AS overview
Test target: 2a13:f400::1 · static prefix probe · address space: PA · prefixes announced: 1
prefix(es): 2a13:f400::/29
Targets & per-vantage-point probe results (1 target(s) across 7 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 | SRB host (SOX, Belgrade) | DE host (Berlin) | DE host (Düsseldorf) | NL host (go6lab) | ITA host (Karsolink) | SLO host (6connect) | SLO host (T-2) | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ping | 1500B | :80 | :443 | reached | ||
2a13:f400::1 | prb | ✗ | ✗ | ? | ? | - | ✗ | ✗ | ? | ? | - | ✗ | ✗ | ? | ? | - | ✗ | ✗ | ? | ? | - | ✗ | ✗ | ? | ? | - | ✓ | ✓ | ? | ? | ✓ | ✓ | ✓ | ? | ? | ✓ |
SIX peering
Not an SIX member, but our traceroute path crosses the SIX LAN from SLO host (6connect), SLO host (T-2) - reached via an SIX-resident transit operator.
RPKI & ASPA
1 of 1 prefix(es) covered by a valid ROA.
| Prefix | RPKI state | Reason | Covering VRP(s) |
|---|---|---|---|
2a13:f400::/29 | ✓ valid | matched VRP (correct origin, length within maxLength) | AS210197 /29 maxLen 29 (ripe) |
Random-IP probe (yarrp) into the AS' prefixes
We probed 28 arbitrary IPv6 address(es) inside AS210197's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:978:2:40::3:1 at hop 24 - that router answers ICMPv6 Echo. This is not in AS210197's announced prefix; operationally it's the AS-edge / peering interface (often on a SIX 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:
- SRB host (SOX, Belgrade): inconclusive: no Echo Reply to 1300-byte probe. (ICMPv6 Echo + forged PTB)
- DE host (Berlin): inconclusive: no Echo Reply to 1300-byte probe. (ICMPv6 Echo + forged PTB)
- DE host (Düsseldorf): inconclusive: no Echo Reply to 1300-byte probe. (ICMPv6 Echo + forged PTB)
- NL host (go6lab): inconclusive: no Echo Reply to 1300-byte probe. (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)
- SLO host (T-2): 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) |
|---|---|---|---|---|---|
| belgrade | 2a09:ab81::91 | 2a13:f400::1 | icmp6-echo | no_echo | 2026-09-23T10:36:41Z |
| berlin | 2a06:d1c1:10b::cccc | 2a13:f400::1 | icmp6-echo | no_echo | 2026-09-23T10:36:40Z |
| duseldorf | 2a06:d1c1:10d::aaaa | 2a13:f400::1 | icmp6-echo | no_echo | 2026-09-23T10:36:38Z |
| go6lab | 2a00:8642:42::75 | 2a13:f400::1 | icmp6-echo | no_echo | 2026-09-23T10:37:12Z |
| karsolink | 2a12:d8c0:105a:9001::a154 | 2a13:f400::1 | icmp6-echo | no_echo | 2026-09-23T10:36:42Z |
| odin | 2607:fae0:a000::42 | 2a13:f400::1 | icmp6-echo | honored | 2026-09-23T10:36:24Z |
| t2 | 2a01:261:313:b814:2a0:98ff:fe5b:13e4 | 2a13:f400::1 | icmp6-echo | honored | 2026-09-23T10:36:40Z |
Attempt log (belgrade):
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 (berlin):
icmp6-echo→ no_echo: no Echo Reply to 1300-byte probedns-tcp→ no_tcp: connect failed: [Errno 101] Network is unreachabletls→ no_tcp: TLS connect failedhttp→ no_tcp: tcp/80 not open
Attempt log (duseldorf):
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 (go6lab):
icmp6-echo→ no_echo: no Echo Reply to 1300-byte probedns-tcp→ no_tcp: connect failed: [Errno 101] Network is unreachabletls→ 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: [Errno 101] Network is unreachabletls→ no_tcp: TLS connect failedhttp→ no_tcp: tcp/80 not open
Attempt log (odin):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing): natural Echo Reply at 1400B was already split into IPv6 fragments without our PTB intervention -- the destination's stack has a cached path MTU below 1400B from a previously-honored ICMPv6 Type 2, which is itself evidence that this destination honors PTB on this path.dns-tcp→ no_tcp: connect failed: timed outtls→ no_tcp: TLS connect failedhttp→ no_tcp: tcp/80 not open
Attempt log (t2):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)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 2a01:261:313:b814:2a0:98ff:fe5b:13e4 or src host 2a06:d1c1:10b::cccc or src host 2a06:d1c1:10d::aaaa or src host 2a09:ab81::91 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 some of our source IPs but not others, the drop is path-asymmetric - at least one transit on the differing route is filtering.
Where the path divergence is
Per-vantage probe + verdict (headline):
- belgrade: probe
icmp6-echo→ verdictno_echo - berlin: probe
icmp6-echo→ verdictno_echo - duseldorf: probe
icmp6-echo→ verdictno_echo - go6lab: probe
icmp6-echo→ verdictno_echo - karsolink: probe
icmp6-echo→ verdictno_echo - odin: probe
icmp6-echo→ verdicthonored - t2: probe
icmp6-echo→ verdicthonored
Full per-method matrix (all four methods run at each vantage):
| vantage | icmp6-echo | dns-tcp | tls | http |
|---|---|---|---|---|
| belgrade | no_echo | no_tcp | no_tcp | no_tcp |
| berlin | no_echo | no_tcp | no_tcp | no_tcp |
| duseldorf | no_echo | no_tcp | no_tcp | no_tcp |
| go6lab | no_echo | no_tcp | no_tcp | no_tcp |
| karsolink | no_echo | no_tcp | no_tcp | no_tcp |
| odin | honored | no_tcp | no_tcp | no_tcp |
| t2 | honored | no_tcp | no_tcp | no_tcp |
✓ All vantages agree on method(s): icmp6-echo - the headline-method spread above is dispatcher noise, not a real Type 2 disagreement.
These vantage-level disagreements are rooted somewhere in the forward paths. Joining each per-vantage traceroute against the IP→AS lookup from our global yarrp mesh, the first hop where the paths land in different ASes is the most likely site of the offending filter / unreachable AS / Type 2 drop.
Suspect transit ASes (ranked by how often they appear at the divergence point on the path of the worse-classifying vantage): AS6939, AS50673.
- From belgrade (all_blocked/Type-2=no_echo) the path enters AS6939 at hop 6; from odin (open/Type-2=honored) the same hop is in AS210197. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From belgrade (all_blocked/Type-2=no_echo) the path enters AS6939 at hop 6; from t2 (open/Type-2=honored) the same hop is in AS210197. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (all_blocked/Type-2=no_echo) the path enters AS6939 at hop 4; from go6lab (all_blocked/Type-2=no_echo) the same hop is in AS50673. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (all_blocked/Type-2=no_echo) the path enters AS6939 at hop 4; from odin (open/Type-2=honored) the same hop is in AS21283. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (all_blocked/Type-2=no_echo) the path enters AS6939 at hop 4; from t2 (open/Type-2=honored) the same hop is in AS21283. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From go6lab (all_blocked/Type-2=no_echo) the path enters AS50673 at hop 3; from odin (open/Type-2=honored) the same hop is in AS56635. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
- From go6lab (all_blocked/Type-2=no_echo) the path enters AS50673 at hop 4; from t2 (open/Type-2=honored) the same hop is in AS21283. Last common AS: no shared transit. The disagreement is most likely rooted in one of those two transit ASes.
Diagnosis is path-level, not packet-level: it tells you which transit AS is the prime suspect, not exactly which firewall rule is to blame. Use the tracepath6 output below (when available) for per-hop PMTU evidence on the same path.
✨ Diagnostic interpretation
Multi-vantage path map
Every hop of all vantages’ traceroutes toward the target, drawn left→right, grouped into per-AS bubbles (a hop seen from several vantages is one shared bubble, so converging paths merge). It answers two questions per vantage — shown on each source bubble as echo ✓/⚠/✗ · trace ✓/✗: did the destination reply to ICMPv6 Echo (✓ honored, ⚠ replied but PTB not honored, ✗ no reply), and did the traceroute reach it. A line to the target is drawn only when that vantage got an echo reply — solid if the PTB was honored, dashed if not (reachable but a broken-PMTUD / RFC 4890 violation). The path depth still shows how far the traceroute itself got, and runs of unanswered (* *) hops collapse into one dashed “silent” bubble. Open full size ↗
- ● SRB host (SOX, Belgrade)
- ● DE host (Berlin)
- ● DE host (Düsseldorf)
- ● NL host (go6lab)
- ● ITA host (Karsolink)
- ● SLO host (6connect)
- ● SLO host (T-2)
- ── solid line = echo reply, PTB honored (clean reach)
- — — dashed line = echo reply but PTB not honored (RFC 4890 violation)
- no line = no echo reply (never reached)
- ◉ target: green = clean, amber = reachable-but-violation / unreachable
- ⚠ suspected drop AS
- ⋯ silent (unanswered) hops
- ● IXP hop
From SRB host (SOX, Belgrade) all blocked
filter likely at: past AS6939 (HURRICANE) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | 2a09:ab81::1 | 0.6ms | 0%* | AS60733 | PERKE-NET - ZORAN PEROVIC trading as Agencija Perke.NET, RS |
| 2 | sox-pn.sox.rs 2001:7f8:1e:8::3a | 0.3ms | 0% | AS13004 | SOX - Serbian Open Exchange DOO, RS |
| 3 | e0-33.core2.beg1.he.net 2001:470:1:6e5::1 | 1.2ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 4 | e0-34.core2.bts1.he.net 2001:470:0:33f::2 | 8.4ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 5 | * | - | 10% | - | |
| 6 | e0-36.core1.lju1.he.net 2001:470:0:578::2 | 14.6ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 7 | * | - | - | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - |
Rate-limited ICMPv6: hop 5 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.010ms pmtu 1500
1: _gateway 0.368ms
1: _gateway 5.280ms
2: sox-pn.sox.rs 0.612ms
3: e0-33.core2.beg1.he.net 1.399ms
4: e0-34.core2.bts1.he.net 8.654ms
5: 100ge0-0-0-2.core1.vie1.he.net 11.453ms
6: e0-36.core1.lju1.he.net 14.489ms
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
Too many hops: pmtu 1500
Resume: pmtu 1500 From DE host (Berlin) all blocked
filter likely at: past AS59645 (WYBT-NET) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | xe-0-0-13-178.gw01.ber01.as59645.net 2a06:d1c1:100:b::1 | 0.3ms | - | AS59645 | WYBT-NET - Tobias Fiebig, DE |
tracepath -6
1?: [LOCALHOST] 0.023ms pmtu 1500
1: no reply
2: xe-0-0-13-178.gw01.ber01.as59645.net 0.660ms !N
Resume: pmtu 1500 From DE host (Düsseldorf) all blocked
filter likely at: past AS6939 (HURRICANE) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | xe-0-0-12-142.gw01.dus01.as59645.net 2a06:d1c1:100:d::1 | 0.3ms | 0%* | AS59645 | WYBT-NET - Tobias Fiebig, DE |
| 2 | ipv6.decix-dusseldorf.core1.dus1.he.net 2001:7f8:9e::1b1b:0:1 | 7.1ms | 0% | - | NA |
| 3 | 100ge0-0-0-18.core4.fra1.he.net 2001:470:0:52e::1 | 13.3ms | 50% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 4 | be8.core1.prg1.he.net 2001:470:e:1e::2 | 20.8ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 5 | be3.core1.vie1.he.net 2001:470:e:a7::2 | 16.7ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 6 | e0-36.core1.lju1.he.net 2001:470:0:578::2 | 20.2ms | 10% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 7 | * | - | - | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - |
Rate-limited ICMPv6: hop 3, hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.021ms pmtu 1500
1: xe-0-0-12-142.gw01.dus01.as59645.net 0.269ms
1: xe-0-0-12-142.gw01.dus01.as59645.net 0.246ms
2: ipv6.decix-dusseldorf.core1.dus1.he.net 6.782ms asymm 3
3: 100ge0-0-0-18.core4.fra1.he.net 14.635ms asymm 4
4: be8.core1.prg1.he.net 19.085ms asymm 5
5: be3.core1.vie1.he.net 18.507ms asymm 4
6: e0-36.core1.lju1.he.net 20.555ms asymm 5
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
Too many hops: pmtu 1500
Resume: pmtu 1500 From NL host (go6lab) all blocked
filter likely at: past AS174 (COGENT-174) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | 2a00:8642:42::2 | 2.3ms | 0% | AS203993 | GNA-DC1-AS - S.J.M. Steffann, NL |
| 2 | gw.friends.steffann.nl 2a00:8642:1000:f000::1 | 5.2ms | 0%* | AS203993 | GNA-DC1-AS - S.J.M. Steffann, NL |
| 3 | 2a00:1ca8:1::194 | 5.1ms | 0% | AS50673 | Serverius-as - Serverius Holding B.V., NL |
| 4 | 2a03:3f40::10:41 | 10.8ms | 0% | AS50673 | Serverius-as - Serverius Holding B.V., NL |
| 5 | 2001:978:2:40::3:1 | 7.3ms | 0% | AS174 | COGENT-174 - Cogent Communications, LLC, US |
tracepath -6
1?: [LOCALHOST] 0.027ms pmtu 1500
1: 2a00:8642:42::2 1.531ms
1: 2a00:8642:42::2 1.057ms
2: gw.friends.steffann.nl 2.674ms
3: 2a00:1ca8:1::194 3.639ms
4: 2a03:3f40::10:41 5.859ms
5: 2001:978:2:40::3:1 11.454ms !N
Resume: pmtu 1500 From ITA host (Karsolink) all blocked
filter likely at: before path completes · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | * | - | 0%* | - | |
| 2 | * | - | 0%* | - | |
| 3 | * | - | - | - | |
| 4 | * | - | - | - | |
| 5 | * | - | - | - | |
| 6 | * | - | - | - | |
| 7 | * | - | - | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.028ms pmtu 1500
1: karsolink-01.net.karsolink.com 0.762ms
2: no reply
3: no reply
4: no reply
5: no reply
6: no reply
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
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 | 0.4ms | 0%* | AS8038 | 6CONNECT - 6connect, Inc., US |
| 2 | * | - | - | - | |
| 3 | 2a03:a100:0:201:1::1 | 0.6ms | 0% | AS56635 | XENYA - XENYA inzeniring, proizvodnja in trgovina, d.o.o. Ljubljana, SI |
| 4 | six.a1.si @SIX 2001:7f8:46::2:1283 | 1.3ms | 0% | AS21283 | A1 Slovenija |
| 5 | 2001:15c0:1000:300::3 | 3.3ms | 0% | - | NA |
| 6 | 2a13:f400::1 | 3.4ms | 0% | AS210197 | RESITVE-AS - ROK TAJZEL, SI |
tracepath -6
1?: [LOCALHOST] 0.018ms pmtu 9000
1: fw1-lju.6connect.com 0.618ms
1: fw1-lju.6connect.com 0.534ms
2: no reply
3: 2a03:a100:0:201:1::1 1.022ms
4: 2a03:a100:0:201:1::1 1.136ms pmtu 1500
4: six.a1.si 1.396ms
5: 2001:15c0:1000:300::3 3.934ms asymm 6
6: no reply
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
Too many hops: pmtu 1500From SLO host (T-2) openRFC 4890 ✓
filter likely at: (none) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | * | - | 0%* | - | |
| 2 | 2a01:260:1::225 | 8.0ms | 0%* | AS34779 | T-2-AS - T-2, d.o.o., SI |
| 3 | 2a01-260-1-1--9c.core6.t-2.net 2a01:260:1:1::9c | 2.3ms | 0%* | AS34779 | T-2-AS - T-2, d.o.o., SI |
| 4 | six.a1.si @SIX 2001:7f8:46::2:1283 | 2.6ms | 0% | AS21283 | A1 Slovenija |
| 5 | 2001:15c0:1000:300::3 | 4.9ms | 0% | - | NA |
| 6 | 2a13:f400::1 | 5.4ms | 0% | AS210197 | RESITVE-AS - ROK TAJZEL, SI |
tracepath -6
1?: [LOCALHOST] 0.030ms pmtu 1500
1: 2a01:261:313:b814::1 0.926ms
1: no reply
2: 2a01:260:1::225 3.322ms
3: 2a01-260-1-1--9c.core6.t-2.net 2.893ms
4: six.a1.si 2.869ms
5: 2001:15c0:1000:300::3 6.070ms asymm 6
6: no reply
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
Too many hops: pmtu 1500
Resume: pmtu 1500