Cisco TelePresence Administrator's Manual page 111

SPNEGO
SPNEGO (Simple and Protected GSSAPI Negotiation Mechanism) is a mechanism used by client
applications when they seek to authenticate with a remote server. It allows the client and server to identify
which authentication protocols they both support and decide which protocol to use.
By default the VCS uses SPNEGO when communicating with an AD Domain Controller. It can only be
enabled or disabled through the CLI by using the command xConfiguration Authentication ADS
SPNEGO.
Ports
The process of joining domains and authenticating credentials involves communications with many services
over different protocols. The following table summarizes the ports used:
Service/protocol
DNS server
Kerberos Key Distribution Center
CLDAP communications with the Domain Controller
LDAP communications with the Domain Controller
Microsoft-DS RPC communications with the Domain Controller
(used for the authentication of client credentials)
Cisco VCS Administrator Guide (X7.1)
Device authentication
Default destination port
UDP/53
UDP/88
Note that Kerberos also uses TCP/88.
UDP/389
TCP/389
TCP/445
Note that if TCP/445 cannot be reached, the
system falls back to using TCP/139.
Page 111 of 479