AS9119 SOFTNET-AS - SOFTNET d.o.o.

AS overview

Test target: 2a02:800:73:2::58 · trixie.softnet.si · address space: unknown · prefixes announced: 9

prefix(es): 2a0f:a6c0::/36, 2a0e:1e80::/29, 2a0b:c306::/32, 2a02:801::/32, 2a0b:c307::/32, 2a0e:2e00::/29, 2a0f:2180::/29, 2a09:e140::/29 (+1 more)

Targets & per-vantage-point probe results (10 target(s) across 3 vantage point(s))

Source codes (hover any badge for full description): CUR=curated · NS/SOA/MX=DNS records · SPF=SPF TXT · DRV=holder-derived (www, ns1, mail, gw, …) · ATL=RIPE Atlas · PDB=PeeringDB · WHOIS=RIPE whois · RDAP=RIPE RDAP · HIT=IPv6 Hitlist · RTR=in-prefix path hop (router) · PRB=static prefix probe · SYN=synthetic prefix::1 fallback

Target IP / hostname	Source	NL host (go6lab)					ITA host (Karsolink)					SLO host (6connect)
Target IP / hostname	Source	ping	1500B	:80	:443	reached	ping	1500B	:80	:443	reached	ping	1500B	:80	:443	reached
`2a02:800:0:3::1`	hit	✓	✓	?	?	-	✓	✓	refused	refused	-	✓	✓	refused	refused	-
`2a02:800:0:3::69`	hit	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓
`2a02:800:0:3::73`	hit	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:800:0:3::80`	hit	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓
`2a02:800:0:3::81` mx1.softnet.eu	MX	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:800:0:3::84`	hit	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓
`2a02:800:73:2::55` mx.softnet.eu	drv	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:800:73:2::56` support.softnet.si	drv	✓	✓	open	open	✓	✓	✓	open	open	✓	✓	✓	open	open	✓
`2a02:800:73:2::58` trixie.softnet.si	NS	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓
`2a02:800:73:2::60` mx2.softnet.eu	MX	✓	✓	?	?	✓	✓	✓	?	?	✓	✓	✓	?	?	✓

SIX peering

SIX member - open peering, peering member, since 1999-04-16. IPv6 LAN: 2001:7f8:46:0:1::9119. Locations: lj_tpl.

rs1-lan1-ipv6 → 2001:7f8:46:0:1::9119 Established (loc: lj_tpl, since 2026-01-05)
rs2-lan1-ipv6 → 2001:7f8:46:0:1::9119 Established (loc: lj_tpl, since 2026-05-12)

Announces via SIX route servers: 29 prefix(es) - 2001:3786:1::/48, 2001:3786:5009::/48, 2001:3786:5011::/48, 2001:3786:9923::/48, 2001:3786:ffff::/48, 2001:678:1ec::/48, 2001:67c:1124::/48, 2001:67c:20b8::/47 (+21 more)

RPKI & ASPA

9 of 9 prefix(es) covered by a valid ROA.

Prefix	RPKI state	Reason	Covering VRP(s)
`2a0e:2e00::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /29 maxLen 29 (ripe)
`2a02:800::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /32 maxLen 32 (ripe)
`2a0f:2180::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /29 maxLen 29 (ripe)
`2a0f:a6c0::/36`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /36 maxLen 36 (ripe)
`2a0e:1e80::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /29 maxLen 29 (ripe)
`2a0b:c307::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /32 maxLen 32 (ripe); AS9119 /29 maxLen 29 (ripe)
`2a02:801::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /32 maxLen 32 (ripe)
`2a0b:c306::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /32 maxLen 32 (ripe); AS9119 /29 maxLen 29 (ripe)
`2a09:e140::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS9119 /29 maxLen 29 (ripe)

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

We probed 30 arbitrary IPv6 address(es) inside AS9119's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:7f8::239f:0:1 at hop 7 - that router does not answer ICMPv6 Echo. This is not in AS9119's announced prefix; operationally it's the AS-edge / peering interface (often on a SIX peering address or an upstream's /127 link). The traceroute boundary is the AS edge: ICMPv6 Time-Exceeded responses from anything inside this AS are filtered.

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

Vantage points disagree about Type 2 acceptance - transit ASes on one path may be filtering Type 2 even though the destination's stack accepts it on another path:

NL host (go6lab): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
ITA host (Karsolink): inconclusive: no Echo Reply to 1300-byte probe. (ICMPv6 Echo + forged PTB)
SLO host (6connect): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)

Why they disagree - reachability mismatch: One vantage couldn't drive a flow at all to this destination (no Echo Reply or no responding TCP port), so the active test had no behavioural change to observe. The other vantage's verdict is the only meaningful one here.

Failure detail — what to grep in your logs

vantage	our source	your target	method	result	tested (UTC)
go6lab	`2a00:8642:42::75`	`2a02:800:73:2::58`	`icmp6-echo`	honored	2026-05-30T10:34:28Z
karsolink	`2a12:d8c0:105a:9001::a154`	`2a02:800:73:2::58`	`icmp6-echo`	no_echo	2026-05-30T10:43:04Z
odin	`2607:fae0:a000::42`	`2a02:800:73:2::58`	`icmp6-echo`	honored	2026-05-30T10:34:15Z

Attempt log (go6lab):

icmp6-echo → honored (size_before=1460, size_after=None)
dns-tcp → inconclusive (size_before=156, size_after=None): max DNS-over-TCP segment 156B; 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 → no_echo: no Echo Reply to 1300-byte probe
dns-tcp → inconclusive (size_before=156, size_after=None): max DNS-over-TCP segment 156B; 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 → honored (size_before=1460, size_after=None)
dns-tcp → inconclusive (size_before=56, size_after=None): max DNS-over-TCP segment 56B; 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 2a12:d8c0:105a:9001::a154)'

If you see our PTBs arriving but the destination's TCP/Echo flow does not shrink, the drop is in the destination kernel (cause 3 below). If you don't see them at all, drop is upstream of you (cause 2). If you only see them from one of our two source IPs, the drop is path-asymmetric — one transit on the asymmetric route is filtering, the other is not.

Where the path divergence is

Per-vantage probe + verdict (headline):

go6lab: probe icmp6-echo → verdict honored
karsolink: probe icmp6-echo → verdict no_echo
odin: probe icmp6-echo → verdict honored

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

vantage	icmp6-echo	dns-tcp	tls	http
go6lab	honored	inconclusive	no_tcp	no_tcp
karsolink	no_echo	inconclusive	no_tcp	no_tcp
odin	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): AS9119, AS203993, AS56635.

From go6lab (open/Type-2=honored) the path enters an opaque hop at hop 8; from karsolink (open/Type-2=no_echo) the same hop is in AS9119. Last common AS: AS9119. The disagreement is most likely rooted in one of those two transit ASes.
From go6lab (open/Type-2=honored) the path enters AS203993 at hop 3; from odin (open/Type-2=honored) the same hop is in AS56635. Last common AS: AS9119. The disagreement is most likely rooted in one of those two transit ASes.
From karsolink (open/Type-2=no_echo) the path enters AS9119 at hop 8; from odin (open/Type-2=honored) the same hop is in an opaque hop. Last common AS: AS9119. 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.

Per-hop PTB acceptance walk

From the local vantage, we walk the forward path hop-by-hop, sending each hop a 1500-byte ICMPv6 Echo, then a forged PTB (MTU=1280) sourced from us, then another 1500-byte Echo. If the second reply arrives fragmented or smaller, that hop honoured the PTB. If unchanged, it didn't. The first ✗ in an otherwise-✓ path is the most likely filter location. Cross-country aggregation: see the global PTB filter atlas for transit ASes ranked by filter rate across all measurements.

#	hop IP	AS	Holder	PTB acceptance
1	2607:fae0:a000::2	AS8038	6CONNECT - 6connect, Inc., US	- skipped (CoPP)
2	2607:fae0:a000:2::2	AS8038	6CONNECT - 6connect, Inc., US	- skipped (CoPP)
3	2a03:a100:0:201:1::1	AS56635	XENYA - XENYA inzeniring, proizvodnja in	✓ honored
4	2001:7f8:46:0:1::9119	AS51988	ARNES-SIX - ARNES, SI	? no_response
5	2a02:800:1:3021::194	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI	? no_response
6	2a02:800:73:2::58	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI	? no_response

Tests host-mode PTB acceptance (PTBs aimed at the hop itself). A router that honours PTBs to itself can still be filtering PTBs transiting through it; this is one indicator, not proof of full PTB transparency. Hops in CoPP-rate-limit ranges are skipped to avoid false signals.

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 `2a02:800:73:2::56`

go6lab — verdict honored

verdict = 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::a500:9119:1
5	2a02:800:e:200d::1
6	2a02:800:1:3021::194
7	2a02:800:73:2::56

karsolink — verdict not_honored

verdict = not_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:6::1
4	<span class='muted'>no reply</span>
5	<span class='muted'>no reply</span>
6	<span class='muted'>no reply</span>
7	2001:7f8::239f:0:1
8	2a02:800:e:200d::1
9	2a02:800:1:3021::194
10	2a02:800:73:2::56

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	2001:7f8:46:0:1::9119
5	2a02:800:1:3021::194
6	2a02:800:73:2::56

Target `2a02:800:0:3::69`

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::a500:9119:1
5	2a02:800:e:200d::1
6	2a02:800:1::11
7	2a02:800:0:3::69

karsolink — verdict not_honored

verdict = not_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:6::1
4	<span class='muted'>no reply</span>
5	<span class='muted'>no reply</span>
6	<span class='muted'>no reply</span>
7	2001:7f8::239f:0:1
8	2a02:800:e:200d::1
9	2a02:800:1::11
10	2a02:800:0:3::69

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	2001:7f8:46:0:1::9119
5	2a02:800:1::11
6	2a02:800:0:3::69

Target `2a02:800:0:3::84`

go6lab — verdict honored

verdict = 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::a500:9119:1
5	2a02:800:e:200d::1
6	2a02:800:1::11
7	2a02:800:0:3::84

karsolink — verdict not_honored

verdict = not_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:6::1
4	<span class='muted'>no reply</span>
5	<span class='muted'>no reply</span>
6	<span class='muted'>no reply</span>
7	2001:7f8::239f:0:1
8	2a02:800:e:200d::1
9	2a02:800:1::11
10	2a02:800:0:3::84

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	2001:7f8:46:0:1::9119
5	2a02:800:1::11
6	2a02:800:0:3::84

From NL host (go6lab) openRFC 4890 ✓

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

4/4

Echo small (56B) 24.8ms

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::3	1.1ms	0%	AS203993	STEFFANN-DC-AS - S.J.M. Steffann, NL
2	gw.friends.steffann.nl 2a00:8642:1000:f000::1	1.1ms	0%*	AS203993	STEFFANN-DC-AS - S.J.M. Steffann, NL
3	ccr2-ccr1.dc1.nogalliance.org 2a00:8642:dc1:2::b	1.1ms	0%	AS203993	STEFFANN-DC-AS - S.J.M. Steffann, NL
4	2001:7f8:1::a500:9119:1	9.8ms	20%	-	NA
5	2a02:800:e:200d::1	23.9ms	20%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI
6	2a02:800:1:3021::194	25.1ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI
7	trixie.softnet.si 2a02:800:73:2::58	24.7ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI

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]                        0.059ms pmtu 1500
 1:  2a00:8642:42::3                                       2.799ms 
 1:  2a00:8642:42::3                                       2.518ms 
 2:  no reply
 3:  ccr2-ccr1.dc1.nogalliance.org                         3.262ms asymm  2 
 4:  no reply
 5:  2a02:800:e:200d::1                                   25.605ms asymm  9 
 6:  2a02:800:1:3021::194                                 26.776ms asymm 10 
 7:  trixie.softnet.eu                                    25.199ms !A
     Resume: pmtu 1500

From ITA host (Karsolink) open

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

4/4

Echo small (56B) 27.2ms

4/4

Echo 1500B (DF) 27.1ms

yes

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	karsolink-01.net.karsolink.com 2a12:d8c0:105a:9001::1	0.3ms	0%*	AS204471	KARSOLINK - 2S Computers SRL, IT
2	2a12:d8c0:109f:121::a1	0.4ms	0%*	AS204471	KARSOLINK - 2S Computers SRL, IT
3	2a12:d8c0:101f:6::1	9.9ms	80%	AS204471	KARSOLINK - 2S Computers SRL, IT
4	*	-	-	-
5	*	-	-	-
6	*	-	-	-
7	decix.softnet.si 2001:7f8::239f:0:1	20.9ms	-	-	NA
8	2a02:800:e:200d::1	26.8ms	70%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI
9	2a02:800:1:3021::194	27.4ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI
10	trixie.softnet.si 2a02:800:73:2::58	26.6ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI

Rate-limited ICMPv6: hop 3, hop 8 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.031ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        1.309ms 
 1:  karsolink-01.net.karsolink.com                        1.177ms 
 2:  2a12:d8c0:109f:121::a1                                1.279ms 
 3:  2a12:d8c0:101f:6::1                                  10.876ms 
 4:  no reply
 5:  no reply
 6:  no reply
 7:  decix.softnet.si                                     21.226ms 
 8:  2a02:800:e:200d::1                                   26.953ms 
 9:  2a02:800:1:3021::194                                 27.728ms 
10:  trixie.softnet.si                                    27.284ms !A
     Resume: pmtu 1500

From SLO host (6connect) openRFC 4890 ✓

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

4/4

Echo small (56B) 2.6ms

4/4

Echo 1500B (DF) 3.1ms

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	0.6ms	0%*	AS8038	6CONNECT - 6connect, Inc., US
2	ccr-to-fw-ccr1-gw-lju.6connect.com 2607:fae0:a000:2::2	78.7ms	-	AS8038	6CONNECT - 6connect, Inc., US
3	2a03:a100:0:201:1::1	3.4ms	80%	AS56635	XENYA - XENYA inzeniring, proizvodnja in trgovina, d.o.o. Ljubljana, SI
4	2001:7f8:46:0:1::9119 @SIX	3.4ms	0%	AS51988	ARNES-SIX - ARNES, SI
5	2a02:800:1:3021::194	5.4ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI
6	trixie.softnet.si 2a02:800:73:2::58	5.2ms	0%	AS9119	SOFTNET-AS - SOFTNET d.o.o., SI

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

tracepath -6

 1?: [LOCALHOST]                        0.034ms pmtu 1500
 1:  fw1-lju.6connect.com                                  0.979ms 
 1:  fw1-lju.6connect.com                                  0.611ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  0.752ms 
 4:  2001:7f8:46:0:1::9119                                 1.927ms 
 5:  2a02:800:1:3021::194                                  3.285ms 
 6:  trixie.softnet.eu                                     2.538ms !A
     Resume: pmtu 1500

AS overview

SIX peering

RPKI & ASPA

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

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

Where the path divergence is

✨ Diagnostic interpretation

Per-hop PTB acceptance walk

tracepath6 per-hop PMTU drilldown

Target 2a02:800:73:2::56

Target 2a02:800:0:3::69

Target 2a02:800:0:3::84

From NL host (go6lab) openRFC 4890 ✓

Path (traceroute + mtr + PTR)

tracepath -6

From ITA host (Karsolink) open

Path (traceroute + mtr + PTR)

tracepath -6

From SLO host (6connect) openRFC 4890 ✓

Path (traceroute + mtr + PTR)

tracepath -6

Target `2a02:800:73:2::56`

Target `2a02:800:0:3::69`

Target `2a02:800:0:3::84`