Filters at EBGP are not good (2)

Filters ban some of important protocols
CA-2003-015: mobile-ip4, PIM
The key architectural importance of Internet: extensibility
Scalability (extensibility in size)
Good scalability of IPv4, v6
Protocol extensibility
It is easy to introduce new protocols
it is not necessary to upgrade routers to introduce new protocols

Filters at EBGP routers will damage protocol extensibility
Extreme example: (pseudo) Internet that pass TCP port 80 only