Subject: [AAA-WG]: Suggestion about hierarchical realms a poor one

From: Johan Johansson <[email-masked]>
Date: Sun, 07 Apr 2002 18:56:12 +0000

Issue:          Suggestion about hierarchical realms a poor one
Submitter name: Johan Johansson
Submitter email address:[email-masked]
Date first submitted: 04-09-2002 
Reference: 
Document:       draft-base-10-2
Comment type:   Technical 
Priority:       1 
Section: 6.1   

Rationale:

The suggestion is that

For routing of Diameter messages to work within an administrative
   domain, all Diameter nodes within the realm MUST be peers. If
   intermediate nodes are desired (see Figure 5), the destination node
   MUST be in a subrealm and routes to that subrealm MUST exist in the
   routing table on the sending node and all intermediate nodes. Figure
   5 shows an example of a hierarchical network that requires the use of
   subrealms. In such a network, routing must be performed with longest
   match from right.

Figure 5 then goes on to describe a realm abc.com with e.g. a subrealm 
called eng.abc.com and a relay node in between. It may not be obvious 
from the draft, but the original example discussed that motivated this 
text and figure in the first place as within the context of the mobile 
ip application where there was a home server in the containing realm 
abc.com and the home agents within the respective subrealms.

Assume that there is a user called [email-masked] whose AMR is 
handled by the server aaah.abc.com. This is a centralized home server 
that serves the entire realm abc.com and therefore it has a route for 
abc.com that on longest match from right has a LOCAL_ACTION entry. 
Unfortunately this will never be selected since it must have a route to 
eng.abc.com in order to send the HAR to the home agent, which means that 
the AMR will arrive at a very surprised home agent.

Requested change:

Given the time constraints my suggestion is to fumble the issue and 
remove all mention of it from the document. Route configuration and 
network topology, within the context of the Mobile IP Diameter 
application at least, is a surprisingly non-intuitive topic.

j

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From: Bernard Aboba <[email-masked]>
Date: Wed, 10 Apr 2002 07:32:18 -0700 (PDT)

Assigned Issue #328.