AS12850 ASN-ENTER Retelit Digital Services S.p.A.

IPv6 prefix announced, but nothing inside is responding yet. AS12850 announces 1 IPv6 prefix(es) to the global routing table - that’s the part that BGP and our route-server scrape confirm. But our active discovery (curated hostnames, holder-derived domains, authoritative DNS NS/SOA/MX, certificate-transparency hostnames, RIPE Atlas, RDAP, IPv6 Hitlist) found no ICMPv6-responsive host inside the prefix on either vantage, and a yarrp pass against random addresses inside the prefix produced zero in-prefix hops (no router on the path through the AS replied with Time-Exceeded for any random target). That combination usually means the announcement is configured but the addresses inside aren’t in active use yet. The BGP route is there; the operational deployment is still ahead.

AS overview

Test target: 2001:4d38::1 · (no live host found) · address space: PA · prefixes announced: 1

prefix(es): 2001:4d38::/32

RPKI & ASPA

1 of 1 prefix(es) covered by a valid ROA.

Prefix	RPKI state	Reason	Covering VRP(s)
`2001:4d38::/32`	✓ valid	matched VRP (correct origin, length within maxLength)	AS12850 /32 maxLen 32 (ripe)

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

We probed 15 arbitrary IPv6 address(es) inside AS12850's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:7f8:54::186 at hop 9 - that router does not answer ICMPv6 Echo. This is not in AS12850's announced prefix; operationally it's the AS-edge / peering interface (often on an IXP 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

Type 2 active test inconclusive: no Echo Reply to 1300-byte probe.
method: ICMPv6 Echo + forged PTB, tested 2026-05-25T12:28:21Z

Failure detail — what to grep in your logs

vantage	our source	your target	method	result	tested (UTC)
go6lab	`2a00:8642:42::75`	`2001:4d38::1`	`icmp6-echo`	no_echo	2026-05-25T12:28:21Z
karsolink	`2a12:d8c0:105a:9001::a154`	`2001:4d38::1`	`icmp6-echo`	no_echo	2026-05-25T12:29:47Z
odin	`2607:fae0:a000::42`	`2001:4d38::1`	`icmp6-echo`	no_echo	2026-05-25T12:28:15Z

Attempt log (go6lab):

icmp6-echo → no_echo: no Echo Reply to 1300-byte probe
dns-tcp → no_tcp: connect failed: timed out
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 → no_tcp: connect failed: timed out
tls → no_tcp: TLS connect failed
http → no_tcp: tcp/80 not open

Attempt log (odin):

icmp6-echo → no_echo: no Echo Reply to 1300-byte probe
dns-tcp → no_tcp: connect failed: timed out
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.

From NL host (go6lab) transit only unreachable

filter likely at: no path · min PMTU on path: 1500

0/4

Echo small (56B) -

0/4

Echo 1500B (DF) -

Type 1 dest-unreach

TCP responds on

Path (traceroute + mtr + PTR)

#	IP / PTR	RTT	mtr loss	AS	AS holder
1	2a00:8642:42::3	1.0ms	0%	AS203993	STEFFANN-DC-AS - S.J.M. Steffann, NL
2	gw.friends.steffann.nl 2a00:8642:1000:f000::1	1.7ms	0%*	AS203993	STEFFANN-DC-AS - S.J.M. Steffann, NL
3	2a00:1ca8:1::194	2.1ms	0%	AS50673	Serverius-as - Serverius Holding B.V., NL
4	2a03:3f40::10:33	5.2ms	0%	AS50673	Serverius-as - Serverius Holding B.V., NL
5	ae22-404.ams10.core-backbone.com 2a01:4a0:1338:155::1	4.9ms	0%	AS201011	CORE-BACKBONE - Core-Backbone GmbH, DE
6	ae3-2072.lon10.core-backbone.com 2a01:4a0:0:2072::19	9.9ms	0%	AS201011	CORE-BACKBONE - Core-Backbone GmbH, DE
7	ae1-2077.lon20.core-backbone.com 2a01:4a0:0:2077::2	11.1ms	0%	AS201011	CORE-BACKBONE - Core-Backbone GmbH, DE
8	ae2-2076.par10.core-backbone.com 2a01:4a0:0:2076::20	17.2ms	0%	AS201011	CORE-BACKBONE - Core-Backbone GmbH, DE
9	enter.par.franceix.net 2001:7f8:54::186	39.7ms	0%	-	NA
10	*	-	-	-
11	*	-	-	-
12	*	-	-	-
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

tracepath -6

 1?: [LOCALHOST]                        0.029ms pmtu 1500
 1:  2a00:8642:42::3                                       1.821ms 
 1:  2a00:8642:42::3                                       1.827ms 
 2:  no reply
 3:  2a00:1ca8:1::194                                      3.616ms 
 4:  2a03:3f40::10:33                                      6.169ms 
 5:  ae22-404.ams10.core-backbone.com                      6.727ms 
 6:  ae3-2072.lon10.core-backbone.com                     12.036ms 
 7:  ae1-2077.lon20.core-backbone.com                     11.892ms 
 8:  ae2-2076.par10.core-backbone.com                     18.764ms 
 9:  enter.par.franceix.net                               42.211ms 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
20:  no reply
21:  no reply
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500

From ITA host (Karsolink) transit only unreachable

filter likely at: no path · min PMTU on path: 1500

0/4

Echo small (56B) -

0/4

Echo 1500B (DF) -

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	*	-	0%*	-
3	*	-	40%	-
4	2a02:2d8:1:b80d:232a	26.6ms	0%	-
5	RT.THV.PAR.FR.retn.net 2a02:2d8::57f5:e0b9	30.4ms	0%	AS9002	RETN-AS - RETN Limited, GB
6	enter.par.franceix.net 2001:7f8:54::186	45.6ms	0%	-	NA
7	*	-	-	-
8	*	-	-	-
9	*	-	-	-
10	*	-	-	-
11	*	-	-	-
12	*	-	-	-
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

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

tracepath -6

 1?: [LOCALHOST]                        0.030ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.674ms 
 2:  2a12:d8c0:109f:121::a1                                0.622ms 
 3:  2a12:d8c0:101f:103::1                                 8.662ms 
 4:  ae8-202.rt.clr.mil.it.retn.net                        7.993ms asymm  5 
 5:  rt.thv.par.fr.retn.net                               23.570ms 
 6:  enter.par.franceix.net                               46.076ms 
 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
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500

From SLO host (6connect) transit only unreachable

filter likely at: no path · min PMTU on path: 1500

0/4

Echo small (56B) -

0/4

Echo 1500B (DF) -

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	0.3ms	0%*	AS8038	6CONNECT - 6connect, Inc., US
2	*	-	0%*	-
3	*	-	90%	-
4	*	-	60%	-
5	100ge0-0-0-5.core1.vie1.he.net 2001:470:0:578::1	8.4ms	0%	AS6939	HURRICANE - Hurricane Electric LLC, US
6	*	-	-	-
7	enter.par.franceix.net 2001:7f8:54::186	51.3ms	0%	-	NA
8	*	-	-	-
9	*	-	-	-
10	*	-	-	-
11	*	-	-	-
12	*	-	-	-
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

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

tracepath -6

 1?: [LOCALHOST]                        0.042ms pmtu 1500
 1:  fw1-lju.6connect.com                                  0.441ms 
 1:  fw1-lju.6connect.com                                  1.718ms 
 2:  no reply
 3:  no reply
 4:  no reply
 5:  100ge0-0-0-5.core1.vie1.he.net                        9.894ms 
 6:  no reply
 7:  enter.par.franceix.net                               47.366ms 
 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
22:  no reply
23:  no reply
24:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500