On 881 L3 switch, vlan IP address does not match endpoint IP address.

[jmaxwellUSAF]

Hello. I'm troubleshooting a situation in which an endpoint lost connectivity 10 days ago. To my uncertain knowledge, nothing has been changed on the network. The below config is suspect...

GIVEN:
C881 is accessable via SSH on 172.16.4.93/29

C881 L3 switch gateway config...

#sh int vlan 33
Vlan33 is down, line protocol is down
Hardware is EtherSVI,
Internet address is 172.16.5.93/29

#sh int f1
interface FastEthernet1
switchport access vlan 33
no ip address
--

Paper documentation...
Endpoint directly connected to int f1= IP address- 172.16.4.94/29

So, the gateway and the endpoint are in the same subnet...
...but the vlan33 interface IP address is not in the same subnet as the vlan33 IP address, and the ingress port connected to the endpoint is in vlan 33.

Question: Will the endpoint 172.16.4.94/29 be able to be IP accessed by the directly connected C881?

Thank you.

[Flavio Miranda · Accepted solution]

Hi

 No. Either you change the vlan 33 to 172.16.4. or you change the endpoint to 172.16.5.

But, your problem does not stop here.

Vlan33 is down, line protocol is down

Your vlan is down.  

Run this command on the router

conf t

vlan 33

exit

int vlan 33

no shutdown

wr

[jmaxwellUSAF]

Thnak you.

Because the vlan is only active on the 1 down port, my understanding is that is why the vlan is down (and it will remain down until this changes. Actually I already executed "vlan 33, no shut" and nothing changed.). Do you agree or not?

[jmaxwellUSAF]

Update... The IT closet with the switch with stated config is inaccessible. The on-site tech established connectivity by disabling the endpoint firewall. Logic concludes the port description on the switch is incorrect (the cable must be plugged into a different port)

Though the below output is curious.. First it states that no vlans are configured, then it states that vlan 2 is up. 

#sh vlans
No Virtual LANs configured.

#sh ip int
Vlan2 is up, line protocol is up
Internet address is 172.16.4.93/29
Broadcast address is 255.255.255.255
Address determined by non-volatile memory
Helper address is not set
Directed broadcast forwarding is disabled
Multicast reserved groups joined: 224.0.0.10

---

I can only conclude that it is possible to create and use a vlan virtual interface while having no actual vlan established.

Is this surprising to you (your thoughts)?

[jframe]

Based on the information you provided, it appears that the IP address of the endpoint (172.16.4.94/29) is in a different subnet than the IP address assigned to the VLAN33 interface on the C881 (172.16.5.93/29).

In order for the endpoint to be able to communicate with the C881 or any other device on the network, it needs to have an IP address that is in the same subnet as the gateway (VLAN33 interface). If the endpoint's IP address is not in the same subnet as the gateway, it will not be able to communicate with other devices on the network.

So, in this case, it is likely that the endpoint is unable to communicate with the C881 or any other device on the network due to the mismatched subnets. To resolve the issue, you will need to reconfigure the network so that the endpoint's IP address is in the same subnet as the VLAN33 interface on the C881.