AS41327 - FIBERTELECOM-AS Fiber TelecomPARFC 4890 ✓RPKI ✓ 2/2ASPA ✓

AS overview

Test target: 2a03:b020:41:327:31:185:102:11 · ns.fibertelecom.com · address space: PA · prefixes announced: 2

prefix(es): 2a09:3e40::/29, 2a03:b020::/29

MIX-IT / NAMEX / MINAP / TOP-IX / VSIX / EQUINIX-MILAN / BGPX-ROME / NAMEX-BARI / PCIX / DECIX-PALERMO peering

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

At least one router inside AS41327's announced prefix replied during the random-target probe. Hop(s): 2a03:b020:1:51::a. 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 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
• DE host (Berlin): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
• DE host (Düsseldorf): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
• NL host (go6lab): inconclusive: no Echo Reply after PTB (probe 1500B). (ICMPv6 Echo + forged PTB)
• ITA host (Karsolink): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
• SLO host (6connect): Type 2 honored. Forged PTB accepted; next response shrunk. (ICMPv6 Echo + forged PTB)
• SLO host (T-2): Type 2 honored. Forged PTB accepted; next response shrunk. (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.

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)'

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.013ms pmtu 1500
 1:  _gateway                                              0.408ms 
 1:  _gateway                                              0.357ms 
 2:  2001:7f8:1e::108                                      0.485ms 
 3:  2001:b28:3ff::a16f:0:1                               44.299ms 
 4:  2a03:b020::252                                       63.265ms asymm 11 
 5:  2a03:b020:0:122::2                                   68.403ms asymm 12 
 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From DE host (Berlin)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.061ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.649ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.556ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        1.118ms 
 3:  ae0-10.cr10.ber03.lwlcom.net                          1.078ms 
 4:  ae0-15.cr11.dtm01.lwlcom.net                          8.645ms asymm  5 
 5:  ae0-20.cr10.dtm01.lwlcom.net                          8.869ms asymm  4 
 6:  ae0-20.cr10.dus04.lwlcom.net                          8.919ms asymm  5 
 7:  ae0-20.cr10.dus01.lwlcom.net                          9.000ms asymm  4 
 8:  ae6-60.cr10.ams01.lwlcom.net                         11.705ms asymm  5 
 9:  2001:7f8:12a::18                                     15.139ms asymm  4 
10:  2a03:b020::252                                       45.454ms asymm  8 
11:  2a03:b020:0:122::2                                   46.145ms asymm  9 
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.030ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.404ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.433ms 
 2:  ipv6.de-cix.dus.as41327.fibertelecom.com              4.325ms 
 3:  2a03:b020::252                                       34.363ms asymm  7 
 4:  2a03:b020:0:122::2                                   34.441ms asymm  8 
 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From NL host (go6lab)   open

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.030ms pmtu 1500
 1:  2a00:8642:42::2                                       1.764ms 
 1:  2a00:8642:42::2                                       2.048ms 
 2:  gw.friends.steffann.nl                                3.615ms 
 3:  speed-ix.fibertelecom.it                              5.634ms 
 4:  2a03:b020::252                                       44.602ms asymm 10 
 5:  2a03:b020:0:122::2                                   40.506ms asymm 11 
 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From ITA host (Karsolink)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

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                        1.099ms 
 2:  no reply
 3:  2a12:d8c0:101f:6::1                                  10.258ms 
 4:  2a03:b020:1:51::a                                    10.360ms 
 5:  2a03:b020::252                                       31.866ms asymm 10 
 6:  2a03:b020:0:122::2                                   31.657ms asymm 11 
 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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From SLO host (6connect)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

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]                        0.075ms pmtu 9000
 1:  fw1-lju.6connect.com                                  2.196ms 
 1:  fw1-lju.6connect.com                                  0.552ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  1.254ms 
 4:  2a03:a100:0:201:1::1                                  1.109ms pmtu 1500
 4:  e0-1.core1.lju1.he.net                                2.081ms 
 5:  100ge0-0-0-5.core1.vie1.he.net                        8.033ms 
 6:  e0-35.core2.muc1.he.net                              12.215ms 
 7:  ipv6.de-cix.muc.as41327.fibertelecom.com             20.980ms asymm 10 
 8:  2a03:b020::252                                       46.371ms asymm 11 
 9:  2a03:b020:0:122::2                                   43.101ms asymm 12 
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
     Too many hops: pmtu 1500

From SLO host (T-2)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.026ms pmtu 1500
 1:  2a01:261:313:b814::1                                  0.850ms 
 2:  2a01:260:1::225                                       3.690ms 
 3:  2a01-260-1-1--9a.core6.t-2.net                        2.096ms 
 4:  2a01-260-1-1--39.core6.t-2.net                        2.524ms asymm  3 
 5:  hurricane-electric.nikhef.nlsix.net                  35.306ms asymm  4 
 6:  no reply
 7:  be47.core3.ams1.he.net                               34.248ms asymm  6 
 8:  2a03:b020::252                                       54.618ms asymm 11 
 9:  2a03:b020::252                                       59.080ms asymm 11 
10:  2a03:b020:0:122::2                                   54.022ms asymm 12 
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500