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Showing posts with label warren sullivan. Show all posts
Showing posts with label warren sullivan. Show all posts

Tuesday, February 28, 2012

q's with warren sullivan ccnp


Today i welcome warren sullivan as a guest of insearchofthecert... i posted his stp enhancements a few days ago which was really well received... he has a site of his own now called http://www.mycertstudies.com/ which you'll want to pay close attention to as it progresses... i asked him if he might take some time and talk about his certfication journey, ups and downs, etc...

  
thanks for chatting warren...
   

Thanks for having me arteq....
  

give us a description of how you began, the road to ccna and then ccnp, study methods and materials, equipment, the whole smash...


No problems Arteq, first of all let me say that my website is in its infancy, there really is nothing of importance to see there yet, but check back in a few months time, there should be some worth while stuff in there by then….i hope! Ha Ha


Where I started is a funny one, it all started back in 2007 when i was on a work related training course and i tried to get a PC to talk to a router, sounds like a simple task doesn’t it…. obvously its clear to me now what the problem was, but at the time....it baffled me, and fascinated me all at the same time. The router already had an interface IP address of 192.168.1.254/25 and i had assigned the PC an IP of 192.168.1.1/25.....same network i thought....why isn’t his PC pinging! Thats what started it all, one of my more geeky course mates told me that they were on different subnets! WHAT! Different subnet?

So i decided to enhance my knowledge with some research into subnetting, and i learnt the basics and realized where i had gone wrong....it fascinated me to the point that all i could think of was subnets and how the mask defined them. I let it be and sort of forgot about networking for a while due to work commitments.



About a year later, my workplace enrolled me on an ICND1 course with a cisco learning partner here in Australia, i thoroughly enjoyed the 5 days, so much so that i decided to self study to fill in any holes in my knowledge and sit the exam, i joined the cisco learning network and started asking questions, i used the course material that i obtained on my ICND1 course, built a small lab of 4 2600 series routers and 5 2950 switches and passed the test with flying colors. My first Certification!

I fell in love with the exam, so well constructed, so well written, i knew i had found my new career path....networking

From there i jumped straight on ebay and purchased some new equipment, a 2511-RJ console server, a 3550 layer 3 switch and a few more 2600's, got some WIC-2t's and a bunch of serial cables from china....i was set, i purchased Wendall Odom's ICND2 Cert guide and Todd Lamlie's CCNA fast pass and i studied hard, reading every chance i had, labbing, reading and more labbing, cisco learing network for questions....i had all i needed, i sat the exam 3 months after my ICND1 and i was a certified network associate!

From here i had some big decisions to make, should i go for a specialization? should i go for the CCNP? i looked at wireless and security, and whilst i love the idea of getting in there and getting dirty with the technologies, i really felt i needed to learn more about core routing and switching, so i started studying for my CCNP.

My plan was an exam every 3 months, that would have me certified CCNP by christmas 2011, that was the plan anyway....



Starting with the ROUTE exam as that was what i was most comfortable with, switching was ok but i didnt have the funds for the required switches anyway at the time. I started by reading the ROUTE Certification guide, cover to cover, no labs, no notes, just reading, its a very in depth book that delves so much deeper into the technologies than CCNA did, i loved it!

Then i went back to chapter one and started reading again, took notes in an A4 book, lots of them and labbed everything i came across, and i mean everything, at the end of every chapter i did a consolidation lab with everything from that chapter in it, and only when i could talk confidently about a technology would i move on to the next one, and that went on for the rest of the book, i sat and passed my ROUTE exam around April 2011 from memory, it was a fantastic exam, really really enjoyed it, hard, detailed and edge of your seat type stuff from start to finish.



Then onto SWITCH, i had ordered the OCG and FLG 2 months prior from the states, they took 3 months to get here! never again amazon! anyway i managed to get together some temp funds for the purchase of 2 x 3560's and 2 more 3550's, my plan was once i passed the exam i would sell them and reclaim the expense.

I followed the exact same routine as for ROUTE, but i focused on the FLG as i had heard that the OCG was lacking somewhat, and i was brand new to switching. I was enthralled with SWITCH, amazing stuff, stuff i never knew existed, it was incredible, i had a small bump in my path to certification, my little baby boy matthew was born on the 8th of May, what an amazing time in my life, i gave myself 3 weeks off and got back into it....having taken that time off i found i had lost some of the knowledge i had learned, as you do when you learn things for the first time, so i started again, finally sitting and passing Switch in November 2011, WOW, what an exam, very tough and very well written once again, cisco has a knack of writing exams that will only be passed by people who know this stuff inside and out.



Passing SWITCH in Nov created a problem with my "certified by christmas" plan, so i booked my TSHOOT exam for December 23, i figured that i was all over the technologies, i just needed to hone my troubleshooting skills, so i watched nuggets and to be honest, it wasn’t a great help, Jeremy has done some amazing work in other series, but the TSHOOT series just didn’t gel with me, so i employed the help of the Cisco learning network, i built my lab buy mimicking the TSHOOT topology with GNS3 and real switches, i bought a truck capable NIC for my PC and i had the lab humming well, a mirror image of the actual testing environment, i uploaded my topology to CLN and ask people to break it for me, and they did!, i would go through and fix it and PM the problems and fixes to the people who broke it, i did this about 20 times and i had a great feel for the environment.



One great piece of advice i received was to treat the environment like your own network, get to know it, inside and out, for example, you should know what would come up on a sh ip route on any router without even hitting the CLI...and i did, a trick i learnt was to simply draw the topology on a piece of paper, all IP addressing, HSRP configurations, VLANS, allowed VLANS....the lot, all on a piece of paper, without looking at any reference material, id then check it against the actual topology and screw it up.....and do it again, and again.....by the time i got in that exam seat, i knew that topology backwards.......i passed

with 100%



I was a CCNP! YAY!



what's next on your agenda?



Present day - I have made my mind up after weeks of thinking, do i go for CCIE? Specializations? or Service Provider certs?

My dream job would be a network engineer at a commercial ISP....so Service Provider Certs it is, starting with CCIP then maybe CCNP SP Operations, then some specializations in wireless, voice and security, then eventually onto CCIE, the Mecca!

Monday, February 13, 2012

guest post - warren sullivan ccnp


warren sullivan is a ccnp who i bump into from time to time on the CLN (cisco learning network)  the following is an excellent treatise on spanning tree port enhancements... for those who have not yet joined an applicable study group on CLN; what in the hell are you waiting for...
and when you go there, be sure to thank warren...


Portfast
Used on access ports connecting to hosts, to immediately transition to the forwarding state, bypassing the listening and learning states.
Can be configured globally with;
Spanning tree portfast default
Which will enable portfast on any port configured as an access port on the switch, or per interface with;
Spanning-tree portfast
Which will enable portfast on the port as long as it is in a non trunking mode, or
Spanning-tree portfast trunk
Which will enable it even if it is a trunk!
Portfast is typically configured on host ports only, although trunks can also be configured as portfast ports too

BPDUguard
Used on Access ports where BPDU’s should never be received, if they are the port will be placed in an err-disabled state.
Implimented either globally with;
Spanning-tree portfast bpduguard default
Which will enable it on any portfast enabled interface on the switch, or per interface with:
Spanning-tree bpduguard enable
Which will enable it explicitly on the port.
BPDUguard is configured on access switch host ports were BPDU's should never be seen.

BPDUfilter
When enabled globally the port will transmit 10 BPDU's to ensure there is no loop in the topology, if the port receives a BPDU it will lose portfast status, bpdufilter will be disabled and the port will begin normal spanning-tree operation.
When enabled per interface, spanning-tree is effectively disabled on the port altogether, it will not send BPDU's and will drop received BPDU's on that port.
It is again enabled either globally with;
Spanning-tree portfast bpdufilter default
Which will enable it on any portfast enabled interface, or per interface;
Spanning-tree bpdufilter enable
Which will enable it explicitly on the port.
BPDUfilter is configured on access switch host ports.

Note: if BPDUguard and BPDUfilter are enabled on a switchport, BPDUguard will have no affect as BPDUfilter takes higher precedence over BPDUguard.

ROOTguard
Root Guard is useful in avoiding Layer 2 loops during network anomalies. It forces a port to become a designated port, if the port were to receive a superior BPDU and ROOTguard was not enabled it would attempt to become a root port, this is what ROOTguard prevents.
This feature effectively enforces the position of the root bridge.
it is used to protect the desired root bridge from becoming over-run by a new or reconfigured switch in the network, it is configured per interface with;
Spanning-tree guard root
If a superior BPDU is received on the port, the port will go into a “root-inconsistent” state (effectively a listening state) until the superior BPDU’s are no longer received on that port.
ROOTguard is configured on distribution switch downlinks to the access layer

LOOPguard
Prevents bridge loops caused by unidirectional communication, it works by detecting BPDU’s received on non-designated (blocked) ports, if the BPDU’s stop coming then LOOPguard places the port into a Loop-inconsistent state preventing a potential loop, if this mechanism was not implemented and the sent BPDUs were not reaching the non-designated port, the non-designated port would transition to a forwarding state, because it believes that the bridge is dead! But it isn’t, a loop is born!
When configured globally, LOOPguard is implimented on all ports considered to be point-to-point links (full duplex ports)
It is configured globally with;
Spanning-tree loopguard default
or per port with;
spanning-tree guard loop
LOOPguard is configured on links between distribution switches and uplink ports on access switches

UDLD
Is a layer 2 protocol that works with layer 1 mechanisms to determine the physical status of a link, in essence it prevents unidirectional communication, unidirectional communication typically occurs with fibre connections being misconnected tx to tx or rx to rx etc, this can play havoc with spanning tree as you can imagine.
It can be configured either globally or per interface, per interface taking precedence, when configured globally, it is enabled on fibre interfaces only.
It can also be configured in two modes, enable or aggressive.
Enable mode simply changes the UDLD enabled port to an "undetermined" state if it stops receiving UDLD packets from its neighbor.
Aggressive mode will first attempt to re-establish connectivity by sending 8 UDLD messages in quick succession, if they fail, the port is place in an errdisabled state. From STP perspective, loop prevention.
It is configured globally with;
udld [aggressive|enable]
or per interface
udld port [aggressive|enable]
UDLD is configured on fibre interfaces