Tuesday, March 4, 2008

Cisco CCNA Certification Exam Tutorial: Configuring Dialer Profiles

The most common method of configuring ISDN is with dialer maps, but dial information can also be configured on a logical interface. To pass the CCNA exam, you must know how to configure and troubleshoot both dialer maps and dialer profiles.

Dialer Profiles allow different dialing information to be configured onto logical interfaces. The logical interfaces may have different dialing destinations, different remote router names, etc., but they'll be using the same physical interface.

Dialer strings are used on dialer profiles. Note that each logical interface has a different IP address, a different remote router to dial, and a different dialer string, but they will be using the same physical interface to dial out. The commands dialer pool and dialer pool-member are used to link the logical and physical interfaces. The number following each command must match for the logical interface to correctly bind to the physical interface.

R1(config)#interface dialer0

R1(config-if)#ip address 172.16.1.1 255.255.255.0

R1(config-if)#encapsulation ppp

<. The encapsulation type is placed on both the logical and physical interfaces. >

R1(config-if)#dialer remote-name Remote0

R1(config-if)#dialer pool 1

< places logical interface into dialer pool >

R1(config-if)#dialer string 5551212

< number dialed to contact router Remote0 >

R1(config-if)#dialer-group 1

< links logical interface to dialer-list 1 >

R1(config)#interface dialer1

R1(config-if)#ip address 172.16.1.2 255.255.255.0

R1(config-if)#encapsulation ppp

R1(config-if)#dialer remote-name Remote1

R1(config-if)#dialer pool 1

R1(config-if)#dialer string 5551234

R1(config-if)#dialer-group 1

R1(config)#interface bri0

R1(config-if)#no ip address

< With dialer profiles, IP addresses are assigned to logical interfaces. >

R1(config-if)#encapsulation ppp

< The encapsulation type is place on both the logical and physical interfaces.>

R1(config-if)#dialer pool-member 1

< The number associated with this command should match the number configured with the dialer pool number on the logical dialer interfaces. >

R1(config-if)#isdn spid1 0835866101

R1(config-if)#isdn spid2 0835866301

When configuring dialer profiles, the encapsulation type should be placed on both the physical BRI interface and the logical dialer interfaces. The SPIDs are configured on the physical interface as well.

Configuring dialer profiles can be a little tricky at first, and the best way to master this skill is to get real hands-on practice in your own CCNA / CCNP home lab or a rack rental service. Either way, hands-on is the best practice. Best of luck in your CCNA studies!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Get your CCNA study guide from The Bryant Advantage!

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Tuesday, February 26, 2008

Cisco CCNA Certification Exam Tutorial: ISDN Details You Must Know

CCNA exam success depends partially on knowing the details of ISDN, and there are plenty of them! To help you review for your CCNA exam, here are a few ISDN details that you must know on exam day. (They help in the real world, too - and there are still plenty of ISDN networks out there!

The Cisco-proprietary version of HDLC is the default encapsulation type for serial and ISDN interfaces.

R2#show interface serial0

Serial0 is up, line protocol is up

Hardware is HD64570

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

While there's only one D-channel in BRI, PRI (US) and PRI (EU), the bandwidth of that D-channel does vary from BRI to PRI. It's 16 kbps in BRI and 64 kbps in both PRI versions.

The global command isdn switch-type must be configured before you can even begin to have ISDN work. show isdn status will tell you whether or not you've done this correctly.

R2#show isdn status

**** No Global ISDN Switchtype currently defined ****

ISDN BRI0 interface

dsl 0, interface ISDN Switchtype = none

Layer 1 Status:

DEACTIVATED

Layer 2 Status:

Layer 2 NOT Activated

Layer 3 Status:

0 Active Layer 3 Call(s)

PAP allows passwords to be different; CHAP requires that they be the same.

PAP requires the "ppp pap sent-username" interface-level command. CHAP has no equivalent command.

Define interesting traffic with dialer-list and link that list to the interface with dialer-group.

R2#conf t

R2(config)#dialer-list 1 proto ip permit

R2(config)#int bri0

R2(config-if)#dialer-group 1

The dialer idle-timeout value is expressed in seconds, not minutes. (Even IOS Help isn't totally clear on this.)

R2(config)#int bri0

R2(config-if)#dialer-group 1

R2(config-if)#dialer idle-timeout ?

<1-2147483> Idle timeout before disconnecting a call

R2(config-if)#dialer idle-timeout 120

Dialer map maps a remote IP address to a remote phone number. You never dial the local router's phone number.

dialer load-threshold requires the ppp multilink command to be configured, and the value of dialer load-threshold is expressed as a ratio of 255, NOT 100. For example, if you want the second b-channel to come up when the first reaches 50% of capacity, the value to express with dialer load-threshold would be 50% of 255 - which equals 127.

R2(config)#int bri0

R2(config-if)#encap ppp

R2(config-if)#ppp multilink

R2(config-if)#dialer load-threshold ?

<1-255> Load threshold to place another call

Success on the CCNA exam depends on knowing the details. Keep studying, keep practicing on real Cisco routers and switches, keep a positive attitude, and you're on your way to CCNA exam success!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Get your CCNA study guide from The Bryant Advantage!

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Friday, February 1, 2008

Cisco CCNP/BCMSN Exam Tutorial: Spanning Tree Protocol (STP) Timers

In your BCMSN / CCNP exam study, it's easy to overlook some of the details of Spanning Tree Protocol (STP). After all, you learned all of that in your CCNA studies, right? Not necessarily! While some of the BCMSN material will be a review for you, there are some details regarding familiar topics that you need to learn. That includes the timers for STP - Hello Time, MaxAge, and Forward Delay.

You may remember these timers from your CCNA studies as well, and you should also remember that these timers should not be changed lightly. What you might not have known is that if you decide to change any and all of these timers, that change must be configured on the root bridge! The root bridge will inform the nonroot switches of the change via BPDUs.

Hello Time is the interval between BPDUs, two seconds by default.

Forward Delay is the length of both the listening and learning STP stages, with a default value of 15 seconds.

Maximum Age, referred to by the switch as MaxAge, is the amount of time a switch will retain a BPDU's contents before discarding it. The default is 20 seconds.

The value of these timers can be changed with the spanning-tree vlan command shown below. Verify the changes with the show spanning-tree command.

SW1(config)#spanning-tree vlan 1 ?

forward-time Set the forward delay for the spanning tree

hello-time Set the hello interval for the spanning tree

max-age Set the max age interval for the spanning tree

priority Set the bridge priority for the spanning tree

root Configure switch as root

SW1(config)#spanning-tree vlan 1 hello-time 5

SW1(config)#spanning-tree vlan 1 max-age 30

SW1(config)#spanning-tree vlan 1 forward-time 20

SW1(config)#^Z

SW1#show spanning-tree vlan 1

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 000f.90e1.c240

This bridge is the root

Hello Time 5 sec Max Age 30 sec Forward Delay 20 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 000f.90e1.c240

Hello Time 5 sec Max Age 30 sec Forward Delay 20 sec

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

Fa0/11 Desg FWD 19 128.11 P2p

Fa0/12 Desg FWD 19 128.12 P2p

Again, you should always take great care in changing these timers. Those defaults are set for a reason - helping to prevent switching loops!
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, and The Ultimate CCNA and CCNP Study Packages. For a copy of his FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download copies! Our new RSS feed gives you free Cisco questions daily!

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Monday, January 28, 2008

Cisco CCNP / BSCI Exam Tutorial: ISIS Router Types

To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers - Level 1 (L1), Level 2 (L2), and L1/L2.

L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.

L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the same area must synchronize their databases with each other.

Just as we have L1 routers, we also have L2 routers. Anytime we're routing between areas (inter-area routing), an L2 or L1/L2 router must be involved. All L2 routers will have synchronized databases as well.

Both L1 and L2 routers send out their own hellos. As with OSPF, hello packets allow ISIS routers to form adjacencies. The key difference here is that L1 routers send out L1 hellos, and L2 routers send out L2 hellos. If you have an L1 router and an L2 router on the same link, they will not form an adjacency.

An ISIS router can act as an L1 and an L2 router at the same time; these routers are L1/L2 routers. An L1/L2 router can have neighbors in separate ISIS areas. The L1/L2 router will have two separate databases, though - one for L1 routes and another for L2 routes. L1/L2 is the default setting for Cisco routers running ISIS. The L1/L2 router is the router that makes it possible for an L1 router to send data to another area.

In the next part of my ISIS tutorial, we'll take a more detailed look at those ISIS hellos!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Get your CCNA study guide from The Bryant Advantage!

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Thursday, January 24, 2008

Cisco CCNA Exam Tutorial: Cisco Discovery Protocol (CDP)

The Cisco Discovery Protocol (CDP) sure looks simple enough, but there are quite a few details to know for success on the CCNA exam. In your CCNP studies, you'll be introduced to additional uses for CDP, but for now it's enough to know that CDP is designed to give you information regarding directly connected Cisco routers and switches.

CDP runs by default between all directly connected Cisco devices. CDP is also a Cisco-proprietary protocol - if the directly connected device is not a Cisco device, you won't see the information you wanted.

The basic CDP command to display information about the directly connected neighbor is "show cdp neighbor".

R2#show cdp neighbor

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port ID

R1 BRI0 167 R 2521 Dialer1

This command is particularly helpful when troubleshooting Cisco switches. There's no need to trace wiring in a rack of Cisco devices to see what routers are connected to a Cisco switch when show cdp neighbor can be used. In the above output, you can see the remote device's hostname, what interface on the remote device is connected to the local device, the capability of the remote device, the remote device's hardware platform, and the local interface that is connected to the remote device.

CDP can be disabled at both the global and interface level. To disable CDP at the interface level, run no cdp enable on the interface, and cdp enable to turn it back on.

cdp timer defines how often CDP packets are transmitted, and cdp holdtime defines how long a device will hold a received packet.

To turn CDP off for the entire router, run no cdp run. To view the current global status of CDP, run show cdp.

R2#show cdp

Global CDP information:

Sending CDP packets every 60 seconds

Sending a holdtime value of 180 seconds

CDP is running by default.

R2#conf t

R2(config)#cdp timer 45

R2(config)#cdp holdtime 100

The CDP timers are changed.

R2#show cdp

Global CDP information:

Sending CDP packets every 45 seconds

Sending a holdtime value of 100 seconds

The CDP values have been successfully changed. "show cdp interface" will give the timer information for each interface on the router.

R2#conf t

R2(config)#interface bri0

R2(config-if)#no cdp enable

CDP is disabled on the BRI interface. This does NOT have to be done to keep the line from dialing.

R2#conf t

R2(config)#no cdp run

CDP is disabled globally.

R2#show cdp

% CDP is not enabled

CDP has been successfully disabled.

Show cdp neighbor gives you a great deal of information, but what if you need the neighbor's IP address? Just run show cdp neighbor detail. You will get even more information about that directly connected neighbor, including its IP address.

SW2#show cdp neighbor detail

 

Device ID: R4

Entry address(es):

IP address: 172.12.23.4

Platform: cisco 2520, Capabilities: Router

Interface: FastEthernet0/4, Port ID (outgoing port): Ethernet0

Holdtime : 158 sec

The details of CDP are important to you on the job and in the CCNA exam room. When you find yourself negotiating a badly documented network, you can use CDP to "walk" through the network and create a network map for your client as well. Sometimes the simplest protocols are the most helpful!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage , home of free CCNA and CCNP tutorials! Pass the CCNA exam with Chris Bryant!

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Wednesday, January 23, 2008

A Night In San Francisco

When traveling to most cities of the world, finding discount accommodations when arriving to your destination is always a possibility. Not so in the diverse and complex city of San Francisco. From the hills of Daly City to the plains of Berkeley, the environments and people are so diverse that your vacation could with one dial of the phone be a paradise made in heaven or an inferno designed in, well you know, that other place.

Families making their hotel reservations at the smaller hotels that dot the periphery of San Francisco might be able to land a bargain, but find they may find themselves sharing accommodations with other crawling critters that would make even the toughest among us parents squirm.

I did this once. I came to San Francisco on a budget and thinking to wing my accommodations; I found a phonebook and booked a motel for $59 a night. Well, the minute I saw the hotel along a poorly lit side street I knew we were in trouble. This hotel was something I would expect to see in medieval Europe, not in actuality. But it was late and we succumbed to our basal instincts for sleep and it was ?just one night.? But the bed was so grimy we actually slept on the floor, and the occasional voices we heard in the alleys were so hair razing I don?t think sleep was an option for any of us - and we were in their ?best room!?

The next day I called numerous hotels in San Francisco city proper. You know, where the Trolley Cars roam and the street performers perform. I found a number of places, ranging from the low 100?s and going up to the high 600?s. We got in our car to make our investigation and inspected one hotel after the other, some dark and dank and some bright and classic. We settled on the Grant Plaza Hotel at $180 a night. We had a rollaway brought for my two children and spent the rest of the day recuperating for our previous nightmare.

That evening, we ventured out to walk around the Streets of San Francisco and I must tell you it was scary. There were destitute people lurking at every doorway, down every alley, sleeping above the street vents for warmth. This was a haven for the homeless and I am not sure where the tourist fits in. It was both sad and a frightening, especially since coming from an isolated small town in Minnesota. I passed out quarters to those asking as if I were passing out flyers for a corner store.

We eventually found a Starbuck near Union Square and quickly ducked in. After a family meeting to discuss our situation, we decided to catch a trolley car and make a dash to the famous Fisherman?s Wharf and Ghirardelli?s Square. We scampered out of Starbucks and caught the next trolley. It was a wild ride straight up and straight down a city built on a mountain. We all screamed with joy. We spent an enchanting evening among all the tourist shops, street performers and family attractions that populate Fisherman?s Wharf. We bought a big pound of fudge at a fudge shop and drank coke and champagne until late in the evening.

Our lesson from all this, at least regarding San Francisco hotel reservations, make your hotel reservations in advance. Don?t waste time looking for a hotel room when you get there, the city is just too big. Since writing this, we went to San Diego. I booked all our accommodations off the Internet which featured discount hotel reservations with pictures and prices clearly explained. Welcome to the 21st century.


Douglas Anchel travels the USA in search of discount hotel reservations and accommodations and writes for All Reservations, Travelviva and World Accommodations

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Friday, January 11, 2008

Cisco CCNA Exam Tutorial: Using Trivial File Transfer Protocol (TFTP)

One of the first things you do when you start studying for the CCNA exam is memorizing a list of port numbers and the protocols that run on those ports. If you're an experienced networker, you know most of the protocols that are mentioned - DNS, DHCP, FTP, SMTP, and so on. But there's one protocol that you might not have experience with, but is actually vital for CCNA exam success and success in working with Cisco routers and switches, and that's TFTP - Trivial File Transfer Protocol.

TFTP is basically FTP's non-secure relative. There are no passwords, no authentication scheme, no nothing! As someone once told me, "If I'm transferring my files, there's nothing 'trivial' about it."

Great. So you?re thinking, ?What the heck do we use TFTP for, anyway??

TFTP is used in the Cisco world to perform IOS upgrades and to save configs to a TFTP Server. Cisco routers can themselves serve as TFTP servers, or you can use a workstation to fill that role.

If you needed to copy an IOS image to a router, for example, you could do so easily by connecting your PC to the router?s console port (via a rollover cable, right?). Your PC would need to run TFTP server software. There are quite a few free TFTP server software programs that work quite well ? just enter ?free tftp server? into Google or your favorite search engine and you?ll see what I mean.

Using TFTP in this fashion is a great way to have backup copies of IOS images or router configs right on your laptop. And take it from me, when the day comes that you need those backups, you?ll be glad you did!

Remember that when using the copy command, you first indicate where you?re copying from, then where you?re copying to:

R1#copy flash tftp

Source filename []? Example

Address or name of remote host []?

When performing such a copy, you?ll need to name the file you?re copying, as well as the IP address of the device you?re copying to.

Using TFTP to perform IOS upgrades takes a little getting used to, especially the syntax of the copy command. But knowing that syntax and how to use TFTP will indeed get you one step closer to the CCNA!



Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Pass your CCNA exam with The Bryant Advantage!

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Sunday, January 6, 2008

Cisco CCNA Exam Tutorial: Password Recovery Procedures

It might happen on your CCNA exam, it might happen on your production network - but sooner or later, you're going to have to perform password recovery on a Cisco router or switch. This involves manipulating the router's configuration register, and that is enough to make some CCNA candidates and network administrators really nervous!

It's true that setting the configuration register to the wrong value can damage the router, but if you do the proper research before starting the password recovery process, you'll be fine.

Despite what some books say, there is no "one size fits all" approach to Cisco password recovery. What works on a 2500 router may not work on other routers and switches. There is a great master Cisco document out on the Web that you should bookmark today. Just put "cisco password recovery" in your favorite search engine and you should find it quickly.

The following procedure describes the process in recovering from a lost password on a Cisco 2500 router. As always, don't practice this at home. It is a good idea to get some practice with this technique in your CCNA / CCNP home lab, though!

The password recovery method examined here is for 2500 routers.

An engineer who finds themselves locked out of a router can view and change the password by changing the configuration register.

The router must first be rebooted and a "break" performed within the first 60 seconds of the boot process. This break sequence can also vary depending on what program is used to access the router, but is the usual key combination.

The router will now be in ROM Monitor mode. From the rom monitor prompt, change the default configuration register of 0x2102 to 0x2142 with the o/r 0x2142 command. Reload the router with the letter i. (As you can see, ROM Monitor mode is a lot different than working with the IOS!)

This particular config register setting will cause the router to ignore the contents of NVRAM. Your startup configuration is still there, but it will be ignored on reload.

When the router reloads, you'll be prompted to enter Setup mode. Answer "N", and type enable at the router> prompt.

Be careful here. Type configure memory or copy start run. Do NOT type write memory or copy run start!

Enter the command show running-config. You'll see the passwords in either their encrypted or unencrypted format.

Type config t, then use the appropriate command to set a new enable secret or enable password.

Don't forget to change the configuration register setting back to the original value! The command config-register 0x2102 will do the job. Save this change with write memory or copy run start, and then run reload one more time to restart the router.

This process sounds hard, but it's really not. You just have to be careful, particularly when you're copying the startup config over the running config. You don't want to get that backwards! So take your time, check the online Cisco documentation before starting, get some practice with this procedure with lab equipment, and you'll be ready for success on the CCNA exam and in your production network!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Pass your CCNA exam with The Bryant Advantage!

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Thursday, December 27, 2007

Cisco CCNP Exam Tutorial: Defining Collision Domains

CCNA exam success depends on mastering the fundamentals, and two important fundamentals are knowing exactly what the terms "collision domain" and "broadcast domain" mean. In this free Cisco tutorial, we'll take a look at the term "collision domain" and how a collision domain is defined.

A collision domain is an area in which a collision can occur. Fair enough, but what "collision" are we talking about here? We're talking about collisions that occur on CSMA/CD segments, or Carrier Sense Multiple Access with Collision Detection. If two hosts on an Ethernet segment transmit data at exactly the same time, the data from the two hosts will collide on the shared segment. CSMA/CD exists to lessen the chances of this happening, but collisions can still occur. To lessen the chances of collisions occurring, we may decide to create multiple, smaller collision domains.

Let's say we have four hosts on a single Ethernet segment. The entire segment is a collision domain; any data sent by one of the hosts can collide with data sent by any of the other hosts. We have one collision domain containing four devices.

To create smaller collision domains, we'll need to introduce some type of networking device into this example. Hubs and repeaters have their place as far as extending the reach of a network segment and cutting down on attenuation, but these OSI Layer One devices do nothing to define collision domains. We could connect each host into a separate port on a hub (a hub is basically a multiport repeater) and we'd still have one single collision domain with four hosts in it.

The most common and most effective way to create multiple collision domains is to use a switch. If we connect each of these four hosts to their own separate switch port, we would now have four separate collision domains, each with one host; each switch port actually acts as a single collision domain, making collisions between these four hosts impossible.

Passing the CCNA is all about knowing the details of how things work, and knowing CSMA/CD theory and how to define collision domains is one of the many details you've got to master. In the next part of this CCNA tutorial, we'll take a look at broadcast domains, and how defining broadcast domains in the right places can dramatically cut down on unnecessary traffic on your network.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, and The Ultimate CCNA and CCNP Study Packages. For a copy of his FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies!

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Tuesday, October 23, 2007

Cisco CCNP/BSCI Certification: BGP Route Reflector Tutorial

When you're studying for your BSCI exam and CCNP certification, you quickly realize that BGP is a whole new world from anything you've previously studies. One topic that sometimes confuses CCNP candidates is when a BGP route reflector needs to be configured. Route reflectors are an excellent workaround for a basic rule of BGP route advertisement that we?ll review in just a moment.

In the following example, the routers R1, R2, and R3 are all in BGP AS 100. This is not a full mesh, however. There are peer relationships between R1-R2 and R1-R3, but not between R2 and R3. R3 is advertising network 3.3.3.0/24 via BGP, and the route is seen on R1. R1's iBGP neighbor, R2 does not see the route, nor would any other iBGP neighbors of R1. Why?

A basic rule of BGP is that a BGP speaker cannot advertise a route to an iBGP neighbor if that route was learned from another iBGP neighbor. Configuring R1 as a route reflector will allow us to circumvent this rule. The entire route reflector process is transparent to the clients, and no configuration is necessary on those clients. We'll configure R1 as a route reflector for both R2 and R3.

R1(config)#router bgp 100

R1(config-router)#neighbor 172.12.123.2 route-reflector-client

3d18h: %BGP-5-ADJCHANGE: neighbor 172.12.123.2 Down RR client config change

R1(config-router)#neighbor 172.12.123.3 route-reflector-client

3d18h: %BGP-5-ADJCHANGE: neighbor 172.12.123.3 Down RR client config change

The BGP adjacencies do come down when this configuration is added, so this isn't something you want to do during a peak traffic time.

Once the adjacencies come back up, R2 will have the route to 3.3.3.0/24.

There are other possible solutions to this iBGP limitation, such as configuring BGP confederations. Those solutions are generally used on larger BGP deployments and with other concerns in mind, though, and configuring route reflectors serves this purpose just as well.


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, ?How To Pass The CCNA? and ?How To Pass The CCNP?, visit the website and download your free copies. Get your CCNA certification with The Bryant Advantage!

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Monday, October 22, 2007

San Francisco

The updated edition of the free Access San Francisco guide for travelers with disabilities is now available. The 34-page book offers detailed information about 150 city venues and travel services that have accessible facilities that have been inspected by an ANC access specialist. These include hotels, restaurants, museums, attractions, shopping centers, recreation facilities, public transportation and others. Inspection notes which add extra insight have been included for clarification. For example, one note states, Path of travel from the street to the entrance is rough paving. Contact: 415-391-2000, (TDD) 415-392-0328

The Baylink Ferry Service has expanded its fleet with the addition of the M/V Solano, a high-speed 135-foot catamaran which ferries 300 passengers between Mare Island in Vallejo, San Franciscos Ferry Plaza at Market and Embarcadero, and Pier 41 at Fishermans Wharf. The trip operates daily. Contact: 877-643-3779.

The San Francisco Museum of Craft+Design has opened at 550 Sutter Street. It offers innovative exhibits and educational programs which celebrate the art and artists of contemporary craft and design. The museum features works in progress and displays showing design trends. It also hosts visiting featured exhibitions and artists. Contact: 415-773-0303, www.sfmcd.org

The Asian Art Museum invites visitors to view its copies, cracks, do-it-yourself fix-its and other imperfections among pieces in collections. The Fakes, Copies, and Question Marks: Forensic Investigations of Asian Art exhibit is part science lesson and part crime scene investigation by examining the authenticity of artworks through forensic testing to reveal the sometimes inexact science of classifying art. The exhibit artifacts are drawn primarily from the museums own collection.

Tibet: Treasures from the Roof of the World, June 12-Sept. 11, features nearly 200 sacred objects from the Potala and Norbu Lingka palaces in Tibet. This exhibition offers a rare insight into the artistic and spiritual traditions of the Dalai Lama and his followers. Contact: 415-581-3500

Del Monte Square, located near Fishermans Wharf, is the site of what was once the worlds largest fruit and vegetable cannery which was operated under the Del Monte name starting in the 1920s. The historic buildings are now home to the Argonaut Hotel, The Visitor Center of the San Francisco Maritime National Historic Park, THE CANNERY and a year-round Certified Organic Farmers Market. The renaming of this area honors the roots of this historic site and celebrates early San Francisco commerce and the influence of the Del Monte company. Throughout the complex are displays and landmark signs that describe various aspects of Del Monte Squares history. Events with historical themes are also planned. Contact: 415-771-3112

Amusing America is at the San Francisco Museum and Historical Societys Mus?e M?canique located at Pier 45 at Fishermans Wharf. This free exhibition tells the story of amusement parks found in American cities including San Francisco and how they influenced the lives of many, from the Gilded Age of the 1880s and 90s to World War II. Displays feature many artifacts including the familiar Laughing Sal, an oversized mechanical manikin which greeted visitors to the citys Playland-at-the-Beach. Antique games which were features of various amusement parks, arcades, swimming baths and dance pavilions are also displayed. Contact: 415-537-1105

Day at the Bay, a popular San Francisco entertainment group, has introduced an all-new cabaret program called A Musical Stroll Along Broadway. The program is filled with music, comedy and lots of nostalgia. The package includes the cabaret show plus lunch options at venues featuring a classic Chinese meal or a Greek feast. After the show, docents lead tours to interesting area sites. This is the perfect package for a day trip or mystery trip. Contact: 415-491-4908.

Vampires are not just for Halloween. Vampire Tours of San Francisco offers spooky tours of the gothic side of Nob Hill. The tour guide is Mina Hacker, the vampiress who was made by Count Dracula in 1897 and who has resided in the darker part of this city for over 100 years. She beckons visitors in a fun and entertaining way into the world of vampires and tells tales of their influence in shaping San Francisco as we know it today. Contact: 650-279-1840.

This article is sponsored by: www.grouptravelblog.com

We are in travel business and wants to provide information about the different travel destinations of united states of america.

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Thursday, October 4, 2007

Cisco CCNA / CCNP Certification: Deciphering Ping Results

As you study for your CCNA and CCNP exams, particularly if you're getting hands-on practice in your home lab or rack rental service, you're going to be sending a lot of pings. As a CCNA or CCNP candidate, you know that five exclamation points (!!!!!) as a ping return indicates that you have IP connectivity to the remote destination. Five periods (.....) indicates that you do not have that connectivity.

It's not enough to know that you don't have IP connectivity to the remote device, you've got to know why. Ping is a great first step to network troubleshooting, but the results are quite limited. As a CCNA and CCNP, you've got to know how to diagnose the problem and resolve it. Just looking at the routing table is not enough - a high-powered Cisco debug, debug ip packet, can often show you exactly where the problem is.

WARNING: debug ip packet should not be run on any production router without understanding the effect of this command on your router. This command results in a lot of output and can actually lock up a router.

In this case, we'll run the command on a home lab router that cannot ping 22.2.2.2. The debug will be turned on and another ping sent.

R1#debug ip packet

IP packet debugging is on

R1#ping 22.2.2.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 22.2.2.2, timeout is 2 seconds:

3d23h: IP: s=1.1.1.1 (local), d=22.2.2.2, len 100, unroutable.

R1#undebug all

All possible debugging has been turned off

I've edited this output for clarity; the important word is "unroutable". This indicates that the packet is not leaving the router because there is no match in the routing table for this destination. We'll configure a static default route and send the ping again.

R1#ping 22.2.2.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 22.2.2.2, timeout is 2 seconds:

U.U.U

Success rate is 0 percent (0/5)

That output may surprise those of you who are used to getting five of the same symbol back whenever you send a ping. We got three "U"s back along with two periods. We'll now run debug ip packet and send the ping again.

R1#debug ip packet

IP packet debugging is on

R1#ping 22.2.2.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 22.2.2.2, timeout is 2 seconds:

3d23h: IP: s=172.12.123.1 (local), d=22.2.2.2 (Serial0), len 100, sending

R1#traceroute 22.2.2.2

Type escape sequence to abort.

Tracing the route to 22.2.2.2

1 172.12.123.2 36 msec 36 msec 36 msec

2 172.12.123.2 !H * !H

R1#undebug all

All possible debugging has been turned off

Again, I've edited this output. The key word in this output is "sending", meaning that the packets are leaving the router. The ping return of "U.U.U" is a general indication that the packets are indeed being transmitted, but that a downstream router is having a problem routing the packets. Running traceroute reveals some more interesting return characters! In this case, the downstream router did not have a match for the destination in its routing table.

It's easy to concentrate on the local router when you're not getting positive ping returns. When troubleshooting this kind of issue, keep in mind the problem could be on an intermediate router and not on the local router. Use debug ip packet to make sure the packets are leaving the local router, and traceroute to determine what downstream router may have the problem. And get used to the fact that pings and traceroutes can give you some unusual-looking returns!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Earn your CCNA certification with The Bryant Advantage!

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Friday, September 28, 2007

Cisco CCNP / BSCI Tutorial: Comparing OSPF And ISIS Hellos

While studying to pass the BSCI exam and preparing to earn your CCNP certification, you'll quickly notice that while OSPF and ISIS are both link-state protocols, there are a lot of differences between the two. One major difference is the way the two protocols handle hello packets.

Hello packets are imperative to keeping OSPF and ISIS adjacencies alive. Since they are both link-state protocols, neither of them will send updates at any specified time. Hello packets are the only method by which routers running OSPF and ISIS can see that a neighboring router is still available.

OSPF gives us some great options when it comes to keeping routing table size down via the use of stub and total stub areas, but to OSPF, a hello packet is a hello packet. ISIS routers are capable of sending two different types of hellos - Level 1 and Level 2.

ISIS routers are classified as Level 1 (L1), Level 2 (L2), and Level 1-2 (L1-L2). By default, Cisco routers are L1-L2 routers; this means that every ISIS-enabled interface will send out both L1 and L2 hellos.

If one of the interfaces is forming only an L1 or L2 adjacency, there's no reason to send out hellos for the other adjacency type. For example, if R1 is forming an L1 adjacency with R2 via its ethernet0 interface, there is no reason to allow the router to transmit L2 hellos. To hardcode a router interface to send only L1 or L2 hellos, use the isis circuit-type command.

R1(config)#interface ethernet0

R1(config-if)#isis circuit-type level-1

Note: To configure this interface to send only L2 hellos, the full command is "isis circuit-type level-2-only", not just "level-2".

This configuration would prevent L2 hellos from being transmitted out ethernet0. While this does save router resources and prevents unnecessary bandwidth usage, there is also no way an L2 adjacency can be formed - so double-check your network topology before using this command!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials! For my FREE "How To Pass The CCNA" or "CCNP" ebook, visit the website and download your copies. Earn your CCNA certification with The Bryant Advantage!

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Thursday, August 30, 2007

Cisco Certification: How To Build Your Own Home Lab

CCNA and CCNP candidates hear it all the time: Get some hands-on experience. From my personal experience climbing the Cisco certification ladder, I can tell you firsthand that there is no learning like hands-on learning. No simulator in the world is going to give you the experience you will get cabling and configuring your own routers.

Whenever I mention this to one of my students, they always say it costs too much. The truth is, it is cheaper now to build your own CCNA and CCNP lab than it has ever been. The secret? Used routers.

The word used turns off a lot of people not many of us buy used computers or used servers. Cisco routers, though, are robust. I personally own a Cisco 4000 router that I use as a Frame Relay switch in my lab that Ive had for about four years, and Ive never had a problem with it.

The good news for current CCNA and CCNP candidates interested in building their own labs is that used Cisco equipment has never been more plentiful or cheaper. eBay is a good way to get an idea of whats out there and what the prices are, but you dont have to assemble your lab one piece at a time. Many eBay vendors who sell used Cisco equipment sell ready-made CCNA and CCNP labs for one price, including cables.

I asked one major vendor of CCNA and CCNP labs, www.ciscokits.com, what the most common questions are regarding building your own home lab. Heres what they had to say:

Why do I need real routers instead of a simulator?

You need a physical router,as the simulators just dont have the ability to give you the hands on you need to see what happens when you disconnect a cable or put a cable in the wrong location. You will come to find quickly that mistakes you make on Router 1 are affecting Router 5 all because you did not screw in a cable properly. No simulator can simulate that.

How many routers do I need?

Two routers really are required to see if anything works. If you have a very limited budget, you can receive value from only purchasing a single router over working with a simulator. However, you will not be able to see the main thing we are trying to accomplish. The propagation of route tables!

The only way you can see if your configurations work, is to have at least two routers. Therefore, I strongly recommend that you purchase a dual router kit that comes with all the accessories you need. Otherwise you can spend days trying to find all the little extra pieces you need to get your lab up and running.

Do I need a switch?

Well, it is nice to have. However, with only about 2 questions on the test dedicated to hands on switch knowledge, if you have to skimp on something, skimp on the switch.

What routers and switches should I buy?

Choices, choices, choices! Which 2500/2600 router do I pick? I will list some pros and cons of each router below, along with current prices (note that prices are generally lower if you buy a dual router kit instead of a single router). Please note that prices are approximations.

1) Cisco 2501 Router with 16 MB Flash/16MB DRAM $94.99. The cheapest introduction router, and it can support a vast majority of the commands that you will need to learn for your CCNA test. All 2500 routers that we will discuss come with a minimum of two serial ports and an Ethernet port.

You will need to add a transceiver to this unit to convert the Ethernet AUI port to an RJ-45 style Ethernet port.

2) Cisco 2503 Router with 16 MB Flash/16MB DRAM $119.99. This is the same as a Cisco 2501, except it adds an ISDN port so you can complete all your ISDN commands for the CCNA test. You will need to add a transceiver to convert the Ethernet AUI port to an RJ-45 style Ethernet port.

3) Cisco 2505/2507 with 16 MB Flash/16MB DRAM $109.99. The same as a Cisco 2501 except it has a built-in 8 or 16 port hub so you do not have to purchase a transceiver.

4) Cisco 2514 Router with 16 MB Flash/16MB DRAM $149.99. This router is the same as a Cisco 2501 except instead of one Ethernet port you have two. You may ask, what is the big deal? Well, you can use this as your Cable Modem/DSL Modem router. Now you can test your ability to setup a firewall and router in a live environment on the Internet. Lots of fun! You will need to add two transceivers to convert the Ethernet AUI ports to an RJ-45 style Ethernet ports.

5) Cisco 2520 Router with 16 MB Flash/16MB DRAM $119.99. This is the same as a 2503 but it also adds two more serial ports so you can use this as a frame relay switch later in your CCNA studies. It costs the same as a 2503, so this is a great money saving tip.

6) Cisco 2612 Router with 32 DRAM and 8 MB Flash $199.99. This is a modular router unlike any of the 2500 series routers. So the big benefit of this is you can buy extra modules to add functionality such as more serial ports, ISDN ports, Ethernet ports, WICs and such. However, due to the flexibility you will pay a bit more. One day it is a frame relay switch, the next it is your ISDN router. In the long run it will be cheaper than purchasing a bunch of dedicated routers for each

discipline you want to learn.

7) Cisco 1912 or 1924 Switch with Enterprise Software $109.99. This is a good low cost switch. The only drawback is it is a 10 MB switch except for the two 100 MB uplink ports. Not a big deal since you have 10 MB routers.

8) Cisco 2912 or 2924 Switch with Enterprise Software $249.99. This switch will run all the current commands needed for the test and is a full 100 MB switch.

And should you desire to sell your lab after you complete your certification, you can either negotiate a price with the vendor who sold it to you, or you can sell it yourself on ebay. Its my experience that 95% of candidates who earn their CCNA go on to pursue their CCNP within one year, though, so dont sell it too quickly.

In the end, you spend only a few hundred dollars, and you gain invaluable experience and knowledge that will help you both in your certification quest and your job performance. Having worked my way from the CCNA to the CCIE, I can tell you that you will learn much more from actually configuring and cabling your own equipment than you ever will from any simulation of the real thing.

To your success,

Chris Bryant
CCIE #12933

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage. The Bryant Advantage's website offers FREE ebooks and tutorials for the CCNA and CCNP exams, FREE subscriptions to "Cisco Certification Central", and sells the best CCNA and CCNP prep courses and books on the market today. Visit his site at www.thebryantadvantage.com today!

chris@thebryantadvantage.com

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