Network Effect: Streaming Services

Patrick Timmons -

Anyone that's asked my opinion on network configurations within the past six months has probably gotten an earful on Quality of Service and traffic prioritization. Ever since becoming homebound by COVID-19, bandwidth has become more precious; the kids relied on Zoom for their distance learning while they were in school, I'm under a constant barrage of conference calls over the various collaboration platforms (Zoom, Webex, Teams, etc.), and the like. When you factor in our (temporary) transplant to a cottage in the Berkshires – replete with aging DSL lines – the contention becomes more apparent.

I've been hunkering down over the past several weeks, doing some investigative analysis of my own family's network consumption. The fruits of this labor are appearing in the form of toolsets for helping the 128T device perform more intelligent application identification. The thought process is this: to extract the most value from a limited resource (network), it becomes of paramount importance to understand the consumers of that resource (appID), and give guidance to the network on priorities when the resource is under contention (QoS).

My blog series on Investigation in Isolation was one piece of this puzzle, and incidentally the lowest hanging fruit. Each of the purpose-built IoT devices tethered to my network typically has a small set of functions, and it's straightforward to quarantine each of them, categorize its network footprint, and put guard rails up around it to limit its scope and appetite. Good for security, good for resource management.

After systematically cordoning off all of my IoT devices, the next phase was moving up the stack to more complex equipment. This is more challenging; our tablets, smartphones, and laptops run a variety of applications that will complicate the investigative process. The obvious candidate for my next round of research was AppleTV.

Not only is AppleTV a "walled garden" of sorts, but its primary raison d'être is to stream video content from cloud providers to my television set. Because streaming video is the largest network consumer worldwide, this also means I'll get a lot of bang for my buck: isolating and prioritizing streaming video traffic appropriately can score a quick win for making the most of a scarce resource. Kids watching YouTube while I'm on a call with the boss? Not so fast, Tic Tac Toy!

You may be asking yourself: why not just put a bandwidth limiter on the AppleTV and be done with it? My answer is: what's the fun in that?

The two step approach

There are only two basic steps required for applying traffic prioritization rules on my 128T: first, identify the application; second, apply service-policy configuration for each application. (Maybe I'm a bit of an odd case, but I find this sort of research fun and therapeutic.) Let's dig in.

Identifying the applications

This is an area where 128 Technology has invested heavily over the course of the past few years. There are two primary tools in your toolbox for this:

  • AppID modules: these are typically implemented as Python scripts (though any executable will do), and will create JSON files that your 128T ingests to create dynamic services. For the ambitious, you can write your own – it's not too difficult, I've even done it myself... and I'm most assuredly not a software developer.
  • Our DNS AppID plugin: this plugin dovetails with ans onboard DNS cache, and associates DNS responses to services dynamically, based on regex pattern matching. It's easy, it's fast, and it's extremely powerful.

When to choose one of these tools over the other is a bit of an art. My general rule of thumb: if a SaaS provider publishes a list of reachable addresses (including those advertised to the internet using BGP), it's best to use an AppID module. If a provider does not publish a list of addresses, the DNS AppID plugin is a good place to start.

The targets: YouTube, Netflix, and Hulu

At our house, these are the big three applications for streaming entertainment. My mission was to create AppID profiles for these applications.

For Netflix, I decided upon the module approach. This is because Netflix conveniently advertises all of their reachable IP addresses publicly using BGP, as AS2906, and RIPE provides a friendly way of grabbing them all in JSON format.

Note: the module I wrote for Netflix is available in the GitHub repo linked above.

For YouTube and Hulu I went with the DNS approach, although for different reasons. It made sense for YouTube, because there is no clean way to disambiguate between Google addresses and YouTube addresses based on BGP advertisements – there's a lot of overlap. For Hulu, while they do advertise their own prefixes into BGP, they also leverage Akamai as a CDN for a lot of their content.

For YouTube, here's my ruleset:

admin@labsystem1.fiedler# show config running authority router becket dns-app-id custom-apps YOUTUBE

config

    authority

        router  becket
            name        becket

            dns-app-id

                custom-apps  YOUTUBE
                    name         YOUTUBE
                    description  YouTube
                    patterns     youtube\.com
                    patterns     .*\.youtube\.com
                    patterns     ytimg\.com
                    patterns     .*\.ytimg\.com
                    patterns     ytimg\.l\.google\.com
                    patterns     .*\.ytimg\.l\.google\.com
                    patterns     youtube\.l\.google\.com
                    patterns     .*\.youtube\.l\.google\.com
                    patterns     googlevideo\.com
                    patterns     .*\.googlevideo\.com
                exit
            exit
        exit
    exit
exit

Here's the set for Hulu:

admin@labsystem1.fiedler# show config running authority router becket dns-app-id custom-apps HULU

config

    authority

        router  becket
            name        becket

            dns-app-id

                custom-apps  HULU
                    name         HULU
                    description  "source: https://www.reddit.com/r/PFSENSE/comments/aurnb7/help_with_firewall_aliases_for_hulu/"
                    patterns     .*\.hulu\.com
                    patterns     .*\.huluim\.com
                    patterns     hulu\.com
                    patterns     huluim\.com
                    patterns     .*\.hulureplay\.com
                    patterns     hulureplay\.com
                    patterns     .*\.hulustream\.com
                exit
            exit
        exit
    exit
exit

You can see in my attribution in the Hulu ruleset that I found a redditor that did the heavy lifting for me in unearthing all of the various FQDNs that Hulu uses. I did validate them, of course.

Policy-based traffic control

Now, the fun part: applying configuration to my 128T to control the traffic appropriately.

Here's what I put in place for YouTube:

admin@labsystem1.fiedler# show config running authority service YOUTUBE.internet

config

    authority

        service  YOUTUBE.internet
            name                  YOUTUBE.internet

            scope                 private
            application-name      YOUTUBE

            access-policy         trusted
                source  trusted
            exit

            access-policy         guest
                source  guest
            exit
            
            access-policy         appletv.iot
                source  appletv.iot
            exit
            service-policy        video-streaming-scavenger
            share-service-routes  false
        exit
    exit
exit

This config fragment references application-name YOUTUBE, which will associate the prefixes learned by the DNS AppID plugin with this service and create FIB entries accordingly. Astute 128T aficionados may have also noticed that my service is named YOUTUBE.internet. This is part of a soon-to-be-released feature wherein services can be organized hierarchically, like tenants. The benefit of the hierarchical organization is that it can leverage the same underpinnings of the parent service (internet in this case) for route selection, yet still provide for the ability to override attributes of the parent service. In this case, I've overridden the generic internet's service-policy, and replaced it with video-streaming-scavenger. You can probably intuit what that policy does for me.

The only other nuance here is that my access-policy statements include the trusted, guest, and appletv.iot tenants. This is because we all tend to watch YouTube videos on our phones, tablets, laptops, etc. in addition to AppleTV.

The service definitions for Hulu and Netflix look similar to one another. Here's Hulu's:

admin@labsystem1.fiedler# show config running authority service HULU.internet

config

    authority

        service  HULU.internet
            name                  HULU.internet

            description           "Hulu streaming"
            scope                 private
            application-name      HULU

            access-policy         appletv.iot
                source  appletv.iot
            exit
            service-policy        video-streaming
            share-service-routes  false
        exit
    exit
exit

Unlike YouTube, this is only available to AppleTV. (We don't use Hulu or Netflix on anything else; if we were to try, it would get "best effort" treatment using an internet service.) Here we can see the service-policy is video-streaming – which, unlike its scavenger counterpart, uses DSCP AF31 (decimal 26) via the built-in MultimediaStreaming service-class:

admin@labsystem1.fiedler# show config running authority service-policy video-streaming

config

    authority

        service-policy  video-streaming
            name                 video-streaming
            description          "Enterprise video streaming services"
            service-class        MultimediaStreaming
            session-resiliency   failover
            path-quality-filter  true
            best-effort          true
            max-loss             5
            max-latency          4000
        exit
    exit
exit
The values for session-resiliency, max-loss, and max-latency are all discussed in the document I wrote on Service Policy Baseline Defaults.

Conclusion

I'm now able to identify streaming video traffic on my network much more easily, and have controls in place to limit bandwidth for YouTube while prioritizing Hulu and Netflix for the times when we sit down for Family Movie Night.

I encourage all of you 128T owners to do your own exploration with the DNS AppID plugin and AppID modules. There's no limit to the things you can learn!