SNMP not routing correctly accross trunked ports

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Sep 27th, 2007
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I have an small SNMP issue that effects my network monitoring systems.

I have a vlan here that manages all my routes and switches. We will call it vlan 1, I have a set of routers that connect via a T-1 to a Cisco 4506 core on the far side. It has a management vlan 2. I can monitor all switches and routers in vlan 1. I can monitor the router on the far side in vlan 2, and the 4506 in vlan 2. Off the 4506 I have several IDFs that are connected via fiber and the ports are trunked. I can not monitor any of these devices in vlan2 Thou the core and router can ping them. I can establish an SSH connection to each of them from the core. I can also get to them if I add a system into that vlan. BTW, I can get to other switches that are not trunked, and servers that are not trunked. And devices off these switches function normally.

If I traceroute the devices I will make it to the core and then get dropped.

I have band-aided the issue by adding a dual-homed polling server into vlan 2 and then it can see all the devices and sends the info-back to our monitoring systems. While that works, I want to solve the real issue(s).

BTW, no ACLs are in place currently on these VLANS

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ebreniz Wed, 10/03/2007 - 18:15
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You would need to do some troubleshooting on the device side to see verify this - get CLI (show vlan, show trunk, etc from both sides) and get SNMP info as well (walk VLAN and VTP related mibs, and look to see what is being returned there).


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