From: Con Spathas (con@spathas.net)
Date: Wed Nov 07 2007 - 19:57:51 ART
I think being able to distinguish what you can and can't do with dynamips is
directly proportional to ones real world experience.
Personally I refrained from using the NM-16ESW for anything but trunking
between "switches" and layer2 connectivity of all the routers. If my
scenario needed L3 etherchannel - I just created another VLAN and used SVI's
instead. So all my routing, multicast, IPv6, most security tasks and IP
services was all taken care of by dynamips.
All the tasks I needed to do that were specifically switch related I left
and covered using rack rentals or access to a friends lab. I spent about 20%
of my prep time on switches - but I was pretty confident in this area as
I've used a chunk of the blueprint topics in production so it was more a
case of speed and accuracy than anything else.
Using dynamips was also more efficient for me. I could "re-wire" from one
scenario to another quickly and rebooting devices doesn't even leave you
with enough time to walk out of a room let alone time to make a coffee. This
alone probably saved me at least over 10% in overall prep time.
At the end of the day - if you know your stuff hardware wise and have been
using the real kit for a long time - I don't think using Dynamips is too
great a deal - whether you decide to integrate real switches or supplement
study with rack rentals.
I do worry though about the users who have never seen a real chassis of any
kind and expect that dynamips alone will carry them all the way and expect
to be spoonfed dynagen configuration files etc in the process.
And I agree with ScottV about the duct tape and swiss army knife - playing
with dynamips and working through its own idiosyncrasies helps (in my
opinion) hone ones troubleshooting skills.
I will continue to use my dynamips box now for testing out ideas etc etc, as
well as studying for the SP track sometime in the future. As much as I'd
like real gear - being mobile is more important to me than having to lug a
large rack around every time I move.
My $0.05 worth. <-- the rate has gone up 2.5 times since I got my digits! ;)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott Vermillion
Sent: Wednesday, 7 November 2007 16:59
To: 'Joseph Brunner'; 'Patrick J Greene'; ccielab@groupstudy.com
Subject: RE: Dynamips Question
Thanks Joe, we share in that hope, I assure you! But I'm not delusional.
(I finally gave up on my dream of a first attempt this calendar year, BTW -
likely sticking with the Feb '08 date I picked up the day after I cleared
the written).
I agree with you and I think that most Dynamipsers actually do too. My
personal approach was to buy 4 x 3650s (wish I had done two of those and two
of 3550, but it's too late). For those that don't need 24 x 7 access to a
lab with physical switches, rack rentals fill the void nicely. That's no
different really than what you do with your own personal remote rack, no?
The bottom line is that people use Dynamips for something approaching 100%
of their routing studies and, according to the Brians, up to 80% of their
switching tasks using the EtherSwitch modules. Then rack rentals round out
the other 20%. I just personally wanted access around the clock and no
rental outfit stepped forward and offered me a good (any, for that matter)
monthly 24 x 7 rate, so I built my hybrid and it has been nothing short of
amazing (still a few quirks now and again, but nothing an aspiring CCIE lab
candidate can't handle with duct tape and a Swiss Army knife)...
-----Original Message-----
From: Joseph Brunner [mailto:joe@affirmedsystems.com]
Sent: Wednesday, November 07, 2007 9:52 AM
To: 'Scott Vermillion'; 'Patrick J Greene'; ccielab@groupstudy.com
Subject: RE: Dynamips Question
I hope you pass on your first attempt also!
But the 3600 with a switch module will NOT prepare you for the switching
tasks you will face. That I can assure you.
Nor will it prepare you for the complexity of handling a large rack in 240
minutes (about all you have until you must proceed carefully to qos, mcast,
and security which are also more points than you can punt.
I just want to let everyone one know, they need to be ready for the
intricacies of the 3550/3560 in depth.
-Joe
-----Original Message-----
From: Scott Vermillion [mailto:scott_ccie_list@it-ag.com]
Sent: Wednesday, November 07, 2007 11:47 AM
To: 'Patrick J Greene'; 'Joseph Brunner'; ccielab@groupstudy.com
Subject: RE: Dynamips Question
Of course the other option many of us go for is to integrate physical
switches with the Dynamips environment. Like I've said before Joe, if your
friendly rack rental outfit swapped physical routers and a Dynamips server
(much like switching someone's normal coffee with Folger's Crystals (for
those of you around and coherent here in the States in the '70s)), how would
you even know the difference? Hint: you wouldn't.
Perhaps for a better understanding that I can offer, ask Con Spathas. He's
the guy who just posted here about his pass on a *first attempt* in Brussels
after preparing with a *Dynamips lab*...
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Patrick J Greene
Sent: Wednesday, November 07, 2007 7:47 AM
To: Joseph Brunner; ccielab@groupstudy.com
Subject: RE: Dynamips Question
Joseph,
Switching is accomplished with a 16-port switch module in the 3600 router.
You still have all of the trunking, channeling, and other switching fun you
can handle.
I am painfully aware of how many points of switching there are.
Thanks,
Patrick
-----Original Message-----
From: Joseph Brunner [mailto:joe@affirmedsystems.com]
Sent: Wednesday, November 07, 2007 9:40 AM
To: Patrick J Greene; ccielab@groupstudy.com
Subject: RE: Dynamips Question
I don't understand this...
How can you study with only routers on a Routing & SWITCHING test...
And believe me when you find out how many points of switching there are, you
may choke
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Patrick J Greene
Sent: Wednesday, November 07, 2007 8:50 AM
To: ccielab@groupstudy.com
Subject: OT: Dynamips Question
I have a laptop with a 1.7Ghz Centrino and 2GB of RAM running bare bones XP.
I was able to bring up the entire IE Lab (14 devices) on 2 Dynamips
instances but obviously it runs like molasses going uphill in January. The
CPU stays pegged at 100% and there is still about 125MB of RAM free. I can
run a browser and wordpad on the laptop without much pain, but when I telnet
to the routers (from another laptop) it is unusable. I do connect but just
painfully slow.
Any performance tuning ideas? I would like to keep the environment on the
laptop because as a consultant I travel a lot. It's nice to have your lab
portable.
Thanks for the advice.
Patrick
This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:28 ART