supports the installation of Locator ID Separation Protocol (LISP) routes in
the routing information base (RIB) corresponding to dynamic site registrations
learned by a LISP Map Server (MS). These LISP routes can be redistributed into
other routing protocols, such as Interior Gateway Protocol (IGP) and Border
Gateway Protocol (BGP), in order to attract traffic from non-LISP sources to
the router that is advertising for these registered endpoint identifier (EID)
When configured, EID
routes are installed by the MS into its RIB and point to the Null0 interface.
For example, if an egress tunnel router (ETR) registers a prefix 192.0.2.0/24
with the MS, and this feature is configured, the MS will install 192.0.2.0/24
as a route in its RIB, with the protocol source as LISP and pointing to the
Null0 interface. When installed in the MS RIB, additional capabilities are
extended to the LISP mapping system.
For a standalone
MS, LISP-installed routes may be redistributed into another routing protocol
for use with other devices. For example, LISP-installed routes may be
redistributed into BGP and advertised to a separate LISP Proxy ingress tunnel
router (PITR). The PITR may then redistribute site EID registrations into a
routing protocol such as IGP or BGP for advertisement from a PITR into a
non-LISP core network to attract non-LISP traffic to the PITR. In addition, the
PITR can also automatically populate its map cache with these same entries in
order to program the LISP prefixes it is responsible to proxy.
For a single
device acting as a combination MS/PITR, installed routes may be directly
redistributed into a routing protocol (IGP or BGP) for advertisement from a
PITR into a non-LISP core network and used to automatically populate the map
cache of the PITR.
The feature also
provides the ability for a combined MS and (P)xTR, which is a device that
functions both as a Map Server and an ingress Tunnel Router (ITR) or Proxy
Ingress Tunnel Router (PITR), to install map-cache entries corresponding to the
site registration prefixes, with an associated forwarding action of
“send-map-request.” Continuing with the example above, when this feature is
configured, the ITR or PITR installs a map-cache entry for 192.0.2.0/24 in its
map cache, with an action of send-map-request, based on this prefix being
registered with the MS function running on the same device. This map-cache
entry indicates that the packet received first with a destination matching this
entry should trigger the sending of a map request to the mapping system, which
results in the full population of the map cache with the positive entry
indicating the locator of the ETR that registered 192.0.2.0/24.