luigi.iannone at uclouvain.be
Sun Jul 20 13:25:13 UTC 2008
Hello FreeBSD Networking Community,
During the last years, there have been many discussions about the
scalability of the Internet architecture notably within the IRTF RRG.
With IPv6, thanks to its huge addressing space, it is possible to
design protocols and mechanisms that are more scalable and more
powerful than with IPv4. A typical example is the multihoming
problem. This problem occurs when a site is attached to several
Internet Service providers. With IPv4, the classical solution is for
the site to obtain one IPv4 prefix and advertise it by using BGP.
This solution works and traffic engineering is possible, but
unfortunately, it contributes to a significant growth of the BGP
routing tables in the global Internet.
Approaches to better scale the Internet architecture are being
discussed, notably within the Routing Research Group of the Internet
Research Task Force. Several of these approaches rely on separating
the two roles of IP addresses: the locator role and the identifier
role. In today's IPv4 Internet, IPv4 addresses are used both to
indicate the location in the Internet topology of a host (the locator
role) and to terminate the transport flows on end-hosts (the
identifier role). This means that it is difficult to change the IP
address of a host without disrupting transport flows.
The techniques that separate identifiers from locators take a
different approach. First, an identifier is attached to each end-
host. This identifier is used to terminate the transport flows.
Second, each identifier may be reachable through multiple locators
and a mapping mechanism is used to map an identifier (or a set of
identifiers) onto a set of locators. This improves the scalability of
the routing system as only the locators need to be distributed by BGP
provided, of course, that the mapping system remains scalable.
Furthermore, separating identifiers and locators has several
additional benefits in terms of path diversity and performance. Some
approaches propose to attach locators to hosts while other prefer to
attach locators only to routers. The latter approach is the solution
chosen by the proponents of the Locator/Identifier Separation
Protocol (LISP). LISP is a router-based solution to solve the scaling
problems of the Internet architecture that is currently being
developed by Cisco.
There are still many open questions concerning notably the mapping
between identifiers and locators. To allow researchers and network
operators to experiment with LISP, the IP Networking Lab of UCLouvain
releases OpenLISP. OpenLISP is the first publicly available
implementation of LISP on the FreeBSD kernel. OpenLISP was designed
and implemented by Luigi Iannone.
You can find more details about OpenLISP from http://inl.info.ucl.ac.be
Any feedback from the FreeBSD Networking community is more than welcome.
luigi.iannone at uclouvain.be
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