AS25303 - KDDPIRFC 4890 ✗RPKI -ASPA -

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AS overview

Test target: 2001:67c:20b8:1::10 · via IPv6 Hitlist (responsive) · address space: PI · prefixes announced: 1

prefix(es): 2001:67c:20b8::/47

Targets & per-vantage-point probe results (6 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 / hostnameSourceSRB host (SOX, Belgrade)DE host (Berlin)DE host (Düsseldorf)NL host (go6lab)ITA host (Karsolink)SLO host (6connect)SLO host (T-2)
ping1500B:80:443reachedping1500B:80:443reachedping1500B:80:443reachedping1500B:80:443reachedping1500B:80:443reachedping1500B:80:443reachedping1500B:80:443reached
2001:67c:20b8:1::10hit??-??-??-??-??-??-??-
2001:67c:20b8:1::9hit??-??-??-??-??-??-??-
2001:67c:20b8:ffff::2hit??-??-??-??-??-??-??-
2001:67c:20b8:ffff::5hit??-??-??-??-??-??-??-
2001:67c:20b8:ffff::6hit??-??-??-??-??-??-??-
2001:67c:20b9:ffff::2hit??-??-??-??-??-??-??-

SIX peering

Not an SIX member, but our traceroute path crosses the SIX LAN from SLO host (6connect) - reached via an SIX-resident transit operator.

RPKI & ASPA

0 of 1 prefix(es) covered by a valid ROA, 1 not-found.

PrefixRPKI stateReasonCovering VRP(s)
2001:67c:20b8::/47- not-foundno covering VRP

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

At least one router inside AS25303's announced prefix replied during the random-target probe. Hop(s): 2001:67c:20b8:1::100. These are candidate targets for direct testing.

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

Type 2 not honored. Forged ICMPv6 PTB (MTU=1280) had no effect: the next 1500-byte Echo Reply still arrived whole (1460 B, no Fragment Header). PMTUD does not work toward this address from us.
method: ICMPv6 Echo + forged PTB, tested 2026-09-23T10:32:15Z

Failure detail - what to grep in your logs
vantageour sourceyour targetmethodresulttested (UTC)
belgrade2a09:ab81::912001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:15Z
berlin2a06:d1c1:10b::cccc2001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:16Z
duseldorf2a06:d1c1:10d::aaaa2001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:15Z
go6lab2a00:8642:42::752001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:27Z
karsolink2a12:d8c0:105a:9001::a1542001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:16Z
odin2607:fae0:a000::422001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:14Z
t22a01:261:313:b814:2a0:98ff:fe5b:13e42001:67c:20b8:1::10icmp6-echonot_honored2026-09-23T10:32:18Z

Attempt log (belgrade):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (berlin):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (duseldorf):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (go6lab):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (karsolink):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (odin):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_tcp: tcp/80 not open

Attempt log (t2):

  1. icmp6-echonot_honored (reply shrank 1460→1460 B)
  2. dns-tcpno_tcp: connect failed: timed out
  3. tlsno_tcp: TLS connect failed
  4. httpno_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.

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 1460 B; after, it was 1460 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

  1. 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.
  2. 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.
  3. 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 (2026-09-23T10:32:15Z) 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.

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 ↗

multi-vantage path diagram for AS25303

From SRB host (SOX, Belgrade)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

4/4
Echo small (56B) 20.7ms
4/4
Echo 1500B (DF) 20.6ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
12a09:ab81::10.3ms0%*AS60733PERKE-NET - ZORAN PEROVIC trading as Agencija Perke.NET, RS
2sox-pn.sox.rs
2001:7f8:1e:8::3a
0.3ms0%AS13004SOX - Serbian Open Exchange DOO, RS
32001:7f8:1e:8::3d0.3ms0%AS13004SOX - Serbian Open Exchange DOO, RS
42a02:2d8:0:a00e:232a12.6ms0%-
52001:7f8:30:0:2:1:3:477917.4ms0%-NA
62a01-260-1-1--d.core6.t-2.net
2a01:260:1:1::d
17.4ms0%*AS34779T-2-AS - T-2, d.o.o., SI
72a01-260-1-1--9b.core6.t-2.net
2a01:260:1:1::9b
17.5ms0%*AS34779T-2-AS - T-2, d.o.o., SI
82a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
17.8ms0%*AS34779T-2-AS - T-2, d.o.o., SI
9*-0%-
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.017ms pmtu 1500
 1:  _gateway                                              0.753ms 
 1:  _gateway                                              0.707ms 
 2:  sox-pn.sox.rs                                         0.457ms 
 3:  2001:7f8:1e:8::3d                                     0.542ms asymm  2 
 4:  ae8-930.RT.IRX.VIE.AT.retn.net                       12.723ms asymm  3 
 5:  2001:7f8:30:0:2:1:3:4779                             17.384ms asymm  8 
 6:  2a01-260-1-1--d.core6.t-2.net                        17.843ms asymm  7 
 7:  2a01-260-1-1--9b.core6.t-2.net                       17.568ms asymm  9 
 8:  2a01-260-4107--2.link6.t-2.net                       18.596ms 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From DE host (Berlin)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

4/4
Echo small (56B) 34.0ms
4/4
Echo 1500B (DF) 34.1ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1xe-0-0-13-178.gw01.ber01.as59645.net
2a06:d1c1:100:b::1
0.3ms0%*AS59645WYBT-NET - Tobias Fiebig, DE
2ae0-2453.cr10.ber01.lwlcom.net
2a06:d1c0::dead:beef:1c02
0.7ms0%*AS59645WYBT-NET - Tobias Fiebig, DE
3ae3-90.cr10.ham01.lwlcom.net
2a00:c380:b200:230::192
4.7ms0%AS50629LWLCOM - LWLcom GmbH, DE
4ae0-50.cr11.ham01.lwlcom.net
2a00:c380:b200:230::45
4.7ms0%AS50629LWLCOM - LWLcom GmbH, DE
52a00:c380:f000::4b5.3ms0%AS50629LWLCOM - LWLcom GmbH, DE
6ae4-2087.dus10.core-backbone.com
2a01:4a0:0:2087::33
11.2ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
7ae21-2071.fra10.core-backbone.com
2a01:4a0:0:2071::4
10.6ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
8ae2-2021.fra20.core-backbone.com
2a01:4a0:0:2021::4
10.5ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
9ae6-2003.nbg20.core-backbone.com
2a01:4a0:0:2003::2
12.0ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
10ae2-2032.muc20.core-backbone.com
2a01:4a0:0:2032::7
14.6ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
11ae1-2028.vie10.core-backbone.com
2a01:4a0:0:2028::10
20.2ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
122a01:4a0:1338:115::232.1ms0%AS201011CORE-BACKBONE - Core-Backbone GmbH, DE
132a01-260-1-1--d.core6.t-2.net
2a01:260:1:1::d
31.3ms0%*AS34779T-2-AS - T-2, d.o.o., SI
142a01-260-1-1--9b.core6.t-2.net
2a01:260:1:1::9b
31.8ms0%*AS34779T-2-AS - T-2, d.o.o., SI
152a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
32.3ms0%*AS34779T-2-AS - T-2, d.o.o., SI
16*-0%-
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.027ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.705ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.461ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.902ms 
 3:  ae3-90.cr10.ham01.lwlcom.net                          5.299ms 
 4:  ae0-50.cr11.ham01.lwlcom.net                          5.727ms 
 5:  2a00:c380:f000::4b                                    5.780ms asymm  4 
 6:  ae4-2087.dus10.core-backbone.com                     11.899ms asymm  5 
 7:  ae21-2071.fra10.core-backbone.com                    11.180ms asymm  5 
 8:  ae2-2021.fra20.core-backbone.com                     11.010ms asymm  4 
 9:  ae6-2003.nbg20.core-backbone.com                     12.735ms asymm  6 
10:  ae2-2032.muc20.core-backbone.com                     15.322ms asymm  7 
11:  ae1-2028.vie10.core-backbone.com                     20.558ms asymm  8 
12:  2a01:4a0:1338:115::2                                 32.485ms 
13:  2a01-260-1-1--d.core6.t-2.net                        31.864ms asymm 11 
14:  2a01-260-1-1--9b.core6.t-2.net                       33.725ms asymm 13 
15:  2a01-260-4107--2.link6.t-2.net                       32.422ms asymm 14 
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  no reply
21:  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

4/4
Echo small (56B) 35.6ms
4/4
Echo 1500B (DF) 35.6ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1*-0%*-
2ipv6.decix-dusseldorf.core1.dus1.he.net
2001:7f8:9e::1b1b:0:1
7.2ms0%-NA
3*---
4be6.core2.ams2.he.net
2001:470:0:61c::2
9.0ms0%AS6939HURRICANE - Hurricane Electric LLC, US
5t-2.interxionfra11.nlsix.net
2001:7f8:13::a503:4779:1
30.0ms0%-NA
62a01-260-1-1--9d.core6.t-2.net
2a01:260:1:1::9d
32.8ms0%*AS34779T-2-AS - T-2, d.o.o., SI
72a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
29.9ms0%*AS34779T-2-AS - T-2, d.o.o., SI
8*-0%-
9*---
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.023ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.455ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.370ms 
 2:  ipv6.decix-dusseldorf.core1.dus1.he.net               7.550ms asymm  3 
 3:  no reply
 4:  be6.core2.ams2.he.net                                11.094ms asymm  6 
 5:  t-2.interxionfra11.nlsix.net                         28.138ms asymm 11 
 6:  2a01-260-1-1--9d.core6.t-2.net                       30.554ms asymm 12 
 7:  2a01-260-4107--2.link6.t-2.net                       32.982ms 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
20:  no reply
21:  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

4/4
Echo small (56B) 155.2ms
4/4
Echo 1500B (DF) 36.1ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
12a00:8642:42::22.5ms0%AS203993GNA-DC1-AS - S.J.M. Steffann, NL
2*-0%*-
32a00:1ca8:1::1942.9ms0%AS50673Serverius-as - Serverius Holding B.V., NL
42a03:3f40::10:336.2ms0%AS50673Serverius-as - Serverius Holding B.V., NL
5t-2.interxionfra11.nlsix.net
2001:7f8:13::a503:4779:1
35.7ms0%-NA
62a01-260-1-1--9d.core6.t-2.net
2a01:260:1:1::9d
38.8ms0%*AS34779T-2-AS - T-2, d.o.o., SI
72a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
42.2ms0%*AS34779T-2-AS - T-2, d.o.o., SI
8*-0%-
9*---
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.045ms pmtu 1500
 1:  2a00:8642:42::2                                       2.693ms 
 1:  2a00:8642:42::2                                       1.985ms 
 2:  no reply
 3:  2a00:1ca8:1::194                                      5.147ms 
 4:  2a03:3f40::10:33                                      6.221ms 
 5:  t-2.interxionfra11.nlsix.net                         42.215ms asymm  6 
 6:  2a01-260-1-1--9d.core6.t-2.net                       38.247ms asymm  7 
 7:  2a01-260-4107--2.link6.t-2.net                       38.540ms asymm  9 
 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
20:  no reply
21:  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

4/4
Echo small (56B) 43.0ms
4/4
Echo 1500B (DF) 42.4ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1*---
2*-0%*-
32a12:d8c0:101f:6::19.8ms80%AS204471KARSOLINK - 2S Computers SRL, IT
4*---
5100ge0-0-0-20.core1.vie1.he.net
2001:470:0:414::1
21.9ms20%AS6939HURRICANE - Hurricane Electric LLC, US
62001:7f8:30:0:2:1:3:477919.9ms0%-NA
72a01-260-1-1--d.core6.t-2.net
2a01:260:1:1::d
44.9ms0%*AS34779T-2-AS - T-2, d.o.o., SI
82a01-260-1-1--9b.core6.t-2.net
2a01:260:1:1::9b
43.4ms0%*AS34779T-2-AS - T-2, d.o.o., SI
92a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
44.7ms0%*AS34779T-2-AS - T-2, d.o.o., SI
10*-0%-
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

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

tracepath -6

 1?: [LOCALHOST]                        0.028ms pmtu 1500
 1:  no reply
 2:  no reply
 3:  2a12:d8c0:101f:6::1                                   9.946ms 
 4:  no reply
 5:  100ge0-0-0-20.core1.vie1.he.net                      22.794ms 
 6:  2001:7f8:30:0:2:1:3:4779                             19.708ms 
 7:  2a01-260-1-1--d.core6.t-2.net                        44.312ms asymm 11 
 8:  2a01-260-1-1--9b.core6.t-2.net                       43.153ms asymm 11 
 9:  2a01-260-4107--2.link6.t-2.net                       44.594ms asymm 13 
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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From SLO host (6connect)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

4/4
Echo small (56B) 3.3ms
4/4
Echo 1500B (DF) 3.5ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1fw1-lju.6connect.com
2607:fae0:a000::2
0.2ms0%*AS80386CONNECT - 6connect, Inc., US
2*---
3*---
4six.t-2.si @SIX
2001:7f8:46::3:4779
1.2ms0%AS34779T-2
52a01-260-1-1--9b.core6.t-2.net
2a01:260:1:1::9b
2.0ms0%*AS34779T-2-AS - T-2, d.o.o., SI
62a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
2.0ms0%*AS34779T-2-AS - T-2, d.o.o., SI
7*-0%-
8*---
9*---
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.019ms pmtu 9000
 1:  fw1-lju.6connect.com                                  0.665ms 
 1:  fw1-lju.6connect.com                                  0.459ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  0.924ms 
 4:  2a03:a100:0:201:1::1                                  0.935ms pmtu 1500
 4:  six.t-2.si                                            1.345ms 
 5:  2a01-260-1-1--9b.core6.t-2.net                        4.179ms 
 6:  2a01-260-4107--2.link6.t-2.net                        2.627ms asymm  7 
 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
20:  no reply
21:  no reply
     Too many hops: pmtu 1500

From SLO host (T-2)   openRFC 4890 ✗

filter likely at: (none) · min PMTU on path: 1500

4/4
Echo small (56B) 4.4ms
4/4
Echo 1500B (DF) 4.9ms
no
Type 1 dest-unreach
-
TCP responds on

Path (traceroute + mtr + PTR)

#IP / PTRRTTmtr lossASAS holder
1*-0%*-
22a01:260:1::2251.6ms0%*AS34779T-2-AS - T-2, d.o.o., SI
32a01-260-4107--2.link6.t-2.net
2a01:260:4107::2
2.7ms0%*AS34779T-2-AS - T-2, d.o.o., SI
4*-0%-
5*---
6*---
7*---
8*---
9*---
10*---
11*---
12*---
13*---
14*---
15*---
16*---
17*---
18*---
19*---
20*---
21*---

tracepath -6

 1?: [LOCALHOST]                        0.033ms pmtu 1500
 1:  2a01:261:313:b814::1                                  0.998ms 
 1:  no reply
 2:  2a01:260:1::225                                       9.729ms 
 3:  2a01-260-4107--2.link6.t-2.net                        2.925ms 
 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
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
     Too many hops: pmtu 1500
     Resume: pmtu 1500