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Multi-vendor troubleshooting lab 10 of 12

Ticket set A with campus Layer 2 and Layer 3 faults

Three support tickets land on a campus built from Cisco, Arista and Aruba switches. Six faults sit behind them, from a Cisco trunk that relied on a protocol its neighbour doesn't speak to a DHCP scope that hands out the wrong gateway. Work through them by layer, and write up each ticket.

Run this lab

It needs Standard: its 6 nodes are set to 7 vCPU and 7,424 MB in total.

In your workspace: Shared, then Multi-vendor interoperability and troubleshooting guided labs, then 10 - Ticket set A with campus Layer 2 and Layer 3 faults

Run it on Standard from £5 a day

The free demo can’t run it: it has 6 vCPU and 8 GB, and this lab’s nodes need 7 vCPU and 7,424 MB together. Every lab plan includes every guided lab.

Level
Advanced
Time
About 90 minutes
Nodes need
7 vCPU, 7,424 MB
Smallest plan
Standard

The scenario

You're on the Larkfield service desk, and last night's campus refresh has gone badly. The new core is an Arista switch, floor 1 is Cisco and the voice floor is Aruba. The change engineer has gone off shift. Three tickets are open:

TicketFromReported problem
INC-4101Floor 1 staff (H1)"No network at all since this morning."
INC-4102Voice floor (H2)"Phones have no address."
INC-4103Service desk"From the core, the WAN router's routes have gone."
DeviceInterfaceAddress or VLAN
R1Gi0/010.0.1.2/30
R1Loopback010.90.0.1/32 (the servers)
EOS1Ethernet410.0.1.1/30
EOS1Vlan10 / Vlan2010.10.10.1/24 / 10.10.20.1/24
EOS1Port-Channel1 (Ethernet1, 2)Trunk to SW1, VLANs 10 and 20
EOS1Ethernet3Trunk to CX1, VLANs 10 and 20
SW1Po1 (Gi0/0, Gi0/1) / Gi0/2Trunk to EOS1 / H1 in VLAN 10
CX11/1/1 / 1/1/2Trunk to EOS1 / H2 in VLAN 20
H1, H2eth0DHCP

Services: R1 is the DHCP server (pools VLAN10 and VLAN20). EOS1 relays for both VLANs. OSPF area 0 runs between EOS1 and R1 and carries both user subnets, and each lease gives the VLAN's EOS1 address as gateway.

What you’ll practise

  • Use a layered method to work from a user's symptom to a root cause
  • Use LLDP to map a mixed-vendor network, and turn it on where it's off
  • Explain why DTP defaults fail against non-Cisco switches
  • Find trunk, VLAN, MTU and routing faults from each vendor's own commands
  • Follow a DHCP request across three vendors, from client to server and back
  • Write a ticket closure that names the root cause and the proof

The tasks

  1. A method that scales
  2. Map the network
  3. Close INC-4103
  4. Close INC-4101
  5. Close INC-4102
  6. Write the closures

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Ticket set A with campus Layer 2 and Layer 3 faults6 nodes, 6 links. Every link is listed as text below the diagram.R1EOS1SW1CX1H1H2Gi0/2eth01/1/2eth0Gi0/0Ethernet4Gi0/0Ethernet1Gi0/1Ethernet21/1/1Ethernet3
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to EOS1 Ethernet4
  • SW1 Gi0/0 to EOS1 Ethernet1
  • SW1 Gi0/1 to EOS1 Ethernet2
  • CX1 1/1/1 to EOS1 Ethernet3
  • SW1 Gi0/2 to H1 eth0
  • CX1 1/1/2 to H2 eth0
Nodes in Ticket set A with campus Layer 2 and Layer 3 faults, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
EOS1Arista vEOSveos-4.33.1.1F1 vCPU, 2,048 MB
SW1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
CX1Aruba AOS-CX virtual switcharubacx-10.142 vCPU, 3,072 MB
H1Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB
H2Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder Multi-vendor interoperability and troubleshooting guided labs.

  3. Open 10 - Ticket set A with campus Layer 2 and Layer 3 faults and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Arista Networks, Cisco, CompTIA, Fortinet, HPE, Juniper Networks and MikroTik. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.