AS6667 filters routes considered harmful at the border. These can be of the following types:
- Our own IP blocks
- IANA reserved IP blocks
- Prefixes longer than /24 (netmask 255.255.255.0)
- Prefixes longer than /22 (netmask 255.255.248.0)
We will never accept prefixes more specific than /24. We will always accept /24 routes within The Swamp (192.0.0.0/7). Outside that range the default filter will get rid of prefixes longer than /22.
If a peer's routes are otherwise well behaved, but they have a few legitimate routes that would get caught by the default filter, we will use a more lenient filter. Should we ever give a peer subnets from our own CIDR allocations (such as if a customer with a large continuous chunk of address space moved to another provider), there's also a filter that lets almost anything through.