What are the deployment decisions for choosing bw PMIPv6 and GTP protocols for S5/S8 interfaces?

Question

S5 interface is in non-roaming LTE core between SGW and PGW. S8 is the same for roaming LTE core nw

Answer 1

I think u have already answered Non Roaming can be S5 which can be GTP or PMIP where as Roaming one will be S8 i.e. PMIP.

Comments

I think PMIP is used when UE handedover from 3GPP network to Non-3GPP  network.

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Both S5 and S8 can be either PMIP or GTP. Courtesy this link (http://3gpp-n-lte.blogspot.in/2010/02/why-pmip-is-being-used-in-s5s8.html), this is what I understood.Some operators prefer using PMIP throughout their n/w as it facilitates connecting to non-3gpp accesses, whereas some operators want only GTP as their n/w is evolved from UMTS and they dont want too much hassles in managing different transport protocols(my guess). As a result of which, a user roaming between these two will not be supported home-routed traffic, he will only be local-breakout'ed. Therefore to support both home-routed and local breakout, S/PGWs have dual stacks.