BSNL routing tables and upstreams
Just was looking at routing tables of BSNL. They have a significant address space in /10 - 117.192.0.0/10. Overall this /10 address space is divided into /18 and /20 subnets.
Let’s pick two of such subnets and observe routing tables from route-views:
- 117.192.0.0/18
- 117.192.0.0/20
Routing table for 117.192.0.0/18:
* 117.192.0.0/18 193.0.0.56 0 3333 3356 6453 4755 9829 9829 9829 i
* 194.85.102.33 0 3277 3216 6453 4755 9829 9829 9829 i
* 194.85.40.15 0 3267 174 6453 4755 9829 9829 9829 i
* 129.250.0.11 6 0 2914 6453 6453 4755 9829 9829 9829 i
* 128.223.253.10 0 3582 3701 3356 6453 4755 9829 9829 9829 i
* 4.69.184.193 0 0 3356 6453 4755 9829 9829 9829 i
* 209.124.176.223 0 101 101 3356 6453 4755 9829 9829 9829 i
* 69.31.111.244 3 0 4436 2914 6453 6453 4755 9829 9829 9829 i
* 207.46.32.34 0 8075 6453 4755 9829 9829 9829 i
* 66.59.190.221 0 6539 6453 4755 9829 9829 9829 i
* 12.0.1.63 0 7018 6453 4755 9829 9829 9829 i
* 208.74.64.40 0 19214 2828 6453 4755 9829 9829 9829 i
* 203.181.248.168 0 7660 2516 6453 4755 9829 9829 9829 i
* 66.185.128.48 111 0 1668 6453 4755 9829 9829 9829 i
* 134.222.87.1 0 286 6453 4755 9829 9829 9829 i
* 157.130.10.233 0 701 6453 4755 9829 9829 9829 i
* 114.31.199.1 0 0 4826 6939 1299 6453 4755 9829 9829 9829 i
* 89.149.178.10 10 0 3257 6453 4755 9829 9829 9829 i
* 154.11.98.225 0 0 852 3561 6453 4755 9829 9829 9829 i
* 202.249.2.86 0 7500 2497 6453 4755 9829 9829 9829 i
* 154.11.11.113 0 0 852 3561 6453 4755 9829 9829 9829 i
* 144.228.241.130 0 1239 6453 4755 9829 9829 9829 i
* 217.75.96.60 0 0 16150 1299 6453 4755 9829 9829 9829 i
* 207.172.6.20 0 0 6079 3356 6453 4755 9829 9829 9829 i
* 206.24.210.102 0 3561 6453 4755 9829 9829 9829 i
* 195.66.232.239 0 5459 6453 4755 9829 9829 9829 i
* 208.51.134.254 2523 0 3549 6453 4755 9829 9829 9829 i
* 207.172.6.1 0 0 6079 3356 6453 4755 9829 9829 9829 i
* 216.218.252.164 0 6939 1299 6453 4755 9829 9829 9829 i
* 203.62.252.186 0 1221 4637 6453 4755 9829 9829 9829 i
*> 66.110.0.86 0 6453 4755 9829 9829 9829 i
* 164.128.32.11 0 3303 6453 4755 9829 9829 9829 i
* 202.232.0.2 0 2497 6453 4755 9829 9829 9829 i
Routing table for 117.192.0.0/20:
Network Next Hop Metric LocPrf Weight Path
* 117.192.0.0/20 193.0.0.56 0 3333 3356 6453 9829 i
* 194.85.102.33 0 3277 3216 6453 9829 i
* 194.85.40.15 0 3267 174 6453 9829 i
* 129.250.0.11 6 0 2914 6453 9829 i
* 128.223.253.10 0 3582 3701 3356 6453 9829 i
* 4.69.184.193 0 0 3356 6453 9829 i
* 209.124.176.223 0 101 101 2914 6453 9829 i
* 69.31.111.244 3 0 4436 2914 6453 9829 i
* 207.46.32.34 0 8075 6453 9829 i
* 66.59.190.221 0 6539 6453 9829 i
* 12.0.1.63 0 7018 6453 9829 i
* 208.74.64.40 0 19214 2828 6453 9829 i
* 203.181.248.168 0 7660 2516 209 6453 9829 i
* 66.185.128.48 111 0 1668 6453 9829 i
* 134.222.87.1 0 286 6453 9829 i
* 157.130.10.233 0 701 6453 9829 i
* 114.31.199.1 0 0 4826 6939 1299 6453 9829 i
* 144.228.241.130 0 1239 6453 9829 i
* 89.149.178.10 10 0 3257 6453 9829 i
* 154.11.98.225 0 0 852 2914 6453 9829 i
* 202.249.2.86 0 7500 2497 6453 9829 i
* 154.11.11.113 0 0 852 2914 6453 9829 i
* 217.75.96.60 0 0 16150 1299 6453 9829 i
* 207.172.6.20 0 0 6079 3356 6453 9829 i
* 195.66.232.239 0 5459 6453 9829 i
*> 66.110.0.86 0 6453 9829 i
* 216.218.252.164 0 6939 1299 6453 9829 i
* 206.24.210.102 0 3561 6453 9829 i
* 203.62.252.186 0 1221 4637 6453 9829 i
* 202.232.0.2 0 2497 6453 9829 i
* 208.51.134.254 2523 0 3549 6453 9829 i
* 207.172.6.1 0 0 6079 3356 6453 9829 i
Looking at table 1 for /18 - Clearly path is always via 6453 > 4755 > 9829 and then prepending. This is for sure BSNL’s transit links inside India since AS4755 is Tata-VSNL and is present only inside India (as far as I know!). Although it seems like /18 is not being announced to anyone else other then Tata-VSNL in for this subnet but I am sure there are some other prefixes which are announced to Reliance and Airtel as well.
Next looking at table 2 for /20 - path is always 6453 > 9829 with no prepending. Clearly this is IPLC link since AS6453 is Tata Comm outside India and they usually do not connect to anyone inside India on 6453 but rather via Tata-VSNL AS4755 backbone. Thus likely 6453 > 9829 (direct with no AS4755 in between) is where BSNL is purchasing bandwidth outside India over IPLC. Now since /18 is less specific and even has long AS path - direct transit upstream link via Tata > Tata-VSNL > BSNL is being less preferred and IPLC is more preferred.
There are also cases of /20’s where BSNL is not doing any prepends and announcing it to VSNL directly which actually is good since Tata AS6453 is connected to more networks in Asia, Europe and North America. While BSNL’s IPLC link seems only to London, New York and Los Angeles which causes issues in return paths (world > BSNL) entery points and eventually increases latency for all Asian traffic.
One of prefixes which is announced correctly - 117.200.48.0/20
Network Next Hop Metric LocPrf Weight Path
* 117.200.48.0/20 66.59.190.221 0 6539 6453 4755 9829 ?
* 164.128.32.11 0 3303 6453 4755 9829 ?
* 128.223.253.10 0 3582 3701 3356 6453 4755 9829 i
* 193.0.0.56 0 3333 3356 6453 4755 9829 i
* 194.85.102.33 0 3277 3216 6453 4755 9829 ?
* 194.85.40.15 0 3267 3356 6453 4755 9829 i
* 129.250.0.11 6 0 2914 6453 6453 4755 9829 ?
* 4.69.184.193 0 0 3356 6453 4755 9829 i
* 209.124.176.223 0 101 101 3356 6453 4755 9829 i
* 69.31.111.244 3 0 4436 2914 6453 6453 4755 9829 ?
* 207.46.32.34 0 8075 6453 4755 9829 ?
* 12.0.1.63 0 7018 6453 4755 9829 ?
* 208.74.64.40 0 19214 2828 6453 4755 9829 ?
* 203.181.248.168 0 7660 2516 6453 4755 9829 ?
* 66.185.128.48 111 0 1668 6453 4755 9829 ?
* 134.222.87.1 0 286 6453 4755 9829 ?
* 157.130.10.233 0 701 6453 4755 9829 ?
* 114.31.199.1 0 0 4826 6939 1299 6453 4755 9829 i
* 89.149.178.10 10 0 3257 6453 4755 9829 ?
* 154.11.98.225 0 0 852 1299 6453 4755 9829 ?
* 202.249.2.86 0 7500 2516 6453 4755 9829 ?
* 154.11.11.113 0 0 852 1299 6453 4755 9829 ?
* 144.228.241.130 0 1239 6453 4755 9829 ?
* 217.75.96.60 0 0 16150 1299 6453 4755 9829 i
* 207.172.6.20 0 0 6079 3356 6453 4755 9829 i
* 195.66.232.239 0 5459 6453 4755 9829 ?
* 208.51.134.254 2523 0 3549 6453 4755 9829 ?
* 207.172.6.1 0 0 6079 3356 6453 4755 9829 i
* 202.232.0.2 0 2497 6453 4755 9829 ?
*> 66.110.0.86 0 6453 4755 9829 ?
* 216.218.252.164 0 6939 1299 6453 4755 9829 i
* 206.24.210.102 0 3561 6453 4755 9829 ?
* 203.62.252.186 0 1221 4637 6453 4755 9829 ?
Well that’s all for now. With hope that your section for /20 is announced to everyone - have a good night! :)