In addition to the management hurdles, configuring a VPN using equipment from multiple vendors is gnarly. At this point, support for IPsec (IP Security) interoperability isn't making much difference. The IPsec protocol suite has been in RFC status in the IETF since 1998, and the IPsec vendors-through bake-offs and the ICSA (www.icsa.net)-have shown interoperability among shipping products. Since that time, the number of vendors offering IPsec VPNs has dramatically increased, especially in software-only implementations. Hardware-based IPsec VPN providers have consolidated. This has left two long-standing vendors-RedCreek Communications and VPNet Technologies-contending with large companies like Alcatel, Cisco Systems, Intel Corp. and Lucent Technologies. The next big obstacle for these vendors to overcome is interoperable IPsec with the use of digital certificates. Maybe next year. "
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