Hi All


I have been trying to understand LISP for quite something but hittings huge walls. I understand the working principle of the LISP but couldnt understand the role of a ISP in this. Have listed my questions below , would be great if someone explain


1.All the configuration templates available online has the static configurations for EID prefix under MR/MS(Map Serve/Map Resolver) when its supposed to be registered by XTR automatically.

2. From the prespective of a service provider who plays the role of MAP Resolver/Server , XTRs, Proxy XTRs. 

3. Where does an ISP peer with ALT network

4. Can a PI address space be removed from service and assigned as EID prefix or should it be specifically registerd in some forum

5. Consider a topo where a ship is connected under a POP in india and when it moves near AFRICA it connects with a POP is Africa but , who would be playing the role of PE and CE in lisp. Would the CE or PE perform the role of XTR and if PE plays the role of XTR what is the case when BGP is implement beween the mobile CE and the PE(XTR)



Would be great if some one share your views.


Thanks in Advance.


  • 1) The MR/MS define a LISP "site" with static configuration. This config means "this site is allowed to register these EIDs". There is the option to "allow more specifics", meaning that the MR/MS can be configured with a /16 but the site can register /24s or more specific. This could even be done with (anything). 

    2) a LISP SP would play the roles of Proxy-xTR and MS/MR...the xTR is located at the customer site (the CE)

    3) ALT is not used any more - DDT is what the LISP network is currently using. 

    4) PI space can be removed from the normal BGP advertisement at the custumer site and can instead be advertised as a LISP EID. Keep in mind that the PI space still needs to be advertised into BGP by someone - in the case of an enterprise purchasing LISP service from a LISP SP, the PI space would be advertised into BGP by the SP's Proxy-xTR. This causes all traffic from non-LISP sites destined to the PI space to forward un-encapsulated towards the Proxy-xTR - which then encapsulates the traffic towards the LISP site (the owner of the PI EID).

    5) Dont think of "PE/CE" roles with LISP. A site using LISP no-longer participates in BGP...all it needs is a default route pointing towards the provider.  If a router has a route for a destination via a standard protocol (BGP, OSPF, etc) then it will use that to forward traffic. If there is no route to the destination, or only a default, then the router will engage the LISP system to encapsulate and forward traffic. For this reason, sites uisng LISP don't usually run a routing protocol with their upstream provider.

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