AS48943 KAPPERNET KAPPER NETWORK-COMMUNICATIONS GmbH

AS overview

Test target: 2a02:ab8:4::11 · ns1.kapper.net · address space: mixed · prefixes announced: 2

prefix(es): 2a0c:4e40::/29, 2a02:ab8::/32

Targets & per-vantage-point probe results (10 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)
Target IP / hostname	Source	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:ab8:4::1` dns1.kapper.net	drv	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:ab8:4::100` web.kapper.net	SPF	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	-
`2a02:ab8:4::101` mx1.kapper.net	drv	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓
`2a02:ab8:4::103` relay.kapper.net	SPF	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:ab8:4::105` monitor.kapper.net	drv	✓	✓	?	open	✓	✓	✓	?	open	✓	✓	✓	?	open	✓	✓	✓	?	open	✓	✓	✓	?	open	✓	✓	✓	?	open	✓	✓	✓	?	open	✓
`2a02:ab8:4::107` inbound.kapper.net	MX	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	-
`2a02:ab8:4::11` ns1.kapper.net	NS	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✗	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:ab8:4::2` dns2.kapper.net	drv	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	-
`2a02:ab8:4::5` ns5.kapper.net	NS	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:ab8:8:fab::177` webmail.kapper.net	drv	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓

VIX / AAIX / SAIX / TIROL-IX / ERA-IX peering

VIX / AAIX / SAIX / TIROL-IX / ERA-IX member - Open peering, peering member, since 2014-05-31. IPv6 LAN: 2001:7f8:30:0:1:1:4:8943. Locations: -.

RPKI & ASPA

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

Prefix	RPKI state	Reason	Covering VRP(s)
`2a0c:4e40::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS48943 /29 maxLen 29 (ripe)
`2a02:ab8::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS48943 /29 maxLen 32 (ripe)

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

At least one router inside AS48943's announced prefix replied during the random-target probe. Hop(s): 2a02:ab8:0:ff::1f4, 2a02:ab8:0:ff::1fa, 2a02:ab8:0:ff::207, 2a02:ab8:0:ff::20b, 2a02:ab8:0:ff::212. 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 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
DE host (Berlin): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
DE host (Düsseldorf): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
NL host (go6lab): inconclusive: no Echo Reply after PTB (probe 1500B). (ICMPv6 Echo + forged PTB)
ITA host (Karsolink): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
SLO host (6connect): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)
SLO host (T-2): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (ICMPv6 Echo + forged PTB)

Why they disagree - measurement artifact: One vantage's probe didn't generate enough data to detect segment shrinkage (natural reply too small, or no second response). The other vantage's verdict is the meaningful one.

Failure detail - what to grep in your logs

vantage	our source	your target	method	result	tested (UTC)
belgrade	`2a09:ab81::91`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:14Z
berlin	`2a06:d1c1:10b::cccc`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:12Z
duseldorf	`2a06:d1c1:10d::aaaa`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:14Z
go6lab	`2a00:8642:42::75`	`2a02:ab8:4::11`	`icmp6-echo`	inconclusive	2026-09-22T13:54:56Z
karsolink	`2a12:d8c0:105a:9001::a154`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:10Z
odin	`2607:fae0:a000::42`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:15Z
t2	`2a01:261:313:b814:2a0:98ff:fe5b:13e4`	`2a02:ab8:4::11`	`icmp6-echo`	not_honored	2026-09-22T13:54:12Z

Attempt log (belgrade):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (berlin):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (duseldorf):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (go6lab):

icmp6-echo → inconclusive (reply 1460 B before PTB): no Echo Reply after PTB (probe 1500B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (karsolink):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (odin):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (t2):

icmp6-echo → not_honored (reply shrank 1460→1460 B)
dns-tcp → inconclusive (reply 241 B before PTB): max DNS-over-TCP segment 241B; not big enough to test PMTU shrink
tls → no_tcp: TLS connect failed
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 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

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 (2026-09-22T13:54:14Z) 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 → verdict not_honored
berlin: probe icmp6-echo → verdict not_honored
duseldorf: probe icmp6-echo → verdict not_honored
go6lab: probe icmp6-echo → verdict inconclusive
karsolink: probe icmp6-echo → verdict not_honored
odin: probe icmp6-echo → verdict not_honored
t2: probe icmp6-echo → verdict not_honored

Full per-method matrix (all four methods run at each vantage):

vantage	icmp6-echo	dns-tcp	tls	http
belgrade	not_honored	inconclusive	no_tcp	no_tcp
berlin	not_honored	inconclusive	no_tcp	no_tcp
duseldorf	not_honored	inconclusive	no_tcp	no_tcp
go6lab	inconclusive	inconclusive	no_tcp	no_tcp
karsolink	not_honored	inconclusive	no_tcp	no_tcp
odin	not_honored	inconclusive	no_tcp	no_tcp
t2	not_honored	inconclusive	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, AS48943, AS8218.

From belgrade (open/Type-2=not_honored) the path enters AS48943 at hop 12; from berlin (open/Type-2=not_honored) the same hop is in an opaque hop. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From belgrade (open/Type-2=not_honored) the path enters AS6939 at hop 7; from duseldorf (open/Type-2=not_honored) the same hop is in AS48943. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From belgrade (open/Type-2=not_honored) the path enters AS6939 at hop 7; from go6lab (open/Type-2=inconclusive) the same hop is in an opaque hop. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From belgrade (open/Type-2=not_honored) the path enters AS6939 at hop 7; from karsolink (open/Type-2=not_honored) the same hop is in AS8218. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From belgrade (open/Type-2=not_honored) the path enters AS6939 at hop 7; from odin (open/Type-2=not_honored) the same hop is in AS48943. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From belgrade (open/Type-2=not_honored) the path enters AS6939 at hop 7; from t2 (open/Type-2=not_honored) the same hop is in AS48943. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From berlin (open/Type-2=not_honored) the path enters AS8218 at hop 4; from duseldorf (open/Type-2=not_honored) the same hop is in AS6939. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From berlin (open/Type-2=not_honored) the path enters AS8218 at hop 4; from go6lab (open/Type-2=inconclusive) the same hop is in AS6939. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From berlin (open/Type-2=not_honored) the path enters an opaque hop at hop 7; from karsolink (open/Type-2=not_honored) the same hop is in AS8218. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From berlin (open/Type-2=not_honored) the path enters AS8218 at hop 4; from odin (open/Type-2=not_honored) the same hop is in AS6939. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From berlin (open/Type-2=not_honored) the path enters AS48943 at hop 10; from t2 (open/Type-2=not_honored) the same hop is in an opaque hop. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From duseldorf (open/Type-2=not_honored) the path enters an opaque hop at hop 6; from go6lab (open/Type-2=inconclusive) the same hop is in AS6939. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From duseldorf (open/Type-2=not_honored) the path enters AS48943 at hop 7; from karsolink (open/Type-2=not_honored) the same hop is in AS8218. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From go6lab (open/Type-2=inconclusive) the path enters AS6939 at hop 6; from karsolink (open/Type-2=not_honored) the same hop is in AS8218. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From go6lab (open/Type-2=inconclusive) the path enters AS6939 at hop 6; from odin (open/Type-2=not_honored) the same hop is in an opaque hop. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From go6lab (open/Type-2=inconclusive) the path enters AS48943 at hop 10; from t2 (open/Type-2=not_honored) the same hop is in an opaque hop. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From karsolink (open/Type-2=not_honored) the path enters AS8218 at hop 7; from odin (open/Type-2=not_honored) the same hop is in AS48943. Last common AS: AS48943. The disagreement is most likely rooted in one of those two transit ASes.
From karsolink (open/Type-2=not_honored) the path enters AS8218 at hop 7; from t2 (open/Type-2=not_honored) the same hop is in AS48943. Last common AS: AS48943. 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

An operator-targeted diagnostic interpretation can be generated for this AS on demand. The pipeline holds the raw verdicts and the per-hop walk; an AI pass synthesises where to start looking. Click the button below to run it.

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

4/4

Echo small (56B) 41.0ms

4/4

Echo 1500B (DF) 41.1ms

yes

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	2a09:ab81::1	0.5ms	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	2001:7f8:1e:8::3d	0.3ms	0%	AS13004	SOX - Serbian Open Exchange DOO, RS
4	2001:67c:128c::699	22.7ms	0%	-	NA
5	hu0-15-0-0.lontr4.London.opentransit.net 2001:688:0:2::c3	41.5ms	0%	AS5511	Opentransit - Orange S.A., FR
6	*	-	-	-
7	be4.core2.ams2.he.net 2001:470:0:293::2	41.7ms	0%	AS6939	HURRICANE - Hurricane Electric LLC, US
8	be7.core2.fra2.he.net 2001:470:e:18::2	42.8ms	30%	AS6939	HURRICANE - Hurricane Electric LLC, US
9	be4.core1.vie1.he.net 2001:470:e:149::2	42.5ms	10%	AS6939	HURRICANE - Hurricane Electric LLC, US
10	vix1.kapper.net @VIX / AAIX / SAIX / TIROL-IX / ERA-IX 2001:7f8:30:0:1:1:4:8943	41.1ms	0%	-	NA
11	vl2008.cr02.oe3.kapper.net 2a02:ab8:0:ff::3	40.8ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
12	k130.vss.kapper.net 2a02:ab8:2:2::130	42.6ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
13	2a02:ab8:4::11	41.3ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

Rate-limited ICMPv6: hop 8, hop 9 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.015ms pmtu 1500
 1:  _gateway                                              0.449ms 
 1:  _gateway                                              0.462ms 
 2:  sox-pn.sox.rs                                         0.595ms 
 3:  2001:7f8:1e:8::3d                                     0.821ms asymm  2 
 4:  2001:67c:128c::699                                   23.072ms asymm  5 
 5:  hu0-15-0-0.lontr4.London.opentransit.net             40.102ms asymm  6 
 6:  no reply
 7:  be4.core2.ams2.he.net                                41.195ms 
 8:  be7.core2.fra2.he.net                                41.781ms asymm  6 
 9:  be4.core1.vie1.he.net                                41.469ms asymm  5 
10:  vix1.kapper.net                                      43.368ms asymm  3 
11:  vl2008.cr02.oe3.kapper.net                           41.127ms asymm  4 
12:  k130.vss.kapper.net                                  41.249ms asymm  5 
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

4/4

Echo small (56B) 18.3ms

4/4

Echo 1500B (DF) 18.4ms

yes

Type 1 dest-unreach

TCP responds on

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	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	zayoeurope.bcix.de 2001:7f8:19:1::201a:1	10.2ms	0%	-	NA
4	2001:1b48:2:2::6:2	18.0ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
5	2001:1b48:2:7::1:2	18.0ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
6	2001:1b48:2:107::8:2	18.0ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
7	mt02ix-sfpp3-vl4004.bgp02-mt02ix.core.kapper.net 2a02:ab8:0:ff::23a	24.4ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
8	sfpp5.mt03.ix.kapper.net 2a02:ab8:0:ff::e	18.5ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	vl2007.cr02.oe3.kapper.net 2a02:ab8:0:ff::14	18.2ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
10	k130.vss.kapper.net 2a02:ab8:2:2::130	18.5ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
11	2a02:ab8:4::11	18.3ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

tracepath -6

 1?: [LOCALHOST]                        0.029ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.415ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.534ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.859ms 
 3:  zayoeurope.bcix.de                                   10.726ms asymm  8 
 4:  2001:1b48:2:2::6:2                                   18.404ms asymm  5 
 5:  2001:1b48:2:7::1:2                                   18.405ms 
 6:  2001:1b48:2:107::8:2                                 18.377ms asymm  7 
 7:  mt02ix-sfpp3-vl4004.bgp02-mt02ix.core.kapper.net     24.908ms asymm  8 
 8:  sfpp5.mt03.ix.kapper.net                             19.114ms asymm  9 
 9:  vl2007.cr02.oe3.kapper.net                           18.804ms asymm  6 
10:  k130.vss.kapper.net                                  18.753ms asymm  7 
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

4/4

Echo small (56B) 20.3ms

4/4

Echo 1500B (DF) 20.4ms

yes

Type 1 dest-unreach

TCP responds on

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	ipv6.decix-dusseldorf.core1.dus1.he.net 2001:7f8:9e::1b1b:0:1	7.6ms	0%	-	NA
3	*	-	30%	-
4	be8.core1.prg1.he.net 2001:470:e:1e::2	11.1ms	0%	AS6939	HURRICANE - Hurricane Electric LLC, US
5	be3.core1.vie1.he.net 2001:470:e:a7::2	16.0ms	0%	AS6939	HURRICANE - Hurricane Electric LLC, US
6	vix1.kapper.net @VIX / AAIX / SAIX / TIROL-IX / ERA-IX 2001:7f8:30:0:1:1:4:8943	20.4ms	10%	-	NA
7	vl2008.cr02.oe3.kapper.net 2a02:ab8:0:ff::3	20.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
8	k130.vss.kapper.net 2a02:ab8:2:2::130	20.4ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	2a02:ab8:4::11	20.2ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

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]                        0.025ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.400ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.373ms 
 2:  ipv6.decix-dusseldorf.core1.dus1.he.net               6.816ms asymm  3 
 3:  100ge0-0-0-18.core4.fra1.he.net                       7.861ms asymm  4 
 4:  be8.core1.prg1.he.net                                13.870ms asymm  5 
 5:  be3.core1.vie1.he.net                                20.668ms asymm  4 
 6:  vix1.kapper.net                                      21.103ms 
 7:  vl2008.cr02.oe3.kapper.net                           20.422ms 
 8:  k130.vss.kapper.net                                  20.462ms 
 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 NL host (go6lab) open

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

4/4

Echo small (56B) 22.9ms

4/4

Echo 1500B (DF) 25.3ms

yes

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	2a00:8642:42::2	3.2ms	0%	AS203993	GNA-DC1-AS - S.J.M. Steffann, NL
2	*	-	-	-
3	speed-ix.he.net 2001:7f8:b7::a500:6939:1	10.5ms	20%	-	NA
4	be2.core4.fra1.he.net 2001:470:e:38::2	16.0ms	10%	AS6939	HURRICANE - Hurricane Electric LLC, US
5	be8.core1.prg1.he.net 2001:470:e:1e::2	20.8ms	0%	AS6939	HURRICANE - Hurricane Electric LLC, US
6	be3.core1.vie1.he.net 2001:470:e:a7::2	21.7ms	10%	AS6939	HURRICANE - Hurricane Electric LLC, US
7	vix1.kapper.net @VIX / AAIX / SAIX / TIROL-IX / ERA-IX 2001:7f8:30:0:1:1:4:8943	23.0ms	0%	-	NA
8	vl2008.cr02.oe3.kapper.net 2a02:ab8:0:ff::3	22.8ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	k130.vss.kapper.net 2a02:ab8:2:2::130	21.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
10	2a02:ab8:4::11	23.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

Rate-limited ICMPv6: hop 3, hop 4, hop 6 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.428ms pmtu 1500
 1:  2a00:8642:42::2                                       2.069ms 
 1:  2a00:8642:42::2                                       4.343ms 
 2:  no reply
 3:  speed-ix.he.net                                      16.412ms 
 4:  be2.core4.fra1.he.net                                19.447ms 
 5:  be8.core1.prg1.he.net                                16.925ms 
 6:  be3.core1.vie1.he.net                                26.907ms 
 7:  vix1.kapper.net                                      21.764ms 
 8:  vl2008.cr02.oe3.kapper.net                           21.310ms 
 9:  k130.vss.kapper.net                                  22.036ms 
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

4/4

Echo small (56B) 165.2ms

0/4

Echo 1500B (DF) -

yes

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	*	-	0%*	-
2	*	-	0%*	-
3	*	-	-	-
4	zayoeurope-AS8218.mix-it.net 2001:7f8:b:100:1d1:a5d0:8218:208	8.5ms	0%	-	NA
5	2001:1b48:2:c::1:1	8.6ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
6	2001:1b48:2:2::9:1	19.3ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
7	2001:1b48:2:107::8:2	15.4ms	0%	AS8218	NEO-ASN - Zayo Infrastructure France SA, FR
8	mt02ix-sfpp3-vl4004.bgp02-mt02ix.core.kapper.net 2a02:ab8:0:ff::23a	22.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	sfpp5.mt03.ix.kapper.net 2a02:ab8:0:ff::e	16.3ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
10	vl2007.cr02.oe3.kapper.net 2a02:ab8:0:ff::14	16.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
11	k130.vss.kapper.net 2a02:ab8:2:2::130	15.7ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
12	2a02:ab8:4::11	15.8ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

tracepath -6

 1?: [LOCALHOST]                        0.031ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.659ms 
 1:  karsolink-01.net.karsolink.com                        0.646ms 
 2:  2a12:d8c0:109f:121::a1                                0.744ms 
 3:  no reply
 4:  zayoeurope-AS8218.mix-it.net                          9.133ms 
 5:  2001:1b48:2:c::1:1                                    9.112ms 
 6:  2001:1b48:2:2::9:1                                   19.904ms 
 7:  2001:1b48:2:107::8:2                                 16.130ms asymm  8 
 8:  mt02ix-sfpp3-vl4004.bgp02-mt02ix.core.kapper.net     21.366ms asymm  9 
 9:  sfpp5.mt03.ix.kapper.net                             16.444ms asymm 10 
10:  vl2007.cr02.oe3.kapper.net                           16.062ms asymm  7 
11:  k130.vss.kapper.net                                  16.233ms asymm  8 
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

4/4

Echo small (56B) 8.0ms

4/4

Echo 1500B (DF) 8.2ms

yes

Type 1 dest-unreach

TCP responds on

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	0.8ms	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	50%	AS6939	HURRICANE - Hurricane Electric LLC, US
5	100ge0-0-0-5.core1.vie1.he.net 2001:470:0:578::1	9.3ms	10%	AS6939	HURRICANE - Hurricane Electric LLC, US
6	vix1.kapper.net @VIX / AAIX / SAIX / TIROL-IX / ERA-IX 2001:7f8:30:0:1:1:4:8943	8.4ms	0%	-	NA
7	vl2008.cr02.oe3.kapper.net 2a02:ab8:0:ff::3	8.2ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
8	k130.vss.kapper.net 2a02:ab8:2:2::130	7.9ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	2a02:ab8:4::11	7.6ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

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

tracepath -6

 1?: [LOCALHOST]                        0.025ms pmtu 9000
 1:  fw1-lju.6connect.com                                  1.201ms 
 1:  fw1-lju.6connect.com                                  0.547ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  0.976ms 
 4:  2a03:a100:0:201:1::1                                  0.880ms pmtu 1500
 4:  e0-1.core1.lju1.he.net                                2.043ms 
 5:  100ge0-0-0-5.core1.vie1.he.net                        9.113ms 
 6:  vix1.kapper.net                                       8.425ms asymm  4 
 7:  vl2008.cr02.oe3.kapper.net                            8.239ms asymm  6 
 8:  k130.vss.kapper.net                                   7.825ms asymm  6 
 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

From SLO host (T-2) openRFC 4890 ✗

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

4/4

Echo small (56B) 9.7ms

4/4

Echo 1500B (DF) 10.0ms

yes

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	*	-	0%*	-
2	2a01:260:1::225	2.4ms	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	2a01-260-1-1--38.core6.t-2.net 2a01:260:1:1::38	2.2ms	0%*	AS34779	T-2-AS - T-2, d.o.o., SI
5	*	-	-	-
6	vix1.kapper.net @VIX / AAIX / SAIX / TIROL-IX / ERA-IX 2001:7f8:30:0:1:1:4:8943	9.6ms	10%	-	NA
7	vl2008.cr02.oe3.kapper.net 2a02:ab8:0:ff::3	9.6ms	10%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
8	k130.vss.kapper.net 2a02:ab8:2:2::130	9.6ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT
9	2a02:ab8:4::11	10.0ms	0%	AS48943	KAPPERNET - KAPPER NETWORK-COMMUNICATIONS GmbH, AT

Rate-limited ICMPv6: hop 6, hop 7 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.030ms pmtu 1500
 1:  2a01:261:313:b814::1                                  1.050ms 
 1:  no reply
 2:  2a01:260:1::225                                       3.242ms 
 3:  2a01-260-1-1--9a.core6.t-2.net                        2.696ms 
 4:  2a01-260-1-1--38.core6.t-2.net                        2.546ms asymm  3 
 5:  100ge0-0-0-31.core1.vie1.he.net                      10.295ms 
 6:  vix1.kapper.net                                      10.753ms asymm  5 
 7:  vl2008.cr02.oe3.kapper.net                            9.883ms asymm  6 
 8:  k130.vss.kapper.net                                  10.795ms asymm  7 
 9:  k130.vss.kapper.net                                  10.918ms 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500