F-Root

Has been a while since I checked the status of root servers which are hosted at NIXI. The list as per their official member list stays the same i.e i root in Mumbai, K root in Noida and F root in Chennai. 

 

i root seems to be up!

show ip bgp neighbors 218.100.48.75 received-routes
       There are 5 received routes from neighbor 218.100.48.75
Searching for matching routes, use ^C to quit...
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
       E:EBGP H:HISTORY I:IBGP L:LOCAL M:MULTIPATH m:NOT-INSTALLED-MULTIPATH
       S:SUPPRESSED F:FILTERED s:STALE
       Prefix             Next Hop        MED        LocPrf     Weight Status
1      192.36.148.0/24    218.100.48.75   0          100        0      BE
         AS_PATH: 8674 29216
2      194.58.198.0/24    218.100.48.75   0          100        0      BE
         AS_PATH: 8674 56908
3      194.58.199.0/24    218.100.48.75   0          100        0      BE
         AS_PATH: 8674 56908
4      194.146.106.0/24   218.100.48.75   0          100        0      BE
         AS_PATH: 8674
5      194.146.107.0/24   218.100.48.75   0          100        0      BE
         AS_PATH: 8674

 

Last week I noticed that F root was showing poor connectivity with Indian RIPE Atlas probes for F-root. The graph looked really terrible.

 

I traced to it from one of RIPE Atlas probes and saw this trace:

Probe #6107
  1 2401:7500:fff0:1::1                      0.838 ms     0.747 ms     0.632 ms
  2 2400:5200:1c00:d::1                      1.755 ms     1.745 ms     1.726 ms
  3 2403:0:100::2be                          2.089 ms     2.054 ms     2.049 ms
  4 2404:a800:2a00::13d                     45.589 ms    26.274 ms     33.64 ms
  5 2404:a800::178                          26.376 ms    25.406 ms    25.276 ms
  6 2001:de8:1:2::3                         25.363 ms    25.232 ms    25.223 ms
  7 *                                           *            *            *
  8 *                                           *            *            *
  9 *                                           *            *            *
 10 *                                           *            *            *
 11 *                                           *            *            *

Here the last hop before timeout i.e hop 6 is of NIXI Chennai peering subnet 2001:de8:1:2::/64. As soon as I saw it, it reminded me older issue which happened and broke IPv4 connectivity to root DNS servers. I blogged about it here, here and here. So the problem remains that NIXI is broken cost wise due to charge on in - out policy. This leads to people accepting routes at all NIXI’s but they do not announce their routes. Thus return path is broken and essentially traffic is being blackholed. Earlier this issue was fixed by adding IP transit support to these root DNS servers so that a default route stays in case of all other failures. It seems like same is missing in IPv4 world and routes are not being announced. During this time, I saw two BGP sessions at NIXI Chennai for F root:

Enjoyed ISC’s presentation about their analysis of F root server (one 13 root DNS servers which power the Internet) about anycast performance gloablly for 192.5.5.0/24 announced (and anycasted) by AS3557 (ISC). This was presentation at UKNOF 32.

Embedded presentation below (or click here to watch on YouTube directly)

And finally ACN i.e “Advanced Computer Networks” exam next. Hopefully less to cram in this one and syllabus is pretty interesting. 

Talking about networks - I am very happy to post this update. Finally F root server’s node in Chennai is back up! 

Though ISC did not updated me about this development but anyways I can always assume they were busy in hitting head with India bureaucratic bodies. :)

If you are following my blog, you might have seen my past blog post about “Broken connectivity of F root server” due to NIXI’s routing policies. When I informed ISC (root server operator for F root) about it, they took down the Indian anycasting instance in order to work on fix. 

Time for a quick followup blog post. On 26th April of this year I blogged about broken connectivity of F root server which was hosted in NIXI Chennai. Apart from that blog post, I did informed ISC which operates F root (NIXI was host on behalf of them in India). In my open email on APNIC mailing list, I got a reply from Network Operations Center of ISC that they will verify and will take necessary action. Within 48 hours of that email they figured out root cause and since they couldn’t fix it right at that point, they pulled plug off from that root server.