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 my post on 1st April. Don’t take it as April fool post ;)
Multiple times NIXI’s AS24029 has been reported as acting like transit ASN for multiple networks. I have analysed it in past and this is very much because of route leaks by few specific networks. I have explained difference in peering Vs transit routes and their handling previously on my blog.
In short: A network is supposed to re-announce it’s peering and transit routes only to customer and not to any other peer or upstream. Whenever NIXI’s ASN appears in global routing table, its always the case where one or more networks are re-announcing routes learnt via NIXI to their upstream transits.
I thought about this long back - “Who pays to whom in case of internet bandwidth?” I have been working in this domain from sometime and so far I have learnt that it’s really complex. I will try to put a series of blog post to give some thoughts on this subject. Firstly we have to understand that when we talk about “bandwidth price” it’s often layer 3 bandwidth which you buy in form of capacity over ethernet GigE, Ten-GigE and so on (or STMs if you are in India). As we know from back school class in networking - layer 3 works over layer 2 and so to deliver “bandwidth” on layer 3, one needs layer 2 physical circuit. Price paid by companies on layer 2 Vs layer 3 varies significantly based on their location, type of business, their target goal etc. E.g a content heavy company like Google pays hell lot of money on layer 2 circuits while it is strongly believed among networking community that Google is a tier 1 network and hence a “transit free” zone and they do not pay any amount on layer 3. In general the trend is pretty much as big networks have larger network footprint and connected “PoPs” over layer 2 (leading to a higher layer 2 bill) while relatively lower layer 3 bill while small networks depend significantly just on transit bandwidth (in form of layer3) and have very low layer 2 footprint.
Some free time here in Europe and thus time for another quick blog post & to take my mind away from depressing people!
One of impressive features of major European networks is support for BGP communities. In India it’s almost non-existent. Setting it up isn’t hard technically but from capacity management side, Indian ISPs are somewhat shy in setting it up.
Let’s put a case where we have a Customer router (R1 with AS1), upstream of customer (R2 with AS2), upstream of upstream (R3 with AS3), peer of upstream (R4 with router4). Let’s try to setup communities so that customer at AS1 can control his BGP announcements and announce some prefixes to AS3 and some to AS4 selectively to control inbound traffic flow.
Earlier this month Dyn started with it’s Indian PoP. I came across news from Dyn’s blog post. It’s very good to see first Amazon AWS and now Dyn in India. With a warm welcome to Dyn let’s look at their Indian deployment.
Dyn using AS33517 which seems to be having upstream from Tata-VSNL AS4755 and Airtel AS9498.
Dyn seems to be announcing 103.11.203.0/24 to both networks in Mumbai to transit. There are routes in global IPv4 routing table which show Tata & Airtel as transit for Dyn. It cannot be just a /24. I am sure there are more prefixes which are very likely locally announced. Since deployment is at Mumbai, let’s try to look at NIXI Mumbai for prefixes.We can see Tata AS4755 is using 218.100.48.85 and Airtel is using 218.100.48.86 from NIXI route server at Mumbai with simple “sh ip bgp sum” query. I tried taking entire table of Tata as well as of Airtel from NIXI route server but not able to get it beyond few thousand routes.
This Sunday I was looking at global routing table dump and found AS1 announcing some very weird prefixes.
AS1 i.e Autonomous System Number 1 belongs to Level3 but as far as I know they are not actively using it. They use AS3356 globally (along with Global Crossing’s AS3549). I noticed quite a few prefixes of a Brazil based telecom provider - Netvip Telecomunicaes being announced by AS1.
Some of entries in global routing table belonging to AS1 (as picked from BGP table dump of route-views archive):
Sometimes we see interesting IP’s in traceroute & they confuse lot of people.
I have seen this topic in discussion twice on NANOG and once on Linux Delhi user group.
OK - let’s pick an example:
anurag:~ anurag$ traceroute 71.89.140.11
traceroute to 71.89.140.11 (71.89.140.11), 64 hops max, 52 byte packets
1 router (10.10.0.1) 1.176 ms 0.993 ms 0.941 ms
2 117.220.160.1 (117.220.160.1) 20.626 ms 29.101 ms 19.216 ms
3 218.248.169.122 (218.248.169.122) 23.983 ms 43.850 ms 45.057 ms
4 115.114.89.21.static-mumbai.vsnl.net.in (115.114.89.21) 118.094 ms 81.447 ms 66.838 ms
5 172.31.16.193 (172.31.16.193) 115.979 ms 90.947 ms 90.491 ms
6 ix-4-2.tcore1.cxr-chennai.as6453.net (180.87.36.9) 95.778 ms 98.601 ms 98.920 ms
7 if-5-2.tcore1.svw-singapore.as6453.net (180.87.12.53) 321.174 ms
if-3-3.tcore2.cxr-chennai.as6453.net (180.87.36.6) 331.386 ms 326.671 ms
8 if-6-2.tcore2.svw-singapore.as6453.net (180.87.37.14) 317.442 ms
if-2-2.tcore2.svw-singapore.as6453.net (180.87.12.2) 334.647 ms 339.289 ms
9 if-7-2.tcore2.lvw-losangeles.as6453.net (180.87.15.26) 318.003 ms 328.334 ms 309.234 ms
10 if-2-2.tcore1.lvw-losangeles.as6453.net (66.110.59.1) 306.500 ms 326.194 ms 341.537 ms
11 66.110.59.66 (66.110.59.66) 315.431 ms 330.417 ms 308.372 ms
12 dls-bb1-link.telia.net (213.155.136.40) 354.768 ms 344.360 ms 357.050 ms
13 chi-bb1-link.telia.net (80.91.248.208) 352.479 ms 358.751 ms 359.987 ms
14 cco-ic-156108-chi-bb1.c.telia.net (213.248.89.46) 367.467 ms 370.482 ms 377.280 ms
15 bbr01aldlmi-bue-4.aldl.mi.charter.com (96.34.0.98) 387.269 ms 385.362 ms 365.694 ms
16 crr02aldlmi-bue-2.aldl.mi.charter.com (96.34.2.11) 375.275 ms 375.356 ms 371.621 ms
17 dtr02grhvmi-tge-0-1-0-0.grhv.mi.charter.com (96.34.34.83) 383.539 ms 371.817 ms 383.804 ms
18 dtr02whthmi-tge-0-1-0-0.whth.mi.charter.com (96.34.34.85) 384.400 ms 391.197 ms 393.340 ms
19 dtr02ldngmi-tge-0-1-0-0.ldng.mi.charter.com (96.34.34.87) 371.192 ms 375.679 ms 378.457 ms
20 acr01mnplmi-tge-0-0-0-3.mnpl.mi.charter.com (96.34.40.75) 364.824 ms 385.534 ms 374.401 ms
21 * *^C
anurag:~ anurag$
Let’s try pinging IP on 14th hop (which is with a major backbone Telia) - 213.248.89.46
Today I noticed some traffic on my blog from a link from Broadband forum.
Here’s what poster wrote:
I made a thread a few days ago complaining about BSNL’s horrible routing. Well it looks like it has been fixed. I thank all the guys who made efforts to bring this to BSNL’s notice. Especially Anurag Bhatia who highlighted the issue with much detail on his blog
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.
It’s late night here in India. I am having final 8th semester exams and as usual really bored!
Though this time we have interesting subjects but still syllabus is pretty boring spreading across multiple books, notes and pdf’s. Anyways I will be out of college after June which sounds good.
Tonight, I found a routing glitch. Yes a routing glitch!! :)
These issues somehow keep my life in orbit and give a good understanding on how routing works over the Internet.