IRTFOPEN Meeting Minutes from IETF-126

Thursday, 2026-07-23 12:00-14:00 UTC

• Chair: Dirk Kutscher
• Agenda and
  Presentations
• MeetEcho
• Notes
• IETF-126 Agenda
• Meeting notes adopted from
  https://ietfminutes.org/minutes/ietf126/irtfopen.txt

About

The Applied Networking Research Prize
(ANRP) is awarded to recognise the best
recent results in applied networking, interesting new research ideas of
potential relevance to the Internet standards community, and upcoming
people that are likely to have an impact on Internet standards and
technologies, with a particular focus on cases where these people or
ideas would not otherwise get much exposure or be able to participate in
the discussion.

IRTFOPEN Agenda

2. Formalizing Dependence of Web Infrastructure

Rumaisa Habib

Rumaisa Habib is a 4th year PhD candidate
under the supervision of Zakir Durumeric in the Empirical Security
Research Group at Stanford University. Rumaisa’s primary research focus
is on large scale measurement studies to understand the web beyond the
Western context, and building systems to allow researchers conduct these
studies more efficiently.

Rumaisa Habib presented Formalizing Dependence of Web
Infrastructure,
exploring the centralization and regionalization of the core layers that
make websites reachable and trusted: hosting, DNS, and Certificate
Authorities (CAs).

• Key Concepts & Metrics:
• Centralization: The concentration of web services on a few
  providers. The work leverages Earth Mover’s Distance (EMD) to
  measure how far a country’s provider distribution deviates from a
  fully uniform baseline.
• Regionalization (Geopolitical Dependency): Measured using
  endemicity (how regionalized a provider’s usage is vs. global
  giants like Cloudflare) and insularity (the fraction of a nation’s
  sites served by domestic providers).
• Key Findings:
• Hosting: Centralization is highly non-uniform globally. Thailand
  is the most hosting-centralized country (60% of sites rely on
  Cloudflare), while Iran is the least. Austria is highly
  decentralized, ranking 140th out of 150.
• Regional Providers: Countries with lower centralization scores
  tend to rely heavily on regional providers (e.g., in Bulgaria,
  Lithuania, and Iran) rather than global hyperscalers.
• Geopolitical Alignment: Cross-border infrastructure dependencies
  often mirror historical, colonial, or linguistic ties (e.g.,
  Uzbekistan depending on Russian providers; Afghanistan relying on
  Iranian hosting due to Farsi language overlap).
• Certificate Authorities (CAs): CA distribution is extremely
  consolidated, with only 7 CAs accounting for 98% of the analyzed
  web. This creates extreme foreign dependency for most countries.
  Following the invasion of Ukraine and DigiCert’s exit, Russian web
  properties became heavily dependent on Let’s Encrypt.

Discussion & Comments:

• Generalizability: Brian Trammell asked how the framework
  generalizes to other layers. Rumaisa Habib clarified that the EMD
  metric is highly general and can be applied to any distribution, using
  weights calibrated for traffic volume if needed.
• Topology Concerns: Marwan Fayed suggested extending the work to
  include Autonomous System (AS) topology and path-level upstream
  dependencies.
• CA Concentration Risks: Eliot Lear remarked that the 7-player CA
  concentration is concerning, particularly regarding Let’s Encrypt. He
  noted that geopolitical sanctions restricting access to CAs could
  trigger widespread trust failures.
• Inexorability of Centralization: Marwan Fayed noted that
  historically, no human utility infrastructure has scaled successfully
  without points of concentration, suggesting the focus should shift to
  managing and safeguarding centralization. Ignacio Castro asked how the
  community can mitigate this; Rumaisa Habib responded that
  standardizing measurement metrics within the IETF/IRTF is a crucial
  first step.
• Local Caches vs. Hosting: Sam asked how Cloudflare’s local data
  center deployments inside countries were treated. Rumaisa Habib noted
  that the paper addresses this using IP geolocation.
• Layer Correlation: Jonathan Hoyland asked if there was a way to
  combine dependency scores across layers. Rumaisa Habib advised against
  it, stating that hosting and CA ecosystems are fundamentally
  different, and a combined score would obscure critical nuances (such
  as Austria being decentralized in hosting but highly centralized in
  CAs).
• Additional Context (from Chat): Dave Plonka noted that
  “Cloudflarization” helps transition legacy IPv4 sites to IPv6
  globally. Junxiao Shi pointed out that DDoS mitigation is a primary
  driver forcing operators to migrate to CDNs like Cloudflare, but urged
  hosting providers to enable native IPv6. Gautam Akiwate highlighted
  that the choice of hosting provider often causally dictates the choice
  of DNS and CA (e.g., Cloudflare’s default CA integration).

3. Fingerprinting Deep Packet Inspection Devices by Their Ambiguities

Diwen Xue

Diwen Xue is an Assistant Professor in the
Department of Information Engineering at The Chinese University of Hong
Kong (CUHK). Before joining CUHK, he was a Research Fellow at the
University of Michigan, Ann Arbor. His research sits at the intersection
of Security & Privacy and Systems & Networks, seeking to understand how
network adversaries behave and to build practical defenses for an
increasingly adversarial Internet. He received his Ph.D. from the
University of Michigan and his B.A. from New York University. His work
has been recognized by several awards, including the Internet Defense
Prize and the USENIX Security Distinguished Paper award. His current
research interests include Internet measurement; Traffic analysis &
Obfuscation; and Privacy-enhancing Technologies (PETS).

Diwen Xue presented Fingerprinting Deep Packet Inspection Devices by
Their
Ambiguities,
presenting a method to detect and differentiate on-path Deep Packet
Inspection (DPI) devices.

• The Identification Problem: DPI devices are increasingly generic.
  Explicit, self-identifying block pages have decreased by 85% since
  2020, replaced by generic TCP resets (accounting for 95% of block
  actions). Vendors also intentionally obscure their identities to avoid
  controversy.
• The dMAP Approach: Because DPI devices are invisible on-path
  intermediaries, dMAP uses a binary side-channel (observing the
  presence or absence of censorship/throttling) triggered by varying
  protocol “ambiguities.”
• Exploiting Ambiguities:
• IP Fragmentation Limits: During the 2021 throttling of Twitter in
  Russia, the national firewall was found to have a unique IP
  fragmentation limit of exactly 45 fragments. Sending 46 fragments
  bypassed the throttling. This quirk was uniform across all Russian
  ISPs, revealing a centralized national firewall deployment.
• TCP Option Handling (PAWS): Differential fuzzing of open-source
  DPI engines (Zeek, Suricata, Snort, NDPI) showed significant
  differences in how they process out-of-order sequence numbers or
  invalid TCP timestamps. For example, Snort was found to implement
  the exact opposite of the RFC-required PAWS behavior.
• Results & Limitations: dMAP successfully clusters firewalls by
  vendor and deployment region. However, probabilistic or unreliable
  triggering in countries like China, Turkey, and Cuba introduces noise.
  This is mitigated by repeated measurements and prioritizing
  “fail-open” states.

Discussion & Comments:

• DPI Utility on Encrypted Traffic: An unnamed participant asked
  what value DPI products bring to operators if payloads are encrypted.
  Diwen Xue explained that operators still rely heavily on unencrypted
  metadata, such as the Server Name Indication (SNI) field, to trigger
  filtering or throttling.
• Throttling Mechanisms: Stuart Cheshire asked how the physical
  mechanism of throttling is executed, noting that packets cannot be
  physically “slowed down” over the wire. Diwen Xue clarified that the
  devices use a token bucket filter; once the traffic limit is reached,
  all subsequent packets within that time window (e.g., one second) are
  discarded.
• IPv6 Interference: An unnamed participant shared an anecdote of a
  FortiGate product causing non-deterministic interference with IPv6
  traffic.
• Packet Fragmentation (from Chat): Eliot Lear noted that sending 45
  fragments over a 1500-byte MTU yields tiny 33-byte fragments,
  highlighting how unusual this evasion technique is.

4. Side Meeting Update: Networking for AI

Dirk Kutscher provided a summary of the “Networking for AI” side meeting
held earlier during the IETF 126 week.

• Context: While the IETF is targeting short-term engineering work
  (such as agent gateways and portals), there is a strong appetite for
  longer-term research in the IRTF on both “network systems for AI”
  (infrastructure) and “AI for networking.”
• Potential Scope & Topics:
• Improving infrastructure for AI training, inference, and distributed
  workloads (e.g., utilizing packet spraying, receiver-driven
  transport protocols, and KV-cache centric routing like the Mooncake
  architecture).
• Analyzing Mixture-of-Experts (MoE) architectures and their network
  footprints.
• Security, trust boundaries, and scalable federated communication for
  an “Internet of Agents.”
• Proposed Activities: Creating open-access experimental facilities,
  simulators, standardized datasets, and driving active research rather
  than just hosting informational presentations.

Discussion & Comments:

• Federation and Trust: Eliot Lear noted that the “Internet of
  Agents” concept introduces major research challenges regarding
  federated trust and scalability.
• Document Progression: Speaking as the Independent Submissions
  Editor (ISE), Eliot Lear mentioned that he has received several
  AI-related drafts (e.g., on shared context or secure transport). He
  emphasized that the ISE is not the appropriate starting point for this
  work and strongly supported creating a dedicated IRTF research group
  to provide these drafts with a structured home.

Decisions and Action Items

• Research Group Promotions: The proposed research groups sustain
  (Sustainability) and space (Space Networking) have officially been
  promoted to active, regular IRTF research groups.

Next Steps

• Networking for AI Workshop: The second IRTF-associated workshop on
  Networking for AI will take place at the CoNEXT conference in December
  2024.
• Kuala Lumpur Travel Grants: The application cycle for diversity
  travel grants for IETF 128 (Kuala Lumpur) is scheduled to open in late
  November 2024.
• AI Group Scoping: The IRTF will continue to refine the scope and
  gauge community interest for a potential new research group focused on
  Networking for AI.