LISP and VXLAN Flashcards
Which RFC is LISP specified in?
RFC 6830
What protocol enables separation of an endpoint’s identity and its location?
Locator/ID Separation Protocol (LISP)
What is one of LISP’s greatest limitations at Layer 2?
LISP discards the L2 Ethernet header; it only supports L3 overlay.
What is an overlay technology that is a way to deploy an L2 overlay network over a L3 underlay?
VXLAN
For LISP overlays, what term identifies an endpoint?
Endpoint identifier (EID) address - IPs or prefixes
What is an RLOC address?
Routing Locator - in LISP, these IPs identify different routers in the network that may also represent different sites.
What is the role of an ingress tunnel router (ITR)?
ITRs act as a LISP site edge device. It receives packets from internal hosts (site-facing interfaces), encapsulates them to remote LISP sites or natively routes them to non-LISP sites.
When an ITR receives a packet destined for an EID, where does it look for the EID-to-RLOC mapping?
It first looks in its mapping cache. If it cannot be found in its cache, then the ITR sends a Map-Request to one of its Map Resolvers (MR). It then receives a Map-Reply with the EID-to-RLOC mapping.
What is the role of an egress tunnel router (ETR)?
- ETRs act as a LISP site edge device. It receives packets from outside the site (core-facing interfaces), de-encapsulates LISP packets, then forwards them to local EIDs at the site.
- ETRs will periodically send Map-Register messages to its map servers, to map local EIDs to the ETR’s site.
What is the role of the map server (MS)?
- MSs keep track of the EID-to-RLOC database for the network’s sites. It accepts Map-Register requests from ETRs.
- EID prefixes are aggregated by MSs, and advertised to the ALT router with BGP
What is the role of the map resolver (MR)?
- MRs accept Map-Requests by ITRs, decapsulates them, and forwards them over to the ALT router toward the ETRs responsible for the EIDs being requested.
What is the role of a Proxy ITR (PITR)?
- PITRs handle EID-to-RLOC lookups and LISP encapsulation for non-LISP-capable sites.
- Advertises some or all of the non-routable EID prefixes to the non-LISP-capable sites
What is the role of a Proxy ETR (PETR)?
- PETRs handle ETR functions for non-LISP sites. Typically used when a LISP site needs to send traffic to non-LISP sites, but its access network (ISP) can’t accept non-routable EIDs as packet sources.
- With dual stacking, PETRs can facilitate communication between EIDs in one address family and RLOCs within a different address family to communicate to each other.
What is the role of an ALT router?
- Not present in all mapping database deployments
- ALT routers accept EID prefixes and advertise an aggregated EID prefix, which is a function that MS/MRs may do as well
What is a device called that performs both ITR/ETR functions?
xTR