A Looking Glass or LG is a way to “look” into someone’s network so you can see what they see.
Below are a list of various exchange points and networks.
DE-CIX : https://lg.de-cix.net
INEX : https://www.inex.ie/ixp/lg
INX-ZA : https://lg.inx.net.za
London Internet Exchange : https://alice-rs.linx.net
Netnod : https://lg.netnod.se
Cogent http://www.cogentco.com/en/network/looking-glass
Vodafone https://support.cw.com/prod/tools_lookingglass.html
CT http://ipms.chinatelecomglobal.com/public/lookglass/lookglassDisclaimer.html
Telia https://lg.telia.net/
ATT: telnet route-server.ip.att.net
Telkom: telnet tpr-route-server.saix.net/
Level3: https://lookingglass.level3.net/
NTT https://www.us.ntt.net/support/looking-glass/
http://lg.retn.net
Seacom : https://as37100.net/?lookingglass
NTT : https://www.gin.ntt.net/looking-glass/
Workonline https://as37271.fyi/looking-glass
OVH https://lg.ovh.net
Not quite an LG but can run tests like ping and Traceroute from a host in hetzner in DE https://lg.fsn.fognet.ch