SNMPv2c的读写社区允许的最大长度

Question

你能告诉我SNMPv2c读写社区允许的最大长度吗？.I没有找到任何相关的文档，可以提供关于它的描述。

谢谢-Ravi

Answer 1

基于社区的模型还引用USM表中的条目。在RFC3414中定义的SNMP USM MIB之后，usmUserName和usmSecurityName的定义如下所示，它将用户名限制为32个字符。文本约定SnmpAdminString本身是255个八位字节

usmUserName      OBJECT-TYPE
    SYNTAX       SnmpAdminString (SIZE(1..32))
    MAX-ACCESS   not-accessible
    STATUS       current
    DESCRIPTION "A human readable string representing the name of
                 the user.

                 This is the (User-based Security) Model dependent
                 security ID.
                "
    ::= { usmUserEntry 2 }

usmUserSecurityName OBJECT-TYPE
    SYNTAX       SnmpAdminString
    MAX-ACCESS   read-only
    STATUS       current
    DESCRIPTION "A human readable string representing the user in
                 Security Model independent format.

                 The default transformation of the User-based Security
                 Model dependent security ID to the securityName and
                 vice versa is the identity function so that the
                 securityName is the same as the userName.
                "
    ::= { usmUserEntry 3 }

文本约定usmUserSecurityName是在RFC3411中定义的

SnmpAdminString ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "255t"
    STATUS       current
    DESCRIPTION "An octet string containing administrative
                 information, preferably in human-readable form.

。。

                 Note that when this TC is used for an object that
                 is used or envisioned to be used as an index, then
                 a SIZE restriction MUST be specified so that the
                 number of sub-identifiers for any object instance
                 does not exceed the limit of 128, as defined by
                 [RFC3416].

                 Note that the size of an SnmpAdminString object is
                 measured in octets, not characters.
                "
    SYNTAX       OCTET STRING (SIZE (0..255))

在思科交换机/路由器上，当您通过CLI进行设置时，也会强制执行此设置。

Answer 2

根据RFC 3584，对长度没有明确限制。限制将是实际的(消息大小等)。