Security Comparison: InfiniBand vs Ethernet in AI Environments

A Comparative Security Analysis of InfiniBand and Ethernet Fabrics for Sovereign AI and Regulated Workloads

Executive Summary

For sovereign AI and regulated workloads, choosing between InfiniBand and high-performance Ethernet is more than just a technical decision—it's a core security choice. Think of InfiniBand as providing centralized, hardware-enforced security, similar to having a single, strong gatekeeper. Ethernet, on the other hand, distributes security across multiple layers, akin to having several trusted checkpoints. This aligns with zero-trust principles but demands more management effort.

InfiniBand's control is centralized in the Subnet Manager, making security efficient but also creating a single point of failure. Ethernet distributes trust through features like IEEE 802.1X port-based authentication and MACsec link encryption, which may be more complex but offer layered protection.

When it comes to key security aspects—such as authentication, tenant isolation, and quality of service—each fabric has its strengths and weaknesses. InfiniBand relies on hardware keys and provides strong traffic separation but is less effective at protecting metadata. Ethernet can be more vulnerable to certain attacks, like resource starvation or fabric deadlocks, but offers better metadata security.

On a strategic level, your choice impacts technological independence. InfiniBand often locks you into a single vendor, while Ethernet's open standards promote diversity and transparency. This decision isn't just about performance; it's about sovereignty, resilience, and operational freedom.

Ultimately, the best choice depends on your specific security needs, regulatory environment, and long-term objectives. It's a balance between risk and resilience, vendor lock-in, and flexibility.

Section 1: Architectural Foundations and Their Security Implications

Your network fabric's security mainly relies on how it's built. Both InfiniBand and Ethernet connect high-performance systems, such as those used in AI and supercomputing. However, they are designed on quite different principles. InfiniBand is managed centrally; think of it as a single controller overseeing everything. On the other hand, Converged Ethernet uses layered protocols that have been standardized over many years, making it more decentralized. The key difference? InfiniBand centralizes security policies, while Ethernet distributes security controls—and potential vulnerabilities—across multiple layers.

1.1. The InfiniBand Fabric: A Centrally Managed, Software-Defined Architecture

InfiniBand is a high-performance networking technology that uses a switched fabric setup. Think of all the devices—like your server's Host Channel Adapters (HCAs) and switches—as direct point-to-point connections, all coordinated by a central component called the Subnet Manager (SM). This SM acts as the brain of the network, discovering how everything is connected, assigning IDs to each port, configuring data flow through the switches, and ensuring network policies are followed. Essentially, it makes InfiniBand a kind of software-controlled network, with the SM at its core.

A key feature of InfiniBand is its ability to perform Remote Direct Memory Access (RDMA). This allows data to move directly between computers' memory, without burdening the host CPU or operating system. This direct transfer results in extremely low latency—think under a microsecond. However, this also raises security concerns because traditional security tools like firewalls do not detect this type of traffic.

Since the SM is critical to the network's operation, it can become a single point of failure. To address this, InfiniBand networks often have multiple SMs working together. One SM is designated as the primary, handling all operations, while others remain on standby, ready to take over if the primary fails. These are typically managed through a virtual IP address that always points to the active SM.

1.2. The Converged Ethernet Fabric: A Layered, Standards-Based Architecture for RoCEv2

Ethernet has traditionally been used in enterprise networks, but it has now become suitable for AI workloads thanks to a technology called RDMA over Converged Ethernet, or RoCEv2. This protocol allows data to be transferred directly between computers' memory, bypassing much of the usual processing and speeding things up. RoCEv2 works by wrapping InfiniBand transport packets inside standard UDP/IP packets, which means it can operate over regular IP networks used in data centers.

However, because RDMA is sensitive to data loss, the underlying Ethernet network needs to be carefully managed to prevent packet loss. This is achieved using standards like:

• Priority Flow Control (PFC): Can pause traffic to prevent loss
• Explicit Congestion Notification (ECN): Signals when the network is congested

For large-scale deployments, advanced tools like BGP with Ethernet VPN extensions help manage the complex web of connections, ensuring smooth operation across many tenants and overlay networks.

1.3. The Security Dichotomy: Kernel Bypass vs. the Network Stack

Understanding the security differences between various data transfer architectures is essential. InfiniBand provides an extremely fast connection by transferring data directly via specialized hardware, bypassing the host's usual network software. This makes it less vulnerable to common software-based attacks, but it also means that traditional security tools like firewalls and monitoring agents may not see the data flow. Security in InfiniBand mainly depends on its built-in architecture, which can be a concern if the system management component (SM) is compromised.

In contrast, RoCEv2 (RDMA over Converged Ethernet) takes a different approach. It accelerates data transfer by bypassing the kernel for core RDMA operations, but the data still travels as regular IP packets routed through your network. This allows some network security measures, such as Access Control Lists (ACLs) on routers and switches, to remain effective. While it also provides fast data transfer by bypassing the host's TCP stack, it is more visible to traditional security tools than InfiniBand.

These differences reflect broader security philosophies:

• InfiniBand security is more centralized and relies heavily on the system management (SM) for control. If the SM is compromised, an attacker could potentially reroute data or disable security features across the fabric.
• Ethernet security is designed with layered protections that distribute security responsibilities. Technologies like 802.1X control port access, MACsec protects data integrity on links, and VXLAN segments networks into separate zones. This layered setup aligns well with modern zero-trust security principles. If one layer is breached, others can still provide protection, making Ethernet potentially more resilient against advanced threats—even if it involves more complex setup and management.

In summary, choosing between these options involves balancing speed, security, and operational complexity, depending on your specific needs and threat landscape.

Section 2: Authentication and Authorization: Establishing Trust in the Fabric

Authentication confirms identity, and authorization grants permissions. InfiniBand and Ethernet approach these tasks from different viewpoints, reflecting their architectural differences. InfiniBand uses a fabric-focused model, where the SM verifies its right to manage devices and authorizes communication paths between them. Ethernet employs a device-focused and link-focused model, concentrating on authenticating individual devices as they connect and securing physical links between them.

2.1. InfiniBand's Centralized Trust Model: The Subnet Manager and Key-Based Authentication

InfiniBand security relies on keys that function like access tokens or passwords. They're used for authentication and authorization, not for encrypting data in transit. The SM is your central authority for managing and distributing these keys.

Key Types:

Management Key (M_Key): This key protects the configuration of your fabric devices. The SM assigns an M_Key to each port it manages. Any subsequent management command that attempts to modify a port's configuration must include the correct M_Key. If the M_Key is incorrect, the device drops the packet and can send a "Bad M_Key" trap to the SM. M_Keys can be configured with lease periods, causing them to expire if the SM becomes inactive.

SM_Key and Allowed GUIDs List: These features prevent a rogue SM from taking control of your fabric. The SM_Key is a shared secret that must be presented during the SM mastership election process. You can configure an allowed_sm_guids list, which acts as an access control list, ensuring only SMs with known and trusted Global Unique Identifiers can participate in the election.

Hardware GUIDs: Every InfiniBand device and port has a 64-bit GUID burned into its hardware by the manufacturer. This hard-coded identity makes spoofing extremely difficult. You can configure the SM with a static topology file that maps expected GUIDs to specific physical ports. If a device with an unknown GUID appears, or a known GUID appears on the wrong port, the SM can refuse to configure it.

2.2. Ethernet's Distributed Trust Model: 802.1X, MACsec, and Centralized Authentication Servers

Ethernet's security model builds on open standards that provide layered, distributed trust, often orchestrated by centralized authentication servers.

Key Components:

Port-Based Authentication (IEEE 802.1X): This standard provides robust Network Access Control at the physical port level. When a device connects to an 802.1X-enabled switch port, the port is placed in an "unauthorized" state, blocking all traffic except authentication packets. The switch acts as an authenticator, relaying credentials from the connecting device to a centralized authentication server running RADIUS or TACACS+. Only after the server validates credentials is the port moved to an "authorized" state.

Link-Layer Encryption (MACsec, IEEE 802.1AE): While 802.1X authenticates a device to your network, MACsec secures the data on the wire itself. MACsec provides point-to-point security on Ethernet links, offering strong encryption, data integrity checks, and replay protection for all frames. This protects against physical threats like wiretapping and packet injection attacks.

Centralized Authentication (RADIUS/TACACS+): Protocols like RADIUS and TACACS+ provide the backend Authentication, Authorization, and Accounting services that support secure Ethernet architecture. They enable you to manage user and device credentials in a central database. TACACS+ is often favored in high-security settings because it encrypts the entire AAA packet, whereas RADIUS only encrypts the password field.

The scope of authentication differs significantly between the two protocols. InfiniBand's methods maintain the integrity of your predefined fabric from internal threats. Ethernet's approach does not assume inherent trust. It challenges and verifies every device at the network edge through 802.1X and protects each link from physical breach with MACsec. For regulated environments that require strict, auditable proof of device identity before granting network access, 802.1X's explicit gatekeeper role provides more direct and verifiable control.

Practical Example: Verifying MACsec and 802.1X Configuration on Ethernet Switches

# Example Python code to audit MACsec and 802.1X configuration across switches
# Useful for compliance and zero-trust enforcement in AI fabrics
import json

def verify_ethernet_security(config_path):
    with open(config_path) as f:
        switches = json.load(f)
    for sw in switches:
        macsec = sw.get('MACsec_enabled', False)
        dot1x = sw.get('8021X_enabled', False)
        if not macsec or not dot1x:
            print(f"WARNING: Switch {sw['name']} missing security config (MACsec: {macsec}, 802.1X: {dot1x})")
        else:
            print(f"Switch {sw['name']} OK (MACsec: {macsec}, 802.1X: {dot1x})")

This script provides a simple framework for network engineers to programmatically audit switch configurations, ensuring critical security controls like MACsec and 802.1X are consistently enforced. It can be integrated into larger automation workflows for continuous compliance validation, a key practice for zero-trust enforcement in dynamic AI environments.

Section 3: Tenant Isolation: A Comparative Analysis of Enforcement Mechanisms

In multi-tenant environments such as sovereign AI clouds and shared regulated workloads, strong isolation is not just a feature—it's a fundamental security requirement. It is essential to prevent tenants from accessing or even detecting each other's resources and traffic. InfiniBand and Ethernet achieve this isolation through fundamentally different mechanisms. InfiniBand uses hardware-enforced partitions, while modern Ethernet depends on software-defined network virtualization with overlays.

3.1. InfiniBand Partitions (P_Keys): Silicon-Enforced Segmentation

The Partition Key, or P_Key, is the main way to keep tenants separate in InfiniBand networks. Think of a partition as a virtual group of HCA ports allowed to talk to each other. The Subnet Manager (SM) creates these groups and assigns P_Keys to the ports of different nodes. Every data packet sent across the network includes a 16-bit P_Key in its header. When a switch or HCA receives a packet, it checks this key against a list of allowed keys for that port. If it doesn't match, the packet is dropped quietly and quickly. This hardware-level check ensures that traffic stays isolated between different groups with minimal delay.

InfiniBand also manages access within partitions using "full" and "limited" memberships:

• Full membership: Can communicate with any other member in the same partition
• Limited membership: Can only talk to full members

This setup creates a tiered system: compute nodes with limited access talk only to central storage systems that have full access, but they don't talk directly to each other.

However, despite these strong measures for data separation, there's a notable security weakness: metadata leakage. While the data traffic is well protected, the control and management information isn't necessarily partitioned. Tools like ibnetdiscover, which are used for diagnosing network issues, can often reveal details about the entire network—even information about nodes in other tenants' partitions, like GUIDs and LIDs. This can give potential attackers a detailed map of the network, breaking the tenant isolation principle.

3.2. Ethernet Virtual Overlays (VXLAN/EVPN): Encapsulation-Based Segmentation

Modern high-performance Ethernet networks ensure that different tenants' data remains separate and secure through a technology called network virtualization, often implemented with Virtual Extensible LAN (VXLAN) overlays.

Basically, VXLAN encapsulates a tenant's Layer 2 Ethernet data within standard UDP/IP packets, allowing multiple tenants to share the same physical network without interference. Each tenant's network is identified by a unique 24-bit number called the VXLAN Network Identifier (VNI), which can support up to 16 million separate tenant networks—far more than the approximately 4,000 limits of traditional VLANs. This encapsulation creates a private, logical Layer 2 network for each tenant that operates independently of the physical hardware layout.

To manage these large-scale VXLAN deployments, networks typically depend on BGP-EVPN, a protocol extension of BGP, which conveys information about device locations and connections. Devices known as VXLAN Tunnel Endpoints (VTEPs) handle encoding and decoding of these data packets and learn where tenant devices are through the control plane, rather than relying on slower broadcast methods.

Security in VXLAN depends heavily on the integrity of VTEPs and the security of the control plane. While VXLAN provides strong isolation, it isn't completely foolproof. Common network attacks like ARP spoofing can still pose a threat within a single tenant segment. However, attacks attempting to cross between different VNIs are generally prevented by the architecture because the VNI is embedded within the data header, making such crossings difficult.

3.3. Synthesis: Robustness, Scalability, and Vulnerabilities in Multi-Tenant Isolation

InfiniBand's P_Key feature offers robust safety for data transfer because it is integrated into the hardware, ensuring low latency and reliable protection against traffic leaks. Conversely, Ethernet with VXLAN provides much greater scalability and flexibility. With up to 16 million Virtual Network Identifiers (VNIs), you can essentially have endless network segments. These segments can also extend across any Layer 3 network, making operations more adaptable.

The primary difference between the two lies in what they protect: traffic versus metadata. InfiniBand effectively isolates the actual data traffic, but it is less effective at preventing other tenants from discovering each other's presence and identities. This can violate the core principles of multi-tenancy.

VXLAN operates differently. Within a VNI, tenants cannot see or know about other tenants or the underlying network — they only see their own logical Layer 2 domain, which provides strong metadata protection. However, the security of the traffic depends on the VTEP (the gateway responsible for encapsulating and decapsulating traffic). If a VTEP is compromised, it could potentially direct traffic to the wrong tenant's network.

In environments such as government AI clouds or highly regulated industries, this distinction is critical. Preventing tenants from discovering each other's existence (metadata isolation) is often more vital than simply blocking packet snooping (traffic isolation). While VXLAN depends on trusting the VTEP, its architecture more effectively supports the stringent security separation needed in modern multi-tenant environments.

Section 4: Quality of Service (QoS) as an Attack Vector

Quality of Service (QoS) mechanisms are vital in high-performance fabrics for controlling congestion and prioritizing network access for latency-sensitive applications. These mechanisms can also be misused by malicious or misconfigured actors to launch denial-of-service attacks. Such actions can deplete resources for other users or destabilize the fabric itself. The nature of these attacks varies greatly between InfiniBand and Ethernet due to their different approaches to QoS and congestion management.

4.1. InfiniBand QoS Abuse: Manipulating Service Levels and Virtual Lanes for Resource Starvation

InfiniBand's QoS architecture depends on Service Levels (SLs) and Virtual Lanes (VLs). Each packet is marked with a 4-bit SL value (0-15) by the source HCA. When the packet passes through a switch, the SL determines which VL it uses, along with input and output ports. VLs are separate buffer queues within the switch, providing dedicated resources for different traffic types.

The primary attack vector here is resource starvation. A compromised or malicious tenant could configure applications to tag all traffic with the highest-priority SL. If your fabric's QoS policy lacks sufficient granularity or strictness, this high-priority traffic could monopolize high-priority VLs and scheduler resources. This situation can lead to increased latency and potential packet drops for legitimate traffic from other tenants in lower-priority VLs.

Countermeasures depend entirely on centralized policy enforcement by the SM. You need to configure the SM with a robust QoS policy, including strict SL-to-VL mapping tables and carefully tuned arbiter weights for each partition. The architecture prevents hosts from arbitrarily changing fabric-level settings. The SM can enforce policies that restrict which SLs a tenant can use. InfiniBand's hardware-based, credit-driven link-level flow control makes it naturally resistant to common L2/L3 DoS attacks like SYN floods, which are typically dropped by HCA hardware without involving your host OS.

4.2. Ethernet QoS Abuse: Exploiting CoS/PFC for Denial-of-Service and Congestion Attacks

Ethernet QoS relies on Class of Service (CoS) that uses 3-bit 802.1p priority values in VLAN tags and Differentiated Services Code Point (DSCP) with 6-bit values in IP headers. These classify traffic into different queues on your switches. While general QoS misconfigurations can cause resource starvation similar to InfiniBand, RoCEv2's dependence on Priority Flow Control creates a unique and much more serious attack surface.

PFC is a reactive mechanism designed to establish a lossless fabric. When a switch's buffer for a specific priority class starts to fill, it sends a PFC "pause" frame to the upstream switch, instructing it to stop sending traffic of that class. An attacker can exploit this by generating large, sustained bursts of traffic in a single RoCEv2 priority class. This can trigger a cascade of pause frames propagating backward through your network.

This leads to several severe outcomes:

• Buffer Pressure and Head-of-Line Blocking: The paused flow consumes large amounts of expensive buffer memory in upstream switches, potentially impacting other traffic classes if buffers aren't strictly partitioned.
• PFC Deadlocks: In complex network topologies like a Clos fabric, you can create circular dependencies where switches continuously send pause frames to each other. This results in a deadlock where no traffic in the affected priority class can move, effectively freezing a portion of your fabric. This type of attack represents a "hard" DoS, causing catastrophic fabric instability rather than just performance degradation.

Countermeasures are primarily architectural and configurational. A well-designed RoCEv2 fabric requires meticulous tuning of PFC and ECN thresholds, along with QoS policies that correctly classify and police traffic.

The failure modes from QoS abuse in each fabric have significant implications for regulated workloads. InfiniBand's architecture tends towards "graceful degradation"—an attack leads to unfair resource allocation, but your fabric remains fundamentally stable. The architecture enabling RoCEv2, if not perfectly configured, is susceptible to a more brittle "unstable collapse" failure mode. For critical systems where predictable behavior under attack is paramount, this difference in risk profile is crucial.

Section 5: Telemetry Integrity: Ensuring Trustworthy Fabric Observability

Telemetry—the collection of performance counters, event logs, and diagnostic information—is vital for managing network health, troubleshooting issues, and detecting security anomalies. The integrity of this data is paramount. If an attacker can tamper with or spoof telemetry, they can hide activities, mislead administrators, and undermine your entire security monitoring framework. InfiniBand and Ethernet present different challenges and solutions for ensuring telemetry integrity, stemming from their respective integrated versus open ecosystem approaches.

5.1. Securing InfiniBand Telemetry: Protecting the SM-Agent Channel and Verifying Hardware Counters

InfiniBand telemetry systems are designed to be closely integrated and centrally managed. Each switch and Host Channel Adapter (HCA) runs management agents—called Subnet Manager Agents (SMAs)—that collect various data, such as port statistics on bandwidth, errors, and network congestion. This data is then sent to a central Subnet Manager (SM) and is often displayed through advanced management tools like NVIDIA's Unified Fabric Manager.

A key feature in this setup is "traps." These are alert notifications sent asynchronously from an agent to the central SM whenever unusual or potentially problematic events are detected, offering real-time insights into the network fabric's health and highlighting potential security issues.

A significant challenge in this system is ensuring the security of communication between the SMAs and the central SM. This communication occurs over a dedicated management channel using a specific type of connection called a queue pair (QP0). While mechanisms like Management Keys help authenticate and authorize configuration changes sent to SMAs, it remains unclear from the technical specifications whether the data—such as telemetry reports—are cryptographically signed or otherwise protected from tampering. If a host with sufficient privileges were compromised, it could potentially send false trap alerts or manipulate the reported performance data. This risk is heightened by the kernel-bypass architecture, which renders management traffic invisible to traditional host-based security monitoring tools.

To mitigate these security risks, focus should be on protecting the endpoints of this management communication. Securing the SM itself is particularly important. Features like the SMP firewall can prevent unauthorized hosts from sending management packets. Additionally, modern adapters include built-in security features such as secure boot and hardware roots of trust, which further strengthen the overall security posture.

5.2. Securing Ethernet Telemetry: Integrity in a Diverse Ecosystem

The Ethernet ecosystem provides a variety of standardized telemetry protocols:

• NetFlow and IPFIX: Give detailed records of network traffic flows
• sFlow: Offers real-time insights through statistical packet sampling
• Streaming telemetry: Continuously sends detailed data directly to collectors

This diversity offers great flexibility in monitoring your network infrastructure. However, since many of these protocols were designed prioritizing performance and flexibility over security, they usually transmit data unencrypted over UDP by default. This makes the data vulnerable to interception, spoofing, and tampering by attackers who may be in a position to intercept network traffic.

To address these security challenges, additional layers of protection are necessary. Securing the transmission of telemetry data with protocols like IPsec or TLS helps prevent unauthorized access. Additionally, ensuring the physical security of devices reduces the risk of interceptions, especially in wired connections, which are inherently more secure than wireless options.

When comparing different systems, a trust dilemma emerges. InfiniBand's telemetry is based on a closed, proprietary management ecosystem that, although designed with security in mind, is hard for external parties to independently verify or audit. On the other hand, Ethernet telemetry relies on open, transparent standards. Its protocols are verifiable, but security is not guaranteed by default and depends on the user to implement proper protections. For organizations that need high levels of assurance, accountability, and auditability—especially in regulated environments—the explicit security measures of a well-implemented Ethernet telemetry setup may be more reliable than the more opaque, trust-based approach of InfiniBand.

Section 6: Implications for Sovereign AI and Regulated Environments

Your choice of network fabric for sovereign AI initiatives and regulated industries extends beyond technical specifications. It directly impacts your nation's technological autonomy, infrastructure auditability, and ability to enforce data residency and security mandates. The distinct security models of InfiniBand and Ethernet have profound implications in these high-stakes contexts.

6.1. Meeting the Demands of Sovereign AI: Data Residency, Control Plane Sovereignty, and Verifiable Isolation

Sovereign AI refers to your nation's capability to develop and control its own AI technologies and infrastructure. This ensures sensitive data and models are subject to your own laws and regulations. This concept builds on principles of data sovereignty (legal authority over data) and data residency (physical location of data).

Control Plane Sovereignty and Vendor Diversity

A critical aspect of technological sovereignty is avoiding dependency on a single foreign supplier for critical infrastructure. The InfiniBand market is dominated by NVIDIA following its Mellanox acquisition. This creates significant supply chain risk and potential for geopolitical leverage. Your entire nation's AI infrastructure could become dependent on one company's hardware, software, and security patching cadence.

Ethernet, by contrast, is a multi-vendor ecosystem built on open IEEE and IETF standards. This diversity fosters competition, reduces costs, and provides you with supplier choice. This mitigates single-vendor lock-in risk and enhances technological sovereignty.

Data Residency and Verifiable Isolation

Enforcing data residency requires not only storing data within national borders but ensuring tenants in a shared cloud environment cannot access or become aware of each other's existence. InfiniBand's P_Key mechanism, while strong for traffic isolation, has a critical weakness in metadata isolation. A tenant's ability to use tools like ibnetdiscover to map their entire fabric topology is a significant security risk in a sovereign cloud.

Ethernet with VXLAN provides far superior metadata isolation, confining a tenant's visibility strictly to their own virtual network. This better fits the stringent separation requirements of multi-tenant sovereign platforms.

Auditability and Transparency

For a system to be trusted by your national government, it must be auditable. Ethernet's reliance on open, well-documented protocols like IP, UDP, and BGP makes its control and data planes transparent to network analysis. Your national security agencies and auditors can use standard tools to monitor traffic, verify configurations, and validate security controls. InfiniBand's control plane, with its more proprietary SMPs and centralized SM logic, presents greater challenges to independent, third-party verification.

6.2. Aligning with Regulated Workloads: A Compliance Mapping for HIPAA and PCI-DSS

Regulated industries operate under strict compliance frameworks mandating specific security controls. HIPAA requires technical safeguards for electronic Protected Health Information, including access control, audit trails, and transmission security. PCI-DSS requires strong network segmentation to isolate the Cardholder Data Environment, firewalling, and protection of data in transit.

The table below maps these high-level requirements to each fabric's capabilities:

This mapping reveals that while both fabrics can be configured to meet compliance goals, Ethernet's layered security controls often map more directly to explicit requirements found in standards like HIPAA and PCI-DSS. The requirement for transmission security is natively met by MACsec in Ethernet, whereas InfiniBand lacks a comparable standardized, fabric-level encryption mechanism.

Section 7: Strategic Recommendations and Conclusion

Your choice and implementation of a high-performance network fabric for sovereign AI or regulated workloads have long-term security and operational implications. The best option isn't the same for everyone; it depends on a careful understanding of the trade-offs between InfiniBand and Ethernet systems. Based on the earlier analysis, here are strategic recommendations for organizations designing these critical setups.

7.1. Hardening InfiniBand Fabrics for High-Assurance Deployments

For organizations selecting InfiniBand, security should focus on protecting the Subnet Manager as the fundamental trust anchor for your fabric. Isolate and secure the SM: It must run on a physically secure device. All management access to the SM and switches' out-of-band management ports should be restricted to a dedicated, isolated management network, safeguarded by firewalls and strict access controls.

Key Hardening Steps:

Enforce Control Plane Authentication: Always use strong, non-default SM_Keys to protect the mastership election process and configure a static allowed_sm_guids list to prevent rogue SMs from attempting takeover.

Use Static Topology: Where possible, define your fabric topology in a static file. This allows the SM to verify every device's GUID and physical location, preventing spoofing or unauthorized device additions.

Mitigate Information Disclosure: Use the SMP firewall feature on HCAs to block tenant hosts from sending or receiving subnet management packets. This is critical to prevent tenants from running tools like ibnetdiscover and mapping your fabric beyond their partition.

Compensate for Lack of Encryption: Since InfiniBand lacks a standard for on-the-wire encryption, security for data in transit must be enforced at the application layer using TLS/SSL or application-specific encryption. This must be a primary consideration in your overall system design.

7.2. Architecting Secure and Resilient RoCEv2 Ethernet Fabrics

For organizations opting for Ethernet, your aim is to develop a resilient, lossless network while implementing a layered security strategy. Design for PFC resilience: The biggest threat to RoCEv2 fabric stability is PFC-based DoS attacks. Your network design should include conservative buffer provisioning on switches, careful tuning of PFC and ECN thresholds, and strong QoS policies to separate and control traffic classes. For new deployments, consider switch architectures that use Virtual Output Queueing to proactively prevent congestion.

Key Architecture Steps:

Implement Layered Security Controls: A zero-trust approach is recommended. Mandate IEEE 802.1X for port-based admission control to ensure no unauthorized device connects to your fabric. Deploy MACsec for link-layer encryption on all inter-switch links and, where feasible, on host-facing ports.

Secure the Control and Overlay Planes: When using VXLAN with BGP-EVPN, secure BGP sessions between devices using strong authentication. Implement control plane policing to protect switch CPUs from DoS attacks.

Ensure Telemetry Integrity: Don't treat telemetry as trusted by default. All telemetry streams from network devices to collectors must be secured in transit using IPsec or TLS to prevent tampering and ensure your observability plane is trustworthy.

7.3. A Risk-Based Framework for Fabric Selection in Sovereign and Regulated Contexts

There's no universally "more secure" fabric. Your final decision must be based on a risk assessment that prioritizes your deployment's specific goals.

For Sovereign AI

The strategic imperatives of technological independence and verifiable security strongly favor Ethernet. The multi-vendor ecosystem reduces supply chain risks and reliance on a single foreign entity. Open, transparent standards enable independent auditing and verification by your national authorities. Most importantly, the superior metadata isolation provided by VXLAN is crucial for ensuring strict separation between different government agencies or commercial entities using a national AI cloud.

For Regulated Workloads (HIPAA/PCI-DSS)

Your choice is more nuanced and depends on your organization's technical maturity and risk tolerance. Ethernet provides a security model with layered controls that directly align with the prescriptive requirements of frameworks like PCI-DSS. This can make audits and compliance verification easier. However, managing a secure, high-performance RoCEv2 fabric is complex, and the risk of catastrophic failure from PFC deadlocks cannot be ignored.

InfiniBand offers operational simplicity and a more predictable performance degradation model under QoS attacks, which can be advantageous for certain critical applications. However, its security vulnerabilities—such as the lack of native encryption and susceptibility to metadata leakage—must be explicitly addressed and mitigated through additional controls.

Final Thoughts

In summary, the security debate between InfiniBand and Ethernet highlights a classic trade-off between integrated, high-performance simplicity and layered, flexible, sovereignty-friendly security. Ultimately, choosing between them requires looking beyond performance benchmarks; it involves a strategic decision based on architectural resilience, security auditability, and alignment with the main goals of sovereignty and regulatory compliance.