A multihomed network is a network connected to multiple providers. Organizations use this technique for the following reasons:
- Redundancy: if a provider or the link to the provider or the exit router to the provider is down, then the other provider(s) is used.
- Load balancing: to load balance the providers links.
- Local exit point: to provide multiple exit points with local connectivity for a large network over multiple locations, which usually costs less than having one exit point that aggregates the Internet traffic through private links until it reach the exit router.
- Less transit costs: peering with Tier-2 providers is usually cost-effective because no transit costs are involved.
- Better response time: by peering with other networks nearer to the target customer base.
- Provider-independent addressing which makes the organization independent of providers.
- Policies: internal or external policies.
Many techniques are currently available for IPv6 multihoming, including:
- provider independent address space;
- multiple prefixes;
- cross-tunnels at site exit routers.
Among the other techniques being discussed in the IPv6 community is propagation using router renumbering and advertisements.
This section will describe the above techniques.
Provider Independent Address Space
As in IPv4, there is no technical barrier to using provider independent address space for IPv6 multihoming. In this case, the address space registries would give address space to organizations that are multihomed. ...