vlan and snmp issue

[Mint_Zhang]

Background- We have a NMS which was installed openview in vlan11 attach 4507 which has other vlans.Besides we not using ip routing for 4507, so vlans separated totally.I've seen openview alarm reported that whole nodes for vlan11 and inter vlan11 port down when we disconnecting NMS and 4507.We should seen other vlans down according to above.Did you think it causing due to the ip routing?Maybe i am missing snmp basic?Here is config relates.

interface Vlan1

no ip address

no ip route-cache

no ip mroute-cache

!

interface Vlan9

ip address 192.168.8.250 255.255.255.0

!

interface Vlan10

ip address 192.168.1.250 255.255.255.0

no ip route-cache

no ip mroute-cache

!

interface Vlan11

ip address 172.x.x.x.255.255.0

no ip route-cache

no ip mroute-cache

snmp-server community <removed> RO

snmp-server enable traps config

snmp-server enable traps syslog

snmp-server enable traps envmon fan shutdown supply temperature status

snmp-server host 172.x.x.183 <removed>

[mheusinger]

Hi,

may I recap:

You disconnect your NMS with HP OpenView from the network and get alarms on the NMS, that network nodes are down?

If this is the case, then I would assume the NMS simply polls the nodes and as there is no answer, the alarm is triggered. This is not unusual.

Which devices are managed by HP OV? Through SNMP the NMS might extract information on VLANs, ARP tables CDP neighbors and so on to discover the network. This way other VLANs may show up in the NMS, though no IP connectivity is available.

Hope this helps! Please rate all posts.

Regards, Martin

[Mint_Zhang]

Thanks for your reply.For your first question.In fact,we'v seen all nodes which in vlan11 downed,and inter vlan11 also downed.But we check 4507 log that just port downed which attached NMS due to NIC is unstable .

It only a cisco 4507 managed by HP OV.My question is

why it only get alarms for vlan11s and another vlans is ok.Maybe the NMS and nodes for vlan11 in same vlan?

Best regards

[Mint_Zhang]

Hi have any updates?

Best regards

[glen.grant]

My guess would be you don't have that many people in vlan 11 . If you have no active ports in vlan 11 then the layer 3 SVI will also go down (int vlan 11) and that is what you are seeing . So say if the last active port assigned to vlan 11 decides he is going home for the night and shuts off his pc then interface vlan 11 is also going to go down, you need at least one active port in vlan 11 to keep the SVI active.