AS overview
Test target: 2a02:670:d000:400::7 · ipv6.planetel.it · address space: PA · prefixes announced: 3
prefix(es): 2a02:670::/32, 2a02:5c80::/32, 2a0a:27c0::/32
Targets & per-vantage-point probe results (2 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 | ||
2a02:670:d000:400::7ipv6.planetel.it | drv | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - |
2a02:670:d000:400::cplanetel.it | drv | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - | ✓ | ✓ | open | open | - |
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 2017-03-03. IPv6 LAN: 2001:7f8:b:100:1d1:a5d4:7217:56. Locations: -.
RPKI & ASPA
2 of 3 prefix(es) covered by a valid ROA, 1 not-found.
| Prefix | RPKI state | Reason | Covering VRP(s) |
|---|---|---|---|
2a02:670::/32 | ✓ valid | matched VRP (correct origin, length within maxLength) | AS47217 /32 maxLen 56 (ripe) |
2a02:5c80::/32 | - not-found | no covering VRP | |
2a0a:27c0::/32 | ✓ valid | matched VRP (correct origin, length within maxLength) | AS47217 /32 maxLen 56 (ripe) |
Random-IP probe (yarrp) into the AS' prefixes
At least one router inside AS47217's announced prefix replied during the random-target probe. Hop(s): 2a02:670::, 2a02:670:f000:a::19, 2a02:670:f000:a::1a, 2a02:670:f000:a::b. These are candidate targets for direct testing.
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): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
- DE host (Berlin): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
- DE host (Düsseldorf): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
- NL host (go6lab): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
- ITA host (Karsolink): Type 2 honored. Forged PTB accepted; next response shrunk. (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 - path-asymmetric Type 2 filtering: Both vantages used the ICMPv6 Echo + forged-PTB method on the same destination IP, but reached different verdicts. The destination's stack is the same in both cases - so the difference is in the path: a transit AS on one route filters our forged Type 2 (or its return ICMPv6 carrying the embedded packet) while the other route delivers it intact. The vantage that says honored shows what the destination's stack actually does; the one that says not honored shows that the path between us and them drops Type 2.
Failure detail - what to grep in your logs
| vantage | our source | your target | method | result | tested (UTC) |
|---|---|---|---|---|---|
| belgrade | 2a09:ab81::91 | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:05Z |
| berlin | 2a06:d1c1:10b::cccc | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:04Z |
| duseldorf | 2a06:d1c1:10d::aaaa | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:03Z |
| go6lab | 2a00:8642:42::75 | 2a02:670:d000:400::7 | icmp6-echo | not_honored | 2026-09-23T12:04:05Z |
| karsolink | 2a12:d8c0:105a:9001::a154 | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:05Z |
| odin | 2607:fae0:a000::42 | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:03Z |
| t2 | 2a01:261:313:b814:2a0:98ff:fe5b:13e4 | 2a02:670:d000:400::7 | icmp6-echo | honored | 2026-09-23T12:03:04Z |
Attempt log (belgrade):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)dns-tcp→ no_tcp: connect failed: [Errno 111] Connection refusedtls→ not_honored (reply shrank 4096→4096 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
Attempt log (berlin):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)dns-tcp→ no_tcp: connect failed: [Errno 111] Connection refusedtls→ not_honored (reply shrank 4096→4096 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
Attempt log (duseldorf):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)dns-tcp→ no_tcp: connect failed: [Errno 111] Connection refusedtls→ partial (reply shrank 4096→2856 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
Attempt log (go6lab):
icmp6-echo→ not_honored (reply shrank 1360→1360 B)dns-tcp→ no_tcp: connect failed: timed outtls→ not_honored (reply shrank 4096→4096 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
Attempt log (karsolink):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)dns-tcp→ no_tcp: connect failed: [Errno 111] Connection refusedtls→ not_honored (reply shrank 4096→4096 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
Attempt log (odin):
icmp6-echo→ honored (honored by fragmenting its reply into 2 via the IPv6 Fragment Header, rather than resizing)dns-tcp→ no_tcp: connect failed: [Errno 111] Connection refusedtls→ not_honored (reply shrank 4096→4096 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
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: [Errno 111] Connection refusedtls→ not_honored (reply shrank 2668→2668 B)http→ inconclusive (reply 392 B before PTB): natural max segment 392B already <= 1220B; nothing to shrink
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.
What does "Type 2 not honored" actually mean? - click to expand
What this test does
Using the icmp6-echo method, we send a 1500-byte ICMPv6 Echo Request, then a forged ICMPv6 Type 2 (Packet Too Big) declaring path MTU=1280, and observe whether the next Echo Reply arrives split into IPv6 fragments. RFC 4890 requires hosts and intermediate networks not to filter ICMPv6 Type 2; the destination's TCP/UDP stack must act on a received PTB by lowering its Path MTU cache for that destination, which makes subsequent segments smaller.
What we measured
The TCP segment size your server emitted before our forged Type 2 was 1360 B; after, it was 1360 B. No change. RFC 4890 ("Type 2 messages MUST NOT be filtered") expects subsequent segments to shrink to fit a Path MTU of 1280 B.
Three plausible causes
- Your host firewall is dropping ICMPv6 Type 2 inbound. Many default firewall rule sets only allow Echo Request/Reply and Neighbor Discovery, silently dropping all other ICMPv6 types - including Packet Too Big.
- An upstream / transit network is dropping ICMPv6 Type 2 before it reaches you. Some transit ASes filter ICMPv6 messages other than Echo at the edge. The forged PTB never arrives, so your stack never has a chance to act on it.
- Your kernel is ignoring the PTB. Linux / BSD stacks normally accept ICMPv6 PTB and update the route cache, but a few sysctls (or a hardened kernel) can be configured to ignore PMTU updates - typically as part of an over-aggressive anti-spoofing or uRPF policy.
How to check & fix (Linux examples)
1. Confirm Type 2 is not blocked at the host firewall:
sudo ip6tables -L INPUT -nv | grep -iE 'icmpv6|packet-too-big' sudo nft list ruleset 2>/dev/null | grep -A1 'icmpv6'
If you see rules dropping ICMPv6 unconditionally, change them to permit at least icmpv6 type packet-too-big (and destination-unreachable, time-exceeded, parameter-problem per RFC 4890).
2. Confirm the kernel accepts incoming PTB:
sudo sysctl net.ipv6.conf.all.accept_redirects net.ipv4.ip_no_pmtu_disc net.ipv6.route.mtu_expires
The defaults (accept_redirects=1, ip_no_pmtu_disc=0) are the right values for honoring PTB.
3. Live trace: while we have an open TCP flow with a small MSS (we run our test from 2607:fae0:a000::42 on odin, 2a00:8642:42::75 on go6lab, 2a12:d8c0:105a:9001::a154 on karsolink, 2a09:ab81::91 on belgrade, 2a01:261:313:b814:2a0:98ff:fe5b:13e4 on t2, 2a06:d1c1:10a::bbbb on amsterdam, 2a06:d1c1:10d::aaaa on duseldorf and 2a06:d1c1:10b::cccc on berlin), watch for our forged Type 2 arriving on your interface:
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 or src host 2a09:ab81::91 or src host 2a01:261:313:b814:2a0:98ff:fe5b:13e4 or src host 2a06:d1c1:10a::bbbb or src host 2a06:d1c1:10d::aaaa or src host 2a06:d1c1:10b::cccc)'
If you see our PTBs arriving but TCP segments still stay big, the drop is in your kernel or NIC offload (cause 3). If you don't see them at all, the drop is upstream of you (cause 2) - ask your upstream(s) to permit ICMPv6 Type 2.
4. If your test target above (2026-09-23T12:04:05Z) is a host that you don't own (e.g. a third-party DNS / TLS server you happen to operate prefixes for), the verdict reflects that specific host's behaviour - try the test against a server you do own and we'll happily re-run.
RFC 4890 references: §4.3.1 (Packet Too Big - MUST NOT be dropped), and RFC 8201 for the broader PMTUD requirement.
Where the path divergence is
Per-vantage probe + verdict (headline):
- belgrade: probe
icmp6-echo→ verdicthonored - berlin: probe
icmp6-echo→ verdicthonored - duseldorf: probe
icmp6-echo→ verdicthonored - go6lab: probe
icmp6-echo→ verdictnot_honored - karsolink: probe
icmp6-echo→ verdicthonored - 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 | honored | no_tcp | not_honored | inconclusive |
| berlin | honored | no_tcp | not_honored | inconclusive |
| duseldorf | honored | no_tcp | partial | inconclusive |
| go6lab | not_honored | no_tcp | not_honored | inconclusive |
| karsolink | honored | no_tcp | not_honored | inconclusive |
| odin | honored | no_tcp | not_honored | inconclusive |
| t2 | honored | no_tcp | not_honored | inconclusive |
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): AS47217, AS9002, AS6939.
- From belgrade (open/Type-2=honored) the path enters an opaque hop at hop 13; from duseldorf (open/Type-2=honored) the same hop is in AS47217. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From belgrade (open/Type-2=honored) the path enters AS47217 at hop 6; from go6lab (open/Type-2=not_honored) the same hop is in AS9002. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From belgrade (open/Type-2=honored) the path enters AS9002 at hop 5; from karsolink (open/Type-2=honored) the same hop is in AS47217. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From belgrade (open/Type-2=honored) the path enters AS9002 at hop 4; from odin (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From belgrade (open/Type-2=honored) the path enters AS9002 at hop 5; from t2 (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From berlin (open/Type-2=honored) the path enters an opaque hop at hop 13; from duseldorf (open/Type-2=honored) the same hop is in AS47217. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From berlin (open/Type-2=honored) the path enters AS47217 at hop 6; from go6lab (open/Type-2=not_honored) the same hop is in AS9002. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From berlin (open/Type-2=honored) the path enters AS9002 at hop 5; from karsolink (open/Type-2=honored) the same hop is in AS47217. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From berlin (open/Type-2=honored) the path enters AS9002 at hop 4; from odin (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From berlin (open/Type-2=honored) the path enters AS9002 at hop 5; from t2 (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (open/Type-2=honored) the path enters AS47217 at hop 13; from go6lab (open/Type-2=not_honored) the same hop is in an opaque hop. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (open/Type-2=honored) the path enters AS47217 at hop 13; from karsolink (open/Type-2=honored) the same hop is in an opaque hop. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (open/Type-2=honored) the path enters AS47217 at hop 13; from odin (open/Type-2=honored) the same hop is in an opaque hop. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From duseldorf (open/Type-2=honored) the path enters AS47217 at hop 14; from t2 (open/Type-2=honored) the same hop is in an opaque hop. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From go6lab (open/Type-2=not_honored) the path enters AS9002 at hop 5; from karsolink (open/Type-2=honored) the same hop is in AS47217. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From go6lab (open/Type-2=not_honored) the path enters AS203993 at hop 3; from odin (open/Type-2=honored) the same hop is in AS56635. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From go6lab (open/Type-2=not_honored) the path enters AS9002 at hop 5; from t2 (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From karsolink (open/Type-2=honored) the path enters AS47217 at hop 6; from odin (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From karsolink (open/Type-2=honored) the path enters AS47217 at hop 5; from t2 (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. The disagreement is most likely rooted in one of those two transit ASes.
- From odin (open/Type-2=honored) the path enters an opaque hop at hop 5; from t2 (open/Type-2=honored) the same hop is in AS6939. Last common AS: AS47217. 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
tracepath6 per-hop PMTU drilldown
For each target where Type 2 verdicts disagreed across vantages, tracepath -6 ran from every vantage to capture per-hop PMTU evolution along that vantage's actual forward path. A pmtu change entry on a hop means that hop's router generated a PTB and we observed the shrink; absence of any change combined with a not_honored verdict suggests a router somewhere downstream is silently dropping >MTU packets (an RFC 4890 violation) rather than sending a PTB.
Target 2a02:670:d000:400::7
amsterdam - verdict ?
(no hops captured)
belgrade - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2001:7f8:1e::4 | |
| 3 | 2001:7f8:30:0:2:1:0:9002 | |
| 4 | 2a02:2d8::57f5:e080 | |
| 5 | 2a02:2d8:1:b81d:232a::1 | |
| 6 | 2a02:670:f001::3 | |
| 7 | 2a02:670:f001::3 | |
| 8 | <span class='muted'>no reply</span> | |
| 9 | <span class='muted'>no reply</span> | |
| 10 | <span class='muted'>no reply</span> | |
| 11 | <span class='muted'>no reply</span> | |
| 12 | <span class='muted'>no reply</span> | |
| 13 | <span class='muted'>no reply</span> | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
berlin - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2a06:d1c0::dead:beef:1c02 | |
| 3 | 2001:7f8:19:1::232a:1 | |
| 4 | 2a02:2d8::57f5:e080 | |
| 5 | 2a02:2d8:1:b81d:232a::1 | |
| 6 | 2a02:670:f000:a::12 | |
| 7 | 2a02:670:f001::3 | |
| 8 | <span class='muted'>no reply</span> | |
| 9 | <span class='muted'>no reply</span> | |
| 10 | <span class='muted'>no reply</span> | |
| 11 | <span class='muted'>no reply</span> | |
| 12 | <span class='muted'>no reply</span> | |
| 13 | <span class='muted'>no reply</span> | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
duseldorf - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2001:4ba0:92f4:3::1 | |
| 3 | <span class='muted'>no reply</span> | |
| 4 | 2001:4ba0:ffe9:109::2 | |
| 5 | 2001:4ba0:ffe9:8a::2 | |
| 6 | 2001:4ba0:ffe9:103e::1 | |
| 7 | 2001:4ba0:ffe9:103b::1 | |
| 8 | 2001:4ba0:ffe9:b8:: | |
| 9 | 2001:4ba0:ffe9:a7::1 | |
| 10 | 2001:4ba0:ffe9:da::2 | |
| 11 | 2001:4ba0:ffe9:db::2 | |
| 12 | 2001:7f8:b:100:1d1:a5d4:7217:56 | |
| 13 | 2a02:670:f000:a::12 | |
| 14 | 2a02:670:f001::3 | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
go6lab - verdict not_honored
verdict = not_honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2a00:8642:1000:f000::1 | |
| 3 | 2a00:8642:dc1:2::b | |
| 4 | 2001:7f8:1::a500:9002:1 | |
| 5 | 2a02:2d8::57f5:e080 | |
| 6 | 2a02:2d8:1:b81d:232a::1 | |
| 7 | 2a02:670:f000:a::12 | |
| 8 | 2a02:670:f001::3 | |
| 9 | <span class='muted'>no reply</span> | |
| 10 | <span class='muted'>no reply</span> | |
| 11 | <span class='muted'>no reply</span> | |
| 12 | <span class='muted'>no reply</span> | |
| 13 | <span class='muted'>no reply</span> | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
karsolink - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2a12:d8c0:109f:121::a1 | |
| 3 | 2a12:d8c0:101f:103::1 | |
| 4 | 2001:7f8:b:100:1d1:a5d4:7217:56 | |
| 5 | 2a02:670:f000:a::12 | |
| 6 | 2a02:670:f001::3 | |
| 7 | <span class='muted'>no reply</span> | |
| 8 | <span class='muted'>no reply</span> | |
| 9 | <span class='muted'>no reply</span> | |
| 10 | <span class='muted'>no reply</span> | |
| 11 | <span class='muted'>no reply</span> | |
| 12 | <span class='muted'>no reply</span> | |
| 13 | <span class='muted'>no reply</span> | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
odin - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2607:fae0:a000:2::2 | |
| 3 | 2a03:a100:0:201:1::1 | |
| 4 | 2a03:a100:0:201:1::1 | |
| 5 | <span class='muted'>no reply</span> | |
| 6 | 2001:470:0:2ea::2 | |
| 7 | <span class='muted'>no reply</span> | |
| 8 | 2001:7f8:b:100:1d1:a5d4:7217:56 | |
| 9 | 2a02:670:f000:a::12 | |
| 10 | 2a02:670:f001::3 | |
| 11 | <span class='muted'>no reply</span> | |
| 12 | <span class='muted'>no reply</span> | |
| 13 | <span class='muted'>no reply</span> | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
t2 - verdict honored
verdict = honored; final pmtu = 1500
| # | hop IP | pmtu change |
|---|---|---|
| 1 | <span class='muted'>no reply</span> | |
| 2 | 2a01:260:1::225 | |
| 3 | 2a01:260:1:1::9a | |
| 4 | 2001:7f8:13::a500:6939:1 | |
| 5 | 2001:470:e:43::2 | |
| 6 | 2001:470:e:43::2 | |
| 7 | 2001:470:e:153::2 | |
| 8 | 2001:470:e:dd::1 | |
| 9 | 2001:470:e:dd::1 | |
| 10 | 2001:7f8:b:100:1d1:a5d4:7217:56 | |
| 11 | 2a02:670:f000:a::12 | |
| 12 | 2a02:670:f000:a::12 | |
| 13 | 2a02:670:f001::3 | |
| 14 | <span class='muted'>no reply</span> | |
| 15 | <span class='muted'>no reply</span> | |
| 16 | <span class='muted'>no reply</span> | |
| 17 | <span class='muted'>no reply</span> |
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) openRFC 4890 ✓
filter likely at: (none) · min PMTU on path: 1500
Path (traceroute + mtr + PTR)
| # | IP / PTR | RTT | mtr loss | AS | AS holder |
|---|---|---|---|---|---|
| 1 | 2a09:ab81::1 | 0.3ms | 0%* | AS60733 | PERKE-NET - ZORAN PEROVIC trading as Agencija Perke.NET, RS |
| 2 | 2001:7f8:1e::4 | 0.4ms | 0% | AS13004 | SOX - Serbian Open Exchange DOO, RS |
| 3 | 2001:7f8:30:0:2:1:0:9002 | 48.3ms | 0% | - | NA |
| 4 | RT.MIX.MIL.IT.retn.net 2a02:2d8::57f5:e080 | 24.2ms | 0% | AS9002 | RETN-AS - RETN Limited, GB |
| 5 | GW-AS47217.retn.net 2a02:2d8:1:b81d:232a::1 | 29.3ms | 0% | AS9002 | RETN-AS - RETN Limited, GB |
| 6 | 2a02:670:f001::3 | 28.5ms | 10% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 7 | 2a02:670:f001::3 | 29.2ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 8 | * | - | 0% | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
Rate-limited ICMPv6: hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.012ms pmtu 1500
1: _gateway 0.493ms
1: _gateway 0.578ms
2: 2001:7f8:1e::4 0.632ms
3: 2001:7f8:30:0:2:1:0:9002 13.215ms
4: RT.MIX.MIL.IT.retn.net 24.279ms
5: GW-AS47217.retn.net 29.624ms
6: 2a02:670:f000:a::12 30.512ms
7: 2a02:670:f001::3 29.464ms
8: no reply
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
Too many hops: pmtu 1500
Resume: pmtu 1500 From DE host (Berlin) openRFC 4890 ✓
filter likely at: (none) · 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 | 0.4ms | 0%* | AS59645 | WYBT-NET - Tobias Fiebig, DE |
| 2 | ae0-2453.cr10.ber01.lwlcom.net 2a06:d1c0::dead:beef:1c02 | 0.7ms | 0%* | AS59645 | WYBT-NET - Tobias Fiebig, DE |
| 3 | retn.bcix.de 2001:7f8:19:1::232a:1 | 10.3ms | 0% | - | NA |
| 4 | RT.MIX.MIL.IT.retn.net 2a02:2d8::57f5:e080 | 19.4ms | 0% | AS9002 | RETN-AS - RETN Limited, GB |
| 5 | GW-AS47217.retn.net 2a02:2d8:1:b81d:232a::1 | 19.9ms | 30% | AS9002 | RETN-AS - RETN Limited, GB |
| 6 | 2a02:670:f000:a::12 | 20.9ms | 90% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 7 | 2a02:670:f001::3 | 19.7ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 8 | * | - | 0% | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
Rate-limited ICMPv6: hop 5, hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.042ms pmtu 1500
1: xe-0-0-13-178.gw01.ber01.as59645.net 0.622ms
1: xe-0-0-13-178.gw01.ber01.as59645.net 0.629ms
2: ae0-2453.cr10.ber01.lwlcom.net 0.999ms
3: retn.bcix.de 10.940ms asymm 5
4: RT.MIX.MIL.IT.retn.net 19.803ms asymm 5
5: GW-AS47217.retn.net 20.666ms asymm 11
6: 2a02:670:f000:a::12 21.169ms asymm 12
7: 2a02:670:f001::3 20.244ms asymm 13
8: no reply
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
Too many hops: pmtu 1500
Resume: pmtu 1500 From DE host (Düsseldorf) openRFC 4890 ✓
filter likely at: (none) · 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 | 0.2ms | 0%* | AS59645 | WYBT-NET - Tobias Fiebig, DE |
| 2 | eth1-0-12-h5594.edge5-dus1.bb.wiit.network 2001:4ba0:92f4:3::1 | 1.0ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 3 | lag13.agr3-dus3.bb.wiit.network 2001:4ba0:ffe9:7d::1 | 17.1ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 4 | lag30.core3-dus1.bb.wiit.network 2001:4ba0:ffe9:109::2 | 0.3ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 5 | lag0-vl1011.core1-fra-ix.bb.wiit.network 2001:4ba0:ffe9:8a::2 | 4.4ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 6 | lag0-vl1001.core1-nbg-ncd.bb.wiit.network 2001:4ba0:ffe9:103e::1 | 7.0ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 7 | lag0-vl6.core2-nbg-ncd.bb.wiit.network 2001:4ba0:ffe9:103b::1 | 6.9ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 8 | 2001:4ba0:ffe9:b8 | 14.3ms | 0% | - | |
| 9 | lag0-vl1009.core1-muc-eq3.bb.wiit.network 2001:4ba0:ffe9:a7::1 | 9.8ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 10 | lag0-vl1001.core1-pda-vsix.bb.wiit.network 2001:4ba0:ffe9:da::2 | 20.4ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 11 | lag0-vl1001.core1-mil-mix.bb.wiit.network 2001:4ba0:ffe9:db::2 | 20.2ms | 0% | AS24961 | MYLOC-AS - WIIT AG, DE |
| 12 | planetel-v6.mix-it.net @MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO 2001:7f8:b:100:1d1:a5d4:7217:56 | 20.8ms | 0% | - | NA |
| 13 | 2a02:670:f000:a::12 | 22.1ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 14 | 2a02:670:f001::3 | 21.1ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 15 | * | - | 0% | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.014ms pmtu 1500
1: xe-0-0-12-142.gw01.dus01.as59645.net 0.366ms
1: xe-0-0-12-142.gw01.dus01.as59645.net 0.344ms
2: eth1-0-12-h5594.edge5-dus1.bb.wiit.network 1.221ms
3: no reply
4: lag30.core3-dus1.bb.wiit.network 0.554ms
5: lag0-vl1011.core1-fra-ix.bb.wiit.network 4.401ms
6: lag0-vl1001.core1-nbg-ncd.bb.wiit.network 6.924ms
7: lag0-vl6.core2-nbg-ncd.bb.wiit.network 7.016ms
8: lag0-vl1006.core2-muc2.bb.wiit.network 22.033ms
9: lag0-vl1009.core1-muc-eq3.bb.wiit.network 9.882ms
10: lag0-vl1001.core1-pda-vsix.bb.wiit.network 20.523ms
11: lag0-vl1001.core1-mil-mix.bb.wiit.network 20.703ms asymm 9
12: planetel-v6.mix-it.net 21.399ms asymm 10
13: 2a02:670:f000:a::12 22.356ms asymm 11
14: 2a02:670:f001::3 21.338ms asymm 12
15: no reply
16: no reply
17: no reply
18: no reply
19: no reply
Too many hops: pmtu 1500
Resume: pmtu 1500 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::2 | 0.0ms | 0% | AS203993 | GNA-DC1-AS - S.J.M. Steffann, NL |
| 2 | * | - | 0%* | - | |
| 3 | ccr2-ccr1.dc1.nogalliance.org 2a00:8642:dc1:2::b | 5.2ms | 0% | AS203993 | GNA-DC1-AS - S.J.M. Steffann, NL |
| 4 | ams-ix.retn.net 2001:7f8:1::a500:9002:1 | 6.8ms | 0% | - | NA |
| 5 | RT.MIX.MIL.IT.retn.net 2a02:2d8::57f5:e080 | 20.3ms | 0% | AS9002 | RETN-AS - RETN Limited, GB |
| 6 | GW-AS47217.retn.net 2a02:2d8:1:b81d:232a::1 | 23.9ms | 0% | AS9002 | RETN-AS - RETN Limited, GB |
| 7 | 2a02:670:f000:a::12 | 23.3ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 8 | 2a02:670:f001::3 | 20.6ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 9 | * | - | 0% | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.033ms pmtu 1500
1: 2a00:8642:42::2 3.340ms
1: 2a00:8642:42::2 3.041ms
2: gw.friends.steffann.nl 4.026ms
3: ccr2-ccr1.dc1.nogalliance.org 7.302ms asymm 2
4: ams-ix.retn.net 5.606ms asymm 7
5: RT.MIX.MIL.IT.retn.net 22.246ms asymm 6
6: GW-AS47217.retn.net 22.205ms asymm 7
7: 2a02:670:f000:a::12 20.984ms
8: 2a02:670:f001::3 23.148ms
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
Too many hops: pmtu 1500
Resume: pmtu 1500 From ITA host (Karsolink) 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 | 2a12:d8c0:109f:121::a1 | 0.3ms | 0%* | AS204471 | KARSOLINK - 2S Computers SRL, IT |
| 3 | * | - | - | - | |
| 4 | planetel-v6.mix-it.net @MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO 2001:7f8:b:100:1d1:a5d4:7217:56 | 9.6ms | 0% | - | NA |
| 5 | 2a02:670:f000:a::12 | 10.6ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 6 | 2a02:670:f001::3 | 9.4ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 7 | * | - | 0% | - | |
| 8 | * | - | - | - | |
| 9 | * | - | - | - | |
| 10 | * | - | - | - | |
| 11 | * | - | - | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
tracepath -6
1?: [LOCALHOST] 0.040ms pmtu 1500
1: no reply
2: 2a12:d8c0:109f:121::a1 1.034ms
3: no reply
4: planetel-v6.mix-it.net 10.371ms
5: 2a02:670:f000:a::12 11.189ms
6: 2a02:670:f001::3 10.220ms
7: no reply
8: no reply
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
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 | 0.3ms | 0%* | AS8038 | 6CONNECT - 6connect, Inc., US |
| 2 | * | - | - | - | |
| 3 | 2a03:a100:0:201:1::1 | 0.9ms | 0% | AS56635 | XENYA - XENYA inzeniring, proizvodnja in trgovina, d.o.o. Ljubljana, SI |
| 4 | e0-1.core1.lju1.he.net 2001:470:1:5be::1 | 2.0ms | 70% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 5 | * | - | - | - | |
| 6 | port-channel1.core1.zag2.he.net 2001:470:0:2ea::2 | 4.1ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 7 | * | - | - | - | |
| 8 | 2001:7f8:c0::4:7217:1 | 11.3ms | 0% | - | NA |
| 9 | 2a02:670:f000:a::12 | 12.5ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 10 | 2a02:670:f001::3 | 11.4ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 11 | * | - | 0% | - | |
| 12 | * | - | - | - | |
| 13 | * | - | - | - | |
| 14 | * | - | - | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
Rate-limited ICMPv6: hop 4 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.027ms pmtu 9000
1: fw1-lju.6connect.com 0.516ms
1: fw1-lju.6connect.com 0.464ms
2: no reply
3: 2a03:a100:0:201:1::1 0.963ms
4: 2a03:a100:0:201:1::1 1.351ms pmtu 1500
4: no reply
5: no reply
6: port-channel1.core1.zag2.he.net 4.059ms
7: no reply
8: 2001:7f8:c0::4:7217:1 11.337ms asymm 6
9: 2a02:670:f000:a::12 12.459ms asymm 7
10: 2a02:670:f001::3 11.219ms asymm 9
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
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 | 2a01:261:313:b814::1 | 0.6ms | 0%* | AS34779 | T-2-AS - T-2, d.o.o., SI |
| 2 | 2a01:260:1::225 | 3.0ms | 0%* | AS34779 | T-2-AS - T-2, d.o.o., SI |
| 3 | 2a01-260-1-1--9a.core6.t-2.net 2a01:260:1:1::9a | 2.4ms | 0%* | AS34779 | T-2-AS - T-2, d.o.o., SI |
| 4 | hurricane-electric.nikhef.nlsix.net 2001:7f8:13::a500:6939:1 | 40.1ms | 0%* | - | NA |
| 5 | be7.core2.fra2.he.net 2001:470:e:18::2 | 40.7ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 6 | be3.core4.fra1.he.net 2001:470:e:5a::2 | 44.6ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 7 | be10.core1.zrh2.he.net 2001:470:e:153::2 | 51.8ms | 20% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 8 | be10.core1.zrh2.he.net 2001:470:e:153::2 | 57.8ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 9 | be1.core1.mil2.he.net 2001:470:e:dd::1 | 39.3ms | 0% | AS6939 | HURRICANE - Hurricane Electric LLC, US |
| 10 | 2001:7f8:c0::4:7217:1 | 33.2ms | - | - | NA |
| 11 | planetel-v6.mix-it.net @MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO 2001:7f8:b:100:1d1:a5d4:7217:56 | 37.0ms | 0% | - | NA |
| 12 | 2a02:670:f001::3 | 36.3ms | 30% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 13 | 2a02:670:f001::3 | 37.0ms | 0% | AS47217 | PLANETEL-SPA - Planetel SPA, IT |
| 14 | * | - | 0% | - | |
| 15 | * | - | - | - | |
| 16 | * | - | - | - | |
| 17 | * | - | - | - | |
| 18 | * | - | - | - | |
| 19 | * | - | - | - |
Rate-limited ICMPv6: hop 7, hop 12 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).
tracepath -6
1?: [LOCALHOST] 0.070ms pmtu 1500
1: 2a01:261:313:b814::1 1.278ms
2: 2a01:260:1::225 2.546ms
3: 2a01-260-1-1--9c.core6.t-2.net 3.438ms
4: 2a01-260-1-1--39.core6.t-2.net 3.562ms asymm 3
5: hurricane-electric.nikhef.nlsix.net 39.327ms asymm 4
6: be7.core2.fra2.he.net 38.684ms asymm 5
7: be10.core1.zrh2.he.net 56.997ms asymm 8
8: be10.core1.zrh2.he.net 51.748ms
9: be1.core1.mil2.he.net 34.505ms asymm 7
10: planetel-v6.mix-it.net 38.783ms asymm 7
11: 2001:7f8:c0::4:7217:1 38.446ms asymm 7
12: 2a02:670:f001::3 33.111ms asymm 9
13: 2a02:670:f001::3 37.719ms asymm 9
14: no reply
15: no reply
16: no reply
17: no reply
18: no reply
19: no reply
Too many hops: pmtu 1500
Resume: pmtu 1500