- (man) In this video, we want to take a look
at how we can configure a local SPAN
on a Cisco Catalyst Switch.
You can see our topology here on screen.
We have two hosts connected
into switch one on Gig 0/1 and 0/2,
and on Gig 3/3, we have a traffic analyzer connected.
So we want to configure the switch for SPAN.
We're going to collect the information from
the hosts on Gig 0/1 and 2,
and we're going to send that over to our analyzer on Gig 3/3.
So let's go under global configuration mode
and we can use the keyword monitor
and contextual help is going to indicate
that the keyword session will configure a SPAN session.
And then we need to give that a number.
I'll make this number one.
If we look at contextual help again,
we can see that we have the source options,
so let's choose that.
This is going to allow us to set the source
from which SPAN traffic is going to be copied.
And that can be either an interface, or it can be a VLAN.
And, so in this case, we want to choose an interface option.
And if we look underneath our interfaces,
you'll see that we can choose
either a gigabit ethernet interface,
which is what I have here on this switch,
or we can choose an EtherChannel port-channel.
I'll choose the interfaces where my two hosts are connected.
Again, from the topology,
you can see that those are Gig 0/1 and 0/2.
So I'll choose that option.
And, once more, we'll look at our contextual help,
and you can see right up top
we can use a comma if we want to do that.
If we want to specify more noncontiguous interfaces,
we can do that.
Or, we can choose our monitoring options, here.
We can monitor received traffic, transmitted traffic,
or both received and transmitted.
I'm going to use the both keyword
and that's going to complete this command.
Now, by the way, if you don't specify any direction here,
the default option is going to be both.
So by default, SPAN is going to monitor
both send and receive traffic.
So we've now specified our SPAN source.
Now we need to set the SPAN destination for this session.
So again we want to say, "monitor session one."
And, by the way,
it's important to note that with local SPAN,
you need to use the same session number
for the source and the destination interfaces.
This is very important.
So instead of source, this time we're going to say destination
and if we look at our help options,
we can see the ability to choose
the local interface or a remote interface.
Now, we're going to choose the remote interface
in a different video when we're configuring remote SPAN,
so here, with local SPAN,
we need to choose the interface option once again.
And again we're going to need to specify the local interface.
Notice this time we don't have
the option to choose a port-channel.
We only have the option
for a local gigabit ethernet interface.
We cannot use an EtherChannel or VLAN as a destination
when we're using local SPAN.
So just keep that in mind.
From out topology diagram,
we can see that our traffic analyzer sits on port Gig 3/3.
So we want to do that, hit enter,
and that's all we need to set up local SPAN.
Now, if we wanted to send this
session information to multiple destination ports,
if we had multiple traffic analyzers connected
to this switch that were collecting specific metrics,
we could certainly repeat this command again
and configure that same session
to go out to multiple destination ports.
In our case, we only have the one analyzer on the network,
so we're done.
We can verify this with the command show monitor session
followed by the session number,
which of course was one.
And in this output, we can see that this is listed
as a local SPAN session.
We can see that we have Gig 0/1 and 0/2 configured
and that we are capturing
in both the send and receive directions
and we see the destination port listed as Gig 3/3.
So that all looks great.
And that's a look at how we can very simply configure
local SPAN, source and destination ports
on a CISCO Catalyst Switch.