Custom Traffic Shaping Rules on the MX for Dell Update is Not Taking Effect

[CarloDC]

We have this traffic shaping rule configured on the MX under Security & SD-WAN > SDWAN and Traffic Shaping where we created a custom expression for downloads.dell.com traffic and limited the upload and download bandwidth to 1Mbps. But a couple of days ago we monitored that downloads.dell.com traffic consumed above 40Mbps of BW and this affected our operations. 

I provided Meraki Support the screenshot of the traffic analytics filtered for the last week which clearly shows that the downloads.dell.com traffic consumed BW above 40Mbps if you'll take a look at the Y-axis. But I found their analysis inaccurate.

According two Meraki Support that I got in touch with:

TAC Support 1. In Meraki, bandwidth limits are applied per client, not as a total cap for the destination. (This is correct to some extent because on the custom rule you can choose three method of Bandwidth limiting; first is to obey network per client limit, second is to ignore network per client limit, and third is choose a limit which is what we configured) Can any one tell me if the third method is also applied on a per client basis?

TAC Support 2. The Meraki TAC mentioned that If we distribute the traffic evenly during the week we get a consumption of 760 kb/s which is under the bandwidth configured in traffic shaping. (This is true if you take the average utilization on a span of one week they completely ignore the graph where it shows that a specific date and time (Jan 21), the utilization peaked above 40Mbps. 

I find their statements very contradicting with each other. 

Lastly I want to know if I am missing any configuration here or should I have disabled the default traffic shaping rule as the software updates is included there which I think (but I am not certain) that the dell update is under this category. 

It's not every day nor every week that we get a dell update so I won't be able to recreate the same issue

apologies for the long read. I would appreciate any help

Thank you!

[ww]

All shaping is per client (except for the global wan interface shaper)

111 local clients can use 1 Mbps each.

Consider assigning prio low to the rule

Custom shaping rule takes precedence over the default shaping rules

[alemabrahao]

Traffic‑shaping rules are enforced per client flow, not as a single shared cap per destination or per rule. If you set 1 Mbps on a rule, each matching client flow can get up to 1 Mbps. Ten clients each pulling a Dell payload can therefore add up to 10 Mbps, etc. This is explicitly documented: Traffic and Bandwidth Shaping - Cisco Meraki Documentation

Even if you found downloads.dell.com, Dell update agents often use CDNs and multiple hostnames (e.g., Akamai, edge servers that don't resolve to the exact FQDN you defined). The Meraki classification engine uses SNI, certificate CN, DNS information, IP/port heuristics, etc, to associate flows with applications/hosts, but if the flows don't have downloads.dell.com as the SNI, or are obtained from different hostnames/IPs learned via DNS, your custom single-host expression won't capture them all.

Traffic Analysis and Classification - Cisco Meraki Documentation

[MeqaqiQajaj]

Das Problem scheint darin zu liegen, wie Meraki die Traffic-Shaping-Begrenzungen anwendet. Selbst wenn Sie ein festes Limit konfiguriert haben, ist es möglich, dass dieses pro Client und nicht als Gesamtlimit für den gesamten Datenverkehr zu downloads.dell.com gilt. Das würde erklären, warum Sie einen Spitzenwert von über 40 Mbit/s beobachtet haben, als mehrere Clients gleichzeitig heruntergeladen haben. Die durchschnittliche Nutzung über eine Woche kann solche Spitzenwerte verschleiern, weshalb die Aussagen des TAC widersprüchlich erscheinen. Prüfen Sie außerdem, ob die Standard-Traffic-Shaping-Regel für Software-Updates mit Ihrer benutzerdefinierten Regel übereinstimmt, da Dell-Updates Ihr Limit möglicherweise umgehen, wenn sie darunter kategorisiert sind.