Named issues with T-Mobile 5G for Business

[Philip Prindeville]

> On Jan 6, 2026, at 1:04 PM, Marco Moock <mm at dorfdsl.de> wrote:
> 
> Am 06.01.2026 um 13:02:18 Uhr schrieb Philip Prindeville:
> 
>>                                       Packets               Pings
>> Host                                Loss%   Snt   Last   Avg  Best  Wrst StDev
>> 1. (waiting for reply)
>> 2. 10.170.203.249                   64.9%    57   69.9 255.3  66.8 2003. 488.3
>> 3. 10.164.160.61                    82.1%    57   68.9 330.0  66.4 1930. 605.4
>> 4. ae2.er1.ord2.us.zip.zayo.com     64.9%    57   81.1 235.9  67.6 1857. 437.4
>> 5. (waiting for reply)
>> 6. ae20.cr1.ord8.us.zip.zayo.com    91.1%    56   91.9  78.5  64.7
>> 91.9  12.11
> 
> And here is your issue - massive packet loss.
> 



A lot of core routers do random drop on ICMP to avoid denial-of-service attacks since ICMP isn't fastswitched (i.e. it takes the CPU to process the packets instead of ASICs).

At least that was the case 20 years ago when I was at Cisco.