CCNP security VPN 642-648 official cert guide by Hooper, Howard

MPLS-enabled applications emerging developments and new technologies by Minei, Ina, Lucek, Julian

Available for University of the Philippines Diliman College of Engineering via IEEE Xplore. Click here to access
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MPLS-enabled applications emerging developments and new technologies by Minei, Ina

Deploying next generation multicast-enabled applications label switched multicast for MPLS VPNs, VPLS, and wholesale Ethernet by Joseph, Vinod

Firewalls and VPNs principles and practices by Tibbs, Richard W.

Comparing, designing, and deploying VPNs by Lewis, Mark

Network virtualization by Moreno, Victor CCIE

VPNs a beginner's guide by Mairs, John

Virtual private networks technologies and solutions by Yuan, Ruixi

Building and managing the virtual private networks by Kosiur, David R.