Proposed TLA and NLA Assignment Rule (RFC2450)
Original Publication Date: 1998-Dec-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
This document proposes rules for Top-Level Aggregation Identifiers (TLA ID) and Next-Level Aggregation Identifiers (NLA ID) as defined in [AGGR]. These proposed rules apply to registries allocating TLA ID's and to organizations receiving TLA ID's.
Network Working Group R. Hinden
Request for Comments: 2450 Nokia
Category: Informational December 1998
Proposed TLA and NLA Assignment Rules
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document proposes rules for Top-Level Aggregation Identifiers
(TLA ID) and Next-Level Aggregation Identifiers (NLA ID) as defined
in [AGGR]. These proposed rules apply to registries allocating TLA
ID's and to organizations receiving TLA ID's.
This proposal is intended as input from the IPng working group to the
IANA and Registries. It is not intended for any official IETF
status. Its content represents the result of extensive discussion
between the IPng working group, IANA, and Registries.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
The proposed TLA and NLA assignment rules described in this document
are intended for the first two years of IPv6 TLA address assignments.
As routing technology evolves and we gain additional experience with
allocating IPv6 addresses the procedures proposed in this document
3.0 IPv6 Aggregatable Global Unicast Address Format
This document proposes assignment rules for the TLA ID and NLA ID
fields in the IPv6 Aggregatable Global Unicast Address Format. This
address format is designed to support both the current provider-based
aggregation and a new type of exchange-based aggregation. The
combination will allow efficient routing aggregation for sites that
connect directly to providers and for sites that connect to
exchanges. Sites will have the choice to connect to either type of
While this address format is designed to support exchange-based
aggregation (in addition to current provider-based aggregation) it is
not dependent on exchanges for its overall route aggregation
properties. It will provide efficient route aggregation with only
The aggregatable global unicast address format as defined in [AGGR]
is as follows:
| 3| 13 | 8 | 24 | 16 | 64 bits |
|FP| TLA |RES| NLA | SLA | Interface ID |
| | ID | | ID | ID | |
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