SiPanda This specification defines various limits that may be applied to receiving, sending, and otherwise processing packets that contain IPv6 extension headers. The need for such limits is pragmatic to facilitate interoperability amongst hosts and routers in the presence of extension headers and thereby increasing the feasibility of deployment of extension headers. The limits described herein establish the minimum baseline of support for use of extension headers in the Internet. If it is known that all communicating parties for a particular communication, including end hosts and any intermediate nodes in the path, are capable of supporting more than the baseline then these default limits may be freely exceeded.