AS overview
Test target: 2a04:3280::1 · static prefix probe · address space: mixed · prefixes announced: 1
prefix(es): 2a04:3280::/29
Targets & per-vantage-point probe results (1 target(s) across 3 vantage point(s))
Source codes (hover any badge for full description): CUR=curated · NS/SOA/MX=DNS records · SPF=SPF TXT · DRV=holder-derived (www, ns1, mail, gw, …) · ATL=RIPE Atlas · PDB=PeeringDB · WHOIS=RIPE whois · RDAP=RIPE RDAP · HIT=IPv6 Hitlist · RTR=in-prefix path hop (router) · PRB=static prefix probe · SYN=synthetic prefix::1 fallback
| Target IP / hostname | Source | NL host (go6lab) | ITA host (Karsolink) | SLO host (6connect) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ||
2a04:3280::1 | prb | ✓ | ✓ | ? | ? | - | ✓ | ✓ | ? | ? | - | ✓ | ✓ | ? | ? | - |
MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO peering
MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO member - Open peering, peering member, since 2017-06-07. IPv6 LAN: 2001:7f8:b:100:1d1:a5d2:1176:70. Locations: -.
RPKI & ASPA
0 of 1 prefix(es) covered by a valid ROA, 1 not-found.
| Prefix | RPKI state | Reason | Covering VRP(s) |
|---|---|---|---|
2a04:3280::/29 | - not-found | no covering VRP |
Random-IP probe (yarrp) into the AS' prefixes
We probed 15 arbitrary IPv6 address(es) inside AS21176's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:470:0:2ea::2 at hop 6 - that router answers ICMPv6 Echo. This is not in AS21176'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
Vantage points disagree about Type 2 acceptance - transit ASes on one path may be filtering Type 2 even though the destination's stack accepts it on another path:
- NL host (go6lab): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
- ITA host (Karsolink): inconclusive: no Echo Reply to 1300-byte probe. (ICMPv6 Echo + forged PTB)
- SLO host (6connect): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
Why they disagree - reachability mismatch: One vantage couldn't drive a flow at all to this destination (no Echo Reply or no responding TCP port), so the active test had no behavioural change to observe. The other vantage's verdict is the only meaningful one here.
Failure detail — what to grep in your logs
| vantage | our source | your target | method | result | tested (UTC) |
|---|---|---|---|---|---|
| go6lab | 2a00:8642:42::75 | 2a04:3280::1 | icmp6-echo | honored | 2026-05-30T12:45:03Z |
| karsolink | 2a12:d8c0:105a:9001::a154 | 2a04:3280::1 | icmp6-echo | no_echo | 2026-05-30T12:53:00Z |
| odin | 2607:fae0:a000::42 | 2a04:3280::1 | icmp6-echo | honored | 2026-05-30T12:44:48Z |
Attempt log (go6lab):
icmp6-echo→ honored (size_before=1460, size_after=None)dns-tcp→ no_tcp: connect failed: timed outtls→ no_tcp: TLS connect failedhttp→ no_tcp: tcp/80 not open
Attempt log (karsolink):
icmp6-echo→ no_echo: no Echo Reply to 1300-byte probedns-tcp→ no_tcp: connect failed: timed outtls→ no_tcp: TLS connect failedhttp→ no_tcp: tcp/80 not open
Attempt log (odin):
icmp6-echo→ honored (size_before=1460, size_after=None)dns-tcp→ no_tcp: connect failed: timed outtls→ no_tcp: TLS connect failedhttp→ 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) openRFC 4890 ✓
filter likely at: (none) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | 2a00:8642:42::3 | 1.2ms | 0% | AS203993 | STEFFANN-DC-AS - S.J.M. Steffann, NL |
| 2 | * | - | 0%* | - | |
| 3 | ccr2-ccr1.dc1.nogalliance.org 2a00:8642:dc1:2::b | 1.9ms | 0% | AS203993 | STEFFANN-DC-AS - S.J.M. Steffann, NL |
| 4 | ams-ix.ipv6.itgate.net 2001:7f8:1::a501:2779:1 | 3.8ms | 0% | - | NA |
| 5 | be2.Dastardly-Monster.TRN.ipv6.itgate.net 2001:1418:1::10c2 | 20.4ms | 0% | AS12779 | ITGATE - IT.Gate S.p.A., IT |
| 6 | * | - | 0% | - | |
| 7 | * | - | 0% | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - | |
| 20 | * | - | - | - | |
| 21 | * | - | - | - | |
| 22 | * | - | - | - | |
| 23 | * | - | - | - | |
| 24 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.030ms pmtu 1500
1: 2a00:8642:42::3 1.153ms
1: 2a00:8642:42::3 1.924ms
2: gw.friends.steffann.nl 2.780ms
3: ccr2-ccr1.dc1.nogalliance.org 3.371ms asymm 2
4: ams-ix.ipv6.itgate.net 4.901ms asymm 3
5: if-0-2-0-1.Muttley-Monster.TRN.ipv6.itgate.net 21.541ms
6: 2001:1418:1:900::32 20.798ms
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Too many hops: pmtu 1500
Resume: pmtu 1500 From ITA host (Karsolink) open
filter likely at: (none) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | * | - | - | - | |
| 2 | * | - | - | - | |
| 3 | * | - | - | - | |
| 4 | * | - | 0% | - | |
| 5 | * | - | - | - | |
| 6 | * | - | - | - | |
| 7 | * | - | - | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - | |
| 20 | * | - | - | - | |
| 21 | * | - | - | - | |
| 22 | * | - | - | - | |
| 23 | * | - | - | - | |
| 24 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.027ms pmtu 1500
1: karsolink-01.net.karsolink.com 0.909ms
2: 2a12:d8c0:109f:121::a1 1.103ms
3: 2a12:d8c0:101f:103::1 9.755ms
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Too many hops: pmtu 1500
Resume: pmtu 1500 From SLO host (6connect) openRFC 4890 ✓
filter likely at: (none) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | fw1-lju.6connect.com 2607:fae0:a000::2 | 0.2ms | 0%* | AS8038 | 6CONNECT - 6connect, Inc., US |
| 2 | * | - | - | - | |
| 3 | * | - | - | - | |
| 4 | * | - | 60% | - | |
| 5 | * | - | - | - | |
| 6 | * | - | 30% | - | |
| 7 | * | - | - | - | |
| 8 | * | - | 0% | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - | |
| 20 | * | - | - | - | |
| 21 | * | - | - | - | |
| 22 | * | - | - | - | |
| 23 | * | - | - | - | |
| 24 | * | - | - | - |
Rate-limited ICMPv6: hop 4, hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.035ms pmtu 1500
1: fw1-lju.6connect.com 0.468ms
1: fw1-lju.6connect.com 0.950ms
2: ccr-to-fw-ccr1-gw-lju.6connect.com 1.096ms
3: 2a03:a100:0:201:1::1 0.802ms
4: e0-1.core1.lju1.he.net 2.180ms
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6: port-channel1.core1.zag2.he.net 5.567ms
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Too many hops: pmtu 1500
Resume: pmtu 1500