> # Trust Model, Trust Points, and Identity CAs

> The trust model used in PKI support is hierarchical with multiple configurable trusted CAs. Each participating entity is configured with a list of CAs to be trusted so that the peer’s certificate obtained during the security protocol exchanges can be verified, provided it has been issued by one of the locally trusted CAs. To accomplish this, the CA’s self-signed root certificate (or certificate chain for a subordinate CA) is locally stored. The process of securely obtaining a trusted CA’s root certificate (or the entire chain in the case of a subordinate CA) and storing it locally is called CA authentication and is a mandatory step in trusting a CA.

> The information about a trusted CA that is locally configured is called the trust point and the CA itself is called a trust point CA. This information consists of CA certificate (or certificate chain in case of a subordinate CA) and the certificate revocation checking information.

> The MDS switch can also enroll with a trust point to obtain an identity certificate (for example, for IPsec/IKE). This trust point is called an identity CA.

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