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IP SLA and object tracking — a default route that checks it works
Enterprise Advanced 3 devices 4 checked tasks 100 points Plan lab
A static default route stays in the table as long as its interface is up — even when the ISP’s router behind it is dead. Probe the next hop with an IP SLA ICMP echo, track the result, and tie the primary default route to the track so a backup (with a higher distance) takes over. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
A static default route stays in the table as long as its interface is up — even when the ISP’s router behind it is dead. Probe the next hop with an IP SLA ICMP echo, track the result, and tie the primary default route to the track so a backup (with a higher distance) takes over.
Your role: a network engineer on the enterprise team. Level: Advanced Done when: all 4 goals show as passed (100 points).
Network status
Devices: 3 routers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. Edge starts with addresses (G0/0 198.51.100.1/30, G0/1 203.0.113.1/30). ISP-A starts with addresses (G0/0/0 198.51.100.2/30). ISP-B starts with addresses (G0/0/0 203.0.113.2/30). Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
An IP SLA operation probes ISP-A with ICMP echo (25 pts) A track object follows the probe and is up (25 pts) The primary default route is tied to the track (25 pts) A floating backup default route via ISP-B exists (25 pts) The activity, in order
An IP SLA operation probes ISP-A with ICMP echo Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config A track object follows the probe and is up Why: Each goal is a state the lab can check on the running device. Verify with: show running-config The primary default route is tied to the track Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config A floating backup default route via ISP-B exists Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: An SLA that is configured but never scheduled Common mistake: Tracking the wrong object Common mistake: A backup distance lower than the primary Why this matters
A static route stays in the table as long as its interface is up, even if the router behind it is dead. An IP SLA probe tracked by the route makes failover depend on whether the path actually works.
What you will be able to do
Configure and schedule an ICMP-echo IP SLA
Create a track object and attach it to a static route
Add a floating backup route and explain its distance
The network
ISR 2911, ISR 4331 — 3 devices in all, already cabled.
Gi0/0 198.51.100.1/30 Gi0/0/0 198.51.100.2/30 Gi0/1 203.0.113.1/30 Gi0/0/0 203.0.113.2/30 Edge ISP-A ISP-B Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
Edge ISR 2911 configure it ISP-A ISR 4331 configure it ISP-B ISR 4331 configure it
Cabling
Edge Gi0/0 ↔ ISP-A Gi0/0/0 Edge Gi0/1 ↔ ISP-B Gi0/0/0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
Edge interface g0/0
ip address 198.51.100.1 255.255.255.252
no shutdown
exit
interface g0/1
ip address 203.0.113.1 255.255.255.252
no shutdown
exit ISP-A interface g0/0/0
ip address 198.51.100.2 255.255.255.252
no shutdown
exit ISP-B interface g0/0/0
ip address 203.0.113.2 255.255.255.252
no shutdown
exit Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 An IP SLA operation probes ISP-A with ICMP echo 25 On Edge: show running-config contains the line(s) matching ip sla 1[\s\S]*icmp-echo 198\.51\.100\.2. 2 A track object follows the probe and is up 25 On Edge: show track 1 is Up. 3 The primary default route is tied to the track 25 On Edge: show running-config contains the line(s) matching ip route 0\.0\.0\.0 0\.0\.0\.0 198\.51\.100\.2 track 1. 4 A floating backup default route via ISP-B exists 25 On Edge: show running-config contains the line(s) matching ip route 0\.0\.0\.0 0\.0\.0\.0 203\.0\.113\.2 (200|250|254).
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
An SLA that is configured but never scheduled
Tracking the wrong object
A backup distance lower than the primary
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
Edge ip sla 1
icmp-echo 198.51.100.2
frequency 5
exit
ip sla schedule 1 life forever start-time now
track 1 ip sla 1 reachability
ip route 0.0.0.0 0.0.0.0 198.51.100.2 track 1
ip route 0.0.0.0 0.0.0.0 203.0.113.2 200 Where this is examined
CCNP ENCOR/ENARSI (IP SLA, tracking), CCIE EI.
This lab practises these topics in the zNetLaB certification courses:
NTP/PTP, NAT, HSRP/VRRP, multicast — CCNP Enterprise · ENCOR · Infrastructure Debugs, ping/traceroute, SNMP, syslog, NetFlow, SPAN, IP SLA — CCNP Enterprise · ENCOR · Network Assurance QoS, NAT, FHRP, IP SLA, NetFlow, multicast services — CCIE Enterprise Infrastructure · Infrastructure Security and Services
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