default-originate configured toward the peer¶
Case 17 of the Network Change Verdict Corpus. Category: route-leak. Expected verdict: unsafe (an experienced operator would reject it).
Why it is expected unsafe¶
We offer the peer a default route, so the peer can send all its traffic through us for free.
The config change¶
Against the FRR configs of the base lab:
--- a/pe2.conf
+++ b/pe2.conf
@@ -41,3 +41,8 @@
neighbor 10.0.4.2 route-map TO-PEER out
exit-address-family
!
+router bgp 65000
+ address-family ipv4 unicast
+ neighbor 10.0.4.2 default-originate
+ exit-address-family
+!
What each strategy said¶
The expected verdict was committed to git before any run. All three strategies tested the same running lab (method).
| Strategy | Verdict | Result | Checks that failed |
|---|---|---|---|
| Ping only | safe | ❌ approved a bad change | none |
| All BGP sessions up | safe | ❌ approved a bad change | none |
| Netdryrun intent checks | unsafe | ✅ | I4 no default leaked to peer, I5 peer receives exactly our 2 prefixes |
What Netdryrun flagged¶
These checks from the intent spec failed:
- I4 no default leaked to peer: 0.0.0.0/0 must not be in peer1's routing table as a bgp route
- I5 peer receives exactly our 2 prefixes: peer1 receives exactly 2 prefixes from 10.0.4.1
Reproduce it¶
On Linux or WSL2 with Docker and containerlab, from a checkout of the repository:
Case file: corpus/cases/17-default-leaked-to-peer.yml. Published result: netdryrun 0.2.0, containerlab 0.81.1, FRR quay.io/frrouting/frr:10.4.1, commit ec23379, run on 2026-10-26.