Cisco Tips & Tricks

January 2, 2011

2010 in review

Filed under: Router — ciscotips @ 6:55 am

The stats helper monkeys at WordPress.com mulled over how this blog did in 2010, and here’s a high level summary of its overall blog health:

Healthy blog!

The Blog-Health-o-Meter™ reads Wow.

Crunchy numbers

Featured image

A helper monkey made this abstract painting, inspired by your stats.

The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 150,000 times in 2010. If it were an exhibit at The Louvre Museum, it would take 6 days for that many people to see it.

In 2010, there were 4 new posts, growing the total archive of this blog to 95 posts.

The busiest day of the year was March 18th with 628 views. The most popular post that day was How to block skype.

Where did they come from?

The top referring sites in 2010 were google.com, google.co.in, blog.ioshints.info, stumbleupon.com, and fa.wikipedia.org.

Some visitors came searching, mostly for route summarization, ospf cost, eigrp k values, ospf load balancing, and subnet mask cheat sheet.

Attractions in 2010

These are the posts and pages that got the most views in 2010.

1

How to block skype June 2006
48 comments

2

Route Summarization May 2006
17 comments

3

Configuring a Cisco router as a terminal server June 2006
29 comments

4

Turning the router in to Packet sniffer May 2006
5 comments

5

CCIE notes for EIGRP July 2006
20 comments

December 2, 2010

IPv6 Experts

Filed under: IPv6, Router — ciscotips @ 7:14 pm

Came across an excellent website for IPv6

www.theipv6experts.net

March 18, 2010

CCIE TS Lab Challenge by Narbik

Filed under: ccie — ciscotips @ 2:38 pm

Guys, 

Go  ahead and take this challenge. Last date to submit your solutions is extended to March 21st, Sunday. 

and you can win 

The first twenty students that resolve most or all the trouble tickets will 

receive the following: 

This offer also applies to existing students. 

CCIE “Troubleshooting Mock Labs” (Valued at $350). 

The “Advanced CCIE Routing & Switching 2.0” (Valued at $350). 

$1000.00 discount coupon that can be used for one of the following boot 

camps: 

This offer does NOT apply to existing students 

CIERS1 

+ Narbik’s Boot Camp 

12 Days “End – to – End, No Excuses” boot camp 

CCIE Service Provider 

CCIE Security boot camp 

You can download the challenge lab/instructions from 
http://www.micronicstraining.com/downloads/TS-Challenge.rar 

March 3, 2010

The CCIE Flyer Challenge!

Filed under: ccie — ciscotips @ 11:17 pm

What if you had a chance to get a couple of workbooks that would help you stay sharp or prepare for the CCIE R&S lab?  Yup if you could get both Narbik’s Troubleshooting Workbook and the Advanced Routing and Switching 2.0 Workbook would that be a good deal?

FREE?

Oh that would be better, because free is always good.  If I also threw in an additional $1,000 discount to any of Micronics’ SP, RS or End-To-End classes that would be even better, right?  Well I try to stay on top of what future CCIEs and current CCIEs might want so here’s a great deal for you.

A CONTEST!

You bet, a contest to see who can complete 10 – 15 troubleshooting mock labs is afoot.  The window of opportunity for you is a short five (5) days to complete.  The first twenty (20) lucky people who do the best on these labs will be awarded both workbooks, Troubleshooting Workbook (written by Narbik and Dan) and the Advanced Routing and Switching 2.0 Workbook written by Narbik.  All that plus a $1,000 discount to any one of Micronics’ SP, RS or End-To-End classes, anywhere in the world.

ONLY 20 (TWENTY) LUCKY CONTESTANTS WILL BE AWARDED THESE FABULOUS PRIZES.                                                                       (I feel like a game show host!)

 

WHEN?

Next week I will roll out the announcement and the link to the mock labs and you are invited to, “Start your engines” race fans.

The fine print: If you have attended classes from Micronics you only have to pay $1,500 for future training, so don’t be greedy you will not be allowed to use the $1,000 discount offered in this competition against that price.

January 28, 2010

Spanning Tree 802.1d and RSTP 802.1w

Filed under: Switching, Technology and Software — ciscotips @ 9:37 pm

Great videos from Cisco Learning Network

For Spanning Tree Protocol ( 802.1d)

https://learningnetwork.cisco.com/docs/DOC-1755

For Rapid Spanning Tree Protocol ( 802.1w)

https://learningnetwork.cisco.com/docs/DOC-1754

November 17, 2009

L2VPN/VPLS-Martini and Kompella

Filed under: bgp, ccie, cisco, MPLS — ciscotips @ 2:24 am

Both Martini-draft and Kompella-draft addressed setting up of a Pseudowire emulation over MPLS in order to offer L2VPN services. These drafts were initial efforts to standardise L2VPN services.

Martini draft was named after a former Cisco employee Luca Martini. Martini draft uses LDP as signalling to setup L2VPN over MPLS backbone. The tradeoff of this draft was auto-discovery.

Kompella draft on the other hand uses BGP for both signalling and auto-discovery to establish fully-meshed pseudo wires (multipoint). Kompella-draft is named after author Keerti Kompella (Juniper Employee).

draft-martini and draft-kompella terms are used as labels for the two different L2VPN services methodologies (LDP Vs BGP for signaling). The actual drafts do not exist in IETF.

In dealing with multipoint-fully meshed topologies in edge routers, draft-martini suffered auto-discovery, to overcome aut0-discovery, it suffered configuration overhead. draft-Kompella claimed to be better scalable because of suto-discovery but with complex signalling whereas draft-martini leverages simplicity.

Martini draft was standardized under RFC 4096 . however it has since been superseded by the Pseudowire Emulation Edge to Edge (PWE3) Working Group specifications described in RFC 4447 and related documents. On the other hand draft-kompella is obsolete and was not standardized..

 RFC 4664 – Framework for Layer 2 Virtual Private Networks (L2VPN), it describes the framework for L2VPNs (VPWS, VPLS and IPLS). This framework is intended to aid in standardizing protocols and mechanisms to support interoperable L2VPNs. Requirements for L2VPNs can be found in RFC 4665 – Service Requirements for Layer 2 Provider-Provisioned Virtual Private Networks.

All this was consolidated, and the L2VPN Working Group produced two separate documents, RFC 4761 and RFC 4762, both offered VPLS but using different signaling protocols:

Kireeti Kompella and Yakov Rekhter published “Virtual Private LAN Service (VPLS) Using BGP for Auto-discovery and Signaling” RFC 4761 in January 2007.

Marc Lasserre and Vach Kompella published “Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling” RFC 4762 in January 2007.

L2VPN services for many vendors uses RFC 4762 -Martini ( with LDP) as a standard for example Alcatel 7450’s uses RFC 4762 as the standard

November 8, 2009

CCIE notes for GLBP

Filed under: ccie, cisco, Technology and Software — ciscotips @ 5:47 am

Gateway load balancing protocol performs similar function to HSRP and VRRP. In both HSRP and VRRP,  group of routers participating in first hop-redundancy has one Active and can have multiple Client routers. At one single time, traffic is being passed through Active router, leaving client routers with unused bandwidth. Client routers will only become active once Active router in a group fails. We can create multiple groups and create different active routers but it results in extra administrative burden.

GLBP on the other hand can provide load balancing over multiple routers (gateways) using a Single Virtual IP and multiple Virtual mac-addresses. The bandwidth/traffic load is shared between multiple routers participating in the group rather than being handled by a single active router.

Following are the important points conceptually for GLBP.

  1. GLBP uses single Virtual IP and multiple mac-addresses to provide first-hop Gateway redundancy.
  2. In GLBP, there can be four routers/gateways in a group
  3. Hello messages are used to communicate with in the group destined to 224.0.0.102, udp port 3222 and they will be sent every 3 secs by default.
  4. initially group members will elect one AVG ( Active Virtual Gateway) and other routers will act as backup AVG’s incase the active AVG fails
  5. AVG will assign Virtual mac-addresses to other routers, they are known as AVF’s ( Active Virtual Forwarders)
  6. Each AVF assumes responsibility for  forwarding  packets sent to Virtual Mac’s assigned by AVG.
  7. AVG is responsible for answering ARP requests for Virtual IP’s

Configuring GLBP

R2(config-if)#glbp 1 load-balancing ?
  host-dependent  Load balance equally, source MAC determines forwarder choice
  round-robin     Load balance equally using each forwarder in turn
  weighted        Load balance in proportion to forwarder weighting

There are three different types of Load balancing algorithms in GLBP.

Host-Dependent

  1. The Mac-address of the host is used to determine which AVF’s  mac is the host directed towards.
  2. A given host is guaranteed to use the same Virtual Mac as long as number of VF’s in the GLBP group are constant
  3. Host dependant GLBP is not recommended in situation where there are small number of hosts, for example, less than 20

Weighted

  1. GLBP places a weight on each device to calculate the amount of load sharing that will occur through MAC assignment
  2. Each GLBP router in a group will advertise its weight and AVG will act based on that value
  3. For example  we have two routers, Router A and Router B. If router A has double the bandwidth capacity then router B. Router A will be configured with the double weighting value of router B

Round-Robin

  1. With Round-robin VF mac-address is used sequentially in ARP replies for the virtual IP
  2. This is the default type of GLBP algorithm
  3. It is suitable for any number of hosts.

Steps for  configuring GLBP

  1. enable GLBP with glbp 1 load-balancing
  2. glbp 1 priority ( Higher is better, default is 100)
  3. glbp 1 ip x.x.x.x
  4. glbp 1 preempt < To enable preempt, by default its disabled>
  5. glbp 1 authentication  ( Enabling authentication with in a group)

Verification

Show glbp

October 25, 2009

BGP Regular expressions / Public route-servers

Filed under: bgp, ccie, IP Routing — ciscotips @ 5:28 am

I was looking at some older posts at Groupstudy and Dale  posted the link to public route-servers. I agree the best way to practice regular-expressions for CCIE is to use one of the following public route-servers.

From: http://www.cymru.com/Documents/secure-bgp-template.html

 route-views.oregon-ix.net
 ner-routes.bbnplanet.net
 route-server.cerf.net
 route-server.ip.att.net
 route-server.east.attcanada.com
 route-server.west.attcanada.com
 route-server.cbbtier3.att.net
 route-server.gblx.net
 route-server.as5388.net
 route-server.savvis.net
 route-server.colt.net
 route-server.opentransit.net
 route-server.gt.ca
 public-route-server.is.co.za (South African routes only)
 route-server.belwue.de
 route-views.on.bb.telus.com
 route-views.ab.bb.telus.com
 route-server.ip.tiscali.net
 route-server.wcg.net
 route-server.manilaix.net.ph
 route-server.ip.ndsoftware.net
 route-server.utah.rep.net
 route-server.he.net
 zebra.swinog.ch

Just telnet to one of the above route-servers and you can login via guest/anonymous account. There you go and you can use some basic show commands.

October 21, 2009

A Sneak Peek at the v4 CCIE R/S Lab by Wendell

Filed under: ccie, cisco — ciscotips @ 4:23 pm

The recently announced changes to the CCIE R/S written and lab exams took effect this week. I recently had the chance to take the R/S lab again, as part of the Beta testing – so I decided to save up some observations and post them around the time the new exam has come out. Today I’ll look at a variety of things about the lab exam, and make another post next week concentrating on the biggest change: The 2-hour troubleshooting section.

You know, the strange thing is that many times over the years, I’ve wondered if they’d let me take the CCIE R/S Lab again – and not take away my CCIE number if I failed. It has certainly changed a lot since I took it back in 1995. I’ve always had the itch to try for another CCIE, but I think I’ve had a cumulative 3-4 weeks in the last 5 years without a book to work on (that’s definitely not a complaint), and it obviously takes more than casual effort to prep for another CCIE lab. And getting a CCIE in your spare time pretty much changes your life until you get it done, and I’ve never wanted another CCIE bad enough to make that sacrifice. But, I just always thought it’d be interesting to sit the lab again. And then Maurilio asked a few of us Cisco Press CCIE authors, plus others I’m sure, to sit the lab and give it a test. And it was fun.

OK, on to stuff you folks might care more about. I came to the exam with several specific items to keep an eye out for – things like the impact of adding a 2-hour troubleshooting section, how the config section would be different now that it’s 5.5 hours instead of 7.5, and the supposedly-dreaded open-ended questions. But the biggest surprise was obvious from the first few minutes of lab time – they changed the user interface of what you see to access the lab, and as a result, there’s no printed lab exercise book. The only paper for the lab is the note paper they give you to write on.

In the old days, you got a lab booklet that you couldn’t write on, but you could do the natural thing and pick up the book to look at the various lab requirements. I believe it’s true that the book had some lab diagrams as well. Now you get a GUI interface from which you can pull up the many different lab diagrams, read the various lab exercises. My gut reaction was that I didn’t like not having a book. After experiencing it, I thought the replacement GUI would have been reasonable if I had had time to practice with it.

The good part of the GUI was that once I was used to it, I could navigate to the next topic for both troubleshooting and config easily. The GUI essentially indexed the main lab exercise tasks, which may be a bit more convenient than flipping pages in a booklet. Once I got used to it (20 minutes maybe), I stopped to ask myself if the user interface itself would slow me down compared to the paper booklet, and I decided that if the small bugs were removed (e.g., no back button on the browser to get to the docs), AND if I had a chance to practice before the lab (so that 20 minute learning curve wasn’t part of the timed test), that it wouldn’t have hurt. Otherwise, call it a 20 minute hit for the day, wild unscientific guess. (I did ask, and as of now, there is no tutorial available before the exam; if it’s your first lab with this interface, you’ll get to learn it concurrent with doing the troubleshooting. I’d suggest asking as many questions as you can about the user interface before starting the timer.)

There were negatives to the GUI, but of course GUIs often have to do with personal preference. In this case, a few of my author friends and I were allowed to discuss amongst ourselves our impressions, and we all agreed that the navigation in the GUI was a bit of a problem. EG, to view a figure, you click, and a window pops, which is fine. However, you can’t minimize the window so that the bigger window behind it, where you access the console windows, is hidden. You can re-size, and move, but not minimize. To see another figure, the figure shows up in the same window, so to view both – like a cabling reference and a different VLAN reference – you have to toggle back and forth, and never see both at once. Then, to see the console term emulator windows, you have to move the figure window to the side, and then drag it back to see it again. No minimize/pop-open toggle like with Windows. Each figure required a different window size/shape to see the whole figure, and all the figures showed up in this one window, so there was no ability to make it the right size and find a good place on the screen for it.

Sorry for the ramble, but I wanted enough detail out to make a point: If I were taking it again to pass, I’d consider drawing a few of the figures for the config section, particularly the LAN layer 2 figure – both cabling and VLANs – on paper before even beginning to configure. (I would do this for the config section, but not for the t’shooting section.)

Next, let me give you some idea on the whole “is it too much” issue.

Most CCIE lab candidates that pass seem to do so with at least a little time to spare, and those that fail often run out of time, or don’t have time to review. So, I came to the test asking myself “if I were truly prepared for the lab, could I have finished on time enough to review my work?” This question has a new twist, now that it’s 3-part: open ended questions, then 2 hours of t’shooting, and then 5.5 hours config. (FYI, I didn’t study except on the flight to Raleigh, and I don’t stay current on everything so I could go fast enough to pass – so I estimated what “well prepared” meant.) The short answer is that I think that the troubleshooting section was attainable for a well-prepared candidate, and maybe a little too much (maybe shave 10% of the tasks to be fair), but the config section was too much by at least 20%. (My buddies co-authors thought roughly the same on config, and maybe that the t’shooting needed to be shaved more than my 10% guesstimate.)

Sitting back contemplating the whole “is it too much” thing, I came to two conclusions:

  • 1) It was a Beta, and Cisco needs some experience with specific lab exams to figure out how much is too much. I’m sure they didn’t write all new lab exams, so the trick is to figure out how to compress the former 7.5 hour lab into 5.5 hours. They want you to pass if you know your stuff, and fail if you don’t. They don’t want you to fail if you truly know your stuff but they just gave you too much. From a systematic perspective, I think they’ll get the right mix. (Granted, I’m sure some of you have contradictory experiences on this point!)
  • 2) I wonder if Cisco considered that the shrinkage from 7.5 to 5.5 hours on the build section was like removing the final 2 hours – the hours in which you are most familiar with the lab – rather than removing the first two hours. By the end 3rd hour of the build section, I needed the figures less and less. From a sheer mechanics perspective, I worked faster. Call it 3 hours in the config section before I was somewhat comfortable with the topology. With a 5.5 hour build, that splits the unfamiliar/familiar time as 3/2.5 hours. The old 7.5 hours would have given a 3 /4.5 hour split, so it felt like I was losing 2 hours of very productive time.

The next thing I was particularly curious about was the open-ended question section. Frankly, I’m a Dr. Jekyll/Mr. Hyde on this one. Wendell the cert guy looked at my open ended questions, and asked himself: “If I was truly prepared for the lab, would these questions be a problem?” Absolutely not. As a guy who has an interest in seeing Cisco certs thrive, I see the open-ended questions for what Cisco claims them to be – a cheating prevention tool. However, Wendell the imaginary CCIE R/S lab candidate says that the whole idea scares me to death, and may be too unfair to use as a cheating prevention tool. If I had been taking the lab on my nickel for real, rather than just kicking the tires, I would’ve been pysched out by the open-ended questions. You could get an unlucky draw of questions and get sent home. For real CCIE R/S candidates, I think this means that you don’t get ready for 70% of the topics, and go take the lab to experience it – you may not get past the questions. However, from what I saw, and from other discussions, I think if you’re ready for all aspects of the lab, you’ll be ready for the open-ended stuff. It’s just a little scary.

Last thing for today: general difficulty. I tried to imagine myself as a well-prepared candidate, but not over the top – you know, if I took the classes, did labs from a few lab books, read Doyle/Halabi/etc, practiced a lot for speed, then the lab I got was not too difficult. In fact, I did not see a single item that I viewed as a “trick” – no wording that made me do function X using methods no one in their right mind would try. Everything I saw was detailed – it required mastery of a lot of topics – but it was all stuff that you might come across as something you’d really use in the real world. Really. That was a nice surprise. The difficulty level comes from seeing the requirements, mentally putting it all together, deciding what to configure, configuring, t’shooting to make sure it works, and doing that 5X faster than you would have to do in real life. But it was refreshing to not see anything that looked like tricks just to make sure you knew how to make one parm on one command do its thing.

One more note on the difficulty level: I think if you prepared with the traditional tools – books, classes,  lab books, lots of hands-on practice, and understood it, that the difficulty level was very fair and reasonable.

OK, that’ it for today. Next time, I’ll look at the Troubleshooting section in particular

Source:- http://www.networkworld.com/community/node/46561

October 18, 2009

System MTU / ip ospf mtu-igonore

Filed under: ccie, IP Routing, ospf, Switching — ciscotips @ 6:54 pm

I was working on OSPF lab and suddenly on my 3560’s I saw a OSPF adjacency errors.

%OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.1 on
FastEthernet0/0 from EXSTART to DOWN, Neighbor Down: Too many
retransmissions

%OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.1 on
FastEthernet0/0 from DOWN to DOWN, Neighbor Down: Ignore timer expired

Suddenly I realized that may be I have MTU issues as I just completed a Q-in Q lab and changed my switch MTU ,  but to double check

I thought of checking a “debug ip ospf events” … and here it was.

OSPF: Rcv DBD from 192.168.10.1 on
FastEthernet0/0 seq 0x12A6 opt 0x52 flag 0x7 len 32  mtu 1504 state
EXSTART

OSPF: Nbr 192.168.10.1 has larger interface MTU

There are multiple ways to fix this, you can either issue “system mtu 1500” on switches or use an interface level command on Routers “Ip ospf mtu-ignore” . or the third one will be to change MTU on router interfaces ( Least preferred).

when value is changed, it will not be stored in neither running-config
nor startup-config. On Catalyst 3550, this information is stored in a
separate file on the flash. On Catalyst 3560, you can’t see it, unless
you do “show system mtu”.

“system mtu 1500” on switches is the default command. Even when value is changed, it will not be stored in  running-config  or startup-config. On Catalyst 3550, this information is stored in a separate file on the flash. On Catalyst 3560, you can’t see it, unless you do “show system mtu”.

This is one of the well-know gotchas on the actual lab exam.You have to know how to solve this. Hence, when configuring routing protocols on switches, make sure you know what the MTU is.

One important thing to note is that you might break stuff in the lab if you were suppose to configure MTU for q-in q lab and later you changed “System MTU” in your switch to fix OSPF issue.

You can also use system mtu routing 1500 in your switch to fix OSPF issue as this will be only used for routing but for Q-in-Q lab switch MTU will be still used as 1504.

IMHO,Best way to fix this in the lab would be “ip ospf mtu-ignore” under the interface on your router.

MTU  has to be the same on both ends of the link before the neighbor can form adjacency.

Older Posts »

Blog at WordPress.com.

Follow

Get every new post delivered to your Inbox.

Join 55 other followers