All right now for our last discussion of the day and it's going to be on EtherChannel bundling.
How many of you are doing EtherChannel bundling? How many of you are doing EtherChannel bundling?
Maybe you don't know what EtherChannel is. How about port channeling? How about channel grouping?
How about NIC teaming? I'm just going to throw out those words. Okay we're talking about the
same thing. EtherChannel is Cisco's terminology they use. It's their marketing term for port
channeling, NIC teaming, port aggregation, all of that stuff. All right so when we look at this
particular scenario we might ask ourselves, hey you know we're having some bandwidth issues.
We're having some bandwidth issues here and here and here and here and here. So how can we increase
the bandwidth between our switches? Well we can go ahead and we can upgrade to better switches
with higher port speeds. Well good luck with that if you don't have the budget. Maybe you can upgrade
just the ports on the switch if it's a modular switch. Again good luck with that if you don't
have the budget. Last but not least you can just simply add more links between your switches.
So you know that's pretty cheap. I can, if I have free ports, if I have some free ports on my device
whether they're fiber ports or whether they're copper ports, doesn't matter right. If I have
some free ports that we can utilize between our switches let's go ahead and add more switches.
Add more links. That's all we're doing here. Okay but here's the problem. Here's the problem.
The problem is Spanishy protocol. Spanishy protocol is going to rear its ugly head and say nope sorry
I'm going to block all loops in this particular case. So even though we have eight links between
all of our switches in this scenario we can only take this path, this path, and this path through
this layer two environment. So this is not going to work for us right because we just wasted a
whole bunch of links. We wasted a whole bunch of ports and we're not getting the value we want out
of it. We want to increase our bandwidth right. We want to increase our bandwidth. So what do we have
to do is we have to actually bundle these ports together. Basically take an elastic band and put
an elastic band around them. That's what we're going to do. Bundle them together. Elasticize
them together. Now I mean it's not just you physically putting an elastic band. You don't
even have to put an elastic band around and you won't put an elastic band around them but I'm
trying to give you a mental image of what you're actually doing here. We're aggregating those links
together. So ether channel, link aggregation, port channeling, channel grouping, whatever you want to
call it it's fine. Cisco's naming is ether channel bundling. Okay cost-effective scalable way for you
to what? Get more bandwidth. Get more bandwidth. Fault tolerant meaning that if a link fails in
the in there that's okay. The rest of them still keep working. Another one fails that's okay. They
keep working whoever is left over in that particular bundle. Now we still have a problem with
Spanning Sheet Protocol right because we do have a loop. This is a loop. This is a loop. This is an
entire loop. So Spanning Sheet Protocol is still going to come along and block entire bundles. Hey
this is still better though than blocking all the links except for three that we saw a little bit
earlier. So this is still a lot better at least we've got eight here, eight here, eight here. So
a total of 24 out of all the links that we have. So this is really good. All right so things to
remember we have two or more physical links logically treated as one. Now for Cisco iOS
more maxes out at eight sort of. It depends on the protocol you're using. So if you're using the
protocol called PEG-P Port Aggregation Protocol which is Cisco proprietary then yes the max is
eight. Eight in a bundle, eight max that you can use. But if you're using something like LACP you can
have 16 in the bundle. Okay 16 in bundle but you can only use eight at a time okay. So two or more
physical links logically treated as one but if using LACP you can have 16 but you can only use
eight at a time. Meaning the other eight would be failovers, backups. So if all of a sudden one of the
eight that are being used fails then one of the other eight that are remaining that aren't being
used can be used. So you can have 8, 9, 10, 11, 12, 13, 14, 15, 16 it's up to you with LACP but PEG-P
maxes out at eight. We get more bandwidth. Up here there's one logical port the Spanning Sheet Protocol
that's why we can block that entire bundle or why we can allow all that traffic on that link.
We can do this on layer two interfaces or layer three interfaces. So we can do it on routed ports
or we can do it on access ports. We can do it on trunk ports and there's a variety of ways to load
share as well. One also thing to note I want you to know about ether channel for IOS is that you
can only create your bundles between two devices. So meaning that I cannot do a bundle like this
unless we're doing what stack-wise. So if we take advantage of stacking then I can do that
because remember every switch in a stack is connected together
with a backplane cable called the stacking cable and they're treated as one logical unit
almost like as if they were a single chassis based switch when it's all said and done.
So instead of having a backplane and then all your modules are plugging into it you have individual
switches that you connect to cable with specialized cables. The cables are the same as the
backplane that would be inside of a chassis based switch. So essentially it's a way to do a chassis
based type of switch without doing a chassis based type of switch stacking. So in this case because
they're now treated as one logical entity then I could do bundles from those different devices.
Okay same thing if we're doing VSS virtual switching service up at the distribution layer
then yes we could do this as well. All right so that's something to keep in mind when we're talking
about the bundling. So for the exam though right most of your ether channel examples are not going
to be doing any type of stacking whatsoever. So it's important for you to remember that if they
try to make a bundle like this that is wrong that is the problem that is why it's not working.
Keep that in mind. All right so the protocols PEG-P LACP versus none what does that mean? Well
PEG-P port aggregation protocol that's a cisco proprietary protocol as we said supports up to
eight links only and whereas LACP is an industry standard protocol 802.3 ad
right we can have eight links in use but up to a total of 16 total in a bundle for failover
for failover sakes. So for the exam any scenario that talks about two cisco switches so if this
is cisco and this is cisco you can use either or you can use either or it's up to you.
But if the example has a cisco switch and a non-cisco switch then you have no choice but to
use LACP keep that in mind. Right so cisco to cisco you can use either or but if it's cisco to a
non-cisco you got to be using LACP and more than likely multiple spanning tree protocol as well.
None means you're connecting the devices together without using a protocol
so this would be really good in any type of scenario where for example if you had your switch
and you were connecting to something like a server and you were doing nick teaming on your server
and the server if it didn't support LACP then you could do none on this side over here
meaning you're going to set up your bundle without relying on any type of protocol.
But if the service supports LACP then you might as well go ahead and use LACP.
Another example would be you have a switch connected up to a wireless LAN controller
typically your wireless controllers do not support PEGP or LACP so you're doing your
configuration here so therefore you'd have to have none over here. So just examples if the other
device doesn't support a protocol then you would do none on this side no protocol on this side and
the keyword we'll see later is actually on that's the keyword we'll use whereas PEGP and LACP have
other keywords. Yeah so everything I'm talking about here is iOS because this is exam is on iOS
okay so if you're if you're familiar with using like Nexus products and you have your VPCs with
Nexus products or you're using more links with those Nexus products or anything like that then
that that is not what this discussion is iOS this entire exam is testing you on your knowledge of
Cisco iOS and iOS XE and iOS XE. All right now if there are new products out there that you've
received recently that the numbers are different for them now and they allow you to do more they
allow you to do different things again when this exam was updated and created right they're not
testing you on that they're still testing on what I'm teaching you now and that is what the
fundamentals the total fundamentals of the majority of products that are out there running Cisco iOS
and iOS XE. All right so either channel we're going to focus on our links between DSW-1 and
DSW-2 today. I'll show you some configurations some examples right but the first thing I always
want to tell people about this and this is so important when you're doing an EtherChannel bundle
and you are bundling these interfaces together that device expects every single one of those
interfaces to be the exact same. All those four ports in this scenario have to be the same speed
the same duplex if they're access ports they all have to be in the same VLAN okay if they're trunk
ports they all have to have the same native VLAN if they're trunk ports they all have to have the
exact same VLAN allowed list and if they're not then you're gonna have errors so you're gonna
have to solve those problems so on the exam whenever you're troubleshooting EtherChannel
bundles look for these things look for any of these things in the scenario in the situation
because if any of them are out of alignment and they're not the same on all those physical ports
that's your problem solve that problem meaning oh multiple choice question what does it say
it says option C says to adjust the VLAN allowed list to include duh duh duh duh and duh great
that's my answer because based on what we looked at that was the thing that was wrong
again because it's iOS as we talked about here's a note just what we talked about two switches per
bundle that's it so this switch going to this switch I could not do three switches like a VPC
or anything like that or if we were doing stack wise where I could have more switches in the stack
going to different switches that's not covered here that's not part of this exam this exam is
hey iOS fundamentals two switches therefore all these ports must be going to one other device
can't be two other devices in this scenario so again if all of a sudden you see a bundle
like that on the exam right that's not right in this case
so anytime you have issues it's pretty much usually related to misconfigurations
misconfigurations so what has to match versus what doesn't match that's what you're looking
for on the certification exam if it's if it's a troubleshooting scenario for ether channel
all right peg p keywords are desirable in auto so if the scenario is about
cisco devices connecting the cisco devices then you might have the opportunity to use peg p on
the exam if they throw the term desirable out there that's peg p auto that's peg p
right so desirable initiates the ether channel session auto waits for neighboring switch sounds
a lot like dtp yes same idea so that means desirable works with desirable desirable works
with auto but auto auto doesn't work together so again looking at it looking at a scenario on the
exam if one side is desirable the other side is desirable that's not the problem one side's auto
the other side's desirable that's not the problem both sides are auto there's your problem
i'll show you how to set that up in the command momentarily lacp your keywords are active and
passive so again if it's an lacp scenario so it could be two cisco devices or a cisco device in a
non-cisco device lacp what are you going to do well if passive passive are on both sides not
going to work but if it's passive and active it's going to work if it's active and active it's going
to work why because active says initiate the ether channel session passive says wait
so very straightforward it's about memorizing this and always remember that no protocol so
if you don't use a protocol on one side and use the keyword of on which we'll talk about here
momentarily on then the other side would have to be on it can't be lacp it can't be peggy so
this side is on you can't have active here you can't have passive here you can't have
desirable here you can't have auto here why because you can't have active here you can't
you can't have active here you can't have passive here you can't have desirable here
you can't have auto here why this is on the other side has to be on in that particular case
all right time to do some config
so
perfect just reading my notes in regards to uh things we've talked about so let's go to dsw1
right now and the first thing i want to do is i want to factory default reset my interfaces
because we've done a lot on these four interfaces and we could definitely have some misconfigurations
right now so it's always better to get them to exactly a state where you know they're all the
same and in that way there you can build your configuration on top of that so default interface
range gigabit ethernet 1 0 17 through 20 good and then we'll do the same thing over on dsw2
all right and then over here on dsw1 i'm going to go interface range 17 through 20
and i'm going to shut down all four of those interfaces why because
either channel bundling is very very very
finicky very dependent on order of operations therefore if you are leaving your interfaces up
while you're doing it and you are making changes it's going to cause a lot of changes a lot of
changes a lot of flapping a lot of of adjustments it's going to cause spanning tree protocol to
go crazy and do a lot of topology change notifications and a lot of different things
so the idea here is to you know bring it down the interfaces that you're going to be adjusting make
all the changes and then bring them back up so that way there you're only doing a convergence
twice once on the way down once on the way back up instead of like four or five times as you're
doing your configuration also the differences between configuring one side versus another side
could ultimately affect to your your um your negotiation and as a result of that just based
on timing you could end up in a situation where you're gonna have to bounce all your interfaces
anyways to get it to work which you don't want to have to do so it's better to in my opinion
shut it down do your config bring them back up and then let the magic happen and then everything
should be fine for you so what are we going to do here we are going to begin we are so far in
gigabit one slash zero slash 17 through 20 we're going to start using the command of channel group
and this is where you specify the number the number that will indicate which interfaces are
part of which group so for example if i do channel group uh jeffrey says five jeffrey said five okay
so if i create channel group five since we're configuring all four interfaces at the same time
this is going to be in channel group five channel group five channel group five channel which means
they're all part of the same group so what does that mean it means i can create another group
here so we did another bundle here i could do group seven group seven i could do group six group
six right so i have the number that you specify here indicates which interfaces go together in
the bundle so gigabit 17 is part of group 5 18 is part of group 5 19 is part of group 5 20 is part
of group 5 because i'm configuring them all at the same time with the interface range command
if i did them all individually then i whatever command i'm about to type here i have to copy
and paste to all those interfaces now it says mode so we'll type in mode and then next here's
those keywords active auto desirable honor passive so the on means no protocol so pay attention to
this on the exam right if they're asking you to do a config or troubleshoot or verify or anything
of a config whether it's multiple choice drag and drop simulation doesn't matter fact is pay
attention to the details of the scenario because if they turn around say they want you to use an
industry standard protocol that means active or passive are your options they say they want you
to the cisco proprietary protocol the desirable and auto are your options they say they don't
want you to use a protocol then you on is your only option right but then also pay a little
bit more attention to what if they say on dsw1 you must configure it with an industry standard
protocol but you do not want it initiating the connection then you type in passive
right what about a scenario where they turn around and they say something like you want
to use a cisco proprietary protocol but you don't want it initiating the connection right you see
just those little key words tell you exactly what you must be using in that particular case
right so now that i've used auto on this side i have no choice but to use desirable on the other
side notice what happened as soon as i typed this in notice how it created something called a port
channel okay what is a port channel a port channel is now the virtual interface
that is going to be used for this bundle so 17 18 19 and 20 are bundled together
and they are now represented as port channel number five port channel number five
so if i type in do show ip interface brief and we go all the way to the bottom
you'll see that port channel 5 is now in my list of virtual interfaces that i have on my device
right now it's down down because all the physical interfaces are down right now
that's why it's down right but now port channel 5 is what type of interface it's a layer 2 interface
why is it a layer 2 interface because my interfaces were layer 2 by default so since
they're layer 2 interfaces the port channel is automatically a layer 2 port channel so what does
that mean it means i can configure what oh boo i can configure vlans i can configure trunks i can
configure whatever i need on that interface from a layer 2 perspective i can't configure an ip
address i can't configure dynamic routing protocol why it's layer 2 so layer 2 port channels are
going to allow me to do layer 2 things so let's go ahead right now and type in interface port
channel 5 as an example and we'll type in switch port trunk encapsulation dot one q
switch port mode trunk switch port no negotiate switch port trunk allowed
vlans 10 20 50 200 switch port trunk native vlan 99
oh this device doesn't like that cool all right but that's just a prime example of showing you
that do show run interface
port channel 5 now 5 right there's my configuration
now what about the physical interfaces what i want you to realize is that the physical interfaces
inherit the port channel configuration so we type in the same command but instead of port channel 5
let's say gigabit ethernet 1.0 17 look at that it inherited the configuration that i typed
so anything you type on the port channel goes to the physical interface so that's an important
thing to realize too for the exam is that you don't want to start messing around with the
physical interfaces once you have a port channel just mess around with the port channel anything
you do to the port channel will affect the physical interfaces you know often i get a
question well what if i wanted to change the speed of one of the interfaces you're not allowed
because if you change the speed of one interface the other interfaces no longer match right
so you have to change the speed of all the interfaces yes so you might as well just
change the speed on the port channel which affects all the interfaces so you might as
well just configure the port channel going forward so that way there you affect all the interfaces
all right so there you go there's a prime example of how we would configure this
so now let's go to dsw2 and on dsw2 interface range gigabit ethernet 1.0 17 through 20 okay
and now what are we going to type in we're going to type in channel group now the channel group
number doesn't have to match meaning that this number does not have to match the other side
so i could use something like your 10 10 10 10 if i wanted to i don't have to do the same number
but i like to do the same number why because then i know when i am troubleshooting that anything
that is port channel 5 here is port channel 5 on the other side so i know that 5 goes to 5 6 goes
to 6 7 goes to 7 8 that's how i like to do it but you don't have to do it that way now our mode here
in this particular case is going to be what is going to be it has to be desirable why because
the other side was auto so another thing to pay attention to on the exam is if you're doing any
type of configuration scenario and one side's already configured and you're trying to do the
other side well look at the other side and find out what did they do what did they do in their
particular case well they used auto over here on those physical interfaces okay well then i have
no choice but to use desirable on the other side rejected why why are you rejected what did i do
wrong
oh geez anybody see my mistake
oops oops
that's bad i hope that didn't mess everything up for today
oh i gotta check my work
ouch gotta double check before you hit enter raymond let's hope that didn't mess up the rest
of the topology that's not because i'll be fixing stuff before tomorrow's class then
all right so let's do that now
um
okay so what's the best thing to do what's the best thing to do what's the best thing to do
okay let's go back to this range and let's do this
okay now that i've done that
let's go back to this and try
all right got it all right so we're good there so all i do is negate it from all of those interfaces
and then went back and just did the interfaces i was supposed to i hope i got away with it we'll
see what happens this might be the worst demo ever for ether channel by raymond all right so now
for ether channel by raymond all right so now the port channel the port channel
okay so it was already created as you can see up here
so it didn't recreate it so it already exists so we can type an interface port channel five
and now we need the same config that we have over here so let's just go to this port channel
and we'll copy and paste it my fingers are so crossed we are not toast on this demo
what happens you just got to default it and start all over all right so it looks like we're okay
so now that i have it configured the same way on both sides
do show run interface port channel five that looks good do show run interface gigabit 1 0 17
good 18 good 19 good 20 good okay what else was included in there seven seven's fine eight's fine
good all right so excellent i think we're okay all right so now let's just bring up all the
physical interface so interface range gigabit ethernet 1 size 0 size 17 through 20 let's
confirm that's the right range yep no shut there we go fingers crossed basically what i'm looking
for is port channel 5 up up when it's all said and done is port channel 5 up up when it's all
said and done so we got port channel 5 up we've got port channel 5 up yes we got them both all
right good so we should be a okay so show ip interface brief let's scroll all the way down
to the bottom and we'll see port channel 5 is up up there it is okay let's take a peek now at
something like show interface port channel 5 and you'll see the bandwidth here look at that it is
what it is four gigabits per second theoretically all right it's not a perfect four gigabits per
second because it's still for one gig link so you're only getting the performance of one gig
links but you're getting that performance across four links at that time and you'll see that it
shows you now which members are part of that ether channel bundle all right what else do we want to
take a peek at oh let's take a look at show interfaces trunk now so we can see what this
output might look at look like now and we'll see here that the port channel is showing up instead
of the physical interfaces and our vlan allowed list as we created is showing up there right this
is beautiful all right what about spanning tree protocol then show spanning tree mst1
look it's port channel 5 that is showing up and look at the priority it gave it 544
that's awesome 544 but look look at the cost remember when we were talking about long versus
short i said a gig is a thousand i'm sorry gig is 20 000 so uh two gig would be 10 000 and four gig
would be 5 000 and eight gig would be 2500 well there you go there's 5 000 for four gigs
for spanning tree protocol cost
all right so if you notice here then we're on dsw1 that entire port port channel 5 is now in
the forwarding state so all four of those links are in the forwarding state we go to dsw2 do show
span for mst1 we should see that it's the root port the entire port channel yep so the entire
port channel so as before remember we were blocking three out of those four ports now
all of them are the root port in this example all right and let's take a look at show ether
summary so when we look at show ether channel summary we'll see here that we have
the group number five so any interface that is part of group five is going to show up here and
there they are 17 18 19 and 20 so if we add another interface to the group and we type in
channel group five on that interface and we'd have to use the same mode so mode auto then it would
show up in this list because we typed it as channel group five and if we had other
channel groups here if we had other port channels they would show up in this output as well
so for example we're on dsw2 right now if we had a port channel here and a port channel here we'd
have three port channels and they would all show up here with the interfaces in them we look here
at the port channel it says p05 or p yeah p05 uh su so su stands for what capital s means layer two
which we've talked about already as we had this discussion and in use so this is good su means it
is perfect it's working it's operational as layer two peg p if we were using lacp it's a lacp if
it's an on not on it wouldn't say on typically it shows up as a dash so if you saw a dash especially
on the exam the dash here would mean that you used the keyword of on and then these p's are good p's
mean bundled in the port channel you want to see p's now here's the deal if you see anything else
in this output on the certification exam so if you see d over here or you see eyes over here or you
see s's over here or you see f's or m's or da da da da what i want you to realize is that there
is a problem and you have to figure out what that problem is what does that mean you got to compare
and contrast your configuration it is a configuration problem right remember we said speed
master match duplex has to match for the access ports they all have to be in the same vlan verify
that stuff look at that stuff what else we said if it's a trunk port the native vlan has to match
we said the vlan allowed list has to match so if any of those things are not what they're supposed
to be that is why you have a problem so you may be troubleshooting ether channel on the exam but
in the end what are you really troubleshooting you're troubleshooting vlan allowed list you're
troubleshooting um uh speed you're troubleshooting duplex you're troubleshooting you know things that
are not directly related to ether channel they're related to other technologies but they have an
effect on ether channel so look at compare and contrast the configuration and that is
ultimately going to solve your problem whatever it happens to be and answer your question
now if you see h h is not bad h is actually good
so if you see an h it typically means that you well not typically it means you are running lacp
first and foremost so notice we're running peg p so we would never see an h with peg p we would
never see an h if there was dashes there but we would definitely see an h if we're using lacp
and there are more than eight interfaces so the ninth interface would have an h the 10th interface
would have an h the 11th interface would have an h remember you can have up to 16 interfaces
but only eight are being used so the eight that are being used will have p's and the rest of them
will have h's as hot standbys and then if one of the p's fail then one of the h's get promoted to
a p and then that's the one that's being used so that's a benefit of lacp all right all right so
there's our live configuration i know we are at the end of today's session but there's still a
little bit more we have to cover with either channel and then we'll be done for the day
right so my slides show you the configs basically as we've done them here folks and then this output
here as well so nothing new but there if it's lacp it shows up as that but if it's not lacp it's on
it would show up like that instead so just keep that in mind for the certification exam right
we've already seen this output as well so it's about the bandwidth we never looked at this output
but here's just another way show ether channel port channel it'll show all your different groups so in
this case i created group 12 in this example so for port number 12 what do you have well you need
logical slot and port numbers not exam relevant but you know number of ports that are in it what
protocol did you use are you active and so on and so forth which ports are part of the bundle so you
could get asked a simple question about something like this maybe maybe not probably not but just
something to show you that you know being able to read these things uh based on the fundamentals
that we've learned is the most important skill to have something like this i'll show you here
be careful with the output they show you because if you look at this command it's talking about
the neighbor so what you need to do is you need to look here this is dsw1 we're on dsw1 right now
we're on dsw1 that's who we're on okay so if the neighbor neighbor means this device here
so all of this is referring to this device down here even though we're on dsw1 pay attention to
that sometimes they do these types of questions just to see are you paying attention it has
nothing to do with your knowledge and everything to do with more can you read a question so in the
end they might ask you um which of the following ports are participating in lacp whatever i mean
that's pretty straightforward there's the ports on dsw2 okay dsw2 right or maybe you're looking at
the answer options and they're asking you about um specific things you see here but some of the
answer options are referring to dsw1 dsw1 dsw1 when in actuality if you pick that option even
though the number is right they use dsw1 that means it's wrong you got to look for the one that's on
dsw2 so just be paying attention to that on this exam right these flags here this row right here
you see the a a means active so what does that mean it means dsw2 was configured with the keyword
of active that's what that means so what does that mean dsw1 was configured with well we don't know
by looking at this output but it may be active or it could be passive right so maybe the question
is testing you on something like that right what what could dsw1 had been configured with
so when you look at this output here like oh okay that's the active flag right the other option would
be passive because it's lacp so if this is active then it could be this or that so then you're
looking for an answer option that says active or passive but if these were all p's as an example so
erase these and put p p p p right then you know that oh this is the neighbor of dsw1
so this would have been passive which means dsw1 without a doubt has to be active in this case
so priorities um and device id so that would be your base ethernet mac address that's what that
would be and your priority this would be for um prioritizing interfaces so you have the ability
to prioritize interfaces right meaning maybe have an interface be used more than another interface
or when you have more than eight interfaces especially with lacp how do you ensure that
certain interfaces are being used under normal conditions and if and only if there's a failure
do you want the other ones to be used then you can mess around with the priority you can mess
around with the priority meaning that if you give lower priorities to certain interfaces they're
going to be used uh before the other interfaces are used and those other ones will be h interfaces
as opposed to p interfaces in that other output that we saw right that's that's pretty much it
for this example output just to you know teach you how to pay attention and and make sure that
you can read certain things then we go to dsw2 and run the lacp to c okay so that command also
works with pegp so that command does work with pegp um so i'm not going to switch everything to
lacp on this device i really can't do that right now without having to kill everything
bring it back but what we could do is um show pegp neighbor as an example
all right so that's the different this one's slightly different the output here in this
particular case but if you look and the flags are down here so a for auto mode remember we
configured uh dsw1 for auto mode so there's the a for auto mode but if we had configured it
um for desirable mode so if we look at um let's go to dsw1 show pegp
one so show pegp internal shows me my internal information right so i was what i was configured
with auto and if we do show pegp neighbor
right you'll see in this case there's no flag so no flag
means desirable so that's the way they do it for pegp slightly different so not the exact same
output all right
hope answer your question kind of to give you an idea what's going on there
without me having to switch the entire environment over to lacp okay good
all right so uh layer three ether channel bundle i won't do a configuration here in the live
environment because we are well over the class time but basically what we're doing is we'll be
using routed ports instead so with our routed ports we convert these to routed ports first
and then we set up our ether channel bundle if you try to convert everything to routed ports
after the fact it actually causes significant issues that you may not be able to recover from
i've tried this in a live class before because somebody asked me to try it just i'll just just
convert them to routed ports see what happens okay and it messed everything up it messed
everything up and the only way to recover i spent about 30 minutes after class trying to troubleshoot
we couldn't get it to work properly because the port channel did not want to become a routed port
the physical interfaces were routed ports but the port channel would not become a routed port even
if i typed it in on the port channel as well and it started creating conflicts and it would not
start working right so basically wiped the whole thing out and configured it from scratch and
everything worked properly at that point in time so something to keep in mind but i have had students
say oh no it's worked for me in the past great perfect i loved hearing that but it didn't work
for me in that live environment that day by changing the routed port so typically what
you're going to do is you're going to default your interfaces convert them to routed ports
and and how do you do that so default the interfaces could then go to the interfaces
convert them to routed ports and then type in your channel group command and then create your
port channel from there right and now because these were layer three interfaces this is a layer
three port channel automatically so your port channel inherits the characteristics of the
physical interfaces when it's created so a layer two interface creates a layer two port channel
layer three interfaces create layer three port channels so therefore another thing to think
about in the exam is if you have to bundle interfaces together and two of them are layer
two and two of them are layer three you can't do that because it's not going to work they all have
to be layer two or they all have to be layer three that's another thing to keep in mind
right and now that it's layer three when i go to the port channel i can't create trunks i can't
create vlans i can't do anything like that it is what ip addressing and i could also type in ip osp
f1 area zero as an example and enable ospf on that port channel so now that would actually change
my layer three environment to this so l3 would be this and now l2 you see it's on this side of
the line now so i'm running ospf everywhere here or eigrp everywhere here now so yeah i'm routing
over the bundled links that's really awesome so this is really great when you think about it on
in a bigger scale environment so let's go back to our campus architecture example when you think
about this campus architecture example and we erase everything we have here that is not required
anymore and we think about the fact that the new environment this would be layer two this would be
layer two and everything else is layer three well think about all of these being ether channel
bundles as routed ports ether channel bundles as routed ports all of them everywhere everywhere
and so now we've got layer three routed ports as ether channel bundles and therefore we're running
ospf or eigrp on them so not only can we do load balancing within the ether channel bundle but we
can also load balance across different ether channel bundles because of our dynamic routing
protocols so for example if my dynamic routing protocol is deciding to load balance on two
different paths then i could also load balance inside the ether channel bundle
that is so cool i love it great stuff absolutely great stuff
all right so the only difference here in this output that you're going to see is this value
here everything else is still going to be the same so r for routed layer three so the exam if
they're talking about a routed scenario and you see an s here well that's your problem it wasn't
created properly or if they're talking about a layer two scenario and you see an r there well
then again it wasn't created properly so that would be something you would have to solve okay
maybe delete everything erase everything recreate it so that way they're the port channels created
as layer two for the layer two interfaces or it's created as layer three for the layer three
interfaces and so on and so forth all right and then what else do we have here we have our bandwidth
for example as well right so load balancing for ether channel bundling is actually very finicky
and it's not what we want it to be it's not as easy like our dynamic routing protocols load balance
exceptionally well and that's why in newer modern day networks we really want to do routing
everywhere and do our ether channel bundling as well with layer three links but still within the
layer ether channel bundle it's it's not amazing like it doesn't excite me as much as it excites me
when my dynamic routing protocols are doing load balancing and the reason why is because it's it's
based on certain values like mac addresses or ip addresses or port numbers and it could be in a
combination of different and if you pick the wrong one on your device load balancing is not actually
going to work properly for you so there is a default on your platform and you can verify the
default on your platform by typing in show ether channel load balance so right now india said you
want if i type in show ether channel load balance you're going to see here that i'm load balancing
based on source mac address that's it source mac address so what happens is the device when it
receives a frame looks at the source mac address and then it uses that source mac address to decide
which link to go across that's what it does but you'll see we have different options that we can
choose from and depending on the platform will determine what options you can use now i haven't
updated this for the new 9000 series of catalyst switches which are awesome by the way um but you
know this is what we got okay and so when you look at these options here and you're not gonna have to
worry about the models for the certification exam right but when you look at these options here
right destination ip destination mac first of all does it ever make sense to
load balance in your layer 2 environment based on destination mac address well let me answer that
for you the answer is no why is that because most of the traffic comes from a pc and goes where
in the layer 2 network almost 100 of your traffic goes from the pc to who in a layer 2 network
the default gateway which is going to mean that everybody has the same destination mac address
so that would be like the worst option you could use in your layer 2 network
because the destination mac address is always the same so you would not want to do that in
the layer 2 environment now elsewhere it might work fine but not in that layer 2 environment
so what you choose is going to be the one that gives you the best results based on your traffic
types based on your ip addressing based on your mac addressing based on port numbers as an example
that's right meaning that what you choose you're going to have to test and how do you test it you
choose it you implement it and then you monitor traffic flow on each link in the ether channel
bundle and i'll show you the command that you can do that here i'll show you right now
right the command you can do that with is right here
clear counters and then do show interface the interface name the interface number and then
include packets output yeah definitely i'm going to get to that that is like primarily like
the best option you can use in reality when it's all said and done
for most people that's the one that works best so when you do that for each interface then you'll
be able to see hey are we getting a roughly equalized load balance from our users traffic
now it's never going to be perfect because the load balancing with either channel bundling
is based on what it's going to be based on
using the ip address of the mac address but not the whole thing not the whole thing and it's also
based on the number of links you have so let's say you have two links in your ether channel bundle
that's it just two links and let's say we're load balancing based on destination ip so if we're load
balancing based on destination ip what's the destination ip right here it's 40 so let me break
that out we've got 0 0 1 0 1 0 0 0 2 links means we only look at the very last bit that's it just
look at the very last bit and the reason why is because this link gets a value of 0 this link
gets a value of 1 so whatever the very last bit is in the ip address is going to determine which
link you use so if the destination ip is this then it's going across this link what if the
destination ip was 42 well if it's 42 it also ends in a zero so it's going to use this link
what if it's 44 so all again 44 would end in a zero as a binary so again it would use that same
link so in this case because we only have two links all even destination ip addresses traffic
would go on this link all odd destination ip addresses would go on that link so for some reason
every single destination is even in your organization then you're not going to be
doing any load balancing right so that's why you got to test that's why you got to test
right what if you got four links though what do you got four links like i have now on the screen
well now the numbering changes because it's 0 0 0 1 1 0 and 1 1 so now what does that mean you
have to look at the last two digits now the last two digits so it ends in 0 0 it would go across
this link if it ended in 0 1 it would go across this link if it ends in 1 0 it goes across this
link if it ends in 1 1 it goes across that link what about if you have eight links well then if
you have eight links it's 0 0 0 1 1 0 1 1 uh so 0 0 0 0 0 1 1 0 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 there
you go so again if the last three values end in zero then it's using the first link if it's 0 0 1
etc etc etc etc you get the picture now here's the thing about either channel bundling as well
because it's based on this we're dealing with powers of two so what would happen for example
if you only had three links well if you only had three links how many values would we have to use
we still have to use two values so with three links we would still have to use two values
so what does that mean you'd have 0 0 0 1 1 0 1 1 okay where where's 1 1 where's 1 1 we still
need four values because it's 2 to the power of 4 or 2 to the power of 2 i mean right 2 to the power
of 2 it's 4 we got four values but we only have three links well then that means one of these
links for example is going to get both so now we've got 50 of the traffic going here 25 percent
going here 25 percent going here so the moral of the story is this with either channel bundling you
should use two four or eight links two four or eight links powers of two if you don't then you're
never going to get a proper load balancing you can do it but you're never going to get a proper
load balancing because other links have to take on that extra traffic so for example if you went
ahead and you went with five links just five links that means three out of those five have to
take on double duty for traffic because of the number of what the number of binary values that
have to be referenced in that particular case right so that is how it works so it takes it
takes time you have to decide do you want to use source ip do you want to use destination ip do you
want to use source mac or destination mac right but and then monitor the traffic for a couple of
days and find out what you're getting and if you're getting an even distribution across then
you know it's pretty good but that doesn't mean it's still going to be good in a couple of months
from now if you make changes elsewhere in your organization and ip addresses change elsewhere
in your organization that can change everything so you have to constantly watch it however
jeffrey says we use source and destination ip we use a combination of the two we don't just use
like source ip or destination ip or source mac or destination mac we use source and destination
combined together and that's where an exor operation comes into play so i'm going to use
a mac address as an example but more than likely the um more than likely something like the source
and destination ip would be your better option in the real world meaning if i'd try that one first
folks and see if you get a nice low distribution with source and destination ip and if you do just
stick with it don't waste more of your brain cycles trying to figure out there's another
better option if you're getting good results of source and destination ip go with it if you can
do source and destination port number on higher end platforms use that one because you have more
variety in port numbers than you would in ip addresses because if you think about port numbers
i could have a user going to the same server 10 times using three different source port numbers
so if i do a source and destination port number combination that means that user's traffic could
be distributed across those links really well as a single user so if using just source of destination
ip typically one a user will more than likely use the same link over and over again more than not
but if you do port numbers that's going to change drastically all right but in the end here what do
we have in the end for example with the xor operation so if we're doing 33 and 44 because
we're going to do source and destination in this case so 0 0 1 1 0 0 1 1 for 33 and then 44 is
going to be 0 1 0 0 0 1 0 0 so with the x or you can see my little chart in the bottom right hand
corner 0 0 equals 0 0 1 equals 1 1 0 equals 1 1 1 0 equals 0 so 1 and 0 equals what 1 and 0 equals 1
1 and 0 equals 1 0 and 1 equals 1 so we think about our port 0 0 0 0 0 1 0 1 0 1 0
0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 then now source and destination in this case is 1 1 1 we're
going to take the last link on the thing so typically with the xor operation you're going
to get better results and so i like to uh try source and destination ip first if it works great
if you're still not getting anything uh good out of that then start playing around some of the other
ones and so definitely clear counters but before you clear counters always double check if you can
actually clear counters before you do so the last thing you want to do is clear counters and if
there is some sort of monitoring system that's relying on your counters and you go and clear
them that could be a bad thing so always double check that first and then do a show interface
include packets output and that'll let you double check so if i go over to dsw1 as an example
show interface gigabit 1 0 17 pipe to include packets
output as an example that's the that's what you would see as your option so now if we go to 18
and we go to 19 and we go to 20
17 right now i haven't cleared my counters in ages and we just set up load balancing so
this is kind of misleading isn't it so that's why something like clear counters
yes i want to clear all my interface counters and now if we go back and look through everything
17 you'll see we're back down low so now monitor this for a couple of days
come back and review to see where we're at in regards to all these different interfaces
and then you'll be able to get a better picture of what is going on in regards to ether channel
bundling and there you go folks we are officially done today's session and thanks for hanging out
with me a little bit longer than we had intended i really do appreciate that but hopefully you have
gleaned a lot of valuable information from the discussions that we have been able to have today