Internet Draft


Network Working Group                              Tissa Senevirathne 
Internet Draft                                     Paul Billinghurst 
Document: draft-tsenevir-8021qospf-00.txt           
Category: Informational                            Nortel Networks 
                                                    
                                                   October 2000 
    
    
        Distribution of 802.1Q VLAN information using Opaque LSA 
    
    
Status of this Memo 
 
   This document is an Internet-Draft and is in full conformance with 
      all provisions of Section 10 of RFC2026 [1].  
    
   This document is an Internet-Draft and is NOT offered in accordance 
   with Section 10 of RFC2026, and the author does not provide the IETF 
   with any rights other than to publish as an Internet-Draft  
    
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   For potential updates to the above required-text see: 
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Abstract 
    
   This document presents the use of opaque LSAs to distribute 802.1Q 
   VLAN information across an Autonomous System. The concept of VLAN 
   domains and the identification and distribution of domain specific 
   VLAN information is discussed. 
    
    







  
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                   draft-tsenevir-8021qospf-00.txt       October 2000 
 
 
   Table of Content 
1. Conventions used in this document..................................2 
2. Introduction.......................................................2 
3. Opaque LSA overview................................................3 
3.1 Opaque LSA Types and VLAN flooding Scope..........................4 
4. VLAN LSA ID........................................................5 
5. VLAN distribution TLV format.......................................5 
6. Top Level TLV definitions..........................................6 
6.1. Domain ID TLV....................................................6 
6.2. Router ID TLV....................................................7 
6.3 BPDU TAG TLV......................................................8 
6.4 VLAN Distribution TLV.............................................8 
6.4.1 Top level VLAN Distribution TLV format..........................9 
6.4.2 VLAN sub-TLV format.............................................9 
6.4.3 Scope Label Sub-TLV............................................10 
6.4.4. Service Sub-TLV...............................................11 
6.4.5 Encoding of the VLAN sub TLV...................................11 
7. Global Service TLV................................................12 
7.1 Global Service TLV format........................................12 
7.2 Global Service TLV sub-Types.....................................13 
8. Encoding of Top Level TLVs........................................13 
9. Processing of the VLAN Distribution LSA...........................13 
10. Security Considerations..........................................14 
11. References.......................................................14 
12. Acknowledgments..................................................14 
13. Author's Addresses...............................................15 
Full Copyright Statement.............................................16 
 
1. Conventions used in this document 
    
   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 [2]. 
    
2. Introduction 
    
   There are several discussions and papers published on transporting 
   layer 2 traffic over MPLS networks. MPLS label defines the 
   forwarding of the packet as opposed to Network Layer information in 
   classical routing. Label based forwarding of Layer 3 packets has 
   lead to the popularity of MPLS in transporting non IP data over IP 
   networks. In this scenario the IP network layer is merely the 
   control plane used to establish the label switched data path. 
    
   Recently published papers on transportation of layer 2 traffic 
   across MPLS networks such as [3], assume static configuration of 
   specified layer 2 information such as VLANs and end router 
   information. With large layer 2 networks, such static configuration 
   lead to administrative burden. 
    
   This paper presents a dynamic method for distributing and 
   maintaining VLAN information within an autonomous system. 
    
  
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                   draft-tsenevir-8021qospf-00.txt       October 2000 
 
 
   Within a given autonomous system it is anticipated there will be 
   multiple VLAN domains. The term "domains" is used here to describe 
   VLAN topologies which are mutually exclusive within a defined 
   autonomous system. To reflect this, we define a new concept called 
   "VLAN domain identifier" 
    
   Distributed VLAN information is interpreted within the scope of a 
   "VLAN domain" 
    
   This paper utilizes Opaque LSAs defined in [4] to distribute the 
   required VLAN information. Opaque LSAs provide the necessary 
   flexibility to allow the required information to be transmitted 
   within their payload. Opaque LSAs define 3 different distribution 
   scopes. These distribution scopes are ideally suited to distribute 
   VLAN information, either locally, within an area or throughout an 
   entire autonomous system.   
    
3. Opaque LSA overview 
    
   Opaque LSAs were introduced in [4] as a means of distributing 
   additional information using the OSPF protocol. Opaque LSAs were 
   designed such that the payload of the LSA could contain information 
   that has meaning only within a certain application. The scope of the 
   application is defined by the Opaque Type. 
    
   Opaque LSA header is summarized below. Note fields not discussed are 
   used as specified in [4] 
     
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |            LS age             |     Options   |   9, 10 or 11 | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |  Opaque Type  |               Opaque ID                       | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                      Advertising Router                       | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                      LS Sequence Number                       | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |         LS checksum           |           Length              | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                                                               | 
   +                                                               + 
   |                      Pay Load                                 | 
   +                                                               + 
   |                              ...                              | 
    
   Opaque Type 
    
   Defines that this LSA is caring VLAN distribution information. 
    
   Opaque ID 
  
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   A unique 24 bit number that identify this LSA instance 
    
   Pay Load 
    
   Contain VLAN distribution information in Type/Length/Value (TLV) 
   format. 
    
    
3.1 Opaque LSA Types and VLAN flooding Scope 
    
   Three types of Opaque LSA have been defined. Each type has a 
   different flooding scope. Based on administrative requirements, 
   different LSA types may be used to distribute VLAN and service 
   information. 
    
   Based either on application or administrative requirements it may be 
   necessary to flood VLAN information across the entire autonomous 
   system, within a single area or just to the local subnet. To achieve 
   this we propose a locally configurable parameter "VLAN flooding 
   scope". Each VLAN entry or range of entries may have its own 
   flooding scope. In another words "VLAN flooding scope" is not a 
   system wide configuration but a per VFEC[3] definition. 
    
   Accordingly we define three VLAN flooding scopes as below: 
    
   Local Scope 
    
   LSA Type 9 is chosen for this. LSAs of type 9 are flooded only 
   within the local sub-network. Thus all VLAN (VFEC) information that 
   is to be restricted to the local subnet needs to be configured with 
   a VLAN flooding scope of Local Scope. 
    
   Area Scope 
    
   LSA Type 10 is chosen for this. LSAs of type 10 are flooded 
   throughout the local area. Thus all VLAN (VFEC) information that is 
   to be restricted to the local area needs to be configured with a 
   VLAN flooding scope of Area Scope. 
    
   Global Scope 
    
   LSA Type 11 is chosen for this. LSA of type 11 are flooded 
   throughout the entire autonomous system. Thus all VLAN (VFEC) 
   information that is required to be available through out the entire 
   autonomous system must be configured with a VLAN flooding scope of 
   Global Scope. 
    
   Note on Stub Areas and Not So-Stubby Areas (NSSA) 
    
   LSAs of Type 11 are not flooded to stub areas or NSSAs[4]. Hence 
   special note should be taken when VLAN reacahbility is required to 
   devices which reside in these area types. Devices within these areas 
  
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   should be statically configured with the required VFEC reachability 
   information. 
 
4. VLAN LSA ID 
    
   [4] Defines LSA ID as 8 bits for the Opaque Type and 24 bits for the 
   Opaque ID. Opaque IDs 0-127 are already allocated or reserved by 
   IANA. Values 128-255 are available for private or experimental 
   usage. At present we suggest use of Opaque Type 129 for the 
   distribution of VLAN information. However, if this proposal is 
   accepted it may be required to apply for a dedicated Opaque Type for 
   the VLAN distribution LSA. 
    
   The 24 bits of Opaque ID is VLAN distribution instance. This number 
   is assigned by the originating router and unique within the context 
   of that router. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |Opaque Type    |     VLAN distribution instance                | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Opaque Type 
    
   Identifies the VLAN distribution LSA. Suggested value is 129. 
    
   VLAN distribution instance 
    
   A 24-bit number assigned by the originating router. Unique within 
   the originating router. 
 
5. VLAN distribution TLV format 
    
   The VLAN Distribution LSA payload is defined in form of TLV which is 
   flexible enough to facilitate the introduction of new information as 
   required. In addition the format detailed below allows nested TLVs 
   and the ability to define sub TLVs 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type          |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                                                               | 
   ~                     Value..                                   ~ 
   |                                                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   Defines VLAN information TLVs (NOTE: These TLV values are 
   independent of the Opaque Type) 
  
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   Length 
    
   Length of the value field in bytes. 
    
   Value 
    
   Value of the TLV. The Value field is padded with zeros to the 
   nearest 32 bit boundary. As an example, a 3 byte long Value field 
   has a Length field of 3 and the last byte of the Value field is 
   padded with zero.  
    
6. Top Level TLV definitions 
    
   There are several TLV defined at the top level. Each of these TLVs 
   can possibly carry sub-TLVs. 
    
   Domain ID TLV                Mandatory 
   Router ID TLV                Mandatory 
   BPDU TAG TLV                 Mandatory*    
   VLAN Distribution TLV        Mandatory 
   Global Service TLV           Optional 
    
   * Mandatory only if the Spanning Tree Protocol is enabled on the 
   advertising router for the VLAN domain scope identified in the 
   Domain ID TLV sent in the same update. Otherwise this TLV should be 
   omitted. 
    
    
6.1. Domain ID TLV 
    
   Unlike IP addresses, VLAN allocation is entirely a local policy and 
   there is no global scope for a given VLAN Tag value. For example, 
   router A and B can both have same VLAN V but they may not 
   necessarily communicate or be related. To resolve this ambiguity, we 
   define a VLAN domain. VLANs within a given VLAN domain scope are 
   related. VLANs in different VLAN domains are considered mutually 
   exclusive. 
    
   We define the Domain ID TLV to carry VLAN domain information. The 
   VLAN Domain ID is statically configured. It is assumed that there is 
   an understanding of the Domain ID values between network 
   administrators responsible for each VLAN domain when allocating 
   those VLAN Domain IDs. The assignment of VLAN domain ID is entirely 
   an administrative matter and considered beyond the scope of the 
   discussion. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 1      |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |            Domain ID                                          | 
  
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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   Domain ID Type = 1 
    
   Length 
    
   Length of the Domain ID, presently 4 bytes 
    
   Domain ID 
    
   A 32-bit number that defines the scope of VLAN domain 
    
6.2. Router ID TLV 
    
   The Router ID TLV advertises the router ID of the originating 
   router. Other routers may use this as the end point IP address to 
   reach this VLAN. Hence it may be advisable to select the router ID 
   based on a loop back interface, instead of an interface IP address. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 2      |              Length                           | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |            Router ID - IPV4                                   | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   IP V4 Router ID = 2 
    
   Length 
    
   Length of the Router ID field - 4 bytes 
    
   Router ID 
    
   End point router IP V4 address. 
    
    
    
    
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 3      |              Length                           | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |            Router ID - IPV6                                   | 
   +                                                               + 
   |                                                               | 
  
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   +                                                               + 
   |                                                               | 
   +                                                               + 
   |                                                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   IP V6 Router ID = 3 
    
   Length 
    
   Length of the Router ID field - 12 bytes 
    
   Router ID 
    
   End point router IP V6 address 
    
6.3 BPDU TAG TLV 
    
   The BPDU Tag TLV advertises the TAG that this Router expects in an 
   incoming BPDU. If the 802.1D Spanning Tree Protocol is not enabled 
   on the advertising router for the VLAN domain scope identified in 
   the Domain ID TLV sent in the same update, then the BPDU TLV should 
   not be advertised. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 4      |              Length                           | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |          Reserved                     |  BPDU TAG             | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   BPDU TAG TLV = 4 
    
   Length 
    
   Length of the BPDU TAG TLV = 4 bytes 
    
   Reserved 
    
   Set to zero on transmission and ignored on reception 
    
   BPDU TAG 
    
   12 Bit TAG for the BPDU for this domain 
    
6.4 VLAN Distribution TLV 
    

  
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   VLAN distribution TLV is the top level TLV that distributes several 
   sub-TLVs that contain VLAN specific information. 
    
   There are three sub-TLVs defined under the top level VLAN 
   distribution TLV; 
    
   VLAN TLV             Mandatory 
   Scope Label TLV      Optional 
   Service TLV          Optional 
    
6.4.1 Top level VLAN Distribution TLV format 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 5      |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                                                               | 
   ~                     Value..                                   ~ 
   |                                                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   Top Level VLAN distribution TLV = 5 
    
   Length 
    
   Length of the value field in bytes. 
    
   Value 
    
   Value of the TLV. This contains all the sub TLVs. All sub-TLVs are 
   32-bit aligned and hence the value field of this TLV is a multiple 
   of 32-bit as well.  
    
6.4.2 VLAN sub-TLV format 
    
   VLAN sub-TLVs distribute VFEC entries; the distribution scope is 
   defined by the Domain ID TLV. 
    
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 1      |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |M| Reserved| F | Start VLAN TAG        | End VLAN TAG          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |M| Reserved| F | SP  | EP  |      Reserved                     | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
  
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   VLAN sub-TLV = 1 
    
   Length 
    
   Length of this TLV = 8 bytes 
    
   M 
    
   Matching Criteria. Conservative matching if M == 1 else Liberal 
   matching. See [3] for definition of Liberal and conservative 
   matching. 
    
   Reserved 
    
   All reserved fields are set to zero on transmission and ignored on 
   receipt. 
 
   F 
    
   P bit Range Match    - b'10 
   P bit Exact Match    - b'11 
    
   Start VLAN TAG 
    
   Starting TAG of this VFEC entry 
    
   End VLAN TAG 
    
   End TAG of the VFEC entry 
    
   SP  
    
     Starting value for P bits 
    
   EP  
    
    End value of P bits. This field is ignored if F == 11 
    
    
6.4.3 Scope Label Sub-TLV 
    
   Scope Label TLV distributes a locally significant label, which could 
   be used as a hidden label. The Scope Label, may be used to provide a 
   wider forwarding scope on top of the standard MPLS label. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 2      |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Reserved              |          Label                        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
  
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   Type 
    
   Scope Label Sub-TLV = 2 
    
   Length 
    
   Length of this TLV = 4 bytes 
    
   Reserved 
    
   Set to zero on transmission and ignored on reception. 
    
   Label 
    
   Hidden Label. 20 bit MPLS label. 
    
    
6.4.4. Service Sub-TLV 
    
   Service Sub-TLV defines various services offered in this VLAN or 
   group of VLANs. These services are specific to the corresponding 
   VLAN(s) and supercede equivalent Domain Services if they exist or 
   are specified (See below). Sub-TLV types 3 through 7 are allocated 
   for "VLAN Services". Specifics regarding actual services are 
   considered beyond the scope of this discussion. The purpose of this 
   TLV is to provide a framework to allow distribution of such 
   services. 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type =3 - 7   |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                                                               | 
   ~                     Value..                                   ~ 
   |                                                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Type 
    
   Service Sub-TLV presently 3 to 7 
    
   Length 
    
   Length of the Service Sub_TLV value 
    
   Value 
    
   Value of this TLV TBD 
    
6.4.5 Encoding of the VLAN sub TLV 
  
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   Encoding of nested sub-TLVs within the VLAN distribution TLV should 
   conform to the following sequence. 
    
   There must be at least one or more VLAN sub-TLV.  
    
   Corresponding Scope Label TLVs, if present, should immediately 
   follow the VLAN sub-TLV. If scope label TLV belongs to more than one 
   VLAN sub-TLV, it should appear after all the corresponding VLAN sub-
   TLV.  
    
   Service sub-TLV, if present should follow the Scope Label TLV. 
   Service sub-TLV should follow the VLAN sub-TLV(s), if Scope Label 
   TLV is not present. Presence of a new VLAN sub TLV ends the scope of 
   the Service and Scope Label sub-TLVs.  
    
   VLAN sub TLV that do not have Scope Label Sub-TLV and Service Sub-
   TLV must be encoded at the end. 
      
7. Global Service TLV 
    
   Global Service TLV allows the advertisement of various domain wide 
   services. The types of the services advertised are implementation 
   specific and beyond the scope of this document. However the 
   following nested TLV format with separate sub-TLVs for each service 
   or class of service is proposed. 
    
7.1 Global Service TLV format 
    
   0                   1                   2                   3 
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   | Type = 6      |               Length                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                                                               | 
   ~                     Value..                                   ~ 
   |                                                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
    
    
   Type 
    
   Global Service TLV = 6 
    
   Length 
    
   Length of the Global service TLV 
    
   Value 
    
   Contains nested sub-TLVs 
    
  
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7.2 Global Service TLV sub-Types 
    
   Allocation and definition of Global Service sub-Types are open to 
   discussion. At this point sub-Types 0-255 are reserved for private 
   and experimental usage. 
    
   However, if this proposal is accepted, it is suggested that values 
   0-127 are reserved for IANA allocation of well know services and 
   128-255 are for private and experimental usage. 
    
8. Encoding of Top Level TLVs 
    
   The first TLV in the VLAN distribution LSA payload MUST be the 
   Router ID TLV. Otherwise it is considered an erroneous TLV and MUST 
   be silently discarded. 
    
   The Domain ID TLV defines the scope of the VLAN domain. It MUST be 
   present and MUST immediately follow the Router ID TLV. 
    
   If present, the BPDU TLV MUST immediately follow the Domain ID TLV. 
    
   There MUST be at least one VLAN Distribution TLV. The VLAN 
   Distribution TLV must immediately follow the BPDU TLV, if present, 
   or Domain ID TLV if the BPDU TLV is not present. 
    
   If present, the Scope Label TLV MUST immediately follow the VLAN 
   Distribution TLV. 
    
   If present, the Global Service TLV MUST immediately follow the Scope 
   Label TLV. If the Scope Label TLV is not present, the Global Service 
   TLV MUST immediately follow the VLAN Distribution TLV. 
    
   Within a given VLAN Distribution LSA only information relating to a 
   single VLAN domain may be encoded. Separate VLAN Distribution LSAs 
   MUST be generated for each VLAN domain. Each of these LSAs has 
   unique VLAN distribution instance (see section 4). 
    
   Any VLAN Distribution LSA that violates the above rules MUST be 
   silently discarded. They SHOULD not be flooded. 
    
   At this point, it is suggested that only information relating to a 
   single VLAN domain is included in a single LSA. However there is 
   nothing in the TLV architecture presented here prevents multiple 
   VLAN Domain encoding in single LSA. Exact format for the VLAN 
   distribution LSA is open for discussion. 
    
9. Processing of the VLAN Distribution LSA 
    
   Only VLAN Distribution LSAs that belong to locally enabled VLAN 
   domains are processed and update VFEC tables. LSAs that do not 
   belong to the local domain may still be included in the Link State 
   Database and MUST be flooded according to OSPF[5] conventions. 
    
  
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   VLAN Distribution LSAs should NOT be included in SPF calculations. 
    
   Any changes to VFEC tables should trigger LSA updates. In addition, 
   all OSPF update events should trigger LSA updates. 
    
   VFEC table population based on received LSAs is performed per VLAN 
   domain. The exact procedures  for updating VFEC entries from 
   distributed VLAN information is implementation dependent.  
    
10. Security Considerations 
 
   This implementation does not affect the underlying security 
   requirements of OSPF. Implementations that wish to implement higher 
   levels of security should consider cryptographic OSPF [5]. 
    
    
11. References 
    
 
   1  Bradner, S., "The Internet Standards Process -- Revision 3", BCP 
      9, RFC 2026, October 1996. 
    
   2  Bradner, S., "Key words for use in RFCs to Indicate Requirement 
      Levels", BCP 14, RFC 2119, March 1997 
    
   3  Senevirathne, T and Billinghurst, P, "Use of CR-LDP or RSVP-TE to 
      Extend 802.1Q Virtual LANs across MPLS Networks", Work in 
      Progress, October 2000. 
    
   4  Coltun, R, "The OPSF Opaque LSA Option", Work in Progress, July 
      1998. 
    
   5  Moy, J., "OPSF Version 2", RFC 2328, April 1998. 
    
    
    
    
12. Acknowledgments 
    
   Ideas presented in this document have been influenced by sighted 
   references and ongoing work in the IETF. 












  
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13. Author's Addresses 
    
   Tissa Senevirathne 
   Nortel Networks 
   4401 Great America Pkwy, Santa Clara, CA 95054 
   Phone: 408-565-2571 
   Email: tsenevir@nortelnetworks.com 
    
    
   Paul Billinghurst 
   Nortel Networks 
   4401 Great America Pkwy, Santa Clara, CA 95054 
   Phone: 408-565-2357 
   Emial: pbilling@nortelnetworks.com






































  
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Full Copyright Statement 
 

   "Copyright (C) The Internet Society (date). All Rights Reserved. 
   This document and translations of it may be copied and furnished to 
   others, and derivative works that comment on or otherwise explain it 
   or assist in its implmentation may be prepared, copied, published 
   and distributed, in whole or in part, without restriction of any 
   kind, provided that the above copyright notice and this paragraph 
   are included on all such copies and derivative works. However, this 
   document itself may not be modified in any way, such as by removing 
   the copyright notice or references to the Internet Society or other 
   Internet organizations, except as needed for the purpose of 
   developing Internet standards in which case the procedures for 
   copyrights defined in the Internet Standards process must be 
   followed, or as required to translate it into 
    
    
    



































  
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