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New Member

SNMP Problem...HELP!

Ok, I have aboout 50 switches and SNMP works on all of them great. I have one layer 3 switch that has SNMP enabled with the same commands, everything is the same, but when I try to run some things that use SNMP the layer 3 does not work. Below is my configurations on all of the switches. The Layer 2's range in models but the Layer 3 is a Cisco 3550. Could someone please let me know why the layer 3 will not work correctly with SNMP?

Thanks for any help in advance!!

snmp-server engineID local xxx

snmp-server community *** RO

snmp-server community *** RW

  • LAN Switching and Routing

Re: SNMP Problem...HELP!

This question contains not too much info to go on. For example, what exactly are you doing with snmp and what is it that does not work?

You could have an incorrect MIB for this device but it might as well be a routing issue where the mgmt station cannot properly reach the device.

As a last remark I would advise you to implement some security on your snmp devices, especially as you are using snmp write as well. Please check the link below for guidance:



New Member

Re: SNMP Problem...HELP!

I am trying to use a port mapper, it used the layer 3 to map the ip addresses to the mac addresses. just goes to verify the community string and says that it is wrong.

The layer 3 routing is fine.

Re: SNMP Problem...HELP!

When it says the community string is incorrect, it likely that this is the case.

Have you tried to set the interface from which snmp originates?

This can be controlled via: ip snmp source-interface xxx

You can also try some standard commands from the MIB2 set. If these are working and your port mapper is not, this likely due to the use of a non-standard MIB.


Re: SNMP Problem...HELP!

I don't know whether this is the case here because I don't understand your problem fully. (And I hope you will elucidate it further.)

But this reminds me that sometimes you have to encode the instance into the community string when you interrogate it.

For example, if you want to interrogate the transparent bridge MIB of VLAN 1, you just use the configured community-string, for example CISCO. To interrogate the transparent bridge MIB for VLAN 100, you have to use community string CISCO@100.

I wonder if that is relevant in other cases, e.g. layer-3 VLAN interfaces or VLAN ARP caches?

Kevin Dorrell


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