An IP reservation resource (
IPReservation) represents a collection of IP addresses that Calico should
not use when automatically assigning new IP addresses. It only applies when Calico IPAM is in use.
IP reservation definition
|name||The name of this IPReservation resource. Required.||Alphanumeric string with optional ||string|
|reservedCIDRs||List of IP addresses and/or networks specified in CIDR notation||List of valid IP addresses (v4 or v6) and/or CIDRs||list|
The implementation of
IPReservations is designed to handle reservation of a small number of IP addresses/CIDRs from
(generally much larger) IP pools. If a significant portion of an IP pool is reserved (say more than 10%) then
Calico may become significantly slower when searching for free IPAM blocks.
IPReservations must be consulted for every IPAM assignment request, it's best to have one or two
IPReservation resources with multiple addresses per
IPReservation resource (rather than having many IPReservation
resources), each with one address inside.
IPReservation is created after an IP from its range is already in use then the IP is not automatically
released back to the pool. The reservation check is only done at auto allocation time.
Calico supports Kubernetes annotations that force the use of specific IP addresses. These annotations override any
are in place.
When Windows nodes claim blocks of IPs they automatically assign the first three IPs
in each block and the final IP for internal purposes. These assignments cannot be blocked by an
However, if a whole IPAM block is reserved with an
IPReservation, Windows nodes will not claim such a block.