AS41437 - KNAPP-AS KNAPP AGPARFC 4890 ✓RPKI ✓ 1/1ASPA -

AS overview

Test target: 2001:a00::53 · ns1.knapp.com · address space: PA · prefixes announced: 1

prefix(es): 2001:a00::/32

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

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

We probed 35 arbitrary IPv6 address(es) inside AS41437's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2a02:758:0:8000::1a at hop 15 - that router answers ICMPv6 Echo. This is not in AS41437'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 honored. Forged ICMPv6 PTB (MTU=1280) was accepted by the destination's stack: the next 1500-byte Echo Reply arrived split into 2 fragments via the IPv6 Fragment Header.
method: ICMPv6 Echo + forged PTB, tested 2026-09-23T13:32:19Z

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]                        0.014ms pmtu 1500
 1:  _gateway                                              0.298ms 
 1:  _gateway                                              0.554ms 
 2:  sox-pn.sox.rs                                         0.300ms 
 3:  2001:7f8:1e:8::3d                                     0.637ms asymm  2 
 4:  ae8-930.RT.IRX.VIE.AT.retn.net                       11.240ms asymm  3 
 5:  no reply
 6:  no reply
 7:  2a02:758:0:8000::1a                                  16.421ms asymm  5 
 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
     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]                        0.026ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.496ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.429ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.908ms 
 3:  ae0-40.cr10.muc02.lwlcom.net                         11.504ms 
 4:  ae0-10.cr10.muc01.lwlcom.net                         11.715ms 
 5:  no reply
 6:  no reply
 7:  2a02:758:0:8000::1a                                  53.236ms 
 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
     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]                        0.029ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.351ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.412ms 
 2:  ae0-101.cr10.dus02.lwlcom.net                         0.334ms 
 3:  ae0-20.cr10.dus01.lwlcom.net                          0.671ms 
 4:  ae0-20.cr10.vel01.lwlcom.net                          1.007ms 
 5:  ae0-10.cr10.dus06.lwlcom.net                          0.903ms 
 6:  ae0-40.cr10.fra06.lwlcom.net                          4.700ms 
 7:  ae0-20.cr10.muc01.lwlcom.net                         15.042ms asymm  5 
 8:  no reply
 9:  no reply
10:  2a02:758:0:8000::1a                                  24.372ms asymm  8 
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
     Too many hops: pmtu 1500
     Resume: pmtu 1500 

From NL host (go6lab)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.039ms pmtu 1500
 1:  2a00:8642:42::2                                       1.974ms 
 1:  2a00:8642:42::2                                       2.910ms 
 2:  no reply
 3:  2a00:1ca8:1::194                                      7.922ms 
 4:  2a03:3f40::10:41                                      5.125ms 
 5:  no reply
 6:  no reply
 7:  no reply
 8:  no reply
 9:  no reply
10:  2a02:758:0:8000::1a                                  25.925ms asymm  9 
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
     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, hop 7 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.034ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.733ms 
 1:  no reply
 2:  2a12:d8c0:109f:121::a1                                0.762ms 
 3:  2a12:d8c0:101f:103::1                                 8.828ms 
 4:  no reply
 5:  be47.core1.mil2.he.net                               78.049ms 
 6:  be1.core1.zrh2.he.net                                16.378ms 
 7:  be10.core4.fra1.he.net                               20.691ms 
 8:  no reply
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  2a02:758:0:8000::1a                                  24.800ms asymm  8 
15:  no reply
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  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)

tracepath -6

 1?: [LOCALHOST]                        0.025ms pmtu 9000
 1:  fw1-lju.6connect.com                                  0.530ms 
 1:  fw1-lju.6connect.com                                  0.464ms 
 2:  no reply
 3:  no reply
 4:  2a00:ee0:1:10::2                                      1.863ms asymm  3 
 5:  2a00:ee0:1:15::2                                      1.669ms pmtu 1500
 5:  2a11:4142:2002::                                      1.233ms asymm  6 
 6:  r2-vie1-at.as5405.net                                 7.388ms asymm  9 
 7:  et9-4096.r2-vie2-at.as5405.net                        7.137ms asymm  8 
 8:  no reply
 9:  no reply
10:  2a02:758:0:8000::1a                                  11.298ms asymm  6 
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
     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)

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

tracepath -6

 1?: [LOCALHOST]                        0.029ms pmtu 1500
 1:  no reply
 2:  2a01:260:1::225                                       8.539ms 
 3:  2a01-260-1-1--9c.core6.t-2.net                        2.544ms 
 4:  2a01-260-1-1--38.core6.t-2.net                        3.019ms asymm  3 
 5:  100ge0-0-0-31.core1.vie1.he.net                      11.406ms 
 6:  be3.core1.prg1.he.net                                16.549ms 
 7:  be3.core1.prg1.he.net                                16.864ms asymm  6 
 8:  be8.core4.fra1.he.net                                37.461ms asymm  7 
 9:  no reply
10:  no reply
11:  no reply
12:  no reply
13:  no reply
14:  2a02:758:0:8000::1a                                  24.158ms asymm  7 
15:  2a02:758:0:8000::1a                                  23.512ms asymm  7 
16:  no reply
17:  no reply
18:  no reply
19:  no reply
20:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500