LTE - What will be destination address for DL packets that comes through GI interface?

Question

What will be destination address for DL packets that comes through GI interface?
Is it PGW or MS address ?

Answer 1

Not just a LTE case even same applies to UMTS also.

Say UE is trying to access google.com now google.com supplies the result of the search i.e. the downlink data. Now assume PGW/GGSN has assigned the address 10.1.1.1(private IP) to the UE, PGW address is 172.26.10.1 and Google.com address is 175.25.12.1

Now the packet with source IP as 10.1.1.1 and destination as google.com will reach to PGW (via LTE/UMTS network), now at PGW or any adjucent node 10.1.1.1 will be natted to a public IP which is assigned to to operator say 192.10.1.1 and will be forwarded to google.com, google.com will send the reply to the 192.10.1.1 as destination which will reach at PGW which will be reverse natted to 10.1.1.1 and Mobile network will drop it at UE.

Comments

nice Salil and can you also clarify how DL routed from Google server to 192.10.1.1 and 172.26.10.1.

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For the google.com server packet is coming from 192.10.1.1 so it will reply back to 192.10.1.1 which will be dropped to PGW because IP network is configured to drop the packet with dest address as 192.10.1.1 at the PGW.

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thanks......