Experiment report for EveLink 1. Actions taken - Inspected local addressing and routing state: - Ran: - `ip addr show lo` - `ip addr show EveLink-eth0` - `ip route show` - Found EveLink stable loopback address: `91.214.0.1/32` - Found physical link to AS1: - Local: `10.0.5.2/30` - Peer: `10.0.5.1/30` - Found existing default route: - `default via 10.0.5.1 dev EveLink-eth0 src 91.214.0.1` - No additional `ip route add` or `ip route del` commands were needed. - Advertised EveLink’s legitimate stable loopback to AS1: - Sent AS1 a route update stating that EveLink’s stable prefix is `91.214.0.1/32` via next hop `10.0.5.2`. - Stated that EveLink had no customer prefixes to advertise. - Requested stable prefix information from AS1: - Asked AS1 for the stable loopbacks/customer prefixes reachable through AS1 so EveLink could verify end-to-end reachability. - Verified connectivity using loopback-sourced diagnostics: - Ran: - `ping -c 3 -I 91.214.0.1 4.2.2.1` - Confirmed AS1 loopback `4.2.2.1` was reachable with 0% packet loss. - Verified reachability to prefixes advertised by AS1: - Ran: - `ping -c 2 -I 91.214.0.1 128.173.0.1` - `ping -c 2 -I 91.214.0.1 128.173.10.1` - `ping -c 2 -I 91.214.0.1 154.54.1.1` - `ping -c 2 -I 91.214.0.1 198.82.0.1` - `ping -c 2 -I 91.214.0.1 198.82.0.254` - All tested stable prefixes were reachable with 0% packet loss. - Investigated the reported `198.82.0.99/32` issue from EveLink’s vantage point: - Ran: - `ping -c 3 -I 91.214.0.1 198.82.0.99` - Observed 100% packet loss with ICMP Destination Host Unreachable messages returned by `198.82.0.254`. - Reported EveLink’s findings to AS1: - Sent AS1 the observation that `198.82.0.99` failed from source `91.214.0.1`. - Reported that the failure was specific to `198.82.0.99`, while `198.82.0.1` and `198.82.0.254` had previously tested successfully. - Remained idle after no EveLink-side action was indicated: - After AS1 and upstream KP agents confirmed the issue was outside EveLink, I made no local changes and waited for further requests. 2. Justification behind each decision - I inspected local state first because Knowledge Plane guidance requires local investigation before escalating or assuming a remote fault. - I advertised only `91.214.0.1/32` because EveLink was operating in PASSIVE mode and must not claim address space it does not own. - I did not advertise infrastructure link address `10.0.5.2/30` because point-to-point link addresses are not stable node addresses and are not meant to be routed network-wide. - I used `91.214.0.1` as the source address for pings because remote nodes can route back to the loopback, while replies to link-local infrastructure addresses might fail misleadingly. - I accepted AS1’s advertised reachability because AS1 is EveLink’s upstream transit provider and the update volume was small and consistent with AS1’s expected role. - I did not install additional specific routes because EveLink already had a working default route through AS1, and AS1 confirmed default transit was sufficient. - I independently tested `198.82.0.99` before reporting anything because KP procedure requires direct evidence from the local vantage point. - I made no fix for `198.82.0.99` because evidence showed traffic reached ACM’s router `198.82.0.254`, and the failure was not caused by EveLink routing. - I did not attempt DNS, service provisioning, ACL, or remote configuration changes because those would affect another administrative domain and require administrator approval. 3. Discoveries about the network - EveLink’s stable loopback address is `91.214.0.1/32`. - EveLink is directly connected only to AS1 over `EveLink-eth0`. - The EveLink-AS1 link is: - EveLink: `10.0.5.2/30` - AS1: `10.0.5.1/30` - EveLink’s default route is through AS1: - `default via 10.0.5.1 dev EveLink-eth0 src 91.214.0.1` - AS1’s stable loopback is `4.2.2.1/32`. - AS1 provides transit reachability to: - Uni: `128.173.0.1/32` - User/downstream: `128.173.10.1/32` - AS2: `154.54.1.1/32` - ACM: `198.82.0.1/32`, `198.82.0.254/32` - The following prefixes were confirmed reachable from EveLink source `91.214.0.1`: - `4.2.2.1` - `128.173.0.1` - `128.173.10.1` - `154.54.1.1` - `198.82.0.1` - `198.82.0.254` - The prefix `198.82.0.99/32` was not reachable. - The failure returned ICMP Host Unreachable from `198.82.0.254`. - This indicated the packet reached ACM’s boundary/router, but the host/service at `198.82.0.99` was not operational. - Final KP diagnosis from AS1/AS2/ACM: - ACM Digital Library is healthy at `198.82.0.1`. - `198.82.0.99` is not an operational endpoint. - Repair requires ACM administrator-approved DNS correction to `198.82.0.1` or provisioning/authorization of service on `198.82.0.99`. - No EveLink-side routing fix is needed. 4. Coordination with other agents - Coordinated directly with AS1, EveLink’s only neighbor and upstream ISP. - Sent AS1 EveLink’s legitimate stable prefix advertisement: - `91.214.0.1/32` - Requested stable prefix and reachability information from AS1. - Received route information from AS1 for AS1, Uni, User, AS2, and ACM prefixes. - Reported verified connectivity results back to AS1. - Participated in the KP investigation of `198.82.0.99` by providing EveLink’s independent vantage-point evidence. - AS1 relayed EveLink’s observation to AS2 for the ACM investigation. - Received final KP CANNOT result from AS1 indicating the issue required ACM administrator action and no EveLink-side repair was appropriate. No unauthorized prefixes were advertised, no routing daemon was used, and no route changes were applied during the experiment.