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Coming Updates to the CCIE Program

June 21, 2015 2 comments

With everything going on in the industry, what is happening to the CCIE program?

I recently watched a webinar on coming updates to the CCIE program. I have also been talking to the CCIE and CCDE program managers which I am proud to call my friends. The certifications are a big part of Cisco’s business, people are afraid that certifications will lose value as Software Defined Networking (SDN) gains more traction in the industry. What is Cisco’s response to the ever changing landscape of networking?

We have already seen Cisco announce the CCNA cloud and CCNA industrial which shows that Cisco follows the market. Will we see a CCIE cloud or CCIE SDN? Doubtful… Why? Because SDN is not a track in itself, it will be part of all tracks… The CCIE DC will be refreshed to include topics like Application Centric Infrastructure (ACI) in the blueprint. When? It’s not official yet which means you have at least 6 months. My guess is that we will see an announcement before this year ends which would mean that the update is around a year away.

CCIE DC is the natural fit for SDN. What about the other tracks? Expect other tracks to get updated as well. The CCIE RS will add the Application Policy Infrastructure Controller Enterprise Module (APIC-EM) for sure and maybe some other topics as well. We will definitely see more ofย Intelligent WAN (IWAN) in the next update. The CCIE RS was recently bumped to version 5 so I would expect it to take a bit longer than the DC to refresh but it should not be that far out either. I think we can expect more refreshes since the networking is moving at a much faster pace now.

The CCIE SP will include topics such as Segment Routing (SR), Network Function Virtualizaiton (NFV), service chaining, Netconf and YANG and so on. At least that is what I expect. The CCIE SP recently moved to version 4 so I don’t expect it to change just yet but I’m sure Cisco is working on the next refresh already.

A change we have all been waiting to see is that Cisco is going to implement dual monitors in the CCIE lab. This has been discussed for a long time. According to Cisco only 6% of candidates have requested the dual monitors though which shows how important it is to give Cisco feedback. I’m sure more than 6% were bothered by the single screen in the lab. The delay in implementing it has been due to make sure that all lab centers get the same conditions at the same time to not create any debate about the testing environment.

Cisco is also working a lot with exam integrity, they have made changes to the lab delivery system in the backend to prevent people from leaking the material. There is also a much bigger pool of questions and topologies, a lot thanks to the virtualized environment. The Diagnostic (DIAG) section has also been successful in getting the passing rates down to the expected levels. Cisco does a lot of work with statistics to see how their material is received and what makes sense to ask about and if they need to rephrase something or remove it from the topology. They can also do statistical analysis to look for strange behavior from the candidates at the lab. Exam integrity is the #1 focus from my discussions with Cisco.

You have the chance to leave comments when you are taking an exam. I have been lazy in supplying comments in my tests which I will change from now on. From my discussions with the CCIE program managers this is very important feedback for them and their main source of information for how the test is being received.

If you are truly interested in improving the certifications of Cisco and you are already certified, you can apply to become a Subject Matter Expert (SME), SME’s help Cisco in exam development and in picking out the path of the certifications to include new topics and remove old ones.

I still believe in the CCIE program, it’s not going away. I think it would be a huge mistake for people to start diving into SDN without first getting the basic concepts straight. Everything can’t magically go into a fabric and never fail. Read some of Ivan Pepelnjak’s posts to get some perspective on large layer 2 domains. History always repeats itself.

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Categories: CCIE Tags: , , , , , , ,

CCIE RS v5 – My Thoughts

December 4, 2013 8 comments

When is the Update Coming

Finally the announcement is here, CCIE RS v5 is going live on June 4, 2014. That means
that the last day to take both the written and the lab for v4 is June 3, 2014.
As expected Cisco gives a 6 month heads up for candidates to prepare themselves for
the new version.

Which Version Should I Prepare for

When I started studying for the CCIE, my goal was to become a networking expert and
by that also pass the CCIE certification. That meant that I sometimes studied things
in excess of what was needed for the lab but that would help with my overall career.
I don’t understand why people get stressed out by a few extra topics added, passing
the lab should verify you as an expert, the goal should not be to just squeak by a PASS.

If you have a lab date coming up in the next months or think you can get ready by then,
give v4 a shot but realize that lab dates are probably hard to get by now that many people
are in panic mode. The new topics for v5 are things you could definitely use in your dayjob
so don’t be afraid to learn those.

Changes to CCIE Written

There are some major changes. This document from CLN shows how the different technologies
are weighted.

Written_overvievw

With Layer 3 Technologies at 40% that is the majority of the exam. What’s interesting is
that VPN Technologies and Infrastructure Security adds up to 30% which shows that security
is becoming an important part of the RS exam as well.

Cisco has done a great job of making the blueprint more detailed. If we expand the blueprint
we can see that it’s very detailed:

Written_detail_1

I get the feeling that Cisco has tried to make the new blueprint more relevant to
what people use in production and run into on those networks. I draw this conclusion
from added items like Asymmetric routing and Impact of micro burst. These are things
that can commonly cause issues in real networks.

As expected IPv6 is getting more important as well. There is a section dedicated to
migrating to v6.

Written_detail_2

There is also a section added for troubleshooting. This section contains items like
Embedded Packet Capture (EPC) and the use of Wireshark. These are great additions as well.

Written_detail_3

The Layer 2 section is basically the same as before. There is a section about VSS
and Stackwise. That might be some new topics.

Written_detail_4

The Layer 3 section hasn’t changed that much either. More focus on v6:

Written_detail_5

The addition of 4 byte ASNs is good since the 16 bit ones have pretty much run out:

Written_detail_6

It’s interesting to see that ISIS is back on the written. ISIS is not only useful in
itself. It is used by other protocols like TRILL so that might be why Cisco added it back.

Written_detail_7

The VPN Technologies is completely new and IPSEC is now included as well as DMVPN.
Although these are security topics they are important to know if you work with
routing/switching as well.

Written_detail_8

The Infrastructure Security section has mostly familiar topics with some additional
added for v6:

Written_detail_9

The Infrastructure Services has mostly familiar topics as well. Some additional v6 topics
have been added:

Written_detail_10

Some people at Twitter were disappointed to see v6 NAT and I agree that I don’t like
to see NAT for v6 unless it is used to migrate between v4 and v6.

Overall I think Cisco has done a great job. Topics are relevant and seem to be more
geared to what people work on at our daily jobs.

Some topics have been removed as well. The two major ones being Frame Relay and
Catalyst QoS. This makes sense as well, Fram Relay is rarely used now and Catalyst QoS
is very platform dependant.

Changes to CCIE Lab

There are some updates regarding the lab as well. The entire CCIE lab is now virtualized
including the configuration section. Expect to see larger topologies in the configuration
section now as the topology is virtualized. There has also been added a section called
DIAG. So the new format looks like this:

New_lab_format

First out is the TS section. What’s interesting here is that 120 minutes is alotted to it
as before. However there is the possibility of using 30 minutes extra at the cost of having
less time for the configuration section. This should be good for people that feel stressed
for time on the TS. Be aware though that usually how fast you can solve the TS tickets is
a good indication of how prepared you are for the lab.

The DIAG section is completely new and is alotted 30 minutes. It seems to use a similar
content delivery like the CCDE practical. There are no devices to diagnose, instead the
candidate will read e-mails, look at diagrams, packet captures and logs. I am carefully
optimistic about this section. I think Cisco added it to both make sure that CCIEs have
qualities as expected by them and to make it more difficult to pass by cheating.

The configuration section is the same, it is alotted 330 minutes but if you used the 30
minutes for the TS then this section is 300 minutes. I’m not sure yet if the 30 minutes
is fixed or if it is dynamic so if you use 135 minutes for the TS, do you get 315 minutes
for the config? The configuration section is now virtualized. Expect to see larger topologies.
This is good news in my opinion, this should make it more difficult for people to memorize labs.
It will also be easier to create larger topologies where we can see networks that have
routers for all roles, P, PE, CE and so on. That was difficult to do with only 5 routers
previously.

Note that to pass the CCIE lab you must pass each section, TS, DIAG and Config. Each
section will have a minimum passing score which I could not find a reference to but
the passing score has been 80% before.

Summary of All Changes

This document describes all the updates from v4 to v5.

v4_to_v5_1

The big things being added are once again DMVPN and IPSEC. There is also a focus on IPv6
and on making the blueprint more realistic.

These things have been moved/removed:

v4_to_v5_2

Frame Relay is gone and Catalyst QoS has been moved to the written. To the joy of many
v4 candidates, PfR has been moved to the written as well.

The CCIE RS v5 lab blueprint is here.

Also this page at CLN is a portal for all documents relevant for the CCIE RS v5.

Good Work Cisco!

Overall I’m very happy with this announcement. Cisco has done a great job of making the
blueprint more relevant and have added topics that people should be seeing in todays
networks. They have also taken steps to increase the integrity of the lab.
Virtualizing the entire lab is interesting and should help to create good topologies
and to provide more integrity of the CCIE.

The CCIE has never been more relevant than now.

CCIE plaque

February 6, 2013 11 comments

I received my CCIE plaque a while back. This is what it looks like.

CCIE_Plaque

Good luck to everyone pursuing the CCIE and one day you will have
one of these as well ๐Ÿ™‚

Categories: Announcement, CCIE Tags: ,

Becoming a CCIE – the path and cost associated to my number

November 2, 2012 40 comments

While on IRC I had a request to describe my journey and the costs associated with becoming
a CCIE. Becoming a CCIE is not cheap but I’ve worked for great companies that have covered
all of my costs.

I first started studying for the written back in the summer of 2010. All my posts from back
then are still available in the archives. My strategy for the written was to build a strong
foundation to stand on beforing moving on to labs. I did not want to fast forward through
the written just to get on to the labs. Remember that the CCIE lab is about thinking at a
CCIE level, it is not about commands. You need to read for the CCIE, a lot! If you don’t like
reading then I’m sorry but this exam is not for you. I’ve probably read close to the
amount of someone becoming a doctor if I count the pages of everything I’ve read so far.
Here are some of the books that I read for the written and the costs associated with them:

Interconnections: Bridges, Routers, Switches, and Internetworking Protocols
53$

TCP/IP Illustrated, Vol. 1: The Protocols
45$

Internetworking with TCP/IP Vol.1: Principles, Protocols, and Architecture (4th Edition)
30$

CCIE Routing and Switching Certification Guide (4th Edition)
55$

Routing TCP/IP, Volume 1 (2nd Edition)
63$

Routing TCP/IP, Volume II (CCIE Professional Development)
61$

Developing IP Multicast Networks, Volume I
75$

Sum of books for the written: 382$

In January of 2011 I went to take the written exam. The exam went good and I passed. It
was a bit different than the NP level exams but that was to be expected. The cost for
the written is 350$ Add that up with the cost of the books and you are looking at 732$
to get your ticket to the lab.

I needed to get some vendor workbooks and I decided to use INE due to their reputation and
instructors that were in place. I was able to pick up all the workbooks for something like
399$ on some deal.

I read Petr at INEs post on how to study for the CCIE lab exam

I decided to use the 12 month program because I was in no hurry and time is scarce when
you have kids. Basically you start out with doing all the core labs like the essential
features of the routing protocols which makes up the core knowledge you must have before
starting to do the full scale Vol2 labs. I was able to do most of the labs in Dynamips.
I converted the INE configs to Dynamips with a sed script that I’ve shared on my site earlier.
If you look at IEOC (INEs forum) you can find a user called relativitydrive that has already
converted all the configs for you if you want to run Dynamips.

For the switching tasks you need to either rent a rack or to buy your own switches and hook
them up to your Dynamips topology. My UK friend Darren has a nice post on how to connect
switches to your Dynamips topology
.

I used rack rentals to practice the switching scenarios. I don’t know exactly how much I
spent on rentals but maybe around 500$

After I had done the Vol1 labs I started with Vol2. I was shocked, first of all the
diagrams and having to configure VLANs just from a diagram was a new experience for
me as for most. Also things like configuring OSPF which I felt pretty comfortable with
I could not even complete all those tasks. Expect to be crushed! Everything you thought
you knew will be put to test. CCIE is a whole different level than most of us are used
to so keep your head up even though you will be crushed the first couple of times you
do a Vol2 lab.

There are a few different ways you can do a Vol2 type lab. Either you do all the tasks
you think you can solve in one run and then you come back and look at the things you
could not solve. Or you do the tasks you can and then you peak at the SG for the
things that you could not solve yourself. You need to find what works best for you but
don’t be too worried about speed in the beginning. That will come in time, trust me.
What you should do straight away is abandon Google, no more Google for you my friend!
To find anything you want to reference you need to go to the DOCCD. You will eat, drink
and breathe the DOCCD until you pass the lab so get used to it ๐Ÿ™‚ Basically you will
be going to the IOS 12.4T section or to the 3560 switches. The DOCCD is located here.
INE has a free Vseminar on how to use the DOCCD.

Some people see the written and the lab as two entirely different beasts. I don’t think about
it that way because you are still working towards an end goal and that is to become a CCIE.
What you don’t want to do is stop reading just because you are labbing. You need to do
both. Don’t forget to use the RFC as sources, they are a resource you should tap into.
I can’t remember everyone that I read but these are some major ones.

RFC 791 – Internet Protocol
RFC 826 – An Ethernet Address Resolution Protocol
RFC 2328 – OSPF version 2
RFC 4271 – A Border Gateway Protocol 4 (BGP-4)
RFC 3031 – Multiprotocol Label Switching Architecture
RFC 4594 – Configuration Guidelines for DiffServ Service Classes
RFC 4577 – OSPF as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)

This is a free resource and the RFCs are written by some of the smartest people in
the industry so don’t forget to use them.

If you decide to go for INE then don’t forget to use IEOC which is the
user community (forum) where you can ask questions about labs and most of what you
want to ask will already have been asked by someone previously. You will probably
find my face on a lot of threads in there ๐Ÿ™‚

When you do Vol2 labs don’t be too strict about grading yourself. Your solution can be just as
valid as long as you don’t break any restrictions. Also try to get into the habit of doing
alternate solutions and throw some extra stuff in there to make you think a bit more. When
you start a lab you should not start typing immieditaly. Read through the entire lab and
look for dependencies. Do you need to run IPv6 on 3560? Might as well change the SDM
profile and reload at once. You don’t really want to reload when you have a stable
topology. While the switches are reloading you can do your VLAN config in Notepad or
something else. The CCIE lab is about being smart and effective, typing fast helps
but is not necessary to pass the lab.

Troubleshooting is a big part of the CCIE lab. You have a 2h session with just
troubleshooting and expect to at least mess something up during your config section
as well. Many people ask: How do I learn troubleshooting? The answer is: You don’t!
You can’t just practice troubleshooting like it was a separate skill. You need to
know the protocols! In some ways the troubleshooting is more difficult because you
already have a network running and you must understand what is going on in it.
You need to use the right tools and you need to know how the output looks like.
Sometimes you might have to match output to get something correct.

INE has some cool stuff coming up with their new TS racks. Other than that
I recommend that you make troubleshooting something you do regularly.
If you get stuck on something try to figure it out by yourself first and
use the proper tools before looking for a simple solution. What I did before my
2nd lab attempt was to configure a lof of different technologies like OSPF, EIGRP,
MPLS, BGP, Multicast etc etc. I made a working topology, this in itself is
good practice. If you can’t configure a topology without someone holding your hand
then your are not ready. Then I would try to break things and looked at what happened.
For MPLS, what happens if you disable CEF? What happens when you have a duplicate RID
in OSPF? Is the behaviour the same when you are running EIGRP? This worked very well
for me and for my last 2 attempts I had no issues with the TS section.
Always remember that the network was functioning and then something was altered
to make it break. You need to solve the core issue and not work around the issue.

As I mentioned earlier you don’t want to stop reading books just because you are labbing.
Here are some of the books I read for lab preparation:

OSPF: Anatomy of an Internet Routing Protocol
46$

QOS-Enabled Networks: Tools and Foundations
76$

Practical BGP
44$

Interdomain Multicast Routing: Practical Juniper Networks and Cisco Systems Solutions
42$

MPLS-Enabled Applications: Emerging Developments and New Technologies
60$

So that is another 268$ of books. Now I did not actually buy all these books. I got a Safari
account as well which is really nice. It costs a bit but then you have all the books you need.

Every lab attempt costs around 1800$ I need to go fly to Brussels and spend one night there.
Flying usually costs around 500$ Room for a night maybe 250$ Then you need to eat
something and maybe get a cab etc. So each attempt costs around 2600$

I passed in my 3rd attempt so that is 2600$ * 3 = 7800$

If we sum it all together:

Books 650$
Written exam 350$
Workbooks 399$
Rack rental 500$
3x lab attempts 7800$

Sum: 9699$

I did not include the bootcamp in this since I consider that
optional. But everyone needs books/workbooks and of course to take the tests. If you
live nearer a testing center you can save some on the lab attempts. Hopefully you can
pass in your first or second attempt but the average is somewhere around two to four
attempts before passing. So before starting your journey you should budget for 10-15k
to earn your CCIE. Hopefully if you are lucky as I have been your employer will fund
some/all of the costs but that is no given.

Finally, there is really no way of knowing when you are ready to go to the lab except
for going to the lab and finding out. Mock labs will give you some rough guidance
but it’s not 100% accuracte because you can never simulate the stress fully. What
I do recommend is that you try to get as comfortable as possibly by simulating the
test environment. Practice using only one monitor, use PuTTY, use a US keyboard.
Check out the lab exam demo before you go to the lab. Anything that can help
easen the stress a bit on the lab day will be good.

I hope this post gave you some insight to studying and that becoming a CCIE is
indeed expensive. Hopefully it is all worth it in the end ๐Ÿ™‚

CCIE #37149 – My passing lab experience

October 24, 2012 34 comments

So by now you know that I passed my lab in Brussels yesterday. Here is my story.

I arrived at monday in Brussels around 13.30. I took a walk in the beautiful
weather to the lab location. By now I have no problems finding it but it’s
just kind of a routine. I spent the day doing some final reviews and then
visited the gym at NH hotel. It’s good to clear your head and to get sleep
in the evening if your body is tired. I did not sleep that great however.
I woke up at around 03.30 and then I went back to sleep and woke up at 5 AM
again. I got around 7h sleep so it wasn’t too bad anyway. It’s normal if
you don’t sleep that well. Don’t make too much of a deal of it.

I arrived just before 8 AM to the Cisco building and checked in at the reception
as usual. I was waiting for the proctor to come get us. The proctor goes through
the guidelines for the exam and you get assigned a rack number. It was now time
for the TS section.

I put my earplugs in and went to work. I think it is good to use earplugs for
zoning out from the environment around you. I always start by trying to solve tickets
that look easier. These are usually the ones that contain only a few devices.
The reasoning behind this is to build your confidence and to get the feeling
that time is not running out on you. For TS especially time management is
everything. As engineers we have a narrow mindset when troubleshooting and
we want to solve something before moving on. This can be your pitfall in the
TS. You MUST move on after spending 10 minutes on a ticket. Usually if you
think about something else for a while your mind starts thinking more
creatively and you can find a solution to what seemed impossible earlier.
For the TS it is very important to have a good understanding of the protocols.
You are expected to know what show output looks like so that you can gather
information from that. You need to user proper tools and don’t go hunting
with sh run. Sh run interface and sh run | section are useful though. I solved
all the tickets with about 50 min to go and then spent 15 minutes verifying
that they were still all working. Pay close attention to the restrictions
and don’t skip reading the guidelines in the beginning to save time!

It was now time for the configuration. I ate a banana to refuel some energy.
You are allowed to bring snacks to your desk if you like. I started looking
through the entire lab for dependencies and to see if any devices would need
to be reloaded. Always do this at the beginning! I started with the L2 section
and things were moving on smoothly. I used the L3 diagram to see what VLANs
I needed to configure where. You need to be comfortable with this, don’t expect
to have anything served, it’s all up to you! I did a lot more verification as
I moved along compared to my earlier attempts, don’t blindly trust your config!
I then moved on to the L3 section and that went well. I just finished the L3
section before lunch.

Previously I had only done the L2 before lunch so I knew
I was in a much better position this time. I kept doing all of the tasks
and didn’t run into any major issues. I finished with a lot of time to spare
and now comes the most important part, verification! You need some time at
the end to do extra verification, account for this! You WILL do some mistakes
just due to stress or mistyping. I went through every task and every single
bullet point and made 100% sure that I was meeting the requirement. This took
a while but it was worth it. I still had an hour to go after this so I asked
the proctor if it was possible to start the grading early but he told me that
the grading is not done by them. I decided to stay the full time and did
an extra round of verification. I actually found a small mistake in this round
of verification so my advice is to stick around even if you finish early to
make sure you have done everything that you possibly can.

It was time to head home and I had a good feeling but I did not want to think
too much about it because if you get too high then you come crashing down hard
if you fail. After I landed in Gothenburg I checked my phone and saw that I had
received an e-mail. I rushed through the air port to check my mail on the computer
and to login to the portal. To access the CCIE portal you need your CSCO number, written
date and passing score. I did not know this for my first attempt and you don’t want
to be stranded not being able to login to check your score ๐Ÿ™‚

I had received the e-mail around 19.30 and I had a good feeling that I got the score
fast but I have heard both good and bad examples of receiving a fast score. I logged
in and I saw PASS. At first I thought it might be the written so I didn’t want to
take anything for granted but then I clicked it and there it was! My number!

You all know I’ve worked hard for a long time for this and I am grateful to everyone
that has helped me on the way. I am not abandoning the blog but it might not only
be CCIE focused from now. If you have things you want me to write about make a suggestion
and if it is interesting to me I might write about it. As I don’t have to focus on
studies only now I can explore more interesting technologies and write about them.
Thanks for following on this great journey!

CCIE #37149

October 24, 2012 30 comments

Hey guys!

I’m back from Brussels and I passed the lab! I am now CCIE #37149. I’ll write a longer post tomorrow ๐Ÿ™‚

Categories: Announcement, CCIE Tags: , ,

Catalyst QoS – A deeper look at the egress queues

October 8, 2012 2 comments

I’ve done a post earlier on Catalyst QoS. That described how to
configure the QoS features on the Catalyst but I didn’t describe
in detail how the buffers work on the Catalyst platform. In this
post I will go into more detail about the buffers and thresholds
that are used.

By default, QoS is disabled. When we enable QoS all ports
will be assigned to queue-set 1. We can configure up to two
different queue-sets.

sh mls qos queue-set 
Queueset: 1
Queue     :       1       2       3       4
----------------------------------------------
buffers   :      25      25      25      25
threshold1:     100     200     100     100
threshold2:     100     200     100     100
reserved  :      50      50      50      50
maximum   :     400     400     400     400
Queueset: 2
Queue     :       1       2       3       4
----------------------------------------------
buffers   :      25      25      25      25
threshold1:     100     200     100     100
threshold2:     100     200     100     100
reserved  :      50      50      50      50
maximum   :     400     400     400     400

These are the default settings. Every port on the Catalyst has
4 egress queues (TX). When a port is experiencing congestion
it needs to place the packet into a buffer. If a packet gets
dropped it is because there were not enough buffers to store it.

So by default each queue gets 25% of the buffers. The value is
in percent to make it usable across different versions of the Catalyst
since they may have different size of buffers. The ASIC will have
buffers of some size, maybe a couple of megs but this size is not known
to us so we have to use the percentages.

Of the buffers we assign to a queue we can make the buffers reserved.
This means that no other queue can borrow from these buffers. If we
compare it to CBWFQ it would be the same as the bandwidth percent command
because that guarantees X percent of the bandwidth but it may use more
if there is bandwidth available. The buffers work the same way. There is
a common pool of buffers. The buffers that are not reserved go into the
common pool. By default 50% of the buffers are reserved and the rest go
into the common pool.

There is a maximum how much buffers the queue may use and by default this
is set to 400% This means that the queue may use up to 4x more buffers than
it has allocated (25%).

To differentiate between packets assigned to the same queue the thresholds
can be used. You can configure two thresholds and then there is an implicit
threshold that is not configurable (threshold3). It is always set to the maximum the queue
can support. If a threshold is set to 100% that means it can use 100% of
the buffers allocated to a queue. It is not recommended to put a low value
for the thresholds. IOS enforces a limit of at least 16 buffers assigned
to a queue. Every buffer is 256 bytes which means that 4096 bytes are
reserved.

	 Q1% Q1buffer Q2% Q2buffer Q3% Q3buffer Q4% Q4buffer
buffers  25           25           25           25
Thresh1  100 50       100 50       100 50       100 50
Thresh2  100 50       100 50       100 50       100 50
Reserved 50  25       50  25       50  25       50  25
maximum  400 200      400 200      400 200      400 200

This table explains how the buffers works. Lets say that this port
on the ASIC has been assigned 200 buffers. Every queue gets 25% of the
buffers which is 50 buffers. However out of these 50 buffers only 50%
are reserved which means 25 buffers. The rest of the buffers go to the
common pool. The thresholds are set to 100% which means they can use 100%
of the allocated buffers to the queue which was 50 buffers. For packets
that go to threshold3 400% of the buffers can be used which means 200 buffers.
This means that a single queue can use up all the non reserved buffers
if the other queues are not using them.

To see which queue packets are getting queued to we can use the show
platform port-asic stats enqueue command.

Switch#show platform port-asic stats enqueue gi1/0/25
Interface Gi1/0/25 TxQueue Enqueue Statistics
Queue 0
Weight 0 Frames 2
Weight 1 Frames 0
Weight 2 Frames 0
Queue 1
Weight 0 Frames 3729
Weight 1 Frames 91
Weight 2 Frames 1894
Queue 2
Weight 0 Frames 0
Weight 1 Frames 0
Weight 2 Frames 0
Queue 3
Weight 0 Frames 0
Weight 1 Frames 0
Weight 2 Frames 577

In this output we have the four queues with three thresholds. Note that queue 0
here is actually queue 1. Queue 1 is queue 2 and so on. Weight 0 is
threshold1, weight 1 is threshold2 and weight 3 is the maximum threshold.

We can also list which frames are being dropped. To do this we use the
show platform port-asic stats drop command.

Switch-38#show platform port-asic stats drop gi1/0/25
Interface Gi1/0/25 TxQueue Drop Statistics
Queue 0
Weight 0 Frames 0
Weight 1 Frames 0
Weight 2 Frames 0
Queue 1
Weight 0 Frames 5
Weight 1 Frames 0
Weight 2 Frames 0
Queue 2
Weight 0 Frames 0
Weight 1 Frames 0
Weight 2 Frames 0
Queue 3
Weight 0 Frames 0
Weight 1 Frames 0
Weight 2 Frames 0

The queues are displayed in the same way here where queue 0 = queue 1.
This command can be good to find out if you are having packet loss for important
traffic like IPTV traffic or such that is dropping in a certain queue.

The documentation for Catalyst QoS can be a bit shady and by this post I
hope that you know have a better understanding how the egress queueing works.

Categories: Catalyst, CCIE, QoS Tags: , , ,