Came across this excellent presentation of Peter Hoose (Facebook). It gives a very good logical way of troubleshooting problems. Less about actual problems but about how Ops members companies like Facebook troubleshoot them.
This is from NANOG 64. Enjoy the presentation. :)
Few days back a friend of mine (who works for an ISP) congratulated me for joining HE. Along with wishes he told me that our bgp.he.net doesn’t works well and the reason he fealt so is because he couldn’t see all peers for his ASN in our tool.
This is not a problem and to be more broader - same applies on all popular tools other then bgp.he.net like RIPE Stats, Robtex AS analysis etc. The reason many of these tools do not and cannot show all peers is because they show what they see from the point of collection. E.g right now I am on BSNL (AS9829).
Just was looking around at EDNS support by Google. To find how it supports and how packet looks like I created a test NS records for dnstest.anuragbhatia.com pointing to one of test server (178.238.225.247). I wasn’t running any DNS server on the server. Just ran quick tcpdump.
At server end:
sudo tcpdump 'port 53 and dst 178.238.225.247' -nn -vvv -w sample.pcap
Then I forcefully triggered DNS queries via Google’s recursor using:**
Came across excellent tool called “bgpq3” from one of recent posts in NANOG mailing list. This tool can general filters for a given ASN for Cisco or Juniper based on RADB’s data.
E.g Juniper style config for AS54456 (1st ASN on which I worked on!) :)
anurag@server7 ~> bgpq3 -Jl Cloudaccess as54456
policy-options {
replace:
prefix-list Cloudaccess {
199.116.76.0/24;
199.116.77.0/24;
199.116.78.0/24;
199.116.79.0/24;
}
}
anurag@server7 ~>
Cisco style config:
> anurag@server7:~$ bgpq3 -l Cloudaccess as54456
no ip prefix-list Cloudaccess
ip prefix-list Cloudaccess permit 199.116.76.0/24
ip prefix-list Cloudaccess permit 199.116.77.0/24
ip prefix-list Cloudaccess permit 199.116.78.0/24
ip prefix-list Cloudaccess permit 199.116.79.0/24
anurag@server7:~$
Cisco XR style config:
Few months ago I moved away from Google Chrome to Opera Mobile on my Android device. Google Chrome is pretty loaded and overall slow. Recently I noticed browsing was pretty slow. I noticed that “Off-Road mode” was enabled.
I disabled it and performance was much better. I did heard of it in past and clearly it’s a proxy mode where packets between Opera instance running on cell phone and destination server are routed via an Opera server which uses some special compression technologies and helps in making browsing faster. Carrying with my obsession for looking at ASNs and IP address, I enabled it again and visited bgp.he.net and was surprised to see the result.