×
INTELLIGENT WORK FORUMS
FOR COMPUTER PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

How can i find out what Servers are connected to what ports on 3550
2

How can i find out what Servers are connected to what ports on 3550

How can i find out what Servers are connected to what ports on 3550

(OP)
Hello,
How can i find out what Servers are connected to what ports on Cisco 3550 switch.

I built an arp table. (pinged the servers).
What can i do to find out the mapping of MAC addresses to the switch ports (sh int - shows only switch's ports mac addresses).
Thank you

RE: How can i find out what Servers are connected to what ports on 3550

Hello Leo74,

You only have to combine the ARP table from your router with the "show mac-address-table" output from your switch.
And fortunately there is a perl script which will do this exact thing for you.
Find a MRTG mirror and find the /contrib/ folder.
http://public.planetmirror.com/pub/mrtg/contrib/
Now get your hands on the file "cammer".
Read the cammer.readme.txt and off you go.

I run this perl script every hour and use the output to fill a database. Now I can keep track of MAC addresses which pop up in my network (wanted and unwanted).

RE: How can i find out what Servers are connected to what ports on 3550

(OP)
Thank you PalmTest for your reply.

RE: How can i find out what Servers are connected to what ports on 3550

(OP)
You really help me out this my issue...

RE: How can i find out what Servers are connected to what ports on 3550

I have a dedicated "Network monitor" PC installed for this.
The Monitor-PC does two things.
1: MRTG, to get a graphical overview of my most important switches and connections.
(http://www.openinnovations.com/mrtgbundle.html)
2: Cammer, to get a hold of all the changes in my network.
Cammer runs every 15 minutes.

When a problem occurs (whatever the reason), I can check the global utilization of my important connections to see if Production is in danger, and when necessary, I can trace any MAC address back to it's switchport.
I can even trace MAC addresses which do not use TCP/IP and are not validated (Laptops!!) by the Helpdesk.
It surprises people that I know where a malicious machine is without them loggin in to my Domain.

The Network Monitoring PC is setup in such a way that there is no need to be logged in, so it runs stand-alone.

RE: How can i find out what Servers are connected to what ports on 3550

You can also do this 100% from the switch vs. pinging all of your hosts to gather the arp table. Just to add onto what PalmTable already posted. This is good for just looking up the mac and port of one or two devices. Here's how:

At your Switch# prompt type:

show ip arp | include ip.addy.you.need

ex, show ip arp | include 192.168.100.100

You will get back something like:

Internet 192.168.100.100     5   0010.1801.cc18 ARPA Vlan100

00:10:18:01:cc:18 is your MAC. Then at the Switch# prompt type in:

show mac-address-table | include last_4_of_mac

ex, show mac-address-table | include cc18

You will get back something like:

0010.1801.cc18    DYNAMIC     Gi0/3

Your switchport, using my example, is Gi0/3

Works well for me when I need to look one up quickly, anyways...

HTH,
GWC

RE: How can i find out what Servers are connected to what ports on 3550

(OP)
Thank you all for your responces!
;-0

RE: How can i find out what Servers are connected to what ports on 3550

So i took great interest in this post..now i have a question of my own

As soon as I read the info about MRTG and Cammer, I jumped for joy..this is exactly what i've been looking for!.. I have MRTG working and getting snmp info from both my host router and my cat6500. However, i REALLY want to run cammer to monitor my ports. Being a perl virgin, how in the name of hades would i go about setting up cammer? i'm guessing i have to run it via MRTG somehow?.please help...i'm almost there!

TIA.!

Work Smarter, Not Harder....

RE: How can i find out what Servers are connected to what ports on 3550

Hi CorruptedLogic,

You have MRTG up and running, which means that Perl is installed. To check this, type PERL -V in a Command Prompt (DOS Box).
Place your CAMMER file where you like it the most (e.g. d:\cammer\cammer
For your convenience you can rename the file to CAMMER.PL
Now create a batch file (.cmd) from which you run cammer.pl
It might look something like this:

---- begin cammer.cmd ----
@Echo off
Title Cammer MAC collector
perl d:\cammer\cammer.pl public@SwitchName public@RouterName >>MacAddresses.txt
---- end cammer.cmd ----

Ofcourse you have to change the SNMP read community string (public) and fill in the DNS name or IP address of your Switch and Router.
When all is done you have a text file containing the information. I used the append function ( >> ) so I do not lose previous information.
You might want to (automatically) import this file in a Database.

HTH.

RE: How can i find out what Servers are connected to what ports on 3550

Thanks PalmTest, i played around with cammer / mrtg yesterday. I can get teh script to TRY to run, but it returns SNMP fetch errors. Do i have to setup anything in particualr on the switch by way of SNMP traps? Also, I read a few posts elsewhere which suggests cammer will only work with certain switches. We are using a catlyst 6550..any experience using it with one of those??

Work Smarter, Not Harder....

RE: How can i find out what Servers are connected to what ports on 3550

Hi CorruptedLogic,

Be sure that your machine may ask SNMP questions to your Router and Switches.
Most of the time SNMP access is limited to Management Stations only.
Also be sure to use the correct SNMPReadCommunity string.

Check for ACL's preventing SNMP to/from your machine.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close