From: Joseph Brunner (joe@affirmedsystems.com)
Date: Fri Oct 10 2008 - 12:07:26 ART
I like to approach it this way, so here are some ideas you may like...
Traditional functions of a switch
1. frame filtering forwarding
2. address learning -> and when this breaks, i.e. cam exhaustion
How a switch handles 00, 01, and FF mac addresses by default?
How and why we see unknown unicast frames (stale arp on SVI, etc)
When does a switch act like a hub?
What causes a loop? How does a loop affect Unicast, unknown unicast,
arp, dhcp, CDP, STP frames, etc.
3. Loop prevention - 802.1d, 802.1w
Then I go into the STP bid, election of the root bridge, the 3 tie breakers
non-roots use to elect their sole root port. To teach students to find which
ports will block on a segment, you MUST find which port will be designated
and why (port sending best bpdu's will be designated). You can cover port's
costs, stp port priorities, etc., lowest sender BID, etc., lowest sender
port id, etc.
4. Loop recovery - Do we wait for Max Age, if so when? How long will the
network take to recover under several circumstances? When can we just
wait 2xfwd delay?
Then we go into PVST, PVST+, tunneling bpud's, then why MST is a better
choice (less stp instances, admin control of forwarding paths for vlans,
etc). I show how IST operates with NON-MST or other regions. Once they
understand this, we talk about RSTP, how it converges, and the new port
states, types and roles. How MST uses RSTP...
1. What is an alternate port (vs uplinkfast)
2. what is a backup port (why is it rare)
3. what does "shared" "p2p" "edge" "STP Peer" mean?
4. Cisco's original backbone fast/uplinkfast methods
5. Finally observing 802.1d vs 802.1w convergence in a debug lab
The last lessons on STP I give are BROKEN/INCONSISTENT leading into the
loopguard and rootguard features and how they work to prevent STP failures.
Once they get all this, we go into STP security, bpduguard, portfast
bpduguard, and YIKES- BPDUFILTER!
This is one topic that NEVER GETS OLD when you teach it!
:)
Oh, just as a side note, when I used to teach CCNA until February, there was
one very smart chap who was a Nortel salesman. He actually said "I want to
learn everything you know about OSPF". So we did 6 hours on OSPF up to and
including all my lab prep and troubleshooting skills. I think he got it all!
Never underestimate the 1/100 student who is going to teach you something
one day!
-Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Joe
Rinehart
Sent: Friday, October 10, 2008 10:15 AM
To: 'Joseph Brunner'; ccielab@groupstudy.com; reis.henrique@gmail.com
Subject: RE: How to keep CCIE
Yes, I am prepping for next week's class an teaching on the same
topic...personally I hate spanning tree but the lesson preparation has
helped solidify the concepts in my mind...
Joe Rinehart
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Joseph Brunner
Sent: Thursday, October 09, 2008 10:47 AM
To: ccielab@groupstudy.com; reis.henrique@gmail.com; ccielab@groupstudy.com
Subject: RE: How to keep CCIE
Start teaching the NEW CCNP track in your spare time at a local school or
college, or even amongst junior engineers.
Its good to give back, and you WILL keep your knowledge!
(just taught my spantree PVST/RSTP/MST lesson last night)
;)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
reis.henrique@gmail.com
Sent: Thursday, October 09, 2008 1:27 PM
To: ccielab@groupstudy.com
Subject: How to keep CCIE
Hi Guys,
Maybe this could be a stupid question but I have to ask it.
After you got your number how do you keep all stuff that you studied and
learned, I say because if you don't use for example Multicast, I don't use
it
in my company today so in sometime I can forgot it, the same for QoS I don't
use today either.
I'll starting to study for SP track, so for a while I will keep my
acknowledgement but and after, what do you do??
Thanks in advanced,
Henrique Reis
CCIE #22233
Blogs and organic groups at http://www.ccie.net
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