CISCO ISDN:
http://books.google.hu/books?id=-kjpdduF3dAC&pg=PA246&lpg=PA246&dq=ISDN+Switchtype+%3D+basic-net3&source=bl&ots=rWbWnjNZE9&sig=_j5cYYm5VpODbaHO2pt5ralgGpE&hl=hu&ei=BzDPSvejE5eQsAbigrWsCA&sa=X&oi=book_result&ct=result&resnum=6#v=onepage&q=&f=false
http://www.cisco.com/en/US/docs/internetworking/technology/handbook/ISDN.html
CISCO VPN:
http://techrepublic.com.com/5208-1035-0.html?forumID=102&threadID=251320&tag=rbxccnbdisc1
http://docs.amazonwebservices.com/AmazonVPC/latest/NetworkAdminGuide/images/Detailed_Cisco.gif
http://www.cymru.com/Documents/cisco-ipsec-howto.txt
