Posts Tagged ‘isakmp’


High availability solutions often utilize virtual gateway protocol to avoid single point of failure. We are going to discuss high availability for the IPsec tunnel in the sample topology presented below. In this topology we need to protect traffic between VLAN67 and VLAN58 travelling across VLAN146 segment. In order to accomplish this, we will configure R6 to establish an IPsec tunnel with a virtual gateway representing both R1 and R4.

IPsec HA Scenario

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One of the new technologies to be featured in the CCIE Security 3.0 blueprint is the GET VPN. This blog post will give you the basics of this new and exciting technology.

Here is the scenario; you are a large corporation with multiple branch offices that need VPN connections between them in order to protect data that needs to be shared from branch to branch. The standard Cisco solution is to create point-to-point IPSec VPNs between these branch offices. This can quickly become a nightmare for administration, obviously, as this “any to any” encryption model using traditional VPN methodologies simply does not scale. Helping to exasperate this issue is the replication of multicast traffic and the extreme difficulty of implementing Quality of Service mechanisms across the core of the network.

The Group Encrypted Transport VPN model has your routers become trusted members of VPN groups as a replacement for the point-to-point model. Secured packets now use the existing router infrastructure and have their original IP header preserved. This helps to ensure that intelligent services like QoS and multicast are no longer implementation problems!

Another huge scalability issue with the traditional, point-to-point approach for “any to any” VPNs is key management. The GET VPN features simplified security policy and key distribution thanks to the Group Key Distribution Model. This model uses Group Domain of Interpretation (GDOI) as specified in RFC 3547.  The Group Key Distribution Model features a Key Server (a Cisco router) that authenticates group members, and handles the distribution of security policies and any required keys. In the interests of further scaling this already scalable solution, as well as improving availability, Cooperative Key Servers can be used across wide geographic distributions.

Here are the core technologies to explore with the GET VPN feature:

  • Group Domain of Interpretation (GDOI) RFC 3547
  • Key Servers (KS)
  • Cooperative Key Server (COOP KSs)
  • Group Member (GM)
  • IP tunnel header preservation
  • Group security assocaition
  • Rekey mechanism
  • Time-based anti-replay (TBAR)

Here are the GET VPN core benefits:

  • Large scale any-to-any IPSec security
  • Utilizes the underlying IP VPN routing infrastructure
  • Integration with existing multicast infrastructures
  • IP source and destination address preservation

I certainly hope this post wets your appetite and gives you a framework to begin your studies of the GET VPN technology.

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