Solved

Command to see if IP or MAC is getting to Cisco Router

Posted on 2015-01-16
9
40 Views
Last Modified: 2016-10-14
I have a 2821 router and I'm trying to see if a specific IP or MAC is passing the WAN and hitting this router.  What is the command to monitor for this?
0
Comment
Question by:bergquistcompany
9 Comments
 
LVL 17

Expert Comment

by:Spartan_1337
ID: 40554156
you could try: show mac-address-table address H.H.H

What is it you are trying to do?
0
 
LVL 14

Accepted Solution

by:
John-Charles-Herzberg earned 168 total points
ID: 40554163
I would use Using the ping or trace route commands.  More information on how do do this is attached in the PDF from cisco
13730-ext-ping-trace.pdf
0
 
LVL 17

Expert Comment

by:Spartan_1337
ID: 40554166
Or you can use: show arp
0
PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

 

Author Comment

by:bergquistcompany
ID: 40554171
I have a device on one side of my WAN that isn't talking to the device on the other side of the WAN so I want to see if the request is getting across the WAN (not blocked)  by seeing if I can see any trace of that IP or MAC registering with the router on the other side of the WAN
0
 
LVL 57

Expert Comment

by:giltjr
ID: 40554189
John-Charles-Herzberg suggestion of using tracert is a good place to start.  This assumes that all the routing equipment is configured to allow ICMP packets through.

Depending on the type of routers used, you could look at the ACL's and/or do packet captures of traffic flowing through them.
0
 
LVL 28

Assisted Solution

by:Predrag Jovic
Predrag Jovic earned 166 total points
ID: 40554223
Aside of traceroute, the easiest way is  to turn on debuging on router you are trying to ping #debug ip icmp so if you ping router with debug on -  you will see dubug messages.
Something like:
*Jun  12 17:52:50.311: ICMP: echo reply sent, src 10.1.12.8, dst 10.0.11.100
If it is production router don't forget to turn off debugging.
There is also packet capture function, more complex, but more suitable for use on production router.

MAC addresses are locally significant, so MAC address never passes out of LAN.
0
 
LVL 46

Assisted Solution

by:Craig Beck
Craig Beck earned 166 total points
ID: 40556320
You can't monitor MAC addresses over layer-3, so ARP is out of the question, as is looking at the CAM table..  You would have to monitor using IP instead.  Ping or traceroute won't help either really.

Just create an ACL on the distant router which permits the IP you want to monitor, and use the debug ip packet command to see what traffic hits the router.
0

Featured Post

Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

In the hope of saving someone else's sanity... About a year ago we bought a Cisco 1921 router with two ADSL/VDSL EHWIC cards to load balance local network traffic over the two broadband lines we have, but we couldn't get the routing to work consi…
Short answer to this question: there is no effective WiFi manager in iOS devices as seen in Windows WiFi or Macbook OSx WiFi management, but this article will try and provide some amicable solutions to better suite your needs.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

821 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question