AS12663 - VODAFONE-GROUP Fastweb SpAPI/PARPKI ✓ 2/2ASPA -

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IPv6 prefix announced, but nothing inside is responding yet. AS12663 announces 2 IPv6 prefix(es) to the global routing table - that’s the part that BGP and our route-server scrape confirm. But our active discovery (curated hostnames, holder-derived domains, authoritative DNS NS/SOA/MX, certificate-transparency hostnames, RIPE Atlas, RDAP, IPv6 Hitlist) found no ICMPv6-responsive host inside the prefix on either vantage, and a yarrp pass against random addresses inside the prefix produced zero in-prefix hops (no router on the path through the AS replied with Time-Exceeded for any random target). That combination usually means the announcement is configured but the addresses inside aren’t in active use yet. The BGP route is there; the operational deployment is still ahead.

AS overview

Test target: 2a01:818:1000::1 · (no live host found) · address space: mixed · prefixes announced: 2

prefix(es): 2a01:818:1000::/44, 2a01:818:1060::/44

RPKI & ASPA

2 of 2 prefix(es) covered by a valid ROA.

PrefixRPKI stateReasonCovering VRP(s)
2a01:818:1000::/44✓ validmatched VRP (correct origin, length within maxLength)AS12663 /44 maxLen 44 (ripe)
2a01:818:1060::/44✓ validmatched VRP (correct origin, length within maxLength)AS12663 /44 maxLen 44 (ripe)

Random-IP probe (yarrp) into the AS' prefixes

We probed 30 arbitrary IPv6 address(es) inside AS12663's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:5000:0:305::1 at hop 11 - that router answers ICMPv6 Echo. This is not in AS12663's announced prefix; operationally it's the AS-edge / peering interface (often on an IXP peering address or an upstream's /127 link). The traceroute boundary is the AS edge: ICMPv6 Time-Exceeded responses from anything inside this AS are filtered.

ICMPv6 Type 2 (Packet Too Big) acceptance - active test

Type 2 active test inconclusive: no Echo Reply to 1300-byte probe.
method: ICMPv6 Echo + forged PTB, tested 2026-05-25T12:30:20Z

Failure detail — what to grep in your logs
vantageour sourceyour targetmethodresulttested (UTC)
go6lab2a00:8642:42::752a01:818:1000::1icmp6-echono_echo2026-05-25T12:30:20Z
karsolink2a12:d8c0:105a:9001::a1542a01:818:1000::1icmp6-echono_echo2026-05-25T12:35:25Z
odin2607:fae0:a000::422a01:818:1000::1icmp6-echono_echo2026-05-25T12:30:08Z

Attempt log (go6lab):

  1. icmp6-echo → no_echo: no Echo Reply to 1300-byte probe
  2. dns-tcp → no_tcp: connect failed: timed out
  3. tls → no_tcp: TLS connect failed
  4. http → no_tcp: tcp/80 not open

Attempt log (karsolink):

  1. icmp6-echo → no_echo: no Echo Reply to 1300-byte probe
  2. dns-tcp → no_tcp: connect failed: timed out
  3. tls → no_tcp: TLS connect failed
  4. http → no_tcp: tcp/80 not open

Attempt log (odin):

  1. icmp6-echo → no_echo: no Echo Reply to 1300-byte probe
  2. dns-tcp → no_tcp: connect failed: timed out
  3. tls → no_tcp: TLS connect failed
  4. http → no_tcp: tcp/80 not open

To match the corresponding ICMPv6 packet on your side (host firewall, AS edge, or transit tap), look for our PTBs around the timestamps above:

sudo tcpdump -i any -n -e 'icmp6 and ip6[40] = 2 and (src host 2607:fae0:a000::42 or src host 2a00:8642:42::75 or src host 2a12:d8c0:105a:9001::a154)'

If you see our PTBs arriving but the destination's TCP/Echo flow does not shrink, the drop is in the destination kernel (cause 3 below). If you don't see them at all, drop is upstream of you (cause 2). If you only see them from one of our two source IPs, the drop is path-asymmetric — one transit on the asymmetric route is filtering, the other is not.

From NL host (go6lab)   transit only unreachable

filter likely at: past AS1273 (CW) · min PMTU on path: 1500

0/4
Echo small (56B) -
0/4
Echo 1500B (DF) -
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
12a00:8642:42::30.9ms0%AS203993STEFFANN-DC-AS - S.J.M. Steffann, NL
2*-0%*-
32a00:1ca8:1::1945.5ms0%AS50673Serverius-as - Serverius Holding B.V., NL
42a03:3f40::10:412.1ms0%AS50673Serverius-as - Serverius Holding B.V., NL
5*---
6*---
7*---
8ae19-xcr1.dus.cw.net
2001:5000:0:a9::1		7.1ms0%AS1273CW - IDDQD-AS, EU
9*---
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---
22*---
23*---
24*---

tracepath -6

 1?: [LOCALHOST]                        0.038ms pmtu 1500
 1:  2a00:8642:42::3                                       1.273ms 
 1:  2a00:8642:42::3                                       1.332ms 
 2:  gw.friends.steffann.nl                                1.965ms 
 3:  2a00:1ca8:1::194                                      2.270ms 
 4:  2a03:3f40::10:41                                      1.982ms 
 5:  no reply
 6:  no reply
 7:  no reply
 8:  be8-scr1.amq.cw.net                                  13.616ms asymm 10 
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  no reply
21:  no reply
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500

From ITA host (Karsolink)   transit only unreachable

filter likely at: past AS1273 (CW) · min PMTU on path: 1500

0/4
Echo small (56B) -
0/4
Echo 1500B (DF) -
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1*-0%*-
2*-0%*-
3*-80%-
42a03:b020:1:51::a10.2ms0%AS41327FIBERTELECOM-AS - Fiber Telecom S.p.A., IT
52a03:b020::22226.0ms0%AS41327FIBERTELECOM-AS - Fiber Telecom S.p.A., IT
6fibertelecom.nik-1.rt.hopus.net
2a02:e5c:7:8::1		25.9ms0%AS44530HOPUS - HOPUS SAS, FR
7lag-nik-1.nik-2.rt.hopus.net
2a02:e5c:0:f::2		26.0ms0%AS44530HOPUS - HOPUS SAS, FR
8*---
9ae28-xcr1.dus.cw.net
2001:5000:0:e9::1		27.7ms0%AS1273CW - IDDQD-AS, EU
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---
22*---
23*---
24*---

Rate-limited ICMPv6: hop 3 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.026ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.466ms 
 2:  2a12:d8c0:109f:121::a1                                0.894ms 
 3:  2a12:d8c0:101f:6::1                                  10.156ms 
 4:  2a03:b020:1:51::a                                    10.557ms 
 5:  2a03:b020::222                                       26.097ms 
 6:  fibertelecom.nik-1.rt.hopus.net                      26.235ms 
 7:  lag-nik-1.nik-2.rt.hopus.net                         26.356ms 
 8:  no reply
 9:  ae28-xcr1.dus.cw.net                                 28.219ms asymm  7 
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  no reply
21:  no reply
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500

From SLO host (6connect)   transit only unreachable

filter likely at: past AS1273 (CW) · min PMTU on path: 1500

0/4
Echo small (56B) -
0/4
Echo 1500B (DF) -
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1fw1-lju.6connect.com
2607:fae0:a000::2		0.3ms0%*AS80386CONNECT - 6connect, Inc., US
2*---
3*-90%-
4e0-1.core1.lju1.he.net
2001:470:1:5be::1		1.9ms70%AS6939HURRICANE - Hurricane Electric LLC, US
5*---
6*---
7ae57-22-xcr1.sof.cw.net
2001:501b:100:16::1		13.1ms0%AS1273CW - IDDQD-AS, EU
8ae51-tcr1.fnt.cw.net
2001:5000:0:f1::2		34.3ms0%AS1273CW - IDDQD-AS, EU
9ae25-xcr1.dus.cw.net
2001:5000:0:2e::1		29.7ms0%AS1273CW - IDDQD-AS, EU
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---
22*---
23*---
24*---

Rate-limited ICMPv6: hop 3, hop 4 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.040ms pmtu 1500
 1:  fw1-lju.6connect.com                                  7.802ms 
 1:  fw1-lju.6connect.com                                  3.647ms 
 2:  no reply
 3:  no reply
 4:  no reply
 5:  no reply
 6:  no reply
 7:  ae57-22-xcr1.sof.cw.net                              13.151ms 
 8:  ae51-tcr1.fnt.cw.net                                 42.157ms 
 9:  ae25-xcr1.dus.cw.net                                 29.672ms asymm  7 
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  no reply
21:  no reply
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500