|
|
|
Many VPN deployments involve two completely parallel physical networks, including multi-homed Internet VPNs and hybrid private WANs that combine traditional Frame Relay or MPLS links and Internet VPN links. The addition of CNA enables a policy-based choice at each site to determine which network to use at a particular moment. The corresponding requirement is to allow for a fully connected network that can dynamically sort out all of the required routing.
Prior to ANS6, optimizing a WAN topology with N sites required the CNA instance at each site to know about N-1 links for each parallel network, which causes a multitude of scalability issues. One solution is to add a choke router at each site, as described below in the section “Choosing with Router Route Maps.” However, features added in ANS6 allow you to avoid the additional cost and complexity of these choke routers.
ANS6 can treat all the site-links (typically IPsec, IPsec/GRE, or MPLS VPN tunnels) to the same site as a link-group, but assert an appropriate next hop to send each prefix down whichever tunnel corresponds with the link that CNA decision-making determines is optimal. ANS6 can automatically determine with which remote site each prefix is associated, based on the next hop and/or BGP communities received from the natural routing information. CNA can then choose the appropriate next hop and/or BGP community value for whichever link is asserted by the CNA decision-making process.
The full details of implementing link-groups can be found below in the section Choosing with CNA Link-Groups.
|
|
|