icmp encapsulation

fırat sönmez firatssonmez at gmail.com
Thu Feb 1 07:00:26 UTC 2018


I would like to ask&know how the GGSN holds and finds pdp contexts for icmp
packets that have same source and destination address on the downlink?

For example, if there are two hosts having same IP address behind two
different network pinging same destination address and they are
encapsulated at SGSN and then one GGSN receives both and saves the packet,
decapsulates and sends to the destination. On the downlink destination
responds to the two ping packets (they are different because they have
different identifier in icmp packet), but then how does GGSN finds the pdp
contexts again to encapsulate these packets and send back to the two SGSNs?
The pdp context doesnt include thse icmp identifiers. There is no sockets
either since icmp doesnt have sockets. On the downlink, when there are two
icmp packets recieved by GGSN, there is only icmp identfier that
distinguish each other, but this identifier is not in the pdp context.

Would someone help me figure out this?
Thank you all
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