| Internet-Draft | BGP-LS2C | August 2023 |
| Chen & Su | Expires 12 February 2024 | [Page] |
The goal is to collect the security capabilities of nodes, which will be one of the factors to form the routing topology, and use the routing programming capabilities to form a secure routing path.¶
The BGP-LS protocol is extended to carry the security capabilities of the node. The controller collects topology information, forms a topology path with security capabilities according to security requirements, and supports SRv6 path sending to execute node forwarding through programming.¶
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Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
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This Internet-Draft will expire on 12 February 2024.¶
Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
SRv6 (Segment Routing IPv6, IPv6 segment routing) is based on source routing and centralized routing. It can realize network intelligent programming and select forwarding paths according to customer needs. At present, there is a lack of effective technical means to inject security factors into the process of collecting network topology and centralized routing to achieve safe routing path forwarding.¶
The most important reason for using BGP-LS as the extended basic protocol is that BGP-LS shields the differences of other routing protocols, and the underlying routing protocol types do not need to be considered when transmitting security capabilities.¶
RFC7752 standardized North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP, describes a mechanism by which link-state and TE information can be collected from networks and shared with external components using the BGP routing protocol, using a new BGP Network Layer Reachability Information (NLRI) encoding format.¶
BGP-LS is a new way to collect network topology. The topology information discovered by the IGP protocol is summarized by the BGP protocol and sent to the upper controller. With the powerful routing and routing capabilities of the BGP protocol, there are three types of BGP-LS routes, which are used to carry node, link and route prefix information respectively. The three routes cooperate with each other to complete the transmission of topology information. The node routing function is to record the node information of the topology, the link routing function is to record the link information between two devices, and the address prefix routing function is to record the network segment information that the node can reach.¶
The state information NLRI collected by BGP-LS is described in TLV (type/length/value triplet) format. Each link state described by NLRI can identify a node, link or prefix. Therefore, three types of NLRI are newly set in the standard, of which type 3 and 4 are used to distinguish the prefix of IPv4 and IPv6. There are only two types of NLRI attributes in the original BGP protocol: MP_ REACH_ NLRI, attribute type 14; MP_ UNREACH_ NLRI, attribute type 15.¶
+----------+
+--------+Controller+-----------+
| +----------+ |
BGP-LS(Node) |
| |
xxxxxxxx|xxxxxxxxx |
x | x |
x +-----+-+ x +-----+-+
x |Router | x |Router |
x +----+--+ x +-+---+-+
x | x | |
x | x +------+ |
x | x | |
x +----+----+ x +---+----+ +--+-----+
x |Security | x |Security| |Security|
x |Products | x |Products| |Products|
x +---------+ x +--------+ +--------+
xxxxxxxxxxxxxxxxxx
Figure 1: Router and attached security products are used as node units
¶
The Local Node Descriptors TLV contains Node Descriptors for the node anchoring the local end of the link. This is a mandatory TLV in all three types of NLRIs (node, link, and prefix).¶
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Local Node Descriptors TLV Format
¶
Node attribute TLVs are the TLVs that may be encoded in the BGP-LS attribute with a Node NLRI. The following Node Attribute TLVs are defined:¶
+-------------+----------------------+----------+
| TLV Code | Description | Length |
| Point | | |
+-------------+----------------------+----------+
| 263 | Multi-Topology | variable |
| | Identifier | |
| 1024 | Node Flag Bits | 1 |
| 1025 | Opaque Node | variable |
| | Attribute | |
| 1026 | Node Name | variable |
| 1027 | IS-IS Area | variable |
| | Identifier | |
| 1028 | IPv4 Router-ID of | 4 |
| | Local Node | |
| 1029 | IPv6 Router-ID of | 16 |
| | Local Node | |
+-------------+----------------------+----------+
Table 3: Node Attribute TLVs
¶
The security capability is transferred by adding the security capability attribute to the attributes of the local node.¶
+-------------+----------------------+----------+
| TLV Code | Description | Length |
| Point | | |
+-------------+----------------------+----------+
| TBD1 | Node Security | variable |
| | Capability | |
+-------------+----------------------+----------+
Table 4: New Node Attribute TLV
¶
When programming the routing path, take the security capability requirement as one of the inputs. The description of the security capability requirement can be structured or one-dimensional matrix, which only needs to be consistent with the router's security capability description; There are many routing rules. After introducing security capability requirements, it is necessary to dynamically adjust the security capability as the position of routing rules according to the requirements. The main rule strategies are: ① Select the routing node that meets the security requirements as the forwarding node when the path is reachable; ② Select the shortest path when all the safety requirements are met; ③ When the same path length and security requirements are met, select the path with small load for forwarding.¶
+----------+
+--------+Controller+-----------+
| +----------+ |
| |
| |
xxxxxxxxxxxxxxxxxx |
x | x |
x +-----+-+ x BGP-LS(Link) +-----+-+
x |Router |----x------------------|Router |
x +----+--+ x +-+---+-+
x | x | |
x | x +------+ |
x | x | |
x +----+----+ x +---+----+ +--+-----+
x |Security | x |Security| |Security|
x |Products | x |Products| |Products|
x +---------+ x +--------+ +--------+
xxxxxxxxxxxxxxxxxx
Figure 5: The peer node transmits the security capability through the link
¶
The router and its attached security products are the basic units. When collecting status information, only some nodes can directly transmit the node status information to the controller through the BGP-LS protocol. Other nodes that do not directly transmit the node information need to transmit the node information to the direct node to achieve the transmission of security capability information. Therefore, for non direct nodes, It is required to report its own security capability information through the BGP-LS link state data packet.¶
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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Remote Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: The Link NLRI Format
¶
+-----------+---------------------+--------------+
| TLV Code | Description | IS-IS TLV |
| Point | | /Sub-TLV |
+-----------+---------------------+--------------+
| 1028 | IPv4 Router-ID of | 134/--- |
| | Local Node | |
| 1029 | IPv6 Router-ID of | 140/--- |
| | Local Node | |
| 1030 | IPv4 Router-ID of | 134/--- |
| | Remote Node | |
| 1031 | IPv6 Router-ID of | 140/--- |
| | Remote Node | |
| 1088 | Administrative | 22/3 |
| | group (color) | |
| 1089 | Maximum link | 22/9 |
| | bandwidth | |
| 1090 | Max. reservable | 22/10 |
| | link bandwidth | |
| 1091 | Unreserved | 22/11 |
| | bandwidth | |
| 1092 | TE Default Metric | 22/18 |
| 1093 | Link Protection | 22/20 |
| | Type | |
| 1094 | MPLS Protocol Mask | --- |
| 1095 | IGP Metric | --- |
| 1096 | Shared Risk Link | --- |
| | Group | |
| 1097 | Opaque Link | --- |
| | Attribute | |
| 1098 | Link Name | --- |
+-----------+---------------------+--------------+
Table 7: Link Attribute TLVs
¶
The new attribute describes the link security capability and transmits the link security capability information through this attribute.¶
+-----------+---------------------+--------------+
| TLV Code | Description | IS-IS TLV |
| Point | | /Sub-TLV |
+-----------+---------------------+--------------+
| TBD2 | Link security info | --- |
+-----------+---------------------+--------------+
Table 8: New Link Attribute TLVs
¶
+------+ +------+
| A | | B |
+---+--+ +--+---+
|SCicg A |
+--------------->|
| SCing B |
<----------------+
|SCing <A,B> |
+---------------->
| |
Figure 9: Assosiation security capability interaction
¶
The Assosiation security capability depends on the security capability enabled by the node. As a node directly connected to the controller, node B first interacts with the enabled security capability information of the opposite end in a two-way manner, and then the opposite end initiates the transmission of the assosiation security capability information.¶
The decision of assosiation security capability can be divided into two situations: one is under the same security domain, and the other is under different security domains. 1. The decision rules for link security capabilities under different security domains are as follows: SCing represents the enabled security capabilities of a node. Example: SCing A=[1,0,0,1,0,……]，SCing B=[1,1,0,1,0,……]，SCing Assosiation<A,B> = SCing A && SCing B¶
When the link passes through more than two nodes, it is necessary to logically and operate the security capabilities of all nodes in the path to obtain the link security capabilities.¶
When the link passes through more than two nodes, it is necessary to logically or operate the security capabilities of all nodes in the path to obtain the link security capabilities.¶
+----------+ +----------+
+Controller+ +Controller+
+----------+ +----------+
| |
| AS 100 |
xxxxxxxxxxxxxxxxxx |AS 200
x | x xxxxxxx|xxxxxxxx
x +-----+-+ x BGP-LS(Prefix) x +-----+-+ x
x |RouterA|----x-----------------x--|RouterE| x
x +----+--+ x x +-+---+-+ x
x | x xxxxxxxxxxx | | x
x | x x +------+ | x
x | x x | | x
x +----+--+ x x +---+--+ +--+---+ x
x |Router | x x |Router|--|Router| x
x +-------+ x x +------+ +------+ x
xxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx
Figure 10: Security capability is transferred between ASs through Prefix
¶
The router and its attached security products are the basic units. When collecting the status information, only some nodes can directly transmit the node status information to the controller through the BGP-LS protocol. Other nodes that do not directly transmit the node information need to transmit the node information to the directly connected node to achieve the transmission of security capability information. In the figure, nodes A and E are direct connected nodes, which are connected to their respective controllers. Nodes A and E are responsible for collecting the security capabilities of other nodes in their respective fields.¶
The IPv4 and IPv6 Prefix NLRIs (NLRI Type = 3 and Type = 4) use the same format, as shown in the following figure.¶
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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Prefix Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: The IPv4/IPv6 Topology Prefix NLRI Format
¶
+---------------+----------------------+----------+
| TLV Code | Description | Length |
| Point | | |
+---------------+----------------------+----------+
| 1152 | IGP Flags | 1 |
| 1153 | IGP Route Tag | 4*n |
| 1154 | IGP Extended Route | 8*n |
| | Tag | |
| 1155 | Prefix Metric | 4 |
| 1156 | OSPF Forwarding | 4 |
| | Address | |
| 1157 | Opaque Prefix | variable |
| | Attribute | |
+---------------+----------------------+----------+
Table 12: Prefix Attribute TLVs
¶
An AS has at least one super direct connection node, which has the security capability information of all nodes under the AS. By adding new attributes to Prefix, the security capabilities of the entire AS can be transferred.¶
+---------------+--------------------------+----------+
| TLV Code | Description | Length |
| Point | | |
+---------------+--------------------------+----------+
| TBD3 | AS security capabilities | variable |
+---------------+--------------------------+----------+
Table 13: New Prefix Attribute TLVs
¶
AS Security capabilities means the security capability information of all nodes under the AS, that is, the security capability information of all nodes is spliced, such as {[IP address (A)+node security capability], [IP address (B)+node security capability]...}.¶
This memo includes no request to IANA.¶