling Party Transformations
• Outbound PSTN Calls (Ingress from Phones, Egress to PSTN): Called Party Globalization :: PSTN Patterns – a.k.a. “Translation Patterns are the *New* Route Patterns”
• Outbound PSTN Calls (Ingress from Phones, Egress to PSTN): Called Party Localization :: Digit Manipulation: Calling & Called Party Transformations and IOS Voice Translation Rules & Dial Peers
• Mapping the Global Number to the Local Variant :: + Dialing and One-Button Missed Call DialBack

So stay tuned to this blog as we will shortly post the upcoming modules soon to be held online and recorded.

Are you ready to explore the following?

• HSRP
• VRRP
• GLBP
• NTP
• DHCP
• DNS
• WCCP

Check out the latest chapter posted in the Advanced Technologies Class On Demand.

Next week watch for the final chapter on Network Optimization, where we explore such critical Version 4 topics like EEM, IP SLA, and much more.

Also, soon here on the blog site, watch for a Video Blog episode that discusses study and lab exam strategy for the massive body of knowledge that is IP Services/Optimization in general.

The new version of the best-selling video series, Advanced Technologies Class on Demand (ATCoD) from INE has been updated with Chapters 8 and 9. These topics are Security and QoS respectively.

The final two chapters of the new course, Network Services and Network Optimization, are currently in production and will be posted no later than July 31, 2010.

Enjoy the new lessons everyone!

RFC, or Request for Comments, are documents published that describe various items surrounding computer networking. Generally, these are memorandums published by the Internet Engineering Task Force.

RFCs can be a great resource. For some unknown reason, most candidates preparing for the CCIE don’t take the time to review these documents, which can be very helpful in assisting with understanding the how and why of various networking components. Perhaps the language is a bit dry, or they prefer books with shiny covers.

There are a variety of status classifications. These include, but are not limited to: standards, informational, best current practices. Some are very serious discussions of the deep inner workings, where others are just there for entertainment, such as RFC 1149 and 2549.

If you aren’t sure whether a RFC is intended to be serious or entertainment, check the date. If it was one from 1 April of any year, most likely it falls into the category of entertainment.

http://www.rfc-archive.org/1+april+rfc.php

Language is included to define how an item is intended to behave. RFC 2119 lists some of these requirements. Requirements are shown capitalized, and include the following: MUST, MUST NOT, SHOULD, SHOULD NOT, MAY, RECOMMENDED, NOT RECOMMENDED, OPTIONAL.

RFCs are not a “magic bullet” for lab preparation. Most students that are familiar with RFCs tend to be more comfortable with the technologies discussed.

RFCs can be viewed online at a number of sites, including the following:

http://www.ietf.org/rfc.html

http://www.rfc-editor.org/

Most search engines will also give you results for RFCs by number or topic.

Quick quiz.

Four questions on RFCs that most people are generally familiar with. Questions are True or False, and the answers can be found fairly quickly, if you know where to look.

T or F
RFC 3330, which describes Special Use IPv4 Addresses, is obsolete.

T or F
RFC 1812, which discusses requirements for IPv4 Routers, states that subnet bits MUST be contiguous.

T or F
RFC 2827 discusses ingress filtering mechanisms, including the effects of multihoming.

T or F
RFC 1918 does not address security issues.

How did you do? Two of these are true and two are false. If you got all four correct, congratulations. If you’ve never heard of these RFCs, perhaps it is time to do some additional reading.

Bonus Question:

True or False:
Neither Cisco nor Juniper devices are compliant with RFC 5841.

Join us Friday, June 25th at 11AM Pacific / 2PM Eastern for another installment in the Open Lecture Series.

The topic that will be covered is Privilege Levels and Role Based CLI.

We look forward to seeing you there. Seats are limited.

We will also be announcing the April Open Lectures here in the blog very soon. As always, thank you so much for choosing INE.

April 2, 2010 at 2 PM EST USA  - Volume 2 Lab 6

May 7, 2010 at 11 AM EST USA – Volume 2 Lab 7