HP 3000 Manuals HP 3000 Manuals
Routing and Addressing
The term "routing" is common to any store-and-forward network (for
example, packet switched) in which a message, or block of data may pass
through several switching points or "nodes" in its passage from the
source to the destination. The route is the information that describes
the path to be taken by the data. Usually, a route is calculated as
either the quickest or most economical path for the data to be passed
through the network.
Routing for X.400 occurs on a store and forwardbasis. Each MTA along the
route of a message determines the next MTA to which the message should be
transferred. Thus, the local MTA on X.400 determines to which adjacent
MTAthe message is to be forwarded. If a message has multiple recipients,
and the local MTA determines that the messageneeds to be forwarded to
more than one adjacent MTA, then copies of the message are made.
Route information must be present on each node in the network. When a
message is received at the node, it becomes the responsibility of the
MTAon that node to ensure that the message is correctly routed to the
next point. The route information for X.400 is referred to as the
routing table. It consists of a set of configured routes, such that a
destination like an adjacent MTA can be determined for every
recipientwithin a message arriving. Each route has a destination and a
set of O/R addressattributes. The local MTA calculates the route by
comparing the recipient O/R address within a message to the O/R address
specified for each route.
For X.400 MHS routing, remember the following:
* A route is the path a message takes from the Originating UA to the
Recipient UA.
* The "Recipient O/R address" within the message is used to
calculate each step of the route.
* Each of the nodes through which a message passes has an MTA and
routing information used by that MTA to calculate the next step of
the route.
The complexity of the routing information depends on the topology of the
network and the number of interconnections between MTAs. If one MTA has
only a single MTA connected to it, the routing information used by the
first MTA is simple. There is only one route. If, however, the MTA is
directly connected to two or more MTAs, the routing information is more
complex, and needs to be carefully calculated.
The Network Administrator
responsible for configuring and administering a network must carry out
this process on each node in the network that hosts an MTA. For each
recipient O/R address that is received by that MTA, the next step of the
routeis determined using the routing information on that node. The next
step may be an adjacent MTA, or a locally connected UA if the final
destination of the message is a local user. For HP X.400 using HP
Desk,the next step may also be an HP X.400/HP Desk Node if the message is
destined for an HP Desk user.
In HP's X.400 implementation, the local MTA looks at the recipient O/R
address in a received message and compares it, element by element,
against the attributes specified for a route. If the elements in the
recipient O/R address are perfectly matched with those in the route, then
the destination specified for that route is used. Otherwise, the
recipientO/R address is checked against other routes in the routing
table.
A match occurs only if all attributes in the route match those in the
recipient O/R address. However, the route may contain only a subset of
the attributes in the recipient address. If an attribute in a route is
omitted, the attribute matches any value for that attribute in a received
message. If multiple routes match, then the MTA delivers the message to
the route it first encounters. Use x4rtview to determine the
destination.
One or more wildcards, asterisks (*), can be inserted into a route
attribute. If an asterisk is entered into the country code, the asterisk
must be the only character entered. The asterisk matches any string of
characters. An attribute that consists of only an asterisk is the same
as omitting that attribute. The MTA routes a message more quickly if an
attribute is omitted. The country code can be omitted.
A null character (#)can be entered into a route attribute. If the null
character is entered into a route attribute, the null character must be
the only character entered.
The null character matches an attribute that is not present in an O/R
address. For example, if the null character is entered for the ADMD,
then a route would only match the O/R address if it has no ADMD.
It is possible that no route will match a recipient O/R address. When
this happens, the message becomes nondeliverable. A nondelivery
reportwould be generated and sent to the originatorof the message.
"Try to route messages on the same elements of the O/R address."
For example, try to use the ADMD, PRMD, and Organization Name elements to
route messages from your PRMD, and the Organizational Unit 1 to route
messages within your PRMD.
It is important that all the relevant elements are specified in the
route, such as the Country, ADMD, and PRMD. The key elementthat
determines the route should always be specified.
Example
In the following example, route 1 or route 2 may be used for this
recipient since both match the O/R address attributes. Which route the
MTA uses is determined by which route the MTA first encounters. Use
x4rtview to determine the destination. Route 3 would not be used because
the organization name does not match. Route 4 would not be used because
the ADMD does not match.
Recipient O/R Country = US
Address ADMD = HP-USA
PRMD = HP-PRMD
Org Name = Information Networks Division
Org Unit 1 = Marketing
Org Unit 2 = Customer Support
Personal Name = John Doe
Route 1 Country = US
ADMD = HP*
PRMD = HP-PRMD
Destination = MTA1
Route 2 Country = US
ADMD = HP-USA
PRMD = HP-PRMD
Org Name = Information Networks Division
Destination = MTA2
Route 3 Country = US
ADMD = HP-USA
PRMD = HP-PRMD
Org Name = Business Networks Division
Destination = MTA3
Route 4 Country = US
ADMD = #
PRMD = HP*
Org Name = Information Networks Division
Org Unit 1 = Marketing
Destination = MTA4