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Chapter 13
Management Network Connectivity
13.6.5 TARP
TARP is used when TL1 target identifiers (TIDs) must be translated to NSAP addresses. The
TID-to-NSAP translation occurs by mapping TIDs to the NETs, then deriving NSAPs from the NETs by
using the NSAP selector values
TARP uses a selective PDU propagation methodology in conjunction with a distributed database (that
resides within the NEs) of TID-to-NET mappings. TARP allows NEs to translate between TID and NET
by automatically exchanging mapping information with other NEs. The TARP PDU is carried by the
standard CLNP Data PDU. TARP PDU fields are shown in
Table 13-9
Field
TARP Lifetime
TARP Sequence
Number
Protocol
Address Type
TARP Type
Code
TID Target
Length
TID Originator
Length
Protocol
Address Length
TID of Target
TID of
Originator
Protocol
Address of
Originator
Table 13-10
Table 13-10
Type
1
2
78-18106-01
(Table 13-8 on page
TARP PDU Fields
Abbreviation Size (bytes) Description
tar-lif
tar-seq
tar-pro
tar-tcd
tar-tln
tar-oln
tar-pln
tar-ttg
tar-tor
tar-por
shows the TARP PDUs types that govern TARP interaction and routing.
TARP PDU Types
Description
Sent when a device has a TID for which
it has no matching NSAP.
Sent when a device has a TID for which
it has no matching NSAP and no
response was received from the Type 1
PDU.
13-32).
Table
2
The TARP time-to-live in hops.
2
The TARP sequence number used for loop detection.
1
Used to identify the type of protocol address that the
TID must be mapped to. The value FE is used to
identify the CLNP address type.
1
The TARP Type Code identifies the TARP type of
PDU. Five TARP types, shown in
defined.
1
The number of octets that are in the tar-ttg field.
1
The number of octets that are in the tar-tor field.
1
The number of octets that are in the tar-por field.
n = 0, 1, 2... TID value for the target NE.
n = 0, 1, 2... TID value of the TARP PDU originator.
n = 0, 1, 2... Protocol address (for the protocol type identified in the
tar-pro field) of the TARP PDU originator. When the
tar-pro field is set to FE (hex), tar-por will contain a
CLNP address (that is, the NET).
Actions
After an NE originates a TARP Type 1 PDU, the PDU
is sent to all adjacent NEs within the NE routing area.
After an NE originates a TARP Type 2 PDU, the PDU
is sent to all Level 1 and Level 2 neighbors.
Cisco ONS 15454 Reference Manual, R8.5
13.6.5 TARP
13-9.
Table
13-10, are
13-37
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