для Cisco Cisco Packet Data Gateway (PDG)
Evolved Packet Data Gateway Overview
Features and Functionality ▀
ePDG Administration Guide, StarOS Release 18 ▄
25
Figure 3.
P-GW Static Selection
Table 5. P-GW Static Selection
Step
Description
1.
The AAA server sends the P-GW FQDN (Fully Qualified Domain Name) to the ePDG.
2.
The ePDG receives the P-GW FQDN from the AAA server as part of the MIP-Home-Agent-Host AVP in a Diameter EAP
Answer message.
The ePDG removes the first two labels of the received P-GW FQDN (if the FQDN starts with ‘topon’) to obtain the
Canonical Node Name ID of the P-GW. The ePDG uses this P-GW ID to send an S-NAPTR (Server-Name Authority
Pointer) query to the DNS proxy.
Answer message.
The ePDG removes the first two labels of the received P-GW FQDN (if the FQDN starts with ‘topon’) to obtain the
Canonical Node Name ID of the P-GW. The ePDG uses this P-GW ID to send an S-NAPTR (Server-Name Authority
Pointer) query to the DNS proxy.
3.
The DNS proxy send the S-NAPTR query to the DNS.
4.
The DNS may return multiple NAPTR resource records with an ‘A’ flag (for an address record) with the same or different
service parameters.
service parameters.
5.
The DNS proxy forwards the two NAPTR resource records to the ePDG.
6.
The ePDG selects the replacement string (the P-GW FQDN) that matches the service parameter if ePDG is configured as
MAG for PMIPv6 protocol or service parameter 'x-3gpp-pgw:x-s2b-gtp' when ePDG is configured for GTP protocol
support. The ePDG then performs an A/AAAA query with the selected replacement string (the P-GW FQDN).
MAG for PMIPv6 protocol or service parameter 'x-3gpp-pgw:x-s2b-gtp' when ePDG is configured for GTP protocol
support. The ePDG then performs an A/AAAA query with the selected replacement string (the P-GW FQDN).
7.
The DNS proxy send the A/AAAA query to the DNS.
8.
The DNS returns the IP address of the P-GW.
9.
The DNS proxy forwards the P-GW IP address to the ePDG.