BIG-IP : http profile : insert x-forwarded-for : enabled

From: https://support.f5.com/kb/en-us/solutions/public/4000/800/sol4816.html Many servers and applications expect only a single X-Forwarded-For header, per request. However, the BIG-IP system appends a new X-Forwarded-For header to the existing set of HTTP headers, even if there is an existing X-Forwarded-For header in the request. Both approaches are valid according to the Internet Engineering Task Force (RFC2616, Section 4.2). For applications expecting a single X-Forwarded-For header, it is possible to use an iRule instead of the HTTP profile option to append the client IP value to the end of any existing X-Forwarded-For header. F5 DevCentral iRules codeshare contains an example of such an iRule: X Forwarded For Single Header Insert. A DevCentral login is required to access this content. https://devcentral.f5.com/s/feed/0D51T00006i7OV1SAM

thanks Greg - if added via http profile , is X-Forwarded-For available during irule processing ?

for the case where the incoming request contains a collection of one or more XFF headers , what are the reasons behind BIG-IP's default practice of appending a new XFF header to the end of the collection ( as opposed to consolidating existing values into a comma-separated list of IPs stored in a single XFF header ) ?