In a EPC scenario the Authentication <\/strong>function takes the form verifying the subscriber is valid and knows the K & OP\/OPc keys for their specific IMSI.<\/p>\n\n\n\n The Authorization<\/strong> function checks to find out which features, APNs, QCI values and services the subscriber is allowed to use.<\/p>\n\n\n\n The Accounting<\/strong> function records session usage of a subscriber, for example how many sessional units of talk time, Mb of data transferred, etc.<\/p>\n\n\n\n Diameter Packets are pretty simple in structure, there’s the packet itself, containing the basic information in the headers you’d expect, and then a series of one or more Attribute Value Pairs or “AVPs”.<\/p>\n\n\n\n These AVPs are exactly as they sound, there’s an attribute name, for example username, and a value, for example, “Nick”.<\/p>\n\n\n\n This could just as easily be for ordering food; we could send a Diameter packet with an imaginary command code for Food Order Request<\/em>, containing a series of AVPs containing what we want. The AVPs could belike Food: Hawian Pizza, Food: Garlic Bread, Drink: Milkshake, Address: MyHouse. Diameter packets generally take the form of a request – response, for example a Capabilities Exchange Request<\/em> contains a series of AVPs denoting the features supported by the requester, which is sent to a Diameter peer. The Diameter peer then sends back a Capabilities Exchange Response, containing a series of AVPs denoting the features that it supports.<\/p>\n\n\n\n Diameter is designed to be extensible, allowing vendors to define their own type of AVP and Diameter requests\/responses and 3GPP have defined their own types of messages (Diameter Command Codes) and types of data to be transferred (AVP Codes).<\/p>\n\n\n\n LTE\/EPC relies on Diameter and the 3GPP\/ETSI defined AVP \/ Diameter Packet requests\/responses to form the S6a Interface <\/strong>between an MME and a HSS<\/em>, the Gx Interface <\/strong>between the PCEF and the PCRF<\/em>, Cx Interface<\/strong> between the HSS and the CSCF<\/em>, and many more interfaces used for Authentication in 3GPP networks.<\/p>\n","protected":false},"excerpt":{"rendered":" A primer to the Diameter protocol and it’s usage.<\/p>\n","protected":false},"author":1,"featured_media":1037,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[134,160,133,349,37,22,528,2],"tags":[223,224],"class_list":["post-1036","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-epc","category-eutran","category-lte","category-plmn","category-rf","category-standards","category-sdm","category-voip","tag-diameter","tag-rfc6733"],"_links":{"self":[{"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/posts\/1036","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/comments?post=1036"}],"version-history":[{"count":1,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/posts\/1036\/revisions"}],"predecessor-version":[{"id":1038,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/posts\/1036\/revisions\/1038"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/media\/1037"}],"wp:attachment":[{"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/media?parent=1036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/categories?post=1036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nickvsnetworking.com\/wp-json\/wp\/v2\/tags?post=1036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
The Diameter server could then verify we’re allowed to order this food (Authorization<\/strong>) and charge us for the food (Accounting<\/strong>), and send back a Food Order Response<\/em> containing a series of AVPs such as Delivery Time: 30 minutes, Price: $30.00, etc.<\/p>\n\n\n\n![\"\"](\"https:\/\/nickvsnetworking.com\/wp-content\/uploads\/2019\/06\/2019-06-30-01_32_08-S6aConnect.pcap_.png\")
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