AS213981 - RTLP RTLP SRLPARFC 4890 ✓RPKI ✓ 1/1ASPA -

AS overview

Test target: 2001:3a40:0:30::1:12 · ns1.mb.rtlp.it · address space: PA · prefixes announced: 1

prefix(es): 2001:3a40::/29

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

We probed 35 arbitrary IPv6 address(es) inside AS213981's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:470:0:18d::2 at hop 10 - that router answers ICMPv6 Echo. This is not in AS213981'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

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): Type 2 NOT honored. Forged PTB had no effect (filtered en route or stack ignored it). (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 - path-asymmetric Type 2 filtering: Both vantages used the ICMPv6 Echo + forged-PTB method on the same destination IP, but reached different verdicts. The destination's stack is the same in both cases - so the difference is in the path: a transit AS on one route filters our forged Type 2 (or its return ICMPv6 carrying the embedded packet) while the other route delivers it intact. The vantage that says honored shows what the destination's stack actually does; the one that says not honored shows that the path between us and them drops Type 2.

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)'

sudo ip6tables -L INPUT -nv | grep -iE 'icmpv6|packet-too-big'
sudo nft list ruleset 2>/dev/null | grep -A1 'icmpv6'

sudo sysctl net.ipv6.conf.all.accept_redirects net.ipv4.ip_no_pmtu_disc net.ipv6.route.mtu_expires

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 or src host 2a09:ab81::91 or src host 2a01:261:313:b814:2a0:98ff:fe5b:13e4 or src host 2a06:d1c1:10a::bbbb or src host 2a06:d1c1:10d::aaaa or src host 2a06:d1c1:10b::cccc)'

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                                              0.485ms 
 1:  _gateway                                              0.378ms 
 2:  sox-pn.sox.rs                                         0.488ms 
 3:  e0-33.core2.beg1.he.net                               1.117ms 
 4:  no reply
 5:  port-channel1.core1.tia1.he.net                      15.632ms 
 6:  e0-34.core1.bri1.he.net                              20.704ms 
 7:  2001:470:545::3                                      19.752ms 
 8:  fdb1:172:17:16::21                                   19.991ms 
 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
     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)

Rate-limited ICMPv6: hop 6, hop 7, hop 12 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.031ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.976ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.566ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.835ms 
 3:  hurricane-electric.bcix.de                           17.462ms asymm  6 
 4:  no reply
 5:  be47.core1.prg1.he.net                               16.128ms asymm  6 
 6:  be8.core4.fra1.he.net                                16.098ms asymm  5 
 7:  be10.core1.zrh2.he.net                               21.134ms asymm  6 
 8:  be1.core1.mil2.he.net                                23.536ms asymm  7 
 9:  no reply
10:  e0-35.core1.bri1.he.net                              35.951ms asymm  9 
11:  2001:470:545::3                                      34.323ms asymm 10 
12:  fdb1:172:17:16::21                                   34.491ms asymm 11 
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  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)

Rate-limited ICMPv6: hop 3, hop 10 (loss between 5% and 95% across mtr cycles - the router replies but only sometimes).

tracepath -6

 1?: [LOCALHOST]                        0.018ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.295ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.265ms 
 2:  ipv6.decix-dusseldorf.core1.dus1.he.net               5.972ms asymm  3 
 3:  100ge0-0-0-18.core4.fra1.he.net                       6.574ms asymm  4 
 4:  be10.core1.zrh2.he.net                               12.915ms asymm  5 
 5:  be1.core1.mil2.he.net                                16.599ms asymm  6 
 6:  no reply
 7:  e0-35.core1.bri1.he.net                              26.399ms asymm  8 
 8:  2001:470:545::3                                      25.389ms asymm  9 
 9:  fdb1:172:17:16::21                                   25.675ms asymm 10 
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
     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]                        0.045ms pmtu 1500
 1:  2a00:8642:42::2                                       3.715ms 
 1:  2a00:8642:42::2                                       3.696ms 
 2:  gw.friends.steffann.nl                                5.938ms 
 3:  speed-ix.he.net                                       7.968ms 
 4:  be2.core4.fra1.he.net                                13.995ms 
 5:  be10.core1.zrh2.he.net                               19.952ms 
 6:  be1.core1.mil2.he.net                                24.119ms 
 7:  no reply
 8:  e0-35.core1.bri1.he.net                              33.476ms 
 9:  2001:470:545::3                                      30.882ms 
10:  fdb1:172:17:16::21                                  824.082ms 
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  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]                        0.034ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.672ms 
 1:  no reply
 2:  2a12:d8c0:109f:121::a1                                1.013ms 
 3:  no reply
 4:  no reply
 5:  e0-35.core1.bri1.he.net                              22.944ms 
 6:  2001:470:545::3                                      21.390ms 
 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
     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                                  0.499ms 
 1:  fw1-lju.6connect.com                                  0.474ms 
 2:  ccr-to-fw-ccr1-gw-lju.6connect.com                    0.726ms 
 3:  2a03:a100:0:201:1::1                                  0.972ms 
 4:  2a03:a100:0:201:1::1                                  0.914ms pmtu 1500
 4:  e0-1.core1.lju1.he.net                                1.857ms 
 5:  no reply
 6:  port-channel1.core1.zag2.he.net                       4.763ms 
 7:  no reply
 8:  e0-35.core1.bri1.he.net                              26.259ms 
 9:  2001:470:545::3                                      23.816ms 
10:  fdb1:172:17:16::21                                   24.302ms 
11:  no reply
12:  no reply
13:  no reply
14:  no reply
15:  no reply
16:  no reply
17:  no reply
18:  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]                        0.028ms pmtu 1500
 1:  2a01:261:313:b814::1                                  0.876ms 
 1:  no reply
 2:  2a01:260:1::225                                       5.817ms 
 3:  2a01-260-1-1--9a.core6.t-2.net                        2.578ms 
 4:  2a01-260-1-1--38.core6.t-2.net                        2.920ms asymm  3 
 5:  port-channel1.core1.zag2.he.net                      10.114ms asymm  7 
 6:  port-channel1.core1.zag2.he.net                      10.320ms asymm  7 
 7:  e0-35.core1.bri1.he.net                              29.520ms 
 8:  2001:470:545::3                                      29.215ms 
 9:  2001:470:545::3                                      28.138ms asymm  8 
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
     Too many hops: pmtu 1500
     Resume: pmtu 1500