Phil, The first bit within the Source Address Field is normally the I/G bit, to define if the source address is individual (unicast) or group (multicast) address. In an SRB bridged environment, this one bit is used to indicate if any Routing Information Field (RIF) information is present in the Token frame following the SA field.
This bit will be set by hosts with the SRB environment and used by bridges to indicate the above. The hosts will keep a "forwarding table" on how to reach any required destination host. If the host doesn't know how to get to a particular destination, it will send out an explorer frame (all routes explorer -ARE) or a Spanning tree explorer (SPE) frame to locate the destination. It will depending on your bridged environment which explorer frame is used. The first SRB enabled bridge in the path (from originator to destination) will see that this is an explorer packet and add its route designator (RD) information to the RIF. The first bridge will add the first ring number, it's bridge number, and the ring number of the interface it going to send the explorer packet out of. When all said and done - the host will know how to reach that particular end host and include RIF information in the token frame. The RII, will tell the bridge that a RIF is present and forward the frame according to the RIF RC and RD fields. Ken Sexton Data Network Engineering ICG Communications [EMAIL PROTECTED] -----Original Message----- From: Phil Barker [mailto:[EMAIL PROTECTED]] Sent: Wednesday, March 06, 2002 6:35 AM To: [EMAIL PROTECTED] Subject: certificationZone Bridging White paper ! [7:37393] Just been re-reading this paper by David Wolfsener. See SNIP below. In the instance where the RII indicator is a 1 the frame will be 'source routed' if the frame is 'source routed' then surely this implies that the RIF must be manipulated in order to reflect the true Source Route !!! I havn't got my 'Interconnections' with me so I cannot confirm. Any ideas ? Phil. >>> SNIP Source Route Transparent Bridging (SRT) SRT works by analyzing the RII bit to determine if a RIF is present. If the RII bit is 0, then a RIF is not present and the frame is transparently bridged. If, however, the RII bit is 1 and a RIF is present, then the frame is source routed. Note that SRT bridges do not add or remove RIFs to frames. By now, you ought to wonder how to configure SRT. >>> END __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=37398&t=37393 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
