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BGP: aggregation and conditional advertising
Enterprise Advanced 2 devices 3 checked tasks 100 points Plan lab
Summarise a block to your provider and hide its parts, then advertise a backup prefix only while a tracked route is present. 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
Summarise a block to your provider and hide its parts, then advertise a backup prefix only while a tracked route is present.
Your role: a network engineer on the enterprise team. Level: Advanced Done when: all 3 goals show as passed (100 points).
Network status
Devices: 2 routers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. A, B start with an empty configuration. Known problems
The network worked and now does not: the scenario above says what users report. The cause is a configuration fault, not a cable. Find it with show commands (interfaces, routes, neighbours, running-config) before you change anything; fix only what is wrong. Goals
B has the summary (30 pts) B does not have the component (30 pts) The conditional prefix is advertised while its condition holds (40 pts) The activity, in order
B has the summary Why: Reading a show command is the core skill of troubleshooting: the output is the truth, not your configuration. Verify with: show ip bgp B does not have the component Why: Reading a show command is the core skill of troubleshooting: the output is the truth, not your configuration. Verify with: show ip bgp The conditional prefix is advertised while its condition holds Why: Reading a show command is the core skill of troubleshooting: the output is the truth, not your configuration. Verify with: show ip bgp 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. Why this matters
Summarise a block to your provider and hide its parts, then advertise a backup prefix only while a tracked route is present.
What you will be able to do
B has the summary
B does not have the component
The conditional prefix is advertised while its condition holds
The network
Catalyst 8000V — 2 devices in all, already cabled.
Gi1 Gi1 A B Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
A Catalyst 8000V configure it B Catalyst 8000V configure it
What is configured at the start
Nothing is configured to start with beyond the addresses above: you build the configuration from a clean start.
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 B has the summary 30 On B: show ip bgp output matches 10\.5\.0\.0/16. 2 B does not have the component 30 On B: show ip bgp output matches 10\.5\.1\.0 — it must not . 3 The conditional prefix is advertised while its condition holds 40 On B: show ip bgp output matches 10\.8\.1\.0/24.
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
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:
A interface GigabitEthernet1
ip address 10.1.1.1 255.255.255.0
no shutdown
exit
interface Loopback1
ip address 10.5.1.1 255.255.255.0
exit
interface Loopback2
ip address 10.6.1.1 255.255.255.0
exit
interface Loopback3
ip address 10.8.1.1 255.255.255.0
exit
ip prefix-list ADV seq 5 permit 10.8.1.0/24
ip prefix-list COND seq 5 permit 10.6.1.0/24
route-map AM permit 10
match ip address prefix-list ADV
exit
route-map EM permit 10
match ip address prefix-list COND
exit
router bgp 1
neighbor 10.1.1.2 remote-as 2
network 10.5.1.0 mask 255.255.255.0
network 10.6.1.0 mask 255.255.255.0
network 10.8.1.0 mask 255.255.255.0
aggregate-address 10.5.0.0 255.255.0.0 summary-only
neighbor 10.1.1.2 advertise-map AM exist-map EM
exit B interface GigabitEthernet1
ip address 10.1.1.2 255.255.255.0
no shutdown
exit
router bgp 2
neighbor 10.1.1.1 remote-as 1
exit Related labs
Where to start
The lessons all guided labs plans
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