Capstone: the ticket queue
This is the finished branch from the last lab (PC1 in STAFF VLAN 10 on SW1, PC2 in GUEST VLAN 20 on SW2, Po1 trunk between the switches, router-on-a-stick on R1 with DHCP for both VLANs, SW1 the spanning tree root). After a weekend of changes, the help desk has two tickets:
- "PC1 gets an address but can't reach the internet."
- "PC2 has no network at all."
Find and fix every fault. Don't change the PCs' settings (they use DHCP) and don't remove BPDU guard.
How it works: this is VulnTech NetLab, a network simulator running in your browser. Click a device in the diagram to open its console and type commands, just like on real equipment (? shows help, Tab finishes a word). Click a cable to inspect it. Tasks tick themselves off as you complete them; questions are answered in the box under each task. Your work is kept if you reload; Reset starts the network over.
Solution explanation
Ticket 1 was layer 3: the STAFF pool handed out gateway 192.168.10.254, which doesn't exist, so PC1 could talk only inside its VLAN. Ticket 2 had three causes. VLAN 20 had been deleted on SW2, so Fa0/1 was inactive. SW1's trunk to R1 only allowed VLAN 10, so GUEST traffic never reached Gi0/0.20. And SW2's Gi0/2 was forced to 100 Mb/s, which suspended it from Po1: not the cause of the outage (Gi0/1 still carried traffic), but a real fault that halved the bandwidth and would have become an outage when Gi0/1 failed. show etherchannel summary shows it at once.
Show solution
[PC1]
ipconfig /all
[R1]
enable
show running-config | section dhcp
configure terminal
ip dhcp pool STAFF
default-router 192.168.10.1
end
[PC1]
ipconfig /renew
ping 8.8.8.8
[SW2]
enable
show vlan brief
show etherchannel summary | begin Group
configure terminal
vlan 20
name GUEST
interface g0/2
no speed 100
end
[SW1]
enable
show interfaces trunk
configure terminal
interface fa0/24
switchport trunk allowed vlan add 20
end
[PC2]
sudo dhclient eth0
ping -c 3 8.8.8.8