In order to conserve the limited bandwidth available, ISO images are not downloadable from mirror.centos.org
The following mirrors should have the ISO images available:
http://mirror.ash.fastserv.com/centos/8.1.1911/isos/ppc64le/
http://centos.mirror.ndchost.com/8.1.1911/isos/ppc64le/
http://mirror.shastacoe.net/centos/8.1.1911/isos/ppc64le/
http://mirror.grid.uchicago.edu/pub/linux/centos/8.1.1911/isos/ppc64le/
http://mirror.wdc1.us.leaseweb.net/centos/8.1.1911/isos/ppc64le/
http://packages.oit.ncsu.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.arizona.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.cs.pitt.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.datto.com/CentOS/8.1.1911/isos/ppc64le/
http://mirror.facebook.net/centos/8.1.1911/isos/ppc64le/
http://ftp.osuosl.org/pub/centos/8.1.1911/isos/ppc64le/
http://mirror.mobap.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.metrocast.net/centos/8.1.1911/isos/ppc64le/
http://mirror.web-ster.com/centos/8.1.1911/isos/ppc64le/
http://mirror.rackspace.com/CentOS/8.1.1911/isos/ppc64le/
http://mirrors.unifiedlayer.com/centos/8.1.1911/isos/ppc64le/
http://mirror.linux.duke.edu/pub/centos/8.1.1911/isos/ppc64le/
http://centos.den.host-engine.com/8.1.1911/isos/ppc64le/
http://linux.mirrors.es.net/centos/8.1.1911/isos/ppc64le/
http://mirror.math.princeton.edu/pub/centos/8.1.1911/isos/ppc64le/
http://mirror.us-midwest-1.nexcess.net/CentOS/8.1.1911/isos/ppc64le/
http://mirrors.raystedman.org/centos/8.1.1911/isos/ppc64le/
http://mirror.steadfastnet.com/centos/8.1.1911/isos/ppc64le/
http://mirror.umd.edu/centos/8.1.1911/isos/ppc64le/
http://mirrors.codec-cluster.org/centos/8.1.1911/isos/ppc64le/
http://centos-distro.1gservers.com/8.1.1911/isos/ppc64le/
http://mirror.pit.teraswitch.com/centos/8.1.1911/isos/ppc64le/
http://mirrors.seas.harvard.edu/centos/8.1.1911/isos/ppc64le/
http://centos.mirrors.hoobly.com/8.1.1911/isos/ppc64le/
http://mirror.fileplanet.com/centos/8.1.1911/isos/ppc64le/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/
Mirrors verified Mon Jun 15 05:32:25 2020 UTC
You can also download the ISO images using bittorrent, a peer-to-peer file sharing protocol. The .torrent files can be found from CentOS mirrors. Various bittorrent clients are available, including (in no particular order of preference): utorrent, vuze (Azureus), BitTorrent, Deluge, ctorrent, ktorrent, rtorrent and transmission. Packaged copies of various torrent clients for CentOS can be found in the repositories listed in the following wiki article: https://wiki.centos.org/AdditionalResources/Repositories
The following mirrors should have the ISO images available:
http://mirror.ash.fastserv.com/centos/8.1.1911/isos/ppc64le/
http://centos.mirror.ndchost.com/8.1.1911/isos/ppc64le/
http://mirror.shastacoe.net/centos/8.1.1911/isos/ppc64le/
http://mirror.grid.uchicago.edu/pub/linux/centos/8.1.1911/isos/ppc64le/
http://mirror.wdc1.us.leaseweb.net/centos/8.1.1911/isos/ppc64le/
http://packages.oit.ncsu.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.arizona.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.cs.pitt.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.datto.com/CentOS/8.1.1911/isos/ppc64le/
http://mirror.facebook.net/centos/8.1.1911/isos/ppc64le/
http://ftp.osuosl.org/pub/centos/8.1.1911/isos/ppc64le/
http://mirror.mobap.edu/centos/8.1.1911/isos/ppc64le/
http://mirror.metrocast.net/centos/8.1.1911/isos/ppc64le/
http://mirror.web-ster.com/centos/8.1.1911/isos/ppc64le/
http://mirror.rackspace.com/CentOS/8.1.1911/isos/ppc64le/
http://mirrors.unifiedlayer.com/centos/8.1.1911/isos/ppc64le/
http://mirror.linux.duke.edu/pub/centos/8.1.1911/isos/ppc64le/
http://centos.den.host-engine.com/8.1.1911/isos/ppc64le/
http://linux.mirrors.es.net/centos/8.1.1911/isos/ppc64le/
http://mirror.math.princeton.edu/pub/centos/8.1.1911/isos/ppc64le/
http://mirror.us-midwest-1.nexcess.net/CentOS/8.1.1911/isos/ppc64le/
http://mirrors.raystedman.org/centos/8.1.1911/isos/ppc64le/
http://mirror.steadfastnet.com/centos/8.1.1911/isos/ppc64le/
http://mirror.umd.edu/centos/8.1.1911/isos/ppc64le/
http://mirrors.codec-cluster.org/centos/8.1.1911/isos/ppc64le/
http://centos-distro.1gservers.com/8.1.1911/isos/ppc64le/
http://mirror.pit.teraswitch.com/centos/8.1.1911/isos/ppc64le/
http://mirrors.seas.harvard.edu/centos/8.1.1911/isos/ppc64le/
http://centos.mirrors.hoobly.com/8.1.1911/isos/ppc64le/
http://mirror.fileplanet.com/centos/8.1.1911/isos/ppc64le/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/
Mirrors verified Mon Jun 15 05:32:25 2020 UTC
You can also download the ISO images using bittorrent, a peer-to-peer file sharing protocol. The .torrent files can be found from CentOS mirrors. Various bittorrent clients are available, including (in no particular order of preference): utorrent, vuze (Azureus), BitTorrent, Deluge, ctorrent, ktorrent, rtorrent and transmission. Packaged copies of various torrent clients for CentOS can be found in the repositories listed in the following wiki article: https://wiki.centos.org/AdditionalResources/Repositories