AS20811 BRENNERCOM-AS Retelit Digital Services S.p.A.

IPv6 prefix announced, but nothing inside is responding yet. AS20811 announces 2 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: 2a02:490::1 · (no live host found) · address space: mixed · prefixes announced: 2

prefix(es): 2a02:490::/29, 2a02:54c0::/29

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 - Selective peering, peering member, since 2011-10-25. IPv6 LAN: 2001:7f8:b:100:1d1:a5d2:811:88. Locations: -.

RPKI & ASPA

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

Prefix	RPKI state	Reason	Covering VRP(s)
`2a02:490::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS20811 /29 maxLen 48 (ripe)
`2a02:54c0::/29`	✓ valid	matched VRP (correct origin, length within maxLength)	AS20811 /29 maxLen 48 (ripe)

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

We probed 30 arbitrary IPv6 address(es) inside AS20811's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:1bd0:1:55::2 at hop 13 - that router answers ICMPv6 Echo. This is not in AS20811'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 2026-05-25T12:31:37Z

Failure detail — what to grep in your logs

vantage	our source	your target	method	result	tested (UTC)
go6lab	`2a00:8642:42::75`	`2a02:490::1`	`icmp6-echo`	no_echo	2026-05-25T12:31:37Z
karsolink	`2a12:d8c0:105a:9001::a154`	`2a02:490::1`	`icmp6-echo`	no_echo	2026-05-25T12:39:01Z
odin	`2607:fae0:a000::42`	`2a02:490::1`	`icmp6-echo`	no_echo	2026-05-25T12:31:21Z

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: past AS28716 (RETELIT-AS) · 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	1.4ms	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	1.7ms	0%	AS50673	Serverius-as - Serverius Holding B.V., NL
4	2a03:3f40::10:41	2.1ms	0%	AS50673	Serverius-as - Serverius Holding B.V., NL
5	*	-	-	-
6	*	-	-	-
7	2001:978:3::26	4.4ms	0%	AS174	COGENT-174 - Cogent Communications, LLC, US
8	2001:2034:a:17a	4.0ms	0%	-
9	*	-	-	-
10	mno-b3-link.ip.twelve99.net 2001:2034:a:122::1	28.7ms	0%	AS1299	TWELVE99 - Arelion Sweden AB, SE
11	retelitdigital-ic-375445.ip.twelve99-cust.net 2001:2035:0:24bc::2	26.6ms	0%	AS1299	TWELVE99 - Arelion Sweden AB, SE
12	2001:1bd0:0:2::5	25.0ms	0%	AS28716	RETELIT-AS - Retelit Digital Services S.p.A., IT
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

tracepath -6

 1?: [LOCALHOST]                        0.052ms pmtu 1500
 1:  2a00:8642:42::3                                       2.120ms 
 1:  2a00:8642:42::3                                       1.186ms 
 2:  gw.friends.steffann.nl                                2.225ms 
 3:  2a00:1ca8:1::194                                      3.063ms 
 4:  2a03:3f40::10:41                                      2.953ms 
 5:  2001:978:2:40::3:1                                    5.460ms 
 6:  no reply
 7:  2001:978:3::ca                                        3.926ms asymm  6 
 8:  adm-bb1-link.ip.twelve99.net                          4.479ms asymm  7 
 9:  no reply
10:  mno-b3-link.ip.twelve99.net                          29.684ms asymm  9 
11:  retelitdigital-ic-375445.ip.twelve99-cust.net        25.957ms asymm  7 
12:  2001:1bd0:0:2::5                                     26.540ms asymm  8 
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: past AS28716 (RETELIT-AS) · 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	*	-	-	-
2	*	-	0%*	-
3	*	-	0%	-
4	retelit.topix.it 2001:7f8:23:ffff::26	10.6ms	0%	-	NA
5	2001:1bd0:0:2::5	10.9ms	0%	AS28716	RETELIT-AS - Retelit Digital Services S.p.A., IT
6	*	-	-	-
7	*	-	-	-
8	*	-	-	-
9	*	-	-	-
10	*	-	-	-
11	*	-	-	-
12	*	-	-	-
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

tracepath -6

 1?: [LOCALHOST]                        0.062ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.528ms 
 2:  2a12:d8c0:109f:121::a1                                0.772ms 
 3:  2a12:d8c0:109f:106::a2                                3.580ms 
 4:  retelit.topix.it                                     10.520ms asymm  7 
 5:  2001:1bd0:0:2::5                                     10.398ms asymm  6 
 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
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	0.2ms	0%*	AS8038	6CONNECT - 6connect, Inc., US
2	ccr-to-fw-ccr1-gw-lju.6connect.com 2607:fae0:a000:2::2	0.7ms	0%*	AS8038	6CONNECT - 6connect, Inc., US
3	*	-	50%	-
4	e0-1.core1.lju1.he.net 2001:470:1:5be::1	2.1ms	10%	AS6939	HURRICANE - Hurricane Electric LLC, US
5	*	-	-	-
6	port-channel1.core1.zag2.he.net 2001:470:0:2ea::2	4.1ms	50%	AS6939	HURRICANE - Hurricane Electric LLC, US
7	*	-	-	-
8	brennercom-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:a5d2:811:88	12.9ms	0%	-	NA
9	*	-	-	-
10	*	-	-	-
11	*	-	-	-
12	*	-	-	-
13	*	-	-	-
14	*	-	-	-
15	*	-	-	-
16	*	-	-	-
17	*	-	-	-
18	*	-	-	-
19	*	-	-	-
20	*	-	-	-
21	*	-	-	-
22	*	-	-	-
23	*	-	-	-
24	*	-	-	-

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]                        0.029ms pmtu 1500
 1:  fw1-lju.6connect.com                                  1.549ms 
 1:  fw1-lju.6connect.com                                  2.169ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  0.928ms 
 4:  e0-1.core1.lju1.he.net                                2.804ms 
 5:  no reply
 6:  port-channel1.core1.zag2.he.net                       4.478ms 
 7:  no reply
 8:  brennercom-v6.mix-it.net                             13.136ms asymm  9 
 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