Comcast - Significant v4 vs v6 throughput differences, almost stateful.

Thu Apr 23 15:50:19 UTC 2020

On Thu, Apr 23, 2020 at 8:27 AM Dovid Bender <dovid at telecurve.com> wrote:

> We have customers in CT with the same issues. When did this start?
>

Seems to have started 5 years ago when we ran out of ipv4 and all comers
needed to embrace ipv4 life-support mechanisms

https://www.arin.net/vault/announcements/2015/20150924.html

The e2e ipv6 internet being faster and more robust than life-supported,
bot-ridden, and scarce ipv4 is.... a feature, not a bug.

https://www.internetsociety.org/blog/2015/04/facebook-news-feeds-load-20-40-faster-over-ipv6/

>
> On Thu, Apr 23, 2020 at 11:07 AM Nick Zurku <nzurku at teraswitch.com> wrote:
>
>> Hello all,
>>
>> I would appreciate if someone from Comcast could contact me about this.
>>
>> We’re having serious throughput issues with our AS20326 pushing packets
>> to Comcast over v4. Our transfers are either the full line-speed of the
>> Comcast customer modem, or they’re seemingly capped at 200-300KB/s. This
>> behavior appears to be almost stateful, as if the speed is decided when the
>> connection starts. As long as it starts fast it will remain fast for the
>> length of the transfer and slow if it starts slow. Traces seem reasonable
>> and currently we’ve influenced the path onto GTT both ways. If we prepend
>> and reroute on our side, the same exact issue with happen on another
>> transit provider.
>>
>> This issue does not affect v6 and that is full speed on every attempt.
>> This may be regionalized to the Comcast Pittsburgh market.
>>
>> This is most widely affecting our linux mirror repository server:
>> http://mirror.pit.teraswitch.com/
>> Our colocation customers who are hosting VPN systems are also noticing
>> bottlenecks have started recently for their Comcast employees.
>>
>> --
>> Nick Zurku
>> Systems Engineer
>> TeraSwitch, Inc.
>> nzurku at teraswitch.com
>>
>
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