12-30-2023, 04:22 AM
I believe this question is asking about bi-directional communication between LISP and NON-LISP Sites.
The provided reference shows both PETR an PITR as requirements for LISP to NON-LISP connectivity.
A MR accepts LISP encapsulated map requests from an ITR
Proxy Ingress/Egress Tunnel Router (PxTR)
Sites cannot all be LISP enabled immediately, and not all segments of the network are not capable of running LISP from day 1. With the gradual migration from non-LISP-enabled sites to LISP-enabled sites, network operators still require that the non-LISP-capable sites be able to send traffic destined to LISP-enabled sites. This is where proxy ingress/egress tunnel routers (PxTRs) come into play.
Proxy ingress tunnel routers (PITRs) allow for non-LISP sites to send packets to LISP sites. A PITR is a new network element that shares many characteristics with a LISP ITR. A PITR allows non-LISP sites to send packets to LISP sites without requiring changes in the protocol or devices at the non-LISP sites. PITRs perform two primary functions:
The provided reference shows both PETR an PITR as requirements for LISP to NON-LISP connectivity.
A MR accepts LISP encapsulated map requests from an ITR
Proxy Ingress/Egress Tunnel Router (PxTR)
Sites cannot all be LISP enabled immediately, and not all segments of the network are not capable of running LISP from day 1. With the gradual migration from non-LISP-enabled sites to LISP-enabled sites, network operators still require that the non-LISP-capable sites be able to send traffic destined to LISP-enabled sites. This is where proxy ingress/egress tunnel routers (PxTRs) come into play.
Proxy ingress tunnel routers (PITRs) allow for non-LISP sites to send packets to LISP sites. A PITR is a new network element that shares many characteristics with a LISP ITR. A PITR allows non-LISP sites to send packets to LISP sites without requiring changes in the protocol or devices at the non-LISP sites. PITRs perform two primary functions:
- Originating EID advertisements: PITRs advertise highly aggregated EID-prefix space on behalf of LISP sites to the non-LISP sites so that the non-LISP sites can reach them.
- Encapsulating legacy Internet traffic: PITRs encapsulate non-LISP Internet traffic into LISP packets and route them toward their destination RLOCs.
- Avoiding strict uRPF failures: Some providers’ access networks require the source of a packet to be within the address scope of the access networks. PETRs allow for LISP sites to send packets to non-LISP sites in cases where the access network does not allow for the LISP site to send packets with the source address of the site’s EIDs.
- Traversing a different IP protocol: The transit path network between LISP sites and non-LISP sites may not be IPv4 or IPv6 enabled. LISP support for mixed protocol encapsulation allows PETRs to hop over such networks in order to route the traffic between the LISP and non-LISP sites.