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Use SNMP to find CAM table on a Cisco 4500

khuysmans
Level 1
Level 1

Hi,

OID .1.3.6.1.2.1.17.4.3.1.1 should return the CAM table entries of a given VLAN. This works on a 6500 series switch and on all 3500 I manage.

When I try this on a 4507, it only returns a few of the entries. To illustrate this:

Here is the MAC table of VLAN 102 as seen on the switch:

#sh mac-address-table vlan 102

Unicast Entries

vlan mac address type protocols port

-------+---------------+--------+---------------------+--------------------

102 0001.e69a.ae32 dynamic ip GigabitEthernet3/27

102 0002.a5d2.16b6 dynamic ip GigabitEthernet7/15

102 0004.dd0c.c03b dynamic ip,other GigabitEthernet3/25

102 0008.0216.2641 dynamic ip GigabitEthernet3/32

102 000b.cd30.1629 dynamic ip GigabitEthernet7/7

102 000c.cef1.2e3f static ip,ipx,assigned,other Switch

102 000e.7f61.d1ea dynamic ip GigabitEthernet4/6

102 000e.7f62.52bb dynamic ip GigabitEthernet7/8

102 000e.7fa6.2b5e dynamic ip GigabitEthernet7/27

102 0011.0aa4.0ba4 dynamic ip GigabitEthernet7/29

Here is the output of an snmpwalk from my monitoring host:

$ snmpwalk -v1 -c public@102 192.168.47.25 .1.3.6.1.2.1.17.4.3.1.1

SNMPv2-SMI::mib-2.17.4.3.1.1.0.1.230.154.174.50 = Hex-STRING: 00 01 E6 9A AE 32

SNMPv2-SMI::mib-2.17.4.3.1.1.0.2.165.210.22.182 = Hex-STRING: 00 02 A5 D2 16 B6

SNMPv2-SMI::mib-2.17.4.3.1.1.0.4.221.12.192.59 = Hex-STRING: 00 04 DD 0C C0 3B

SNMPv2-SMI::mib-2.17.4.3.1.1.0.8.2.22.38.65 = Hex-STRING: 00 08 02 16 26 41

SNMPv2-SMI::mib-2.17.4.3.1.1.0.11.205.48.22.41 = Hex-STRING: 00 0B CD 30 16 29

As you can see, only the first 5 are returned.

IOS of the switch: IOS (tm) Catalyst 4000 L3 Switch Software (cat4000-IS-M), Version 12.1(13)EW, EA

Has anyone seen this before and know how to solve this? (I want to get the CAM table via SNMP).

With kind regards,

Kevin

2 Replies 2

nhabib
Level 9
Level 9

You are running into CSCea74925:

Missing entries when performing getnext of dot1dTpFdbTable

This is a duplicate of CSCin28373:

SNMP walk failed on dynamic addr. greater than some static addr.

The fix is in IOS 12.1(13)EW1 and 12.1(19)EW (and newer).

Jason Davis
Cisco Employee
Cisco Employee

It appears you are doing the right thing... Using SNMP community string indexing...

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a00801576ff.shtml

Do you see this with other VLANS when you poll them?

Possibly hitting CSCea74925

Missing entries when performing getnext of dot1dTpFdbTable