Unidentified Network and Switch Can't Ping Gateway

[gtichtla123]

Hello everyone,

I'm currently facing an issue with my test-network setup, and I'm reaching out to seek your expertise in troubleshooting.

Here's a brief overview of the problem:

1. Unidentified Network Issue:

   • The client connected to the switch is displaying an "Unidentified Network" error and is unable to obtain a network connection.

2. Switch Cannot Ping Gateway:

   • The switch, a Cisco 2950, is unable to ping the configured gateway (router).

3. Background Information:

   • The switch and the client are both part of the same VLAN.
   • The switch is configured with VLAN information, and the client is set to the default VLAN.
   • The client is unable to obtain network connectivity, showing the "Unidentified Network" message.
   • The switch cannot successfully ping the configured gateway.
   • The Switch's SFP Uplink is a MirkoTik L2 Switch

4. Troubleshooting Steps Taken:

   • The switch has been reset, and a basic flat network configuration has been attempted.
   • VLAN configurations have been simplified for testing purposes.
   • The switch has been configured with the IP address of the router as the default gateway.
   • Despite these efforts, the issue persists.
   • Checking, if there was a issue with the L2 Mikrotik Switch

I kindly request your assistance in identifying the potential causes of this problem and providing guidance on how to resolve it. Any insights, suggestions, or steps for further troubleshooting would be highly appreciated.

For additional context, here are some relevant details:

• Switch Model: Cisco Catalyst 3750 48TS-S
• Switch Configuration: interface FastEthernet2/0/1
  switchport mode access
  !
• interface GigabitEthernet2/0/1
  switchport mode access

interface Vlan1
ip address 192.168.1.123 255.255.255.0
!
ip default-gateway 192.168.1.1
ip classless
ip http server

The Test client is connected on Fe2/0/1, Uplink is on Gi2/0/1.

Here some pics of the test-network: https://imgur.com/a/Ucu5UjR

Any ideas?

[liviu.gheorghe]

Hello @gtichtla123 ,

How is the IP address configured on the test client - manual or dhcp?

Can you ping the default gateway from the Cisco Catalyst 3750 switch and after that provide the output from the following commands:

• show vlan
• show mac address-table
• show arp
• show interface status

[balaji.bandi]

I take this Switch acting as Layer 2 and your all the Layer 3 sit in your Mikrotik box (192.168.1.1)

On the PC are you using same subnet static or Dynamic using Gateway 192.168.1.1

can you post ipconfig /all (from PC)

from PC are you able to ping 192.168.1.1 ?

Unidentified Network

reasons are - the device not able to reach internet. (above steps should able to fix the issue)

Also suggest to add port-fast device connected PC 

interface gig 2/0/1

spanning-tree portfast

Note : switch showing port number 2/0/1 means this switch was part of stack before, if you like to change to Gig1/0/X port change the #switch 2 re-number 1, save the config and reload. so next reload all the ports start with Gig1/0/X

[Richard Burts]

It might be helpful if you would post the output of these commands on the 3750 switch

show interface status

show arp