IPv6 packet drops
eduPERT case ticket: <br />[DFN#2016091610000414] GGUS-Ticket-ID: #123930 ASSIGNED to "EDUPERT"<br />Author: DFN-NOC - Robert Stoy<br /><br /><br /><br />Problem Description: ----------------------- end users observes on MTR ouptut packet drops on ipv6 traffic between cea.fr and other international sites, In addition end user observes unexpected routing when using ipv6, expectation is that the LHCONE should be used, instead user sees ipv6 path through open internet. Example is shown on path cea.fr <-> desy.de<br /><br />
End systems -------------- end system A: perfsonar01.datagrid.cea.fr 192.54.207.250 2001:660:3031:110:ffff::221 end system B: perfsonar-ps-02.desy.de 131.169.98.29 2001:638:700:1062::1:1d<br /><br />
Paths (and MTR measurements) on both directions --------------------------------------------------------- A -> B My traceroute [v0.75] perfsonar01.datagrid.cea.fr (::) Wed Sep 14 10:38:36 2016 Keys: Help Display mode Restart statistics Order of fields quit Packets Pings Host Loss% Snt Last Avg Best Wrst StDev 1. ipv6test.datagrid.cea.fr 0.0% 96 0.3 1.2 0.2 50.3 6.1 2. 2001:660:7904:142:1::1 7.3% 96 0.7 0.7 0.6 1.4 0.1 3. te0-1-0-5-paris1-rtr-001.noc.renater.fr 17.7% 96 6.3 20.3 2.1 143.6 26.5 4. 2001:660:7903:186:2::2 13.5% 96 8.2 8.7 6.7 12.4 1.1 5. renater.mx1.gen.ch.geant.net 0.0% 96 8.9 9.1 8.8 23.3 1.5 6. ae1.mx1.fra.de.geant.net 0.0% 95 17.3 17.4 17.2 26.9 1.1 7. cr-fra1.x-win.dfn.de 49.5% 95 17.8 17.8 17.6 18.2 0.2 8. cr-han2-be6-7.x-win.dfn.de 28.4% 95 24.6 24.8 24.6 25.1 0.1 9. cr-ham1-hundredgige0-6-0-1.x-win.dfn.de 2.1% 95 30.2 28.9 28.6 30.2 0.2 10. xr-ham1-pc3.x-win.dfn.de 0.0% 95 28.4 29.1 28.3 56.8 3.8 11. xr-des1-pc2.x-win.dfn.de 0.0% 95 29.5 29.7 29.0 65.0 3.7 12. kr-desy.x-win.dfn.de 0.0% 95 28.9 29.0 28.8 37.3 1.1 13. fw-197-22-reth-0.desy.de 10.5% 95 28.8 28.9 28.7 29.2 0.2 14. rt-dc-04-svi-804.desy.de 0.0% 95 29.3 29.4 29.2 29.9 0.2 rt-dc-03-svi-803.desy.de 15. perfsonar-ps-02.desy.de 0.0% 95 28.8 28.9 28.7 29.4 0.2
B -> A My traceroute [v0.75] perfsonar01.datagrid.cea.fr (0.0.0.0) Wed Sep 14 10:36:41 2016 Keys: Help Display mode Restart statistics Order of fields quit Packets Pings Host Loss% Snt Last Avg Best Wrst StDev 1. cvm14.datagrid.cea.fr 0.0% 153 0.2 1.1 0.2 43.3 5.4 2. 193.51.191.234 0.0% 153 1.5 1.5 1.1 41.6 3.3 3. geant-lhcone-gw.mx1.par.fr.geant.net 0.0% 153 1.1 1.2 1.0 11.2 0.9 4. ae2.mx1.gen.ch.geant.net 0.0% 153 8.6 8.6 8.4 14.4 0.5 5. geant-lhcone-gw.mx1.fra.de.geant.net 0.0% 153 16.7 16.8 16.6 25.2 0.9 6. dfn-lhcone-gw.fra.de.geant.net 0.0% 153 17.0 17.4 16.8 36.7 1.9 7. cr-han2-be6-82.x-win.dfn.de 0.0% 152 26.4 26.2 25.9 27.0 0.2 8. kr-des51-2.x-win.dfn.de 0.0% 152 25.8 25.9 25.8 46.1 1.6 9. fw-197-22-reth-0.desy.de 12.5% 152 26.0 26.0 25.9 26.8 0.1 10. rt-dc-04-svi-804.desy.de 0.0% 152 26.2 26.4 26.2 26.7 0.1 11. perfsonar-ps-02.desy.de
Analysis: ------------ Endsystems VPN (VRF) membership endsystems A ipv4 and ipv6 prefixes are visible in VRF LHCONE <b>*and*</b> in open Internet routing tables endsystems A ipv4 and ipv6 prefixes are visible in VRF LHCONE <b>*and*</b> in open Internet routing tables This deciscon is made at the end sites. Path A -> B mtr shows IPv6 path through open internet Path B -> A mtr shows IPv4 path through LHCONE Packet Loss: Packet losses are shown only on intermediate routers. There is no packet loss shown end-to-end on both directions This indicates that rate limits for icmp respectively icmpv6 traffic are active at this time on these routers. These rate limits protect the router CPU and control plane on the router. There is no limit on the forwarding path through the router. Routing: The analysis shows differences on on the path directions with regard to the protocol family used (IPv4,IPv6) and differences on the VPN/open internet usage. The MTR output does not clearly show if the ipv6 or the ipv4 address has been explicitely used as destination addresses. Assumption is that on the MTR commande intentionally on A->B the ipv6 destination address has been used and on on B->A the ipv4 destination address. The reason why the ipv6 path is through the open internet is most probably caused on the routing decision made directly at the end site A on the first hop "ipv6test.datagrid.cea.fr". The second hop 2001:660:7904:142:1::1 is not shown in the routing table of the VRF LHCONE but only on the open internet routing table: Therefore the ipv6 path A->B is using the open internet. This problem should be fixed locally a the end site A.
– KurtBaumann - 2016-10-24