Home > Ask the Networking Experts > Network administration with Lindi Horton Questions & Answers > Is there a command in a Cisco Catalyst that will tell me the IP address of a PC hanging off a port?
Ask The Networking Expert: Questions & Answers
EMAIL THIS

Is there a command in a Cisco Catalyst that will tell me the IP address of a PC hanging off a port?

Lindi Horton EXPERT RESPONSE FROM: Lindi Horton

Pose a Question
Other Networking Categories
Meet all Networking Experts
Become an Expert for this site


Routing and switching news, advice and technical information
Digg This!    StumbleUpon Toolbar StumbleUpon    Bookmark with Delicious Del.icio.us    Add to Google


>
QUESTION POSED ON: 02 April 2007

Is there a command in a Cisco Catalyst (in the 2950 and 3548 series) that will tell me the IP address of the PC hanging off a particular port? I cannot use a sniffer on the network. The network is remote to me. I am using SecureCRT, and I log into the Cisco.


>
EXPERT RESPONSE

A single command won't tell you these things. From what I gather you don't have a lot of access to manage and configure the switches but you are able to view the route and ARP tables in the switches and routers.

Just a note, there are several tools available that utilize SNMP discovery to automate this process for you. You might want to investigate these if you have SNMP access to the switches and routers. In fact, Cisco wrote a fairly good article on how to accomplish this with SNMP: How to get MAC and IP address accounting information using SNMP.

Now to address your question from the CLI, it's a multi-step process. Because the Catalyst switches are Layer 2 switches, they operate mostly on MAC addresses. Therefore you would need the default gateway router to identify the MAC address of the IP in question. The show ARP command on a Cisco router will output the IP address and MAC address. You want to use the show ARP command to just display results for a single IP.

Once you have identified the MAC address you can then identify the port it's attached to on the switch by using a show CAM dynamic or show MAC command. Thus, SNMP is probably the easiest way for you to obtain what you need. Let me know if you want some recommendations on SNMP products for network discovery.


Sound Off! -   Be the first to post a message to Sound Off!


Digg This!    StumbleUpon Toolbar StumbleUpon    Bookmark with Delicious Del.icio.us    Add to Google


RELATED CONTENT
Network Routing Protocols
Does each routing protocol have a different routing table?
How can I load balance between DSLs and LLs?
How to configure ISDN and backup leases on routers
Types of link-state advertisements (LSAs) used in Open Shortest Path First (OSPF)
How do I configure two leased lines in one router?
Why IPv4 and IPv6 don't do fragment reassembly in routers
What is the difference between a GRE tunnel and IPsec tunnel?
How can I check connectivity and ping between sites?
How does asynchronous transfer mode differ from existing network technologies?
Routing with NAT traversal and UPnP
Network Routing Protocols Research

IP Addressing
IPv4 or IPv6 -- Myths and Realities
What is a logical network? How do you improve one?
Why are IPv6's IP addresses in hexadecimal formatting?
Prevent IP address conflicts on your wireless network by managing DHCP scopes
Get IPv6 skills now rather than later
How can I check connectivity and ping between sites?
Can I connect to my wireless network and wired LAN simultaneously?
How to subnet: Subnetting calculations and shortcuts
How do IP addresses work on Layer 2 switches?
What is the procedure for assigning network addresses?

Network Security Best Practices
Securing the new network architecture: Security for distributed, dynamic networks
How to set passwords on folders in Windows 2003 servers
What are the best methods for handling rogue access points?
How to configure Windows Server 2008 advanced firewall MMC snap-in
Governance, compliance, security: How are these network problems?
Holidays are over; now beware the gadgets
Prevent unauthorized USB devices with software restriction policies, third-party apps
Introduction to firewalls: Types of firewall
Network firewall know-how: Avoid network latency while protecting your network
Firewalls for network security and auditing

RELATED GLOSSARY TERMS
Terms from Whatis.com − the technology online dictionary
10-Gigabit Ethernet  (SearchNetworking.com)
Asynchronous Pulsed Radiated Incident Light  (SearchNetworking.com)
BOOTP  (SearchNetworking.com)
CSMA/CA  (SearchNetworking.com)
Dynamic Source Routing  (SearchNetworking.com)
edge device  (SearchNetworking.com)
GMPLS  (SearchNetworking.com)
Link Quality Source Routing  (SearchNetworking.com)
Next Steps in Signaling  (SearchNetworking.com)
STUN  (SearchNetworking.com)

RELATED RESOURCES
2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems
Search Bitpipe.com for the latest white papers and business webcasts
Whatis.com, the online computer dictionary



Search and Browse the Expert Answer Center
Search and browse more than 25,000 question and answer pairs from more than 250 TechTarget industry experts.
Browse our Expert Advice

HomeNewsTopicsITKnowledge ExchangeTipsAsk the ExpertsWebcastsWhite PapersNetworking Product Trials
About Us  |  Contact Us  |  For Advertisers  |  For Business Partners  |  Site Index  |  RSS
SEARCH 
TechTarget provides enterprise IT professionals with the information they need to perform their jobs - from developing strategy, to making cost-effective IT purchase decisions and managing their organizations' IT projects - with its network of technology-specific Web sites, events and magazines.

TechTarget Corporate Web Site  |  Media Kits  |  Reprints  |  Site Map




All Rights Reserved, Copyright 2000 - 2008, TechTarget | Read our Privacy Policy
  TechTarget - The IT Media ROI Experts