Oh hold on. the *service cluster IP range* is not for pod IPs at all. It's for the ClusterIP of services, so you can have up to 64k services in a cluster at the default setting. The range for pods is the --cluster-cidr flag on kube-controller-manager.
On Fri, Aug 11, 2017 at 3:05 PM David Rosenstrauch <dar...@darose.net> wrote: > Actually, that begs another question. The docs also specify that k8s > can support up to 5000 nodes. But I'm not clear on how the networking > can support that. > > So let's go back to that service-cluster-ip-range with the /16 CIDR. > That only supports a maximum of 256 nodes. > > Now the maximum size for the service-cluster-ip-range appears to be /12 > - e.g., --service-cluster-ip-range=10.240.0.0/12 (Beyond that you get a > "Specified service-cluster-ip-range is too large" error.) So that means > 12 bits for the high part of the address, and with each node taking the > lower 8 bits for the IP address of individual pods, that leaves 12 > remaining bits worth of unique IP address ranges. 12 bits = 4095 > possible IP addresses for nodes. How then could anyone scale up to 5000 > nodes? > > DR > > On 2017-08-11 10:47 am, David Rosenstrauch wrote: > > Ah. That makes a bit more sense. > > > > Thanks! > > > > DR > > > > On 2017-08-11 10:41 am, Ben Kochie wrote: > >> Kuberentes will be giving a /24 to each node, not each pod. Each node > >> will give one IP out of that /24 to a pod it controls. This default > >> means you can have 253 pods-per-node. This of course can be adjust > >> depending on the size of your pods and nodes. > >> > >> This means that you can fully utilize the /16 for pods (minus per-node > >> network, broadcast, gateway) > >> > >> On Fri, Aug 11, 2017 at 4:36 PM, David Rosenstrauch > >> <dar...@darose.net> wrote: > >> > >>> According to the docs, k8s can support systems of up to 150000 pods. > >>> (See https://kubernetes.io/docs/admin/cluster-large/ [1]) But > >>> given k8s' networking model, I'm a bit puzzled on how that would > >>> work. > >>> > >>> It seems like a typical setup is to assign a > >>> service-cluster-ip-range with a /16 CIDR. (Say 10.254.0.0/16 [2]) > >>> However, I notice that my cluster assigns a full /24 IP range to > >>> each pod that it creates. (E.g., pod1 gets 10.254.1.*, pod2 gets > >>> 10.254.2.*, etc.) Given this networking setup, it would seem that > >>> Kubernetes would only be capable of launching a maximum of 256 pods. > >>> > >>> Am I misunderstanding how k8s works in this r? Or is it that the > >>> networking would need to be configured differently to support more > >>> than 256 pods? > >>> > >>> Thanks, > >>> > >>> DR > >>> > >>> -- > >>> You received this message because you are subscribed to the Google > >>> Groups "Kubernetes user discussion and Q&A" group. > >>> To unsubscribe from this group and stop receiving emails from it, > >>> send an email to kubernetes-users+unsubscr...@googlegroups.com. > >>> To post to this group, send email to > >>> kubernetes-users@googlegroups.com. > >>> Visit this group at https://groups.google.com/group/kubernetes-users > >>> [3]. > >>> For more options, visit https://groups.google.com/d/optout [4]. > >> > >> -- > >> You received this message because you are subscribed to the Google > >> Groups "Kubernetes user discussion and Q&A" group. > >> To unsubscribe from this group and stop receiving emails from it, send > >> an email to kubernetes-users+unsubscr...@googlegroups.com. > >> To post to this group, send email to > >> kubernetes-users@googlegroups.com. > >> Visit this group at https://groups.google.com/group/kubernetes-users. > >> For more options, visit https://groups.google.com/d/optout. > >> > >> > >> Links: > >> ------ > >> [1] https://kubernetes.io/docs/admin/cluster-large/ > >> [2] http://10.254.0.0/16 > >> [3] https://groups.google.com/group/kubernetes-users > >> [4] https://groups.google.com/d/optout > > -- > You received this message because you are subscribed to the Google Groups > "Kubernetes user discussion and Q&A" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to kubernetes-users+unsubscr...@googlegroups.com. > To post to this group, send email to kubernetes-users@googlegroups.com. > Visit this group at https://groups.google.com/group/kubernetes-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Kubernetes user discussion and Q&A" group. To unsubscribe from this group and stop receiving emails from it, send an email to kubernetes-users+unsubscr...@googlegroups.com. To post to this group, send email to kubernetes-users@googlegroups.com. Visit this group at https://groups.google.com/group/kubernetes-users. For more options, visit https://groups.google.com/d/optout.
