Introduction
In this case study, we will explore a common issue in domain networks: intermittent connectivity between devices due to dropping connections on three specific switches. We will focus on the OneDC, FS Switch voice=172.Data=173, and HP switch voice=1.17. By following a systematic approach, we will identify and resolve the root cause of the problem.
Understanding the Domain Environment
The domain environment consists of three switches: OneDC, FS Switch voice=172.Data=173, and HP switch voice=1.17. Their IP addresses are as follows:
- OneDC: IP address not provided
- FS Switch voice=172.Data=173: IP address 172.16.1.5
- HP switch voice=1.17: IP address 172.16.117.1
Identifying the Issue: VLANs and IP Addresses
To begin troubleshooting, we need to identify the VLANs and IP addresses associated with each switch:
OneDC: VLANs and IP addresses not provided
FS Switch voice=172.Data=173:
VLAN 1 - IP address 172.16.1.5 (voice VLAN)
VLAN 2 - IP address 172.16.1.6 (data VLAN)
HP switch voice=1.17:
VLAN 1 - IP address 172.16.117.1 (voice VLAN)
VLAN 2 - IP address 172.16.117.2 (data VLAN)
Verifying Connectivity: Ping and Traceroute
Next, we will verify connectivity between the switches using ping and traceroute:
% On FS Switch voice=172.Data=173 (switch A):
Switch# ping 172.16.1.6
PING 172.16.1.6 56(84) bytes of data.
64 bytes from 172.16.1.6: icmp_seq=1 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=2 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=3 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=4 RTT=1 ms
% On HP switch voice=1.17 (switch C):
Switch# traceroute 172.16.1.5
Tracing the route to 172.16.1.5
VLAN1: 172.16.117.1 1 ms 1 ms 1 ms
VLAN2: 172.16.1.6 4 ms 4 ms 4 ms
Checking Configuration: Show Commands
We will now check the configuration of each switch using show commands:
% On FS Switch voice=172.Data=173 (switch A):
Switch# show interface fastEthernet 0/1
FastEthernet0/1 is up, line protocol is up
Hardware: FAST Ethernet, Address: 0011.2222.3333.4444
Description: Connection to switch B
Switch port mode: dynamic desirable
Switching Path Cost: 19
Switching Path State: up
Switching Path last input: 00:01:54 ago
Switching Path last output: 00:01:53 ago
Switching Path Data: 0x0
Switching Path Transmit Hold Count: 1
Switching Path Receive Hold Count: 1
Switching Path Forward Transmit Queue Length: 0
Switching Path Forward Receive Queue Length: 0
Switching Path Switch: 0011.5555.6666.7777 (switch B)
Switching Path Protocol: static
Switching Path Interface: FastEthernet0/1
Switching Path Cost: 19
Switching Path State: up
Switching Path last input: 00:01:55 ago
Switching Path last output: 00:01:54 ago
Switching Path Data: 0x0
Switching Path Transmit Hold Count: 1
Switching Path Receive Hold Count: 1
Switching Path Forward Transmit Queue Length: 0
Switching Path Forward Receive Queue Length: 0
Switching Path Switch: 0011.5555.6666.7777 (switch B)
Switching Path Protocol: static
% On HP switch voice=1.17 (switch C):
Switch# show interface FastEthernet0/1
Name: FastEthernet0/1
Switching Port: Enabled
Switching Path Cost: 1
Switching Path State: up
Switching Path last input: 00:00:38 ago
Switching Path last output: 00:00:37 ago
Switching Path Data: 0x0
Switching Path Transmit Hold Count: 1
Switching Path Receive Hold Count: 1
Switching Path Forward Transmit Queue Length: 0
Switching Path Forward Receive Queue Length: 0
Switching Path Switch: 0011.8888.9999.AAA (switch B)
Switching Path Protocol: static
Resolving the Issue: Misconfigured Interfaces
Based on the show commands output, we can see that the interfaces on both switches are configured with static addresses. However, the IP addresses do not match:
FS Switch voice=172.Data=173: IP address 172.16.1.5, interface FastEthernet0/1
HP switch voice=1.17: IP address 172.16.117.1, interface FastEthernet0/1
To resolve the issue, we need to ensure that the IP addresses on both interfaces match:
% On FS Switch voice=172.Data=173 (switch A):
Switch# configure terminal
Switch(config)# interface fastEthernet 0/1
Switch(config-if)# ip address 172.16.1.6 255.255.255.0
Switch(config-if)# no shutdown
% On HP switch voice=1.17 (switch C):
Switch# configure terminal
Switch(config)# interface FastEthernet0/1
Switch(config-if)# ip address 172.16.1.5 255.255.255.0
Switch(config-if)# no shutdown
Verifying Connectivity: Ping and Traceroute
After configuring the IP addresses, we will verify connectivity once again:
% On FS Switch voice=172.Data=173 (switch A):
Switch# ping 172.16.1.6
PING 172.16.1.6 56(84) bytes of data.
64 bytes from 172.16.1.6: icmp_seq=1 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=2 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=3 RTT=1 ms
64 bytes from 172.16.1.6: icmp_seq=4 RTT=1 ms
% On HP switch voice=1.17 (switch C):
Switch# traceroute 172.16.1.5
Tracing the route to 172.16.1.5
VLAN1: 172.16.117.1 1 ms 1 ms 1 ms
VLAN2: 172.16.1.5 4 ms 4 ms 4 ms
In this case study, we identified and resolved an issue with intermittent connectivity between three switches in a domain network. The root cause was misconfigured IP addresses on the interfaces of two switches. By following a systematic approach, we were able to identify the issue and resolve it, ensuring stable connectivity between the devices.