TLS_ECDH_RSA_WITH_AES_256_CBC_SHATLS_ECDH_RSA_WITH_AES_128_CBC_SHATLS_DH_RSA_WITH_AES_256_CBC_SHATLS_DH_RSA_WITH_AES_128_CBC_SHATLS compression is disabled by default. TLS session resumption is also supported to reduce processor and traffic overhead due to publickey cryptographic operations and handshake traffic. However, the maximum time allowed for a TLS session to resume without repeatingthe TLS authentication or handshake process is configurable with a default of 1 hour. You can also disable session resumption.Syslog over TLSSyslog over TLS mandates that a client certificate must be presented, to ensure that all Syslog entries written to the server are from atrusted client.Online Certificate Status Protocol (OSCP)Use the Online Certificate Status Protocol (OSCP) to obtain the revocation status of a X.509v3 certificate.A device or a Certificate Authority (CAs) can check the status of a X.509v3 certificate by sending an OCSP request to an OCSP server orresponder. An OCSP responder, a server typically run by the certificate issuer, returns a signed response signifying that the certificatespecified in the request is 'good', 'revoked', or 'unknown'. The OCSP response indicates whether the presented certificate is valid.OCSP provides a way for Certificate Authorities to revoke signed certificates before the expiration date. In a CA certificate, OCSPResponder information is specified in the authorityInfoAccess extension.A CA can verify the revocation status of a certificate with multiple OCSP responders. When multiple OCSP responders exist, you canconfigure the order or preference the CA takes while contacting various OCSP responders for verification.Upon receiving a presented certificate, the system sends an OCSP request to an OCSP responder through HTTP. The system then verifiesthe OCSP response using either a trusted public key or the OCSP responder’s own self-signed certificate. This self-signed certificateinstalls on the device's trusted location even before an OCSP request is made. The system accepts or rejects the presented certificatebased on the OCSP response.In a scenario where all OCSP responders are unreachable, the switch accepts the certificate. This action is the default behavior. You canalso configure an alternate system behavior when all OCSP responders are unreachable. However, the switch may become vulnerable todenial-of-service attack if you configure the system to deny the certificate when OCSP responders are not reachable.The system creates logs for the following events:• Failures to reach OCSP responders• Invalid OCSP responses—for example, cannot verify the signed response with an installed CA certificate.• Rejection of a certificate due to OCSPConfiguring OCSP setting on CAYou can configure the CA to contact multiple OCSP servers.To configure OCSP server for a CA, perform the following step:In the certificate mode, enter the following command:ocsp-server URL [nonce] [sign-requests]X.509v3 1079
