Margaret Wasserman wrote: >>In 3GPP, the SGSN keeps track of the status of the GGSN and will inform >>hosts if their GGSN went down. The 'keeps track' mechanism involves an IP packet >>exchange, so in order for the SGSN to think that the GGSN is up, the GGSN >>must be responding at layer 3. If the GGSN is up but not forwarding, I >>believe it would send ICMP errors. > > Does the SGSN inform the host of the fact that the GGSN is up on an ongoing basis? > Or only contact the host when the GGSN goes down? > > If the former, whatever host process receives this notification could give advice to >ND > to avoid NUD messages. > > If the latter, then we probably don't want to supress NUD messages based on a lack > of bad news from the SGSN -- what if we can't reach either the SGSN or the GGSN?
The former. If the 2-way connection to the SGSN dies or the whole SGSN dies, the air link is down in a manner that is observable to the host. In conclusion, I think we should formulate the text to indicate that lower layer connectivity information is available in this specific case, and should be used to suppress NUD, as described in the original RFC. Jari -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
