The ability to monitor/change the boot order of line-cards on a modular chassis based on topology and user configuration presents a significant value-addition to the functionality of a network controller. Such functionality not only prevents problems like traffic loss and its undesirable consequences, but it also gives a user the ability to observe the order in which line-cards and their ports are booted. This metering may provide valuable insights to help improve the boot-up and link-up time of modular chassis solutions

Mishra, Ramesh

Ryali, Ravichandra

Yoo, Jay

English

Technical Disclosure Common

Technical Disclosure Commons Defensive Publications Series 17 May 2024 NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFIC LOSS ON ENTERPRISE MODULAR SWITCHES Ravichandra Ryali Jay Yoo Ramesh Mishra Follow this and additional works at: https://www.tdcommons.org/dpubs_series Recommended Citation Ryali, Ravichandra; Yoo, Jay; and Mishra, Ramesh, "NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFIC LOSS ON ENTERPRISE MODULAR SWITCHES", Technical Disclosure Commons, (May 17, 2024) https://www.tdcommons.org/dpubs_series/7021 This work is licensed under a Creative Commons Attribution 4.0 License. This Article is brought to you for free and open access by Technical Disclosure Commons. It has been accepted for inclusion in Defensive Publications Series by an authorized administrator of Technical Disclosure Commons.  1 8054 NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFIC LOSS ON ENTERPRISE MODULAR SWITCHES  AUTHORS:   Ravichandra Ryali Jay Yoo Ramesh Mishra   ABSTRACT The ability to monitor/change the boot order of line-cards on a modular chassis based on topology and user configuration presents a significant value-addition to the functionality of a network controller. Such functionality not only prevents problems like traffic loss and its undesirable consequences, but it also gives a user the ability to observe the order in which line-cards and their ports are booted. This metering may provide valuable insights to help improve the boot-up and link-up time of modular chassis solutions.   DETAILED DESCRIPTION When an enterprise modular switch is booted up, downlink ports can boot-up much quicker than the uplink ports. In some extreme cases, this difference in time could be of the order of minutes. Such disparity in bootup in uplink/downlink port boot-up times can  cause traffic loss because the endpoints (e.g., servers) can start sending traffic as soon as they detect that a link is up (e.g., a downlink port) but the uplinks on the switch may not yet be booted because they are located on a different line-card that could inherently take longer to boot-up. As a corollary to the above statement, there is a need to have the ability to monitor the order and timestamps of boot-up and link-up of different line-cards on a modular chassis. Proposed herein is an innovation in which a network controller may be provided with a complete view of a network such that insights provided by the network controller can be used to help individual network nodes fine-tune their boot-up behavior.  For example, the network controller can be used to enable a particular boot-up sequence for a network node (e.g., causing uplink ports to boot-up before downlink ports, or some other boot/configuration sequence).  2Ryali et al.: NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFICPublished by Technical Disclosure Commons, 2024 2 8054 Such tailored boot behavior could be achieved through a command-line interface (CLI) mechanism, but such a mechanism would require providing a configuration for each network node individually, which does not scale well.  In accordance with techniques of this proposal, a network controller may be able to deduce that by querying each of given node/device, such as network switches, and processing output(s) from the switches in an algorithmic way, the network controller can then push uplink boot information to each access switch based on the results of the algorithm. As referred to herein, the terms network node/device, modular switch, etc. can be used interchangeably. Consider various background information through which the techniques of this proposal may be further explained. For example, uplink cards may be considered line-cards configured with uplink ports, however, this does not mean that the cards are not configured with downlink ports; whereas downlink cards may be considered any line-card that is not assigned as an uplink card.  Further, if port-channel is be provided for a network implementation that spans multiple line-cards, then only some of the cards can be identified as uplink cards. The logic follows that if every card is defined as uplink card, then there may be no benefit for prioritizing the cards, as all are of the same priority in boot order and, thus, do not have any priority. To avoid such a scenario, consider that only some cards of an implementation may be assigned as uplink cards when port-channels across multiple line-cards serve as uplinks. If port-channel is entirely contained within one line-card, then this is a non-issue. Similarly, if supervisors are used as uplink cards, then this is also a non-issue. Based on the above information and assumptions, an algorithm may be defined for fine-tuning the boot-up sequence of network nodes/devices for a given network implementation, as follows: • Since a 4-slot chassis has a maximum of 2 Line-cards, the maximum number of uplink cards that can be assigned is 1. If supervisor cards are assigned as uplink cards, then both supervisors can be assigned; • Since a 7-slot chassis has a maximum of 5 Line-cards, the maximum number of uplink cards that can be assigned is 2. If supervisor cards are assigned as uplink cards, then both supervisors can be assigned; and 3Defensive Publications Series, Art. 7021 [2024]https://www.tdcommons.org/dpubs_series/7021 3 8054 • Since a 10-slot chassis has a maximum of 8 Line-cards, the maximum number of uplink cards that can be assigned is 2. If supervisor cards are assigned as uplink cards, then both supervisors can be assigned.   In general, uplinks are configured on supervisor cards as they have high- bandwidth ports. However, there is no rule that line-cards should not have uplinks. Some line-cards have 25G/40G/100G ports.  Figure 1, below, is a flow chart illustrating example details of the algorithm that can be executed once a user selects a node upon which to trigger the algorithm.  Figure 1: Algorithm Flow  During operation of the network controller, when there is a new Internet Protocol (IP) interface created on a given node, or a change in topology, then the algorithm is retriggered to determine if there is any change in uplinks. If there is a change, the controller 4Ryali et al.: NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFICPublished by Technical Disclosure Commons, 2024 4 8054 can inform a user through appropriate notification via a dash-board user interface (UI) and can push the information to the corresponding node.  Similarly, when there is an Insertion/Removal on a given card, the algorithm can again be triggered for that node. Each node can also exercise some intelligence while implementing the algorithm. For example, a given uplink card might be removed or replaced with another/different type of line-card while the system is reloading or while the system is power cycled. In such scenarios, the node will not hold up the booting of downlink cards. Another piece of logic that can be exercised by a given node is identifying if a given line-card is booting up as part of an overall system boot-up or if it is a freshly inserted line-card. If a line-card is a freshly inserted line-card, then there may be no need for any sequencing such that the card can be booted-up straight away. It does not matter whether it is a downlink card or uplink card in this case. Figure 2, below, illustrates an example topology in which the solution of this proposal may be provided. For example, as illustrated in Figure 2, switches at different layers of a topology can be discovered and configured by a network controller in accordance with the techniques of this proposal. Network Controller Figure 2: Example Topology  5Defensive Publications Series, Art. 7021 [2024]https://www.tdcommons.org/dpubs_series/7021 5 8054 Based on the description of the algorithm above, access switches E1 and E3 of the example topology shown in Figure 2 may be considered the simplest nodes for the algorithm to identify the uplinks because they have only one link connecting to the upstream switch. On the contrary, to identify the uplinks on E2, the algorithm might have to look at multiple sources of data from the switch to deterministically identify the uplink cards.  As to the distribution layer, both D1 and D2 may also be considered simple cases for the algorithm to determine uplink cards. Similarly, C1, which is a stack wise virtual system connecting to the core, may also be considered a simple case for determining uplink cards by the algorithm. For example, C1 likely has a Layer 3 (L3) port-channel connecting to the core, which  might trigger the part of the algorithm that has to artificially restrict the uplink cards to "1" or "2" though the port-channel members are spread across more than those many line-cards.  Figure 3, below, illustrates an example UI component that may be provided via the network controller in order to facilitate various operations as discussed herein. Device1TYPE 1LC-1SUP-1SUP-2LC-4 Figure 3: Example User Interface   It is to be understood that the example UI shown in Figure 3 is provided only to illustrate various features of a UI that could be provided for the system described herein.  Such a UI could indicate various information, such as when each line-card has booted-up, the first link to come up, etc., which can be useful to a user.  Reporting to a user the result the result of "assigning uplink cards" may be considered an essential feature of the solution 6Ryali et al.: NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFICPublished by Technical Disclosure Commons, 2024 6 8054 proposed herein, which information could be visualized for a user through a variety of techniques.  Accordingly, the solution proposed herein may broadly facilitate the use of insights available to a network controller in order to dictate a boot-up sequence of nodes/devices in order to address boot-up timing problems that could otherwise exist in a network.  The network controller, therefore, may be considered the 'brain' of a network,  which can help to reduce dependence on CLI usage, which can be cumbersome, time consuming, and does not scale well.  In contrast, the controller-based solution proposed herein may implement a behavior or control at scale from a single point of control.   Additionally, the controller may maintain records that can be used to measure performance of the controller and/or the algorithm triggered for different devices/nodes in a network, which a user can compare and contrast (e.g., via a UI) in order to view/analyze the boot-up and link-up times of nodes/devices that utilize the algorithm as compared to those that do not. Moreover, the innovation provided herein may lead to further enhancements, such as metering boot-time related parameters, such as authentication, etc., and then improving boot-times. For example, in conventional implementations, ever line-card is authenticated when it is booted.  The authentication is performed as a security concern and should not be bypassed. However, if a user is confident that if a single authentication is sufficient and does not want to impose authentication each time a card is booted, then, in accordance with the techniques proposed herein, the user could tailor authentication to only be performed once and then be bypassed thereafter altogether, to be performed on-demand and not at boot-time, and/or variations thereof, which could help to lower boot-time of a chassis. The benefits of such a feature may be more pronounced for larger nodes, such as 7-slot and 10-slot chassis. Thus, the innovation provided herein may serve as a fountainhead for many other impactful innovations.  7Defensive Publications Series, Art. 7021 [2024]https://www.tdcommons.org/dpubs_series/7021

NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFIC LOSS ON ENTERPRISE MODULAR SWITCHES

https://www.tdcommons.org/cgi/viewcontent.cgi?article=8164&context=dpubs_series

NETWORK CONTROLLER DIRECTED BOOT-UP SEQUENCING TO PREVENT TRAFFIC LOSS ON ENTERPRISE MODULAR SWITCHES

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