Lisp Site Devices; Lisp Infrastructure; Lisp Internetworking Devices - Cisco Nexus 7000 Series Configuration Manual

Configuring Locator ID Separation Protocol

LISP Site Devices

The LISP site devices are as follows:
Ingress Tunnel Router (ITR)—This device is deployed as a LISP site edge device. It receives packets from
site-facing interfaces (internal hosts) and either LISP encapsulates packets to remote LISP sites or the ITR
natively forwards packets to non-LISP sites.
Egress Tunnel Router (ETR)—This device is deployed as a LISP site edge device. It receives packets from
core-facing interfaces (the Internet) and either decapsulates LISP packets or delivers them to local EIDs at
the site.
Note Customer Edge (CE) devices can implement both ITR and ETR functions. This type of CE device is referred
to as an xTR. The LISP specification does not require a device to perform both ITR and ETR functions,
however.
For both devices, the EID namespace is used inside the sites for end-site addresses for hosts and routers. The
EIDs go in DNS records. The EID namespace is not globally routed in the underlying Internet. The RLOC
namespace is used in the (Internet) core. RLOCs are used as infrastructure addresses for LISP routers and ISP
routers and are globally routed in the underlying infrastructure. Hosts do not know about RLOCs, and RLOCs
do not know about hosts.

LISP Infrastructure

The LISP infrastructure devices are as follows:
Map Server (MS)—This device is deployed as a LISP Infrastructure component. It must be configured to
permit a LISP site to register to it by specifying for each LISP site the EID prefixes for which registering
ETRs are authoritative. An authentication key must match the key that is configured on the ETR. An MS
receives Map-Register control packets from ETRs. When the MS is configured with a service interface to the
LISP ALT, it injects aggregates for the EID prefixes for registered ETRs into the ALT. The MS also receives
Map-Request control packets from the ALT, which it then encapsulates to the registered ETR that is authoritative
for the EID prefix being queried.
Map Resolver (MR)—This device is deployed as a LISP Infrastructure device. It receives Map-Requests
encapsulated to it from ITRs. When configured with a service interface to the LISP ALT, the MR forwards
Map Requests to the ALT. The MR also sends Negative Map-Replies to ITRs in response to queries for
non-LISP addresses.
Alternative Topology (ALT)—This is a logical topology and is deployed as part of the LISP Infrastructure
to provide scalable EID prefix aggregation. Because the ALT is deployed as a dual-stack (IPv4 and IPv6)
Border Gateway Protocol (BGP) over Generic Routing Encapsulation (GRE) tunnels, you can use ALT-only
devices with basic router hardware or other off-the-shelf devices that can support BGP and GRE.

LISP Internetworking Devices

The LISP internetworking devices are as follows:
Proxy ITR (PITR)—This device is a LISP infrastructure device that provides connectivity between non-LISP
sites and LISP sites. A PITR advertises coarse-aggregate prefixes for the LISP EID namespace into the Internet,
which attracts non-LISP traffic destined to LISP sites. The PITR then encapsulates and forwards this traffic
Cisco Nexus 7000 Series NX-OS LISP Configuration Guide
LISP Site Devices
5