EP-4738783-A1 - BORDER GATEWAY PROTOCOL SESSION MANAGEMENT

Abstract

Devices and methods are provided for exchanging route type capabilities between peer network devices, for example, Border Gateway Protocol (BGP) speakers, to prevent a BGP session reset when a particular route type is not supported by one of the peer network devices. A network device, that supports a set of route types, receives an announcing message indicating a route type capability of a peer network device. The network device selects a subset of route types supported by the peer network device from the set of route types based on the route type capability of the peer network device. The network device transmits an update message that advertises the subset of route types to the peer network device. Thus, a route type supported by the network device is not included in the update message if the route type is not advertised in the announcing message by the peer network device.

Inventors

• ANANTHAMURTHY, KRISHNASWAMY
• KUMAR, NITIN
• MOHANTY, Satya R.
• KRATTIGER, LUKAS
• MISHRA, MANKAMANA PRASAD

Assignees

• Cisco Technology, Inc.

Dates

Publication Date

20260506

Application Date

20250910

Claims (16)

1. A network device, comprising: means for receiving an announcing message configured to indicate a route type capability of a peer network device, wherein the network device supports a set of route types; means for selecting, based on the route type capability of the peer network device, a subset of route types from the set of route types, wherein the subset of route types is supported by the peer network device; and means for transmitting an update message configured to advertise the subset of route types to the peer network device.
2. The network device of claim 1, further comprising means for transmitting another announcing message configured to indicate a route type capability of the network device to the peer network device.
3. The network device of claim 2, further comprising means for transmitting the another announcing message prior to transmitting the update message.
4. The network device of any of claims 1 to 3, further comprising means for establishing a Border Gateway Protocol session between the network device and the peer network device based on the announcing message, optionally further comprising means for transmitting the update message during the Border Gateway Protocol session.
5. The network device of any of claims 1 to 4, wherein the route type capability indicates one or more route types supported by the peer network device.
6. The network device of any of claims 1 to 5, wherein the announcing message corresponds to a Border Gateway Protocol OPEN message, optionally wherein the Border Gateway Protocol OPEN message includes an optional parameters field that is configured to indicate the route type capability.
7. The network device of any of claims 1 to 6, wherein the update message corresponds to a Border Gateway Protocol UPDATE message, optionally wherein the Border Gateway Protocol UPDATE message includes a network layer reachability information field that is configured to advertise the subset of route types.
8. The network device of any of claims 1 to 7, wherein the route type capability is associated with at least one of an Address Family Indicator (AFI) or a Subsequent AFI (SAFI), optionally wherein the announcing message is further configured to indicate at least one of the AFI or the SAFI.
9. The network device of any of claims 1 to 8, wherein the route type capability is associated with a unique identifier code, optionally wherein the announcing message is further configured to indicate the unique identifier code.
10. A network device, comprising: means for transmitting an announcing message configured to indicate a route type capability of the network device to a peer network device, wherein the peer network device supports a set of route types; and means for receiving, in response to the announcing message, an update message from the peer network device, wherein: the update message is configured to advertise a subset of route types selected from the set of route types based on the route type capability, and the subset of route types is supported by the network device.
11. The network device of claim 10, wherein the session logic is further configured to receive another announcing message that indicates a route type capability of the peer network device.
12. The network device of claim 10 or 11, wherein the network device and the peer network device are acting as Border Gateway Protocol speakers.
13. The network device of any of claims 10 to 12, wherein the session logic is further configured to determine an update in the route type capability, optionally wherein the session logic is further configured to transmit a new announcing message configured to indicate the updated route type capability to the peer network device.
14. A method, comprising: receiving an announcing message configured to indicate a route type capability of a peer network device, wherein a network device supports a set of route types; selecting, based on the route type capability of the peer network device, a subset of route types from the set of route types, wherein the subset of route types is supported by the peer network device; and transmitting an update message configured to advertise the subset of route types to the peer network device, the method optionally further comprising the steps implemented by the network device of any of claims 2 to 9.
15. A method comprising: transmitting an announcing message configured to indicate a route type capability of a network device to a peer network device, wherein the peer network device supports a set of route types; and receiving, in response to the announcing message, an update message from the peer network device, wherein: the update message is configured to advertise a subset of route types selected from the set of route types based on the route type capability, and the subset of route types is supported by the network device, the method optionally further comprising the steps implemented by the network device of any of claims 11 to 13.
16. A computer program, computer program product or computer readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method of claim 14 or 15.

Description

The present disclosure relates to network session management. More particularly, the present disclosure relates to an exchange of route type capabilities between peer network devices for Border Gateway Protocol (BGP) session management. BACKGROUND Border Gateway Protocol (BGP) has become a popular routing protocol among leading operators and service providers. BGP, as an exterior gateway protocol (EGP), facilitates the exchange of routing information among network devices (for example, routers) across different autonomous systems and networks. A network device that executes a BGP process is commonly referred to as a BGP speaker. To initiate communication and exchange routing information, BGP speakers establish a transport control protocol (TCP) connection. This connection may form a basis for a BGP session. A BGP session may refer to a logical connection and communication channel established between two BGP speakers or BGP peers. Through the BGP session, the BGP speakers exchange routing information including, for example, network layer reachability information (NLRI) attribute, and make informed routing decisions across different autonomous systems. The routing information transmitted by a BGP speaker may include complete routing details for each network destination reachable from the BGP speaker. In an example, the routing information can include an address prefix of a destination location and attributes that describe a path to a destination host. Once a BGP session is set up, updates to the routing information may be exchanged or advertised between the BGP speakers for the remainder of the BGP session. For example, the BGP speakers may continue to exchange BGP messages including updates (e.g., prefixes, path attributes, routing policies, or the like) about reachable networks. Within the context of BGP, various address families have emerged to cater to specific networking needs. Examples of these address families may include Ethernet Virtual Private Network (EVPN), Multicast VPN (MVPN), or the like. These address families exhibit a capability to support multiple route types and such capability is advertised within a Multiprotocol Reachable NLRI (MP_REACH_NLRI) attribute. The MP_REACH_NLRI attribute may be utilized in the BGP to carry routing information for multiple network layer protocols. Different route types have different key lengths and include multiple fields, which are utilized as a BGP route key. If a BGP speaker encounters a particular route type that it does not support, the BGP session is reset as the BGP speaker may be unable to interpret the BGP route key from the MP_REACH_NLRI. However, resetting a BGP session is expensive, and may impact a network adversely. SUMMARY OF THE DISCLOSURE Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims. Features of one aspect may be applied to each aspect alone or in combination with other features. Devices and methods for exchanging route type capabilities between peer network devices for Border Gateway Protocol (BGP) session management in accordance with embodiments of the disclosure are described herein. In many embodiments, a network device comprises a processor and a memory communicatively coupled to the processor. The memory comprises a session logic that is configured to receive an announcing message configured to indicate a route type capability of a peer network device. The network device supports a set of route types. The session logic is further configured to select, based on the route type capability of the peer network device, a subset of route types from the set of route types and transmit an update message configured to advertise the subset of route types to the peer network device. The subset of route types is supported by the peer network device. In a number of embodiments, the session logic is further configured to transmit another announcing message configured to indicate a route type capability of the network device to the peer network device. In a variety of embodiments, the session logic is further configured to transmit the another announcing message prior to transmitting the update message. In several embodiments, a Border Gateway Protocol session is established between the network device and the peer network device based on the announcing message. In numerous embodiments, the session logic is further configured to transmit the update message during the Border Gateway Protocol session. In more embodiments, the route type capability indicates one or more route types supported by the peer network device. In various embodiments, the announcing message corresponds to a Border Gateway Protocol OPEN message. In further embodiments, the Border Gateway Protocol OPEN message includes an optional parameters field that is configured to indicate the route type capability. In yet more embodiments, the update message corresponds to a Border Gateway Protocol UPDATE message. In st