AS57913 - toscanatlc ToscanaTLC s.r.lPARFC 4890 ✓RPKI ✓ 1/1ASPA ✓

AS overview

Test target: 2a13:f600::1 · static prefix probe · address space: PA · prefixes announced: 1

prefix(es): 2a13:f600::/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

We probed 35 arbitrary IPv6 address(es) inside AS57913's announced prefix(es). No router inside the prefix responded. The deepest visible hop was 2001:7f8:c5::a505:7913:1 at hop 13 - that router does not answer ICMPv6 Echo. This is not in AS57913'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]                        0.087ms pmtu 1500
 1:  _gateway                                              0.505ms 
 1:  _gateway                                              0.629ms 
 2:  2001:7f8:1e::108                                      0.544ms 
 3:  2001:b28:3ff::a16f:0:1                               41.512ms 
 4:  2a03:b020::225                                       46.487ms asymm  6 
 5:  2a03:b020:1:66::b                                    41.963ms asymm  6 
 6:  lo0-f1a01-itmil01.as57913.net                        42.815ms reached
     Resume: pmtu 1500 hops 6 back 5 

From DE host (Berlin)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.024ms pmtu 1500
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.604ms 
 1:  xe-0-0-13-178.gw01.ber01.as59645.net                  0.447ms 
 2:  ae0-2453.cr10.ber01.lwlcom.net                        0.721ms 
 3:  ae0-10.cr10.ber03.lwlcom.net                          1.210ms 
 4:  ae0-15.cr11.dtm01.lwlcom.net                          8.813ms asymm  5 
 5:  ae0-20.cr10.dtm01.lwlcom.net                          8.614ms asymm  4 
 6:  ae0-20.cr10.dus04.lwlcom.net                          8.618ms asymm  5 
 7:  ae0-20.cr10.dus01.lwlcom.net                          8.824ms asymm  4 
 8:  ae6-60.cr10.ams01.lwlcom.net                         11.559ms asymm  5 
 9:  2001:7f8:12a::18                                     15.014ms asymm  4 
10:  2a03:b020::225                                       24.417ms asymm  4 
11:  2a03:b020:1:66::b                                    24.482ms asymm 12 
12:  lo0-f1a01-itmil01.as57913.net                        24.776ms reached
     Resume: pmtu 1500 hops 12 back 11 

From DE host (Düsseldorf)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.019ms pmtu 1500
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.360ms 
 1:  xe-0-0-12-142.gw01.dus01.as59645.net                  0.385ms 
 2:  eth1-0-12-h5594.edge5-dus1.bb.wiit.network            1.198ms 
 3:  no reply
 4:  lag30.core3-dus1.bb.wiit.network                      0.353ms 
 5:  lag0-vl1011.core1-fra-ix.bb.wiit.network              4.547ms 
 6:  lag0-vl1001.core1-nbg-ncd.bb.wiit.network             7.139ms 
 7:  lag0-vl6.core2-nbg-ncd.bb.wiit.network                7.123ms 
 8:  lag0-vl1006.core2-muc2.bb.wiit.network                9.759ms 
 9:  lag0-vl1009.core1-muc-eq3.bb.wiit.network             9.680ms 
10:  lag0-vl1001.core1-pda-vsix.bb.wiit.network           20.546ms 
11:  lag0-vl1001.core1-mil-mix.bb.wiit.network            20.598ms asymm  9 
12:  lag0-vl5.core3-mil-irid.bb.wiit.network              20.408ms asymm  8 
13:  toscanatlc.minap.it                                  20.732ms asymm 11 
14:  lo0-f1a01-itmil01.as57913.net                        20.685ms reached
     Resume: pmtu 1500 hops 14 back 10 

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                                       6.013ms 
 1:  2a00:8642:42::2                                       2.644ms 
 2:  gw.friends.steffann.nl                                2.479ms 
 3:  speed-ix.fibertelecom.it                              3.323ms 
 4:  2a03:b020::225                                       22.414ms 
 5:  2a03:b020:1:66::b                                    22.207ms 
 6:  lo0-f1a01-itmil01.as57913.net                        25.778ms reached
     Resume: pmtu 1500 hops 6 back 6 

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]                        0.036ms pmtu 1500
 1:  karsolink-01.net.karsolink.com                        0.517ms 
 1:  karsolink-01.net.karsolink.com                        0.623ms 
 2:  no reply
 3:  no reply
 4:  lo0-f1a01-itmil01.as57913.net                         9.367ms reached
     Resume: pmtu 1500 hops 4 back 4 

From SLO host (6connect)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

tracepath -6

 1?: [LOCALHOST]                        0.020ms pmtu 9000
 1:  fw1-lju.6connect.com                                  0.579ms 
 1:  fw1-lju.6connect.com                                  0.734ms 
 2:  no reply
 3:  2a03:a100:0:201:1::1                                  1.226ms 
 4:  2a03:a100:0:201:1::1                                  0.837ms pmtu 1500
 4:  e0-1.core1.lju1.he.net                                2.464ms 
 5:  no reply
 6:  port-channel1.core1.zag2.he.net                      50.360ms 
 7:  no reply
 8:  lo0-f1a01-itmil01.as57913.net                        12.470ms reached
     Resume: pmtu 1500 hops 8 back 8 

From SLO host (T-2)   openRFC 4890 ✓

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

Path (traceroute + mtr + PTR)

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

tracepath -6

 1?: [LOCALHOST]                        0.015ms pmtu 1500
 1:  no reply
 2:  2a01:260:1::225                                       6.500ms 
 3:  2a01-260-1-1--9c.core6.t-2.net                        3.217ms 
 4:  2a01-260-1-1--39.core6.t-2.net                        2.324ms asymm  3 
 5:  hurricane-electric.nikhef.nlsix.net                  35.904ms asymm  4 
 6:  be7.core2.fra2.he.net                                38.864ms asymm  5 
 7:  be3.core4.fra1.he.net                                41.977ms 
 8:  be1.core1.mil2.he.net                                32.967ms asymm  7 
 9:  no reply
10:  lo0-f1a01-itmil01.as57913.net                        33.741ms reached
     Resume: pmtu 1500 hops 10 back 7