Some useful lab designs

OSPF - COSTS

Open Shortest Path First ( follow Dijkstra Algorithm) have following costs depending on line:

COST = 100 / bandwidth in Mbps (or bps per conversion)

Interface type	Interface Bandwidth in bits per sec	OSPF Cost
Serial	56000.00	1785
ISDN	64000.00	1562
T1	1544000.00	64
E1	2648000.00	48
Ethernet	10000000.00	10
Fast Ethernet	100000000.00	1
Gigabit Ethernet	1000000000.00	1
OC48	2500000000.00	1

My choice of Lab - What I think

After spending more than 10 hours and reading all details, I came up with list of equipment for my Home Lab. As of now I do not have any plan of giving any certification exam but I want to have my own lab because of my interest in networks. Just want to have fun with whatever new I can try on the set up. I already have Masters Degree under my belt and its not doing any thing good to me on comparing it with real world experience. What really matters for me now is to enjoy what I fond of doing rather than filling my resume with more stuff. May be in near future if I like, can give a shot on Cisco exams in a row.

Requirements:

~ frame relay switch, an ISDN simulator, and an access server
~ DCE-DTE cables/ console cable/ rollover cables/ straight-through cables/ octal cables
~ Rack - 12 u

Switches: Cisco – 2 Cisco 2950 and 1 Cisco 2924
Routers: Cisco 3640, 2611XM, 2520 and 2511

Setting up Home Lab

Click Here - Wendell Odom's Cisco Cert Zone
or read the following:

Building a CCNA lab, Part 1

Submitted by wendell on Thu, 01/10/2008 - 7:18am.

So you decided to pursue a Cisco cert, and you're just getting started. If you have to go the self-study route, one of your early tasks will be to find/scrounge/buy some gear so you can practice all the features covered on the exams. The problem is that when you're starting to prepare for an exam, you may not know enough about the technology to make good decisions about what to buy - and by the time you know enough to confidently purchase the lab, you've gone well past the date by which you would have wanted to have a lab handy for practicing. (See what your peers are pursuing this year on last Monday's post.)

Well, I promised to spend more time on practical helps for passing Cisco cert exams this year, so I intend to do a series on how to build a lab for some of the more popular certs. I'll start with CCNA and CCENT, and probably look at either CCNP or CCVP following that. (I'm willing to take requests.)

Briefly, a few disclaimers. I'll make some observations about what could and should work, with caveats. However, I may miss something, so the advice comes with a disclaimer that these are just opinions, and your results may vary. OK, on to the details!

I'll address the following aspects of your choices with the lab over the next several posts, as follows:

• Router hardware options and choices
• Router IOS options and choices
• LAN switch options
• Comparing lab packages

For routers, you've got several options, but assuming that cost is a major factor, you could look at 2500 series routers, 2600's, and 1800's, listed in oldest/cheapest to newest/most expensive. Today I'll look at 2500's, and then get to the 2600's and 1800's next time. Regardless of model, you'll want your CCNA prep routers to have (at least) 2 serial interfaces, and at least 1 Ethernet interface or some flavor.

2500's have been around since dirt, and for a long time have been one of the most popular model series for building home CCNA prep labs. The pros are that many models have 2 serial interfaces and one Ethernet (10Mbps) interface, which meets most of today's needs for interfaces. In fact, the 2501 model is relatively popular on Ebay even today. The most important pro for 2500s for exam prep today is the low cost - I just checked Ebay, and you can find some with "buy it now" prices for US$20 or less - making it a ridiculously-cheap option. While they won't support every IOS feature you'd want to see, you can try out most of the router commands related to both CCENT and CCNA, assuming you have the right IOS version and feature set.

On the con side, 2500's are so old that Cisco stopped selling it in the 1990's, and they are not supported anymore - meaning that Cisco doesn't bother offering the latest IOS images for the 2500 series. (However, you can get IOS 12.3 mainline, which is current enough for CCNA - more on that when I hit the IOS topic in a later post.) If you're buying routers expecting to use them for other certs down the road, 2500's maybe simply be too old to consider. Also, the 2500 series Ethernet interfaces are 10 Mbps Ethernet, with no support for LAN trunking. The physical Ethernet interfaces use a DB-15 connector - requiring an external transceiver (buy it now prices around 10 bucks on Ebay.)

So, if you want cheap lab to just try things on routers, ignoring switches, and cheap is the absolute first priority, just to get real-hands on with the core router commands for CCENT and CCNA, you could buy:

2 2501's (2 serial, 1Ethernet)

2 Ethernet external transceivers

2 crossover serial cables

2 power cables (frequently included with the router)

2 crossover Ethernet cables (or straight-through if you have switches available)

1 console cable and connector

The most common topology for this gear would look something like this:

Based on a quick look at Ebay, you could score all these for roughly US$100, and be ready to learn. You could get by with 1 serial cable, and with one Ethernet cable and 1 PC as well. However, before rushing out to buy, stay tuned for my next post, where I'll compare this option to using 2600's and 1800's in my next post, so stay tuned!

CCNA lab – 2600’s and 1800’s

Submitted by wendell on Mon, 01/14/2008 - 4:35am.

If you have any intention to go beyond CCNA, the 2500 series routers we looked at last week may be a bad choice. Today I'll compare a couple of other options, one that's cheaper but gives you some investment protection, and one that's more expensive but positions you well for having a viable lab for other more advanced Cisco certs.

First, let me start with a gross characterization of some alternatives verses the 2500 series I blogged about last week. The 2600 series, particularly 2610, 2611, 2612, and 2613 became very popular as access routers following the 2500 series era. Later, Cisco enhanced the hardware, giving later similar models the "XM" designation, for example the 2610 XM router. Of note, the non-XM routers had 10 Mbps Ethernet interfaces and no support for LAN trunking, while the XMs have 100 Mbps FastEthernet interfaces and do support LAN trunking.

The 2600 series, including the XMs, are no longer marketed by Cisco, and like 2500's, Cisco no longer supports the latest IOS versions on the 2600 series routers. Like 2500's, 2600's (both types) can run up through 12.3 mainline IOS, but that's it. Again, for CCNA and CCENT prep today, that's not a big deal.

Next, consider one of the lower-end but still-marketed routers, the 1841. From the 1800 series, I picked the 1841 for the blog because the 1841 is the least expensive 1800 series router that supports WIC slots, which allows you to put a WIC-2T card into the router. With a WIC-2T in each 1841, you have 2 serial interfaces to support the serial interfaces need for ICND1 exam, ICND2, and BSCI exam prep. Also, 1800's support more features, and all the latest IOS versions. For example, 2500's and 2600's do not support MPLS, but 1841's do - and MPLS is now on the BSCI exam (one of the 4 CCNP exams).

It's clear that buying 1841's makes much more sense than buying 2600's if you plan to continue on from CCNA to CCNP. However, the cost difference in the used router market makes the decision difficult. Again using "buy it now" on Ebay as a gauge, there are plenty of 2600's (non-XM) available for under US $50. However, I only found a few 2610XM's under US $400. The lowest-priced options on Ebay for 1841's run around US $600, at least with my spot check.

I summarized a few of these points for easy reference here:

Feature or Issue 2500 2600 (non-XM) 2600 XM 1841

Old, no support X X X

Newest IOS is

12.3 mainline X X

No support for FE

and trunking X X

Does not use same

Serial WIC as

current routers X

Does not support MPLS X X X

So, you've got some options. You could buy 2600 (non-XM) and WIC-2T's, going the cheap route. That gets you similar support for CCENT and CCNA as you did with 2500's - most commands supported, but no ability to configure trunking on the router. However, you'd get a little investment protection if you did later buy 2600 XMs, 1841's, or other more recent routers, because the WIC-2T's you bought would still have value - just move them to the new routers.

You could go the more expensive route as well. If you're going that way, getting a pair of 1841's, each with a WIC-2T, might be expensive, but if you plan to move on to the BSCI exam right after passing CCNA, then you'd have a good start without wasting money. However, building a lab with 2500's or (non-XM) 2600's for just a few hundred bucks is pretty compelling.

All of this ignores the issues related to IOS, feature sets, and the flash/RAM required to support the required IOS and feature set. I'll look at what's appropriate for CCNA next post.

(Before closing, a standard disclaimer - I make no claims as to whether the suggestions made here have been tested, or do I guarantee any results you might see if following these suggestions. Also, I make no claims as to the legality of using any Cisco hardware or software that you might buy.)

CCNA Lab, Part 3 - What about 3640's and 2620 non-XM?

Submitted by wendell on Thu, 01/17/2008 - 9:18am.

Well, I led last time with some discussion of 2500's, 261X's, and 1841's as possible options for routers in a CCNA lab. Today I'll add, at the suggestion from a couple of posts since Monday, a little discussion on 3600's, particularly 3640's, plus the 2620/2621 non-XM router line.

(On a personal note, I must say I'm enjoying spending a little time blogging instead of writing books - I can spout out some ideas without as much time/review/etc, get some others to comment and collaborate, and end up with a good discussion - it's very refreshing to get some interaction as compared to the relative vacuum when writing a book. Thanks to all ya'll - take the boy out of Georgia, but can't take the Georgia out of the boy - for posting so much already this year.)

This is part 3 of a series. Part 1; Part 2.

First, someone had posted a suggestion that 3640's might be good options. That got me thinking that I should look at 3620's as well - 3620's, 3640's, and 3660's were all based on the same technology, supporting mostly the same network modules, and were popular to buy as medium-powered routers for production network maybe 5-7 years ago. The 3620's, like 2600 non-XM models, only support through IOS 12.3, and no further, and buying all the parts to use 3620's in a lab add up to more than the non-XM 2600's - so I'll ignore 3620's. However, the 3640's do support the current-latest IOS versions, and the cost is reasonable, so they're worth a look.

3640's are a bit larger (2 rack units) compared to the other 1 RU routers we've looked at here. 3640's have 4 network module slots, and were often used for WAN aggregation in production networks. However, the used market has lots of inventory, keeping the price down. A quick peek at EBay shows plenty for sale that also have max memory of 128M RAM and 32 M flash, at around $200. However, the 3640 chassis only has 4 network module slots, with no fixed LAN interfaces or WIC slots. Translated, you have to buy at least 1 network module, or 2, to get at least one LAN interface and one WIC slot. For example, you could get a NM-1FE2W, which include 1 FastE interface and 2 WIC slots. Once you buy the router and NM-1FE2W, you need a few serial interfaces, so you can buy the same WIC-2T that you would have bought for the 2600's or 1841's.

Another posting suggested the non-XM 2620, which does have 1 built-in FE port, and supports trunking, which was a missing piece when buying the 261X non-XM routers. To be honest, I ignored 2620 non-XM's in the last post due to prior prejudice - last time I had looked a while back, the 2620's were in the $600-700 range on EBay. However, it's been a while, so I looked, and indeed the prices have fallen a lot. Like the 261X non-XM's, you only get up through 12.3 mainline IOS, but you do get trunking. To get 2620 non-XM's with max memory of 64RAM/32Flash looks like it takes around $150-200. (Note that the installation notes say you need a new 2620 boot ROM in order for the 2620 to recognize the 32M flash - it may be better to search for 2620's with all the memory and boot ROM in place.

So, where does that leave us with all the options I've brought up here so far? Well, first let's summarize the cost to get a router on EBay, with at least 1 Eth or FastE interface, plus 2 serial interfaces. I did a quick browse of the prices of components, but didn't try to find the absolutely lowest possible cost.

Next, I've revised the table to list some of the main comparison points. In the table above, the green columns show routers that can run the more recent IOS versions. (Note that in Monday's post I had incorrectly stated that 2610-XM's couldn't run the latest IOS's, but that was wrong - they can run more recent IOS versions.) Next, the table below summarizes a few other points, with an additional note of support for MPLS Provider Edge (PE) functionality. MPLS PE is where most of the fun stuff happens for MPLS VPNs, so for CCNP, which I'll get to next, you'll want at least a couple of routers that support PE. (FYI, even 2610 non-XM can act as Provider (P) routers in MPLS VPN). But as I said, I'll wait until I get into the CCNP stuff before looking at it further.

So, what'd I miss this time? Let me know what else you think we should consider, and then I'll move us towards wrapping up the router pieces of this CCNA lab puzzle, and move on to switches useful for CCNA preparation.

CCNA Lab Part 4: Bigger Picture of Router Hardware

Submitted by wendell on Mon, 01/21/2008 - 1:25pm.

Well it certainly seems that there are a lot of you out there that watch the used router market for lab hardware pretty closely. Thanks for the continued insights into what makes sense, and what doesn't, for getting a lab built. Today I'll step back from the details on the models of routers and discuss a few options for a parts list for what you'll need to buy for the router part of your CCNA lab.

First, you need to choose whether you will buy 2, 3, or 4 routers. The main decision factors, in my opinion, are:

• How much you can spend
• How badly you want to experiment with Frame Relay
• How likely you are to pursue CCNP soon after CCNA

I really think that the last item in my list should really be the first consideration. If you don't plan on moving on to CCNP, then you can get by with the older and really inexpensive routers (see last post for the reference table), and build a 3 or 4 router lab for a few hundred bucks. However, if you intend to pursue CCNP, then you're better off with at least routers that let you re-use the WIC's down the road, or even go ahead and buy routers that support the latest IOS releases. However, with more expensive routers, you may not be able to afford as many routers.

The biggest downside of just having 2 routers is the extra confusion caused when trying to experiment with Frame Relay. Typically, most people use one router as a Frame Relay switch, as in the first figure below. However, if you have a router with at least 3 serial interfaces, that router can act as both Frame Relay switch and Frame Relay DTE. Frankly, for $25 bucks on Ebay, you can get another 2500 series router and have a 2-serial-port router to use as a FR switch, and avoid the confusion, but You'd need 1 router to act as Frame Relay switch. - but with more expensive routers.

To finish out your lab, you'll need power cables for each router, which are often included when you buy routers used most anywhere. You'll need 1 console cable - again often included with the router. If your PC doesn't have a DB-9 serial port, you might need to pick up a USB-to-DB9 converter somewhere for a couple of bucks. (Just 1 console cable needed - you can swap it around to the routers as needed.)

Finally, you need some "back-to-back" serial cables. These cables allow you to connect 2 routers' serial interfaces to each other to create a serial link. The important considerations are that the connectors fit your router. If you have 2500's, or use a WIC-1T, the serial ports use DB-60 connectors. If you use routers with a WIC-2T, you'll need serial cables with "smart serial" connectors. If you mix and match, you can get cables with different connectors on opposite ends - for example, a DB-60 on one end, and smart serial on the other.

Finally, I'll tackle the LAN cabling once I get to a post on switches, but for now, if you have at least one straight-through and one crossover UTP cable, with RJ-45 connectors, you can at least connect the routers to any existing PCs or switches.

So, let me outline three scenarios for a final CCNA lab, and give a parts list:

1) Cheap, CCNA-only: 2 older model routers, plus cables

2) Tight budget, 3 router, some upgrade path

3) Good prep for CCNP next, without going overboard

I'll give the list for #1 today, and get to the other two for the next post, as I'm already running a bit long. The ending network diagram is as follows:

• 1 2501 router ($25)
• 1 2520 router ($125)
• 2 back-back serial (DB-60) serial cables ($20)
• 1 console cable (free with router probably)
• 2 AC power cables (free with router probably)
• 1 Ethernet transceiver ($20)
• 2 Ethernet cables (crossovers, if using as shown in the following figure) ($20)

This lab totals $210 in part due to the 2520. I haven't mentioned this model before, but one of the posts you guys made here mentioned it. It's a reasonable choice to get a single router with at least 3 serial port in case you want to try and do Frame Relay with one router acting as a switch and a DTE, as should earlier in today's post. 2520's don't' need an external transceiver, either. (You wouldn't need any more serial cables, either.)

Alternately, you could've gotten a 2610 with 2 WIC-2T's, and spent maybe $150 instead of $125, and spent just a little more.

Finally, if you want really cheap, you can get this design down to a really cheap $120, using a 2501 (plus external transceiver) instead of the 2520, losing the ability to do Frame Relay, and just buying 1 serial cable.

I'll spec out a few other options next post.

CCNA LAB 5: Picking IOS revisions and Memory

Submitted by wendell on Mon, 01/28/2008 - 10:41am.

Anyone that's made it past the first few hours of CCNA study, or used a Cisco router, knows that Cisco routers run IOS, more formally known as "Cisco IOS Software". However, if you've not worked with routers on a regular basis, it's sometimes scary to pull the trigger to buy some used gear for a home lab. I'll address some of the issues related to choosing an IOS today, and how figure out the amount of flash and RAM needed to support each IOS.

(Disclaimer - I make no claims as to the legality for anyone to obtain and use IOS images. I'm only attempting to describe the process of getting the IOS image files - the legal issues are left to you.)

First, a quick overview. Today, IOS for the router models you'd use in a CCNA or CCNP lab ships as a single compiled file. Cisco builds different IOS images (files) based on the model of router and the feature set, as well as different images for each maintenance level (version and release).

The IOS feature set determines what commands and functions that IOS supports - the more functions in the IOS image, the more it costs, and the more RAM and flash required when using it. The best way to figure out what features are in each feature set is to use the Cisco Feature Navigator, where you can select features from a list, and then find out what router models support it, in which IOS versions. It also displays the amount of flash and RAM needed for each version.

For example, I used the feature navigator to find out the details of IPv6 OSPF Version 3 support. I found that you had to at least have a 12.4 IOS version, which means that the 1500's and 2600 non-XM models can't run OSPF version 3 (see earlier posts in the CCNA lab series regarding the fact that some older models can't run the latest IOS versions.) For 2610XM's, many feature sets support OSPF V3, but the one that requires the least memory is called "IP plus" - a popular feature set to support a wide range of IP features. In this particular case, to support the IP plus feature set in version 12.4 IOS, a 2610XM would need 64M of RAM and 32M flash.

So, what do you need for a CCNA lab? Well, an exhaustive search requires a bit more research than I can afford for my blog-time. However, you'd probably get most everything with the most basic feature set, typically just called "IP" or "IP Basic". For example:

• With IP Base at version 12.3 mainline, 2500's and 2600 non-XM's support basic IPv6 address and RIP features - so you could test IPv6 with these older routers.
• With IP Basic and 12.4 mainline, you could test Secure Shell (SSH). However, 2500's and 2600 non-XM's don't support 12.4. However, the issue isn't the feature set, it's the IOS version.
• If you're thinking about CCNP, for example, to support EIGRP for IPv6, you'd need a 12.4T version (next version after 12.4 mainline) - but still with the basic "IP" feature set.
• If you wanted to get more into security, or voice, or MPLS, you'd need more functional feature sets.

(Anyone out there know of a CCNA-level topic that you've discovered wasn't supported by an IOS "IP" feature set? Please post it! Thanks...)

CCNA LAB 5: Picking IOS revisions and Memory

Submitted by wendell on Mon, 01/28/2008 - 10:41am.

By the way... a quick aside on IOS version numbering. The major releases look like 11.2, 12.1, 12.2, and so on. If this number is NOT followed by a letter, it is a "mainline" release, meant for eventual general deployment (aka it's the safest version to use). Releases with a "T" designator (eg, 12.3T) have been deployed less time, so there's a highest statistical liklihood of bugs. Of particular interest in this context is that when Cisco is ready to start a new mainline version, they take the then-current T-train release of the earlier version, and those versions tend to track one another as fixes are made. For example, 12.3T train was the basis for mainline release 12.4. So, while some minor differences may exist, you can generally count on 12.3T and 12.4 release to support the same features, as well as 12.2T/12.3, and so on.

Why the long aside? Well, now it's time to buy some routers on the used market. The seller may claim that the router has version whatever installed and with a valid license. If you don't have the rights or ability to download other IOS versions and feature sets, you want to make sure the router you buy has the right version and feature set - and the feature navigator is a good place to start.

Additionally, if you buy a router expecting to load a new IOS, you have to do a little planning for memory as well. You have two options, and for home labs, I much prefer the 1^st option:

1) Buy the router with max RAM/flash already installed

2) Pick the IOS, and then buy enough RAM/flash to support the IOS

Why get the max memory? Well, by the time a router model is old enough to be pretty cheap on EBay, the memory modules are pretty cheap as well. It varies from router to router, but there have been times that ordering the memory separately has been more expensive than the routers on the used market. But you can typically find routers that also have max RAM and flash installed, and not have to worry about getting the memory and install it - and oddly enough it may well be cheaper than buying the memory later. For reference, here's the max memory allowed for some of the router models I've discussed in this blogspace:

Model RAM/Flash

3640: 128/32

2501: 16/16

2610: 64/16

2620: 64/32

2610XM: 256/48

1841: 384/128

So, what's the conclusion for CCNA? You'll mostly be fine with an "IP Base" feature set, and a little better off with an "IP plus" or "Advanced IP" feature set. But check the memory requirements for those with feature navigator, and compare that to what you intend to buy, before pulling the trigger.

CCNA Lab, Part 6: CCNA Router Labs on a Slightly-less Constrained Budget

Submitted by wendell on Thu, 01/31/2008 - 4:32pm.

Today, I'm going to wrap up the bigger picture of the three options for a CCNA lab. You might recall from early last week, I blogged about the first of 3 options for your CCNA lab, at least the router part:
1) Cheap, CCNA-only: 2 older model routers, plus cables
2) Tight budget, 3 router, some upgrade path
3) Good prep for CCNP next, without going overboard

Today, I'll get to the details on the other two options.

First, my suggested topology for options 2 and 3 are the same - three routers, with a need for 2 serial and 1 LAN interface per router. The following figure shows the basics, and how I'd probably leave it cabled most of the time - ignoring the switches for the time being.

Obviously, you'll need 3 routers - but which ones? Well, I've updated a table from a few weeks ago, this time in also include the 2520 model router, which I'm going to include in both my samples for options 2 and 3.

So, for option 2, I'll pick the following:
* 2520 (quantity 1)
* 2501 (quantity 1)
* 3640 (quantity 1)
The reasoning is that while the 2520 can't run the latest IOS versions, it does have 4 serial ports, and does not require an external Ethernet transceiver (cost savings). So, when you decide to study for CCNP, you can use the 2520 permanently as your Frame Relay switch, with 4 ports, which is probably enough. I chose the 2501 just to keep the cost down - boy, is it cheap! I chose the 3640 so that you could at least have 1 router with the most recent IOS version, just in case. The 3640 is the least expensive option (at least for the models I checked, when I checked), so that keeps cost down a little, and the WIC-2T can be used across most of Cisco's product line. Here's the parts list:

* 1 2501 router ($25)
* 1 2520 router ($125)
* 1 3640, WIC-2T, NM-1FE2W ($400)
* 1 back-back serial (DB-60/DB-60) cable ($10)
* 2 back-back serial (DB-60/Smart serial) cables ($20)
* 1 console cable (free with router probably)
* 3 AC power cables (free with router probably)
* 1 Ethernet transceiver (for 2501) ($20)
* 3 Ethernet cables (crossovers, if using as shown in the following figure) ($30)

This lab totals $630, with the 3640 being the majority of that cost.

Finally, for the 3rd option, I'd use the same basic choices, except I'd replace the 2501 with either:
* An 2610 non-XM
* An 1841
The 2610 has appeal for 2 reasons: even though it doesn't support the most recent IOS versions, it does support frame-mode MPLS. For example, when I built my lab network to create the MPLS chapter for my CCIE R/S Written exam cert guide, I used old (cheap) 2610's as the PE's, and my nice new 1841's as the PE routers. So, it's probably worth the extra $75 for the 2610 instead of a 2501. Also, the WIC-2T in the 2610 can at least be used in other newer routers down the road, which gives us a little bit of an upgrade path.

The 1841 has appeal for many reasons, with the primary reason being that of all the router models I've examined in the blog, the 1841 is the most likely router to still support the more recent IOS versions 2-3 years down the road. If I had to guess, I'd bet 2600-XM's won't support 12.5 mainline (down the road), but 1841's will. It's just a bigger bump in cost.

So, to be complete, here's the part list for option 3:
* 1 2610 non-XM router ($100), or 1841 ($650)
* 1 2520 router ($125)
* 1 3640, WIC-2T, NM-1FE2W ($400)
* 1 back-back serial (Smart serial) cable ($10)
* 2 back-back serial (DB-60/Smart serial) cables ($20)
* 1 console cable (free with router probably)
* 3 AC power cables (free with router probably)
* 3 Ethernet cables (crossovers, if using as shown in the following figure) ($30)

That totals $685 (2610, option 3A) or $1235 (1841, option 3B), with the 1841's cost being roughly half of the entire lab purchase for option 3B.

So, what's that give us? Here's a summary of the progression of prices and the changes relative to the previous option:

Option 1: $210 (2 routers, 2 serial links)
Option 2: $630 (adds 1 more router, latest IOS in 1 router, better FR switch for future)
Option 3A: $685 (replaces 2501 with MPLS P router capable 2610 non-XM)
Option 3B: $1235 (replaces 2610 non-XM with still-production 1841, with 2 routers running the latest IOS versions)

Next week, it's on to LAN switches, and possibly an end to the CCNA lab talk for a bit.

CCNA Lab, Part 7: Which Switch?

Submitted by wendell on Tue, 02/05/2008 - 5:15am.

So, we've discussed routers and tradeoffs in buyed used routers for a few weeks now. So... what do you do for switches? Well, at first glance, the task can be a bit daunting if oyu're still pretty new to the Cisco world. I'll give a few opinions today about what's clutter, and what I think makes a lot of sense for CCNA prep in regards to your choices when buying switches.

First, if you go to the age old (but soon to be replaced by a less intuitive URL) doc site at www.cisco.com/univercd, and pick the switch pull down, you get a long list of switch models. In fact, for perspective, I've put a section of the list here in the blog - note that there are 10 different models listed that begin with "29".

So, how to sift through it all? Well, first let me give a little background that may help us get to a reasonable choice or two.

On routers, if you run IOS on 5 different models of routers, the commands used to configure and examine a particular feature act the same, with the same syntax, with only minor exceptions to that rule. That makes studying router topics for the exams easier, and it makes writing exam questions easier, because the syntax and show command output should be the same across routers.

Most of Cisco's switch product line runs IOS - not the exact same IOS that runs on routers, but an OS whose user interface acts like router IOS. There are slight differences in command syntax on some models of IOS switches, and in defaults for commands - and that poses a bit of a problem for exam preparation and for the people writing the exam questions. If they write a question whose answer might be different depending on the model of switch, then they'd have to tell us all that the exam is based on a particular model series of switches.

So, how does Cisco deal with those differences for the exams? They keep the switching questions sufficiently generic so to avoid the differences. The questions may still be challenging, but they avoid the differences - which means we can pretty much buy any Cisco switch that runs IOS and get some benefit for studying for the CCENT and CCNA exams.

That's the good part. The bad part is that to get the most benefit from studying the switching stuff, you'd do best with the model used in the labs suggested by Cisco for their authorized ICND1 and ICDN2 courses - namely, 2960 switches. Those switches haven't seen any real reduction of prices in the used market yet. In prior versions of the courses, Cisco specified the 2950 switch, which is very close to the 2960 switch terms of command syntax and output. So, I'll treat 2950's as the high-end of the range, and look at two popular cheaper alternatives - the 1900 series and the 2900XL series.

Here's a quick look at the "buy it now" best prices when I looked on Ebay when writing this blog entry:

1900: $13

2924XL: $90

2950: $200

In closing, when I did this with the routers, I got a lot of good suggestions for other model series to look at, particularly for price ranges and functions. Next post, I'll compare these 3, but if you have another you'd like me to consider putting in the mix, let me know!

Part 8: Picking a Switch Based on History

Submitted by wendell on Thu, 02/07/2008 - 6:22am.

Two big things here today as I get close to wrapping up the CCNA practice lab discussion. 1) why I think the 1900, 1900XL, and 2950 (versus other switch models) are your best compromises for a CCNA lab, and 2) some comments comparing those three models.

Cisco uses the 2960's as the basis for labs in their authorized ICND1 and ICND2 courses. However, don't overemphasize the model per my comments last Tuesday. But I'll treat the 2960 as the best option for CCNA, and compare from there. (2960's are probably too expensive for most home CCNA labs today - around $600 on EBay.)

A bit of history can help sift through some of the options. Briefly, 1900's are old and were no longer a currently-pushed switch from Cisco almost 10 years ago. Then, around the same time, Cisco introduced the 2900 XL and 3500 XL series switches. The 3500's are more powerful that 2900's, but they run the same software, with the same command syntax, so for CCNA exam prep, there's no real benefit to the 3500 over the 2900.

Next in the progression are the 2950 and 3550 series - totally different from the 2900/3500 XL series. 2950's essentially replaced the 2900 XL series in the product line, and 3550's replaced the 3500 XL series. (That may be oversimplified, but it's enough for our purposes here.) Both the 2950 and 3550 switches run two major IOS options - a standard image and enhanced image. The 2950 series switches cannot be upgraded to the enhanced image, so that choice is a buy-time decision. The 3550's can be field upgraded - and yes, standard disclaimer here, I'm stating what can be done, and it's up to you to figure out your legal rights based on your company's relationship with Cisco.

Finally, Cisco came out with the 2960 and 3560 series switches, essentially replacing the 2950/3550 product series. The 2960 and 3560's have the same 2 options for software, the same field upgrade capabilities (no on the 2960's, yes on the 3560's). And the prices haven't fallen significantly in the used market yet.

Enough history then - what does this mean if I'm thinking CCNA, and CCNA only? Well, in my opinion - and feel free to chime in with yours, I think it's helpful - you can do the following:

• Ignore 3500 XLs in deference to the very similar but less expensive 2900 XLs
• Ignore the 3550's and 3560's, because the much cheaper 2950's/2960's work just as well for CCNA prep
• Ignore 2960's, because 2950's are very similar, and much cheaper

Going with those assumptions, next let's look at 1900's, 2900 XL's, and 2950's. That's basically where I left off on last Tuesday's post.

Catalyst 1900 switches have been around since dirt - so old that I don't even have any sitting around any more. Most of the early CCNA exams showed output from 1900 series models, if at all - but frankly the CCNA exam mostly ignored switch commands way back then. (Man, I'm gettin old - CCNA's 10 years old in April?!?!) 1900's are cheap - really cheap. If $$ is your #1 factor, 1900's it is.

On the con side, several 1900's either didn't support 100M, or if so, it wasn't 10/100 autonegotiating - just 100M. Also, the commands differ between the 1900 IOS and the IOS used by more current models, like the 2960. (eg, there's no "switchport access" interface command on the 1900.) In fact, the whole process of saving config files differs. So, if saving $100-$150 per switch matters to you, think 1900.

The 2900 XL series has some significant benefits for CCNA exam prep compared to 1900's. The commands match up better with 2960 command syntax compared to 1900s - generally, the same base command is used on the 2900XLs as on the 2960's. It supports trunking (both types), so it can trunk using 802.1Q with 2960's or 2950's in case you get one of the more recent switches. (2950's and 2960's only support 802.1Q, which is fine for real life.) On the con side for 2900 XL's, the parameters on commands supported on the 2900's and 2960's differ, in part due to the different features supported. So, you can learn the concepts behind the commands, but with differences in the syntax.

Finally, the 2950's match the 2960's almost exactly, at least for the use for CCNA exam preparation. But why not get a 2960? Well, EBay buy it now at $750 (cheapest today), versus $200 for 2950. When I was writing the most recent edition of the exam cert guides, I compared the two switch models a lot - and the only difference I found that could possibly matter for CCNA was that the 2960 defaults to "switchport mode dynamic auto", whereas 2950's default to "dynamic desirable" - meaning that two 2960's won't automatically trunk by default when connected, whereas 2950's would. Nit picky, and no big deal in regards to choosing a switch for CCNA lab preparation.

OK, quick summary table on all that:

Next post - which should be the last post in the CCNA lab series for now - will wrap up the discussion of switches for the CCNA lab. Until then, tell me what I'm missing! Thanks...

CCNA Lab, Part 9: The Bigger Picture for CCNA Switch Hardware

Submitted by wendell on Mon, 02/11/2008 - 6:11am.

To wrap up this CCNA home lab series today, I'll summarize the main options for the switches in your CCNA home lab. And I'll go ahead and spill the beans - I'd rather see you with a pair of 2900XL's instead of a single 2950.

First, let's review a few of my price guesstimates, and let me expand a bit on a key difference between the 2950's. First, the 2950's with the standard IOS image cannot be field upgraded to use the Enhanced IOS image. To get a 2950 (or 2960) with the Enhanced image, if must have been originally purchased from Cisco with the Enhanced image. To see which models have which IOS (standard or enhanced), look at this URL, and look at two different docs from the list.

If you look at this URL, you can see a comparison of features on the 2950 for both images. (Thanks to G for posting this URL last week.) Of the items missing in the Standard image, the only one I think matters for CCNA study is the lack of RSTP (aka 802.1w). The Enhanced image 2950's, whose product names include a T at the end, are still considerably more expensive than their Standard image cousins - around $400, verses around $200 for the Standard image models. In my mind, for CCNA study, it's not worth the difference. (For CCNP study, that's another matter - and CCNP's on my list for later this month!)

So, I'll suggest the 1900's, 2900XL's, and 2950C's (standard image), with these price guesstimates for comparison:

1900: $13

2900XL: $90

2950C: $200

To build a useful lab for CCNA study, I think the following are the primary criteria, in order:

• 1. At least 2 switches, preferably 3 - allows STP and Etherchannel practice
• 2. The ability to trunk between the switches - allows VTP and trunking practice
• 3. The ability to use realistic commands/syntax - generally better chance of making sense of the output seen on the exams

So, lets take a look at a $50 budget, $100 budget, $200 budget, and $300 budget. Keeping the above criteria in mind, in order, here's what I'd recommend:

$50: 3 x 1900's

$100: 1 x 1900, 1 x 2900XL

$200: 2 x 2900XL

$300: 1 x 2900XL, 1 x 2950C

Here's a few comments why: First, all choices give you the minimum 2 switches to try experiments with STP. And for just a few dollars more on the last 3 options, you could add 1 more 1900 or 2900XL to the mix, and get a triangle of switches in those cases as well. However, at $100, I'd rather see you with at least 1 2900XL, because the IOS is much more similar to the 2960 than is the IOS in the 1900.

Additionally, on the $200 budget, I'd rather see you with 2 2900XLs, rather than a single 2950C. The benefit of having two switches to experiment with STP and VTP outweighs the benefit of having the most similar IOS (commands and syntax) compared to the 2960's, at least among the three model series that I've chosen.

Finally, for $300, I think the 2950 (standard image) is well worth it, plus a 2900XL. You can do trunking between these two switches. However, because the 1900's only support ISL, and the 2950's only support 802.1Q, at the $300 budget, I'd rather avoid 1900's altogether.

So, tell me what you think. You agree with my 3 priorities, and their order? Would you go for the 2950T (enhanced image IOS)? How about 3 2900XLs if you've got a $300 budget?

Etherchannel & other features

Submitted by Shaun. (not verified) on Mon, 02/11/2008 - 2:27pm.

The only thing that worries me a little is some of the more esoteric features that 2950's support that the 2900XL's do not support or support slightly differently.

2900XL's don't handle port security in exactly the same way as 2950's or 2960's

If 2900XL's do Etherchannel, I've never seen it. I'm not even sure if plain 2950's do it and you may need 2950T or 2960's which do Etherchannel.

How big of an issue these 2 things are on exam day I would not know, and I would agree that to pass the CCNA exam it is probably more important to have a decent basic understanding of how STP works and VLANS & VTP function.

If you have a look at Scott Empson's excellent CCNA Command Quick Reference guides (both editions) you will quickly see that at least in the switching area, that 2900XL's do things differently to 2950's for some features and in other cases, there are features that you can't even do on 2900XL's that in theory a CCNA is supposed to be aware of.

Finally, when discussing 2900XL's typically we would be talking about WS-C2924XL-24 & WS-C2924XL-EN-24.

The 2924XL has a chassis that has a similar depth to a 3550 where as a 2924XL-EN has a chassis depth equivalent to most 2950's, and of course the 2924XL-EN obviously has more IOS features and will cost correspondingly more, although not that much more, say $20-$40 more.

Thanks for all your articles though Wendell, as it is a good exercise to keep evaluating my own lab as I work my way through the Certification jungle.

Lab Set up - Home - Cisco Stuff

Routers Comparison as per need:

DRAM/Flash Memory Required for Feature Support

Model	IPv6	SDM	Max IOS Ver.
Cisco 2500	16/16	Not Available	12.3
Cisco 2600	64/16	Not Available	12.3
Cisco 2600XM	128/32	128/32	12.4
Cisco 3620	64/16	Not Available	12.3
Cisco 3640	128/32	64/16	12.4

Summary of Router Interfaces

Model	Ethernet	Sync Serial (DB-60)	Async/Sync Serial Ports		NM Slots Available	Wan Slots Available
Cisco 2501	1- AUI 10mb	2	0		0	0
Cisco 2503	1- AUI 10mb	2	0		0	0
Cisco 2507/16	16 Port Hub10mb	2	0		0	0
Cisco 2514	2- AUI 10mb	2	0		0	0
Cisco 2520	1- AUI 10mb	2	2		0	0
Cisco 2610	1- RJ-45 10mb	0	0		1	2
Cisco 2611	2- RJ-45 10mb	0	0		1	2
Cisco 2612	1- RJ-45 10mb	0	0		1	2
Cisco 2610/20XM	1-RJ-45 100mb	0	0		1	2
Cisco 2611/21XM	2-RJ-45 100mb	0	0		1	2
Cisco 1720	1- RJ-45 100mb	0	0		1	2
Cisco 2620	1- RJ-45 100mb	0	0		1	2
Cisco 2621	2- RJ-45 100mb	0	0		1	2
Cisco 3620	0	0	0		2	0
Cisco 3640	0	0	0		4	0
AUI = attachment unit interface.