Thursday, March 19, 2009

CCNA Certification: Three Occasions To Reload Or Reopen A Cisco Router Interface

Passing the CCNA certification exam means that you know how to configure and troubleshoot a Cisco router instead of using what I call the "hope method" - you know, "Let's reload the router and hope that takes care of it." The majority of Cisco router configurations take effect without the need for a reload, but every once in a while you just have to reload a router or shut and reopen an interface. Let's take a look at three such scenarios.

The first is when you change an OSPF Router ID from its default. For the new RID to take effect, you must either reload the router or clear the OSPF process, which means that all existing adjacencies will come down. Cisco routers are kind enough to tell you this with the following message after you configure a new RID: "Reload or use "clear ip ospf process" command, for this to take effect".

In a previous tutorial, I showed you how to configure an Etherchannel. You have to place each port into the Etherchannel with the channel-group command, and if you do so individually, some of the ports may go into error-disabled state, or "err-disable". This can also happen as a result of port security enforcement. You can see this with the show interface command:

sw1#show int fast 0/1

FastEthernet0/1 is down, line protocol is down (err-disabled)

A syslog message putting that port into err-disabled state will look like this:

04:10:23: %PM-4-ERR_DISABLE: channel-misconfig error detected on Po1, putting Fa0/1 in err-disable state

If this happens during an Etherchannel configuration, just finish the config and then shut and reopen the ports in err-disabled state. They'll come back up and be placed into the Etherchannel.

Finally, our old friend the SPID often makes us shut and reopen the BRI interface. If the BRI interface is open and you configure SPIDs on it, the SPID can be absolutely correct and you'll still see this in the output of show isdn status:

spid1 configured, spid1 NOT sent, spid1 NOT valid

At least the Cisco router puts "NOT" in caps, right? It's easier to see that way! With SPIDs, before you call the service provider or check the SPID you entered about 40 times, just shut and reopen the interface. That usually does the trick.

When you earn your CCNA certification, that means that you know what you're doing instead of hoping that you do - and part of that knowing is knowing when a simple reload or open/shut will take care of the issue.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 200 free certification exam tutorials, including CCNA certification training articles. His exclusive CCNA study guide is also available!

Visit his blog and sign up for Cisco Certification Central, a daily newsletter packed with CCNA, Network+, Security+, A+, and CCNP certification exam practice questions! A free 7-part course, ?How To Pass The CCNA?, is also available, and you can attend an in-person or online Cisco CCNA training boot camp with The Bryant Advantage!

 

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Thursday, February 12, 2009

California Dreaming on Highway One from San Francisco to Lose Angeles

As a teenager in the mid-sixties I was greatly inspired by the music of the Beach Boys. One balmy evening during the summer of 1964 I was stirred by the driving tempo of I Get Around by a group I'd never heard of blasting from the huge old bakelite valve-driven radio that dominated my bedroom. It was during those times when, against the British government?s wishes, every teenager was tuned to Radio Caroline, broadcasting illegally from an old coaster moored somewhere out on the North Sea. I?d heard nothing like this before. It was certainly beyond the play lists of Auntie BBC and her tedious Home Service! I was hooked, not only to the vibrant, close harmonies and falsettos of the vocals but by the very images the lyrics portrayed of sun, sand, striped-shirt freedom and long=legged bikini clad girls. Flower power, love-ins, peace movements and the whole Haight-Asbury thing followed. Then, in 1969, Pirelli published their highly collectible California calendar, containing evocative close-up images by photographer Harry Peccinotti of beautiful sun tanned Californian maidens. By modern standards the photographs were very tame, more like snapshots. Nevertheless that calendar re-enforced a yearning to visit California because it seemed the best place on earth. My vision was of stunning blond California girls, a youth culture driving Chevrolet Corvette Stingrays and a wild freedom that seemed unknown to teenaged Britain.

For various reasons, ok I?ll be honest ? a lack of funds, forced me to wait a decade before I managed to realize my dream and by this time LA, Carmel, Santa Monica, Santa Cruz and San Francisco had become household names through the lyrics of a continuous stream of hit songs by The Beach Boys, Eagles, Jan and Dean and The Mamas and Papas, California Dreaming really had become something of a reality. By the time I arrived in the City of Angels aboard a TWA westbound seven-forty-seven and things were every bit as I imagined. Once bitten, I was smitten and vowed to return as soon as I could. But it took more than twenty years, but with the love affair still intact, I was going back. Maybe I?d become an ageing hippie still listening to those melodic surfin? sounds that had continued to drive my mind through all of these years. Previously I?d flown from San Francisco to LA this time I was going to do things for real by driving the Pacific route between the two largest cities along California State Highway One.

Despite claims that the USA lacks culture, nobody can deny that what it does have is scenery ? huge, mind blowing scenery such as Yosemite, the Grand Canyon and Zabriski Point. California?s Pacific coast similarly does not go begging. It is where nature competes with itself for superiority along rugged cliff tops that rise and fall against the might of the great ocean; mist encrusted mountains against mighty sequoia forests. The Pacific is everything the Atlantic lacks. It can be wilder, more belligerent; the breakers tend to roll higher making it, sometimes a surfer?s paradise, at others a seafarer?s grave. California, despite an element of confident brashness, has always appealed more for its natural untamed beauty than say the tourism evoked retirement condominiums of Florida on America's opposite coast.

Many claim that Highway One is best tackled north to south. Route One really beings at Legett where the road clings tightly to the ocean for nearly 150 salt splashed miles as it passes close to the giant redwoods at Muir Woods before becoming US 101, the Golden Gate freeway, and crossing the magnificent, often fog enshrined, bridge of the same name. Most don?t bother with the first part, choosing to join the route at San Francisco and continuing at a gentile pace with a stop or two before reaching the congestion rush of greater Los Angeles. If you?re in a hurry, then the 400 mile drive can comfortably be made in a day although there?s little point in missing the enormous potential it offers. It?s best to stop and linger a while if you can. The West Coast can be chilly, often hemmed in by coastal fogs held in by the mountains, despite this you?ll still feel at one with the elements and it's best driven in an open-top sports car. I didn?t but, but should have and I regret that I didn?t!

San Francisco is a beautiful city of over six million and a delicate charm of its own, especially where the palatial Victorian homes have survived a series of earthquakes. There?s Lombard Street, short but steep, rising 27 degrees through a series of eight hairpins that twist and turn forcing a cars to proceed at a snail?s pace. Some of the main streets reach 300 feet at Pacific Heights before dropping through amazing gradients to the Marina District below. As you top each crest you?ll be transformed and in your minds-eye you are Steve McQueen playing Bullitt flooring the accelerator of that throaty Shelby-Mustang and bouncing over those bumps at breathtaking speed as you fight to tame this out-of-control beast. In reality you?ll take it slow, real slow, fearing the consequences should your brakes fail! A more sober way is to take the cable car from Nob Hill to the Bay and watch the floor show performed by the driver and his agile grip man as they work together to traverse the undulating tarmac. These days the cable cars are usually packed with tourists and it can be hard to get a ride.

Once more in the real world I start my journey at Fisherman?s Wharf, the trendy waterside area of good fish restaurants, a waxworks and tourist shops that compete with a fine view of the Bay. Alcatraz Island, the former penal establishment that is now a crumbling State Museum, stands formidably in turbulent waters three miles east of the Golden Gate. This, for seventeen years, was the home of Robert Stroud the infamous Bird Man but he was never the gentile ornithologist Bert Lancaster portrayed. It was also where Al Capone was finally caged up for, of all things, tax evasion.

Leaving behind the squawking sea lions feeding off restaurant scraps at one of the piers, I head south leaving the city behind, past San Francisco International Airport and some of the wealthy outlying suburbs. The car radio informs me that ?It?s going to be a fine day right across the whole of the Bay Area and there are no reported traffic snarl ups?. That?s good to hear because only weeks before floods had caused landslides that were still keeping the coast road closed until twenty miles south at Half Moon Bay. Between here and Ano Nuevo lie a number of State beaches renowned for their outstanding natural beauty. This is where the northern elephant seals and sea lions come to breed or just to wallow lazily in the sun. This was March however and the beaches were deserted.

For much of the way the route is a two-lane blacktop ? no dual carriageway, just a well maintained twin-lane tarmac highway that clings heroically around the cliff tops that tower and fall above the Ocean. I am surprised at so little traffic, most of the locals preferring to take highway 101, a faster route that meanders on an almost parallel inland course for most of the way. Better still I haven?t seen a single cop. But beware, I am told they patrol from low flying helicopters (bears in the air) so I watch my speed and although I try to keep to a steady 55mph my instincts push me to go ever faster.

The highway runs via Pescadero where there is a lighthouse built in 1872, then onward to the seaside resort of Santa Cruz on the northern point of Monterey Bay. A further 28 miles south around the coast and I reach the old Spanish town and former Californian capital. Monterey, a town made famous by John Steinbeck in his novels Cannery Row and Tortilla Flat. The old sardine canneries are now long closed but the buildings have been transformed into trendy shops and restaurants. There is also an excellent aquarium. Beyond the beach, in waters stretching 110 miles out to sea is the Monterey National Marine Sanctuary, containing the largest underwater cavern anywhere in offshore US.

I didn?t have sufficient time to take the 17 mile drive but if you do it starts just south at Pacific Grove, ends at Carmel and passes the world class golf courses at Pebble Beach and Spyglass Hill. Although you pay for the privilege, those that have taken the detour say that the beauty of the drive, much of it man-made, is exceptional. Instead, I remain on Highway One and head for Carmel, home of Clint Eastwood, aka Dirty Harry and the former mayor. He wasn?t about. At least he wasn?t driving the West Coast. The city dates back to 1770 when a Franciscan monk, Father Juniperro Serra built a mission and church. Although it fell into disrepair after being abandoned in 1834, the Mission, one of several along the coast, has been carefully restored.

South of Carmel is a truly wonderful stretch of coastline that runs almost a 100 miles below the Ventana Wilderness, part of the Los Padres National Forest. This is Big Sur, a mood-inspiring rocky, wild area of State Parks and exceptional natural beauty. I Linger for a while just listening to the breakers crashing against the rocks before continuing, crossing the Bixby Creek Bridge, once the world?s longest single-arch span at 550 feet. This was built in 1932 two years after the Highway was opened at Big Sur. In 1983 storms here swept much of the highway away forcing it to close for over a year.

At San Simeon there is a wooden pier on a rugged shale beach. I decide to stay the night at a reasonably priced motel. In the hills above the highway is Hearst Castle, a stately palace folly created from treasures imported from all over the world by newspaper magnate, William Randolph Hearst and bequeathed to the state of California in 1958. Visitors must park at the tourist center and be transported by buses up a long, winding hilltop drive to reach the surrealistic Castle. The creation reputedly cost $10 million to build but it is very much a statement of bad taste, nevertheless it?s sure to impress.

Just south of San Simeon is the artist?s colony of Cambria. It is also a weekend retreat for those wishing to escape the heavy yellow smogs of LA. Next, Morro Bay where the chimneys of the PG & E power station are the singular blot on the landscape of the entire route The road turns inland here around a sand spit and causeway that leads to a huge extinct Volcano known as Morro Rock. Soon I reach the halfway point between San Francisco and LA at San Luis Obispo where there is another mission. Now highway one unites with 101 for a brief stretch until Pismo, a 20 mile stretch of wide, sandy beaches.

The beautifully kept Spanish colonial style terracotta roofed houses and picturesque clean streets of Santa Barbara make it, for me, one of the loveliest small cities anywhere. Following the earthquake in 1925, the city was rebuilt in the adobe fashion and the buildings are now preserved by law but this didn?t stop nature from coming perilously close to covering some of the dwellings in mud washed down from by the floods from the surrounding hills. The high street is full of interesting shops, excellent, but expensive, restaurants and a wonderful book shop where I enjoyed a coffee and a muffin while browsing the shelves. There is a prosperous, relaxed air to Santa Barbara and I can see why the city has attracted so many Hollywood stars who have come to build their homes in the exclusive hills above the city.

The last leg of my journey takes me through Ventura and on to Santa Monica Bay. At the northern end is Malibu, where a long, wide stretch of state beach is exclusive to surfers (no swimming allowed). At Malibu Colony, another place favoured by the famous names of Hollywood, the lavish mansions line the shoreline but there is no public access to beach. In the hills above, the J Paul Getty museum claims to house some of the finest art in the world.

Santa Monica, a lively resort on the fringes of Los Angeles is the setting for Bay Watch. The city sits atop a cliff overlooking the beach and separated by a palm lined strip known as Pallisades Park. From here there are fantastic views of the Bay especially at sunset. My time however does not allow me to linger. As highway one turns inland away from the Pacific Coast cities of Venice, Marina Del Ray (where Beach Boy drummer Dennis Wilson drowned in 1983) and Long Beach before rejoining the ocean at Seal Beach, I bid a fond farewell. A short distance away my journey takes me to LAX and my flight home. As my jet climbs above the twinkling lights of Beverley Hills I reflect on my memories of this trip and in those famous words of Arnold Schwarzeineger I swear ?I?ll be back?.

Robert Bluffield is a full time professional photographer and writer based in Milton Keynes. As a writer he specialises in features on travel, cars, food and wine, business, current affairs and photography. He is an author of 3 published books and he is currently working on a history of Imperial Airways and the Birth of British Airlines. Web site: http://robertbluffield.co.uk

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Thursday, October 16, 2008

Cisco CCNP Certification Training: What's New On The BSCI 642-901 Exam

CCNP certification is getting a new look at the end of 2006. The BSCI and BCMSN exams are being updated, and the CIT and BCRAN exams are being retired. Let's take a look at what to expect from the new BSCI exam.

According to Cisco's exam blueprint - admittedly a very broad blueprint at this time - the major new topics are IP version 6 (IPv6) and multicasting. The addition of these two topics will make an already demanding Cisco certification exam that much tougher, but this is a great change for the exam and for the candidate. IPv6 is just going to become more and more prevalent in today's networks, and multicasting is as well.

Multicasting for the Cisco CCNP BSCI exam is going to go far beyond what you learned about it in your CCNA studies. For the new BSCI exam, you'll need to know the different methods of creating multicast groups as well as assigning members to them. This material was previously limited to CCIE-level books, and while I don't look for the questions to be as hard as the CCIE written exam, multicasting is not an easy topic and should not be taken lightly by the CCNP candidate in 2007.

One major CCNP exam topic that isn't going anywhere is BGP. The Border Gateway Protocol has been a big part of previous BSCI exams, and that looks to continue.

If you're pursuing your CCNP certification in 2007, be sure to monitor Cisco's website for additions to the CCNP blueprint. It's obvious that Cisco has raised the bar for CCNP certification, and earning this important Cisco certification will in turn raise your market value and networking knowledge like never before. Watch for future tutorials examining the other three new CCNP exams!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free certification exam tutorials, including Cisco CCNA certification test prep articles. His exclusive Cisco CCNA study guide and Cisco CCNA training is also available!

Visit his blog and sign up for Cisco Certification Central, a daily newsletter packed with CCNA, Network+, Security+, A+, and CCNP certification exam practice questions! A free 7-part course, ?How To Pass The CCNA?, is also available, and you can attend an in-person or online CCNA boot camp with The Bryant Advantage!

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Wednesday, March 19, 2008

Cisco CCNA Certification Exam Tutorial: Port-Based Authentication

To pass your CCNA exam and earn this coveted certification, you must understand the details of port-based authentication. This knowledge has a great deal of value in production networks as well, since this authentication scheme is regularly implemented. Let's take a look at this particular CCNA skill.

Consider a situation where you have a server that will be connected to your switch, and you want the port to shut down if a device with a different MAC address that that of the switch attempts to connect to that port. You could also have a situation where you have someone who has a connection to a switch port in his office, and he wants to make sure that only his laptop can use that port.

Both of these examples are real-world situations, and there are two solutions for each. First, we could create a static MAC entry for that particular switch port. I don't recommend this, mainly because both you and I have better things to do than manage static MAC entries. The better solution is to configure port-based authentication on the switch.

The Cisco switch uses MAC addresses to enforce port security. With port security, only devices with certain MAC addresses can connect to the port successfully. This is another reason source MACs are looked at before the destination MAC is examined. If the source MAC is non-secure and port-based authentication is in effect, the destination does not matter, as the frame will not be forwarded. In essence, the source MAC address serves as the password.

MAC addresses that are allowed to successfully communicate with the switch port are secure MAC addresses. The default number of secure MAC addresses is 1, but a maximum of 132 secure MACs can be configured.

When a non-secure MAC address attempts to communicate with the switch port, one of three actions will occur, depending on the port security mode. In Protect mode, frames with non-secure MAC addresses are dropped. There is no notification that a violation has occurred. The port will continue to switch frames for the secure MAC address.

In Restrict mode, the same action is taken, but a syslog message is logged via SNMP, which is a messaging protocol used by Cisco routers.

In Shutdown mode, the interface goes into error-disabled state, the port LED will go out, and a syslog message is logged. The port has to be manually reopened. Shutdown mode is the default port-security mode.

Port-based authentication is just one of the many switching skills you'll have to demonstrate to earn your CCNA certification. Make sure you know the basics shown here, including the action of each particular mode, and you're on your way to CCNA exam success!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCN

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Monday, March 10, 2008

Cisco CCNP / BSCI Exam Tutorial: Ten IP Routing Details You Must Know!

To pass the BSCI exam and earn your CCNP, you've got to keep a lot of details in mind. It's easy to overlook the "simpler" protocols and services such as static routing and distance vector protocols. With this in mind, here's a quick review of some details you should know for success in the exam room and real-world networks!

When packets need to be routed, the routing table is parsed for the longest prefix match if multiple paths exist with the same prefix length, the route with the lowest AD is preferred. If there are still multiple valid paths, equal-cost load-sharing goes into effect.

The ip route command is used to create static routes the command ip route 0.0.0.0 0.0.0.0 < next-hop-IP or local exit interface> creates a default static route.

A static route with a next-hop IP address has an AD of one, while a static route with a local exit interface has an AD of zero.

A floating static route is a static route with an AD higher than that of the dynamic routing protocols running on the router, ensuring that the static route can only be used if the routing protocol goes down.

On-Demand Routing (ODR) is only appropriate in a hub-and-spoke network. The spokes effectively become stub routers. ODR uses Cisco Discovery Protocol (CDP) to send route information.

To propagate a default route with IP routing, use the ip default-network command. To do so with IP routing disabled, use ip default-gateway. You can also redistribute a static route into most protocols, but not IGRP. IGRP does not understand a static route to 0.0.0.0.

The ip helper-address command takes certain broadcasts and translates then into unicasts in order to allow the router to forward them. These default ports are:

TIME, port 37

TACACS, port 49

DNS, port 53

BOOTP/DHCP Server, port 67

BOOTP/DHCP Client, port 68

TFTP, port 69

NetBIOS name service, port 137

NetBIOS datagram services, port 138

To name other ports, use the ip forward-protocol command. To remove any of these ports from the default list, use the no ip forward-protocol command.

ICMP Router Discovery Protocol (IRDP) hosts hear multicast Hellos from routers, allowing host-router discovery. HSRP routers create a virtual router that hosts think is a real router. Both protocols help networks cut over to a functional router quickly when their primary router goes down.

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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Sunday, March 9, 2008

Cisco CCNP / BCMSN Exam Tutorial: Changing The Active Router In HSRP

To pass the BCMSN exam and earn your CCNP certification, you've got to know HSRP inside and out. While the operation and basic commands of HSRP are pretty simple, there are some important details that are easily overlooked but are vital in getting HSRP to work the way you want it to. Let's take a look at using the priority command correctly on both the exam and in production networks.

A key value in the show standby command is the priority. The default is 100, and the router with the highest priority will be the primary HSRP router. We'll raise the default priority on R2 and see the results. R3 is currently the Active router and R2 the standby, so let's raise the priority on R2 and see what happens.

R2(config)#interface ethernet0

R2(config-if)#standby 5 priority 150

R2#show standby

Ethernet0 - Group 5

Local state is Standby, priority 150

Hellotime 4 sec, holdtime 12 sec

Next hello sent in 0.896

Virtual IP address is 172.12.23.10 configured

Active router is 172.12.23.3, priority 100 expires in 8.072

Standby router is local

1 state changes, last state change 00:14:24

R2 now has a higher priority, but R3 is still the active router. R2 will not take over as the HSRP primary until R3 goes down - OR the preempt option is configured on R2.

R2(config-if)#standby 5 priority 150 preempt

1d11h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Standby -> Active

R2#show standby

Ethernet0 - Group 5

Local state is Active, priority 150, may preempt

Hellotime 4 sec, holdtime 12 sec

Next hello sent in 1.844

Virtual IP address is 172.12.23.10 configured

Active router is local

Standby router is 172.12.23.3 expires in 10.204

Virtual mac address is 0000.0c07.ac05

2 state changes, last state change 00:00:13

In just a few seconds, a message appears that the local state has changed from standby to active. Show standby confirms that R2, the local router, is now the active router - the primary. R3 is now the standby. So if anyone tells you that you have to take a router down to change the Active router, they're wrong - you just have to use the preempt option on the standby priority command.

Another vital part of HSRP configurations is knowing how to change the MAC address of the virtual router, as well as interface tracking. We'll look at those features in the next part of my HSRP tutorial!

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

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Friday, March 7, 2008

CCNA Certification Exam Tutorial: Cisco Switching Modes

To pass the CCNA exam and earn this important certification, you've got to know switching inside and out. While you're learning all the basic switching theory, make sure to spend some time with the one of three switching modes Cisco routers can use.

Store-and-Forward is exactly what it sounds like. The entire frame will be stored before it is forwarded. This mode allows for the greatest amount of error checking, since a CRC (Cyclical Redundancy Check) is run against the frame before it is forwarded. If the frame contains an error, it is discarded. If there's no problem with the frame, the frame is then forwarded to its proper destination.

While store-and-forward does perform error checking, the delay in processing the frame while this error check is run results in higher latency than the other modes you're about to read about. The latency time can also vary, since not all frames are the same size.

Cut-through switching copies only the destination MAC address into its memory before beginning to forward the frame. Since the frame is being forwarded as soon as the destination MAC is read, there is less latency than store-and-forward. The drawback is that there is no error checking.

There is a middle ground, fragment-free switching. Only part of the frame is copied to memory before it is forwarded, but it's the first 64 bytes of the frame, not just the destination MAC. (Why? Because if there is a problem with the frame, it's most likely in the first 64 bytes.) There is a little more error checking than cut-through, but not as much latency as with store-and-forward.

Note that the latency of both cut-through and fragment-free is fixed; these modes always look at the first six or 64 bytes, respectively. Store-and-forward's latency depends on the size of the frame. Learning the similarities and differences between these modes is an often-overlooked part of CCNA studies. Spend some time studying this important CCNA topic - you'll be glad you did!

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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Monday, January 28, 2008

Cisco CCNP / BCMSN Exam Tutorial: BPDU Skew Detection

You may look at that feature's name and think, "What is a BPDU Skew, and why do I want to detect it?" What we're actually attempting to detect are BPDUs that aren't being relayed as quickly as they should be.

After the root bridge election, the root bridge transmits BPDUs, and the non-root switches relay that BPDU down the STP tree. This should happen quickly all around, since the root bridge will be sending a BPDU every two seconds by default ("hello time"), and the switches should relay the BDPUs fast enough so every switch is seeing a BPDU every two seconds.

That's in a perfect world, though, and there are plenty of imperfect networks out there! You may have a busy switch that can't spare the CPU to relay the BDPU quickly, or a BPDU may just simply be lost in transmission. That two-second hello time value doesn't give the switches much leeway, but we don't want the STP topology recalculated unnecessarily either.

BDPU Skew Detection is strictly a notification feature. Skew Detection will not take action to prevent STP recalculation when BDPUs are not being relayed quickly enough by the switches, but it will send a syslog message informing the network administrator of the problem. The amount of time between when the BDPU should have arrived and when it did arrive is referred to as "skew time" or "BPDU latency".

A busy CPU could quickly find itself overwhelmed if it had to send a syslog message for every BPDU delivery that's skewed. The syslog messages will be limited to one every 60 seconds, unless the "skew time" is at a critical level. In that case, the syslog message will be sent immediately with no one-per-minute limit.

And what is "critical", according to BDPU Skew Detection? Any value greater than 1/2 of the MaxAge value, making the critical skew time level 10 seconds or greater.

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

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Sunday, December 9, 2007

Cisco CCNP / BCMSN Exam Tutorial: Dynamic VLANs and VMPS

Knowledge of Dynamic VLANs and VMPS is important in your efforts to pass the BCMSN exam and earn your CCNP, and it's also a great skill to have for your networking career.

As a CCNA and CCNP candidate, you know how and why to configure static VLANs. Static VLANs can be a powerful tool for reducing unnecessary broadcast and multicast traffic, but if hosts are moved from one switch port to another, you've got to make those changes manually on the switch. With Dynamic VLANs, the changes are made - how else? - dynamically.

The actual configuration of dynamic VLANs is out of the scope of the BCMSN exam, but as a CCNP candidate you need to know the basics of VMPS - a VLAN Membership Policy Server.

Using VMPS results in port VLAN membership changes being performed dynamically, because the port's VLAN membership is decided by the source MAC address of the device connected to that port. (Yet another reason that the first value a switch looks at on an incoming frame is the source MAC address.)

In my home lab network, I've got a host connected to switch port fast0/1 that resides in VLAN 12. What if we had to move Host 1's connection to the switch to port 0/6? With static VLANs, we'd have to connect to the switch, configure the port as an access port, and then place the port into VLAN 12. With VMPS, the only thing we'd have to do is reconnect the cable to port 0/6, and the VMPS would dynamically place that port into VLAN 12.

I urge you to do additional reading regarding VMPS. Use your favorite search engine for the term configuring vmps and you'll quickly find some great official Cisco documentation on this topic.

To review, the VLAN membership of a host is decided by one of two factors. With static VLANs, the host's VLAN membership is the VLAN to which its switch port has been assigned. With dynamic VLANs, it is dependent upon the host's MAC address.

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

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Sunday, November 4, 2007

Web Design Tools - San Jose, San Francisco, Oakland, Japan


"Web Design Tools - San Jose, San Francisco, Oakland, Japan Web designing entails use of a whole gamut of tools - for text, graphics, menus, animation, navigation design, color selection, font selection, authoring, programming and ecommerce development. The use of technologically advanced and effective tools ensure that the website attracts target audience and lists high in the search engines and directories.

Different tools are used in different aspects of web designing. Text links use HTML meta tags, graphic links use graphics along with navigation buttons, drop down menus use JavaScript and CGI among others, and special effects need tools such as Macromedia Flash and Adobe Photoshop. By far, Macromedia and Adobe Photoshop are the most commonly used tools in web design. Certain graphic designers also use Macromedia DreamWeaver. Flash helps in animation that if used well, can be an attractive feature in a website. Visual Basic is the most common language for scripting and SQL with other database engines are used for database management on the website. Templates are also used for the layout of a web page.

Apart from tools that make the site presentable and easily navigable, there are also content creation tools that help in creating Search Engine Optimized content. A word or a phrase, based on the worldwide searches is rated on tools such as Overture. Once the most popularly searched words in your industry are identified and short-listed, the content creators write content using these search words. This ensures that your website lists high in the search engines and directories. A combination of the right HTML text, background images, and graphic images with the right and most legible typefaces and fonts are required if the website has to be popular among your target audience.

Web promotion and ecommerce tools help in marketing your website. Pay-Per-Click Search Engine Promotion, Loyalty Programs, Email Campaigns and Online Games are some tools used for website promotion. Tools such as site statistics software and reporting from site searches let you know what exactly your visitors are looking for. The content and marketing strategies are then adjusted accordingly.

Apart from the tools, designing a good website also requires the skills and expertise of a range of professionals. A web site must essentially be written, programmed, and designed for the end users. A site that is written, coded and designed for user friendliness and search engine visibility gets the most traffic and results in boosting sales. Again, understanding the products, services or information that your target audience is looking for is important in the design, maintenance and re-design of your website.

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I write articles for www.web-design.nr10.com, a San Francisco Web Development and Web Design Services, #10 is a Marketing and Technology Agency focused on delivering design, web technology development and e-business strategy solutions.

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Tuesday, September 18, 2007

San Francisco A City Gauide

Introduction

The City and County of San Francisco is the fourth-largest city in the state of California, in the United States. A consolidated city-county, mainland San Francisco is located on the tip of the San Francisco Peninsula. Insular San Francisco includes several islands in the San Francisco Bay and the Golden Gate Strait, notably Alcatraz, Treasure Island, and the Farallon Islands 27 miles offshore in the Pacific Ocean and also most of the privately owned Red Rock Island near the Richmond-San Rafael Bridge.

History

San Francisco has a long history of events marking its growth from a small town to a big city

? In 1776, the Spanish were the first Europeans to settle in San Francisco

? In 1848, with the advent of the California gold rush the city entered a period of rapid growth

? In 1822, serious development by non-Spanish speakers began, when William Richardson, an English whaler redeveloped a section of Yerba Buena in what is now Portsmouth Square in Chinatown.

? In 1846, the Mexican-American War broke out.

? On January 30, 1847, a naval force under Commodore John D. Sloat claimed it in the name of the United States and renamed it "San Francisco"

? On April 18, 1906, a devastating earthquake resulted from the rupture of over 270 miles of the San Andreas Fault, from San Juan Bautista to Eureka, centered immediately offshore of San Francisco.

? The city was quickly rebuilt after the earthquake.

? The phoenix on the city's flag represents San Francisco's "rebirth" from the ashes of the fire that resulted from the quake.

? In the 1950s San Francisco hired Harvard graduate Justin Herman to head the redevelopment agency for the city and county.

? Justin Herman began an aggressive campaign to renew blighted areas of the city.

? His planning led to the creation of Embarcadero Center, the Embarcadero Freeway, Japan town, the Geary Street super blocks, and Yerba Buena Gardens.

Place of Interest

San Francisco's parks, museums, tours, and landmarks are favorites for travelers the world over and offer an array of activities to suit every visitor. But no particular activity or place makes the city one of the most popular destinations in the world. It's San Francisco itself -- its charm, its atmosphere, its perfect blend of big metropolis with small-town hospitality. Some of its main attractions are:

? Alcatraz Island
? Cable Cars
? California Academy of Sciences
? Coit Tower
? Ferry Building Marketplace (and Farmers' Market)
? Fisherman's Wharf
? Ghiradelli Square
? Golden Gate Bridge
? Lombard Street
? Pier 39
? The Cannery
? Yerba Buena Center for the Arts / Yerba Buena Gardens

Museums & Art Galleries

Notable San Francisco Museums include

? The Museum of Modern Art (SFMOMA),
? The Palace of the Legion of Honor,
? The M. H. de Young Memorial Museum,
? The Asian Art Museum.

Other museums include

? The International Museum of Women,
? The Museum of the African Diaspora,
? The Contemporary Jewish Museum,
? The Museum of Craft & Folk Art,
? The Mexican Museum.

In terms of performing arts, San Francisco boasts

? The San Francisco Symphony,
? The San Francisco Opera
? The San Francisco Ballet.

San Francisco's Ballet and Opera are some of the oldest continuing performing arts companies in the United States.

Shopping

Like its population, San Francisco's shopping is both worldly and intimate. Every persuasion, style, era, and fetish is represented, not in big, tacky shopping malls, but in hundreds of quaint, dramatically different boutiques scattered throughout the city. San Francisco has many shopping areas, but the following places are where one will find most of the actions:

? Union Square & Environs
? Chinatown
? Union Street
? Chestnut Street
? Fillmore Street
? Haight Street
? SoMa
? Hayes Valley

Food & Drink

San Francisco's restaurants are so renowned that many people visit the city just to eat -- and with good reason. The city's brilliant chefs, combined with California's abundance of organic produce, seafood, free-range meats, and Northern California wine, guarantee some of the world's finest dining. San Francisco also has varied nightlife ranging from bars to lounges to clubs. Major areas of nightlife in San Francisco are North Beach, the Mission District, the Marina, the Castro, and South of Market. San Francisco also boasts of legendary pop music venues such as The Fillmore and The Warfield.

Universities

San Francisco Unified School District and the Archdiocese of San Francisco?s dozens of Catholic elementary and high schools serve the city. Despite its limited geographical space, San Francisco is home to a multitude of Universities and Colleges. Public universities include:

? University of California, San Francisco, primarily a graduate level health-sciences school, located north of Forest Hill

? San Francisco State University located in the southwest corner of the city near Lake Merced

? University of California, Hastings College of the Law located downtown at its Civic Center

? City College of San Francisco, one of the largest community colleges in the country is located in the Ingleside, with several extension campuses.

Private universities:

? The Jesuit-run University of San Francisco, one of the first universities established west of the Mississippi, located in the center of the city

? Golden Gate University, a business and law school located downtown

? California Culinary Academy Le Cordon Bleu program located in the Tenderloin

? Academy of Art University

? San Francisco School of Digital Filmmaking

? Alliant International University.

Sports

San Francisco is the home of many major league teams like

? The San Francisco 49ers National Football League team, who play at Monster Park

? The San Francisco Giants Major League Baseball team, who play at SBC Park

? MLB 's Oakland Athletics

? NFL's Oakland Raiders

? The National Basketball Association's Golden State Warriors play across the bay in Oakland

? The regional National Hockey League team, the San Jose Sharks play in San Jose

The Warriors and Sharks were once based just south of San Francisco, at the Cow Palace, located several yards south of San Francisco, in Daly City. The city is also home to some famous golf courses, including the Harding Park Golf Course and the courses of the Olympic Club.

Hotels & Accommodation

Luxury Hotels

San Francisco has elegant and grand hotels in its possession. Westin St. Francis, Westin Saint Francis, Palace Hotel, Argent Hotel, Mark Hopkins Intercontinental, Hilton, Fairmont, W San Francisco, Pan Pacific, Park Hyatt, Hyatt Regency, Renaissance Parc 55, Ritz Carlton - are some of these big names.

All famous luxury hotels like Hilton, Hyatt, Palace Hotel, etc. have their branch in Fisherman Wharf.

Budget Hotels

If the visit to San Francisco is in a particularly busy season and booking in prominent hotels are over, here's a list of moderate to very inexpensive alternatives - Alisa Hotel, Edward II Inn & Suites, Hotel Beresford Arms, King George Hotel, The Marina Inn, The San Remo Hotel.

Tours and Sightseeing

San Francisco has different type of organized tours they differ in the contents as well as the transport system. Tours are available by Bus, Boat, BART (Bay Area Rapid Transit) or on foot. The San Francisco Visitor Information Center, at Powell and Market streets, distributes free route maps. Blue & Gold Fleet and Red & White Fleet are two boat tours available. And Gray Line Bus tour is the San Francisco?s largest bus tour operator. The self-guided Private SUV tour, 49-mile drive is one easy way to grasp the beauty of San Francisco and its extraordinary location. Beginning in the city, it follows a rough circle around the bay and passes virtually all the best-known sights, from Chinatown to the Golden Gate Bridge, Ocean Beach, Seal Rocks, Golden Gate Park, and Twin Peaks.

Transport

San Francisco has the most extensive public transit system on the West Coast and one of the most diverse in the country. Muni is the city-owned public transit system, which operates the Muni Metro light rail system. BART (Bay Area Rapid Transit) is the regional transit system, which connects San Francisco with the East Bay, through an underwater tunnel, and Northern San Mateo County, California communities and San Francisco International Airport on the San Francisco Peninsula. In addition, a frequent commuter rail service, Caltrain, operates between San Francisco, San Jose, California and Gilroy, California.

San Francisco International Airport (SFO) is located 12.9 km (8 miles) south of the city in San Mateo County on a landfill extension into the San Francisco Bay. It is the only major international hub airport in California other than LAX in Los Angeles.

Name: Mary Scott. Occupation: Traveler. Website: http://www.thereservationcenter.com http://www.looktours.com Biography: Mary Scott is with The Reservation Center - providers of discounted tours to make your vacations and sightseeing trips in various cities across the world as comfortable and enjoyable as possible.

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Thursday, August 30, 2007

Cisco CCNA/CCNP Home Lab Setup: How To Configure Reverse Telnet

Occasionally, during your CCNA and CCNP studies, you'll run into a term that just doesn't quite make sense to you. (Okay, more than occasionally!) One such term is "reverse telnet". As a Cisco certification candidate, you know that telnet is simply a protocol that allows you to remotely connect to a networking device such as a router or switch. But what is "reverse telnet", and why is it so important to a Cisco CCNA / CCNP home lab setup?

Where a telnet session is started by a remote user who wants to remotely control a router or switch, a reverse telnet session is started when the host device itself imitates the telnet session.

In a CCNA / CCNP home lab, reverse telnet is configured and used on the access server. The access server isn't a white box server like most of us are used to; an access server is a Cisco router that allows you to connect to multiple routers and switches with one session without having to move a rollover cable from device to device.

Your access server will use an octal cable to connect to the other routers and switches in your home lab. The octal cable has one large serial connector that will connect to the access server, and eight rj-45 connectors that will connect to your other home lab devices. Your access server then needs an IP Host table in order to perform reverse telnet.

An IP Host table is easy to put together (and you better know how to write one to pass the CCNA!). The IP Host table is used for local name resolution, taking the place of a DNS server. A typical access server IP Host table looks like this:

ip host FRS 2007 100.1.1.1

ip host R3 2003 100.1.1.1

ip host R1 2001 100.1.1.1

ip host R2 2002 100.1.1.1

ip host R4 2004 100.1.1.1

ip host R5 2005 100.1.1.1

ip host SW1 2006 100.1.1.1

interface Loopback0

ip address 100.1.1.1 255.255.255.255

no ip directed-broadcast

This configuration will allow you to use your access server to connect to five routers, a frame relay switch, and a switch without ever moving a cable. When you type "R1" at the console line, for example, you'll be connected to R1 via reverse telnet. If you have a smaller lab, an access server is still a real timesaver and an excellent investment. And by getting a static IP address to put on your access server, you can even connect to your home lab from remote locations!


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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