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New Member

CDP Query

Hi,

Can we discover two different devices through CDP on a same port? Please find the output below:

CHBNBAN2_2950A#sh cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port ID

CHBNBAN4_4506A Gig 0/1 144 R S I WS-C4506 Gig 2/4

CHBNBAN2_2950C Gig 0/2 177 S I WS-C2950G-Gig 0/1

CHBNBAN2_2950B Gig 0/2 172 S I WS-C2950G-Gig 0/1

CHBNBAN2_2950A#

Thanks and Regards,

Mayank Nauni

11 REPLIES
New Member

Re: CDP Query

Mayank

CDP is a layer 2 protocol

If your Cisco devices are connected to a Hub

then all the devices will be discovered.

Mark

New Member

Re: CDP Query

Thanks for your response Mark, but there is not Hub over there… I've confirmed the same from my counterpart. And one more query... using a hub will hamper the network performance... isn't it?

Thanks :)

Silver

Re: CDP Query

are the 2950C and B clustered ? (managed by one single IP address)

New Member

Re: CDP Query

Good point

Are the switches connected via Giga-stack connectors

detailed here

http://www.cisco.com/en/US/products/hw/modules/ps872/products_data_sheet09186a00800a1789.html

New Member

Re: CDP Query

Thanks ohassairi and Mark... will check and revert...

:)

Purple

Re: CDP Query

As a previous poster said I would venture to guess the 2950's are setup as a cluster or are tied together using stack ports ,you will see this type of dsiplay if that is the case.

Hall of Fame Super Silver

Re: CDP Query

The symptom will also happen if the devices are connected by a switch that is not a Cisco switch. If CDP frames are sent and received by a Cisco switch then the switch just processes it, you will see the switch but not see anything connected through it. But if the switch is not a Cisco switch then it does not recognize CDP and will flood the CDP frame through all of its other interfaces and you could easily see multiple devices as connected on one interface of your Cisco device.

Perhaps Mayank can tell us what kind of device is connected on Gig0/1 of CHBNBAN2_2950A?

HTH

Rick

New Member

Re: CDP Query

Hi Rick,

It's a Cisco 4506 ( output is attached in the first post)

Thanks,

Mayank Nauni

Hall of Fame Super Silver

Re: CDP Query

Mayank

Thank for for this. Could you also tell us what is physically connected on Gig 0/2?

HTH

Rick

New Member

Re: CDP Query

HI Rick,

CHBNBAN2_2950C Gig 0/2 177 S I WS-C2950G-Gig 0/1

CHBNBAN2_2950B Gig 0/2 172 S I WS-C2950G-Gig 0/1

These are two different C2950G Switches..

Thanks and Regards,

Mayank Nauni

Hall of Fame Super Silver

Re: CDP Query

Mayank

This is the CDP output which tells us what is logically connected to the interface. I would like to know what is physicall connected to Gig0/2 of CHBNBAN2_2950A.

HTH

Rick

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