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Community Member

Can't walk GRE tunnel interface via SNMP

Hi to all,

I'm not able to walk a tunnel interface in my router, one day the tunnel came down but after the problem was solved it came up again and since that i'm not able to walk it using snmp, i have 4 other tunnels configured and those i can see them.

I use whatsUp to monitor my network and the support says that there is a problem with the device that i'm monitoring wich is the router, i also tried with different snmp tools and the result is the same, i only see 4 of 6 tunnels.

do you know what can be causing this?

Thanks in advance.

12 REPLIES
Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

What does it mean that you can't walk it? What objects are you polling? What type of SNMP request are you using? what version of IOS is running on this router?

Community Member

Re: Can't walk GRE tunnel interface via SNMP

Hi jclarke,

I mean that using snmp i can't see all the tunnels that are configured in the router, i only see 4 and the router has 6, this is the OID .1.3.6.1.2.1.2.2.1.2, the IOS version is Cisco IOS Software, 3800 Software (C3825-ADVIPSERVICESK9-M), Version 12.4(3i), RELEASE SOFTWARE (fc2)

I also tried with different snmp tools and the result is the same.

Here i attach you some images where you can see the problem.

Thanks in advance for your help

Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

Post the output of "show snmp mib ifmib ifindex" from this router.

Community Member

Re: Can't walk GRE tunnel interface via SNMP

Hi,

Here you have it:

rncleon-cor02-3825#show snmp mib ifmib ifindex

Async0/0/0: Ifindex = 11

GigabitEthernet0/0: Ifindex = 1

Loopback0: Ifindex = 13

Null0: Ifindex = 9

Serial0/0/0: Ifindex = 7

Loopback1: Ifindex = 20

Vlan1: Ifindex = 10

FastEthernet0/1/0: Ifindex = 3

GigabitEthernet0/1: Ifindex = 2

Async0/0/1: Ifindex = 12

Serial0/0/1: Ifindex = 8

FastEthernet0/1/1: Ifindex = 4

FastEthernet0/1/2: Ifindex = 5

Tunnel1002: Ifindex = 14

Tunnel2002: Ifindex = 19

FastEthernet0/1/3: Ifindex = 6

Tunnel1003: Ifindex = 15

Tunnel1004: Ifindex = 16

Tunnel1005: Ifindex = 17

Tunnel1007: Ifindex = 18

rncleon-cor02-3825#

Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

All of the interfaces are here. What is WhatsUp doing to walk the ifTable? Is it using get-next or get-bulk requests? If you do a get on 1.3.6.1.2.1.2.2.1.2.15 do you get a response from the router?

Community Member

Re: Can't walk GRE tunnel interface via SNMP

Hi,

It uses a get-bulk, i did the get on 1.3.6.1.2.1.2.2.1.2.15 and there was no answer but i believe the mib-walker doesn't support that sintax because i also tried 1.3.6.1.2.1.2.2.1.2.14 wich is an interface that it is recognized by the whatsup and there was no answer too, i also use the getif snmp tool and i have the same result, just 4 tunnels of 6 and no info using the sintax 1.3.6.1.2.1.2.2.1.2.14 where the 14 is the index of the interface.

Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

You need to do a GET, not a get-bulk or get-next on that OID. You can use the net-snmp toolchain from http://net-snmp.sourceforge.net to do this. I would also be interested if a get-net walk works on ifTable to see this missing instances.

Community Member

Re: Can't walk GRE tunnel interface via SNMP

Hi jclarke,

I'll try it using the netsnmp, but i wonder why in all the other routers in the network it works fine, i mean using snmp i see all the tunnels configured?? the ios version is the same.

I'll tell you if it works with the netsnmp.

Thanks alot for your help.

Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

This is most likely an IOS bug, but figuring out which SNMP PDUs work and which do not will be helpful in isolating it.

Community Member

Re: Can't walk GRE tunnel interface via SNMP

I understand, i'll use the netsnmp and tell you what happens.

Thanks alot!

Community Member

Re: Can't walk GRE tunnel interface via SNMP

Hi jclarke,

I did the test using the netsnmp and there is no result when i perform an snmpget to the specific interfaces that i can't see in whatsup, here are the results:

C:\Program Files\net-snmp\bin>snmpget -v 2c -c cossnmpro 10.233.71.252 IF-MIB::ifDescr.15

IF-MIB::ifDescr.15 = No Such Instance currently exists at this OID

C:\Program Files\net-snmp\bin>snmpget -v 2c -c cossnmpro 10.233.71.252 IF-MIB::ifDescr.17

IF-MIB::ifDescr.17 = No Such Instance currently exists at this OID

and if i ask for one that is seen by whatsup i get the correct result:

C:\Program Files\net-snmp\bin>snmpget -v 2c -c cossnmpro 10.233.71.252 IF-MIB::ifDescr.16

IF-MIB::ifDescr.16 = STRING: Tunnel1004

Do you think i should do an ios upgrade?

Thanks in advance for your help.

Cisco Employee

Re: Can't walk GRE tunnel interface via SNMP

Yes. I believe this is related to CSCek30711 which is fixed in 12.4(10).

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