RFC 1156
Management Information Base for network management of TCP/IP-based internets
5.4. The IP Group Implementation of the IP group is mandatory for all systems. OBJECT: ------- ipForwarding { ip 1 } Syntax: INTEGER { gateway(1), -- entity forwards datagrams host(2) -- entity does NOT forward datagrams } Definition: The indication of whether this entity is acting as an IP gateway in respect to the forwarding of datagrams received by, but not addressed to, this entity. IP gateways forward datagrams; Hosts do not (except those Source-Routed via the host). Access: read-only. Status: mandatory. OBJECT: ------- ipDefaultTTL { ip 2 } Syntax: INTEGER Definition: The default value inserted into the Time-To-Live field of the IP header of datagrams originated at this entity, whenever a TTL value is not supplied by the transport layer protocol. Access: read-write. Status: mandatory.
OBJECT:
-------
ipInReceives { ip 3 }
Syntax:
Counter
Definition:
The total number of input datagrams received from
interfaces, including those received in error.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipInHdrErrors { ip 4 }
Syntax:
Counter
Definition:
The number of input datagrams discarded due to errors in
their IP headers, including bad checksums, version number
mismatch, other format errors, time-to-live exceeded,
errors discovered in processing their IP options, etc.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipInAddrErrors { ip 5 }
Syntax:
Counter
Definition:
The number of input datagrams discarded because the IP
address in their IP header's destination field was not a
valid address to be received at this entity. This count
includes invalid addresses (e.g., 0.0.0.0) and addresses
of unsupported Classes (e.g., Class E). For entities
which are not IP Gateways and therefore do not forward
datagrams, this counter includes datagrams discarded
because the destination address was not a local address.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipForwDatagrams { ip 6 }
Syntax:
Counter
Definition:
The number of input datagrams for which this entity was
not their final IP destination, as a result of which an
attempt was made to find a route to forward them to that
final destination. In entities which do not act as IP
Gateways, this counter will include only those packets
which were Source-Routed via this entity, and the
Source-Route option processing was successful.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipInUnknownProtos { ip 7 }
Syntax:
Counter
Definition:
The number of locally-addressed datagrams received
successfully but discarded because of an unknown or
unsupported protocol.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipInDiscards { ip 8 }
Syntax:
Counter
Definition:
The number of input IP datagrams for which no problems
were encountered to prevent their continued processing,
but which were discarded (e.g. for lack of buffer space).
Note that this counter does not include any datagrams
discarded while awaiting re-assembly.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipInDelivers { ip 9 }
Syntax:
Counter
Definition:
The total number of input datagrams successfully
delivered to IP user-protocols (including ICMP).
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipOutRequests { ip 10 }
Syntax:
Counter
Definition:
The total number of IP datagrams which local IP user-
protocols (including ICMP) supplied to IP in requests for
transmission. Note that this counter does not include
any datagrams counted in ipForwDatagrams.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipOutDiscards { ip 11 }
Syntax:
Counter
Definition:
The number of output IP datagrams for which no problem
was encountered to prevent their transmission to their
destination, but which were discarded (e.g., for lack of
buffer space). Note that this counter would include
datagrams counted in ipForwDatagrams if any such packets
met this (discretionary) discard criterion.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipOutNoRoutes { ip 12 }
Syntax:
Counter
Definition:
The number of IP datagrams discarded because no route
could be found to transmit them to their destination.
Note that this counter includes any packets counted in
ipForwDatagrams which meet this "no-route" criterion.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipReasmTimeout { ip 13 }
Syntax:
INTEGER
Definition:
The maximum number of seconds which received fragments
are held while they are awaiting reassembly at this
entity.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipReasmReqds { ip 14 }
Syntax:
Counter
Definition:
The number of IP fragments received which needed to be
reassembled at this entity.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipReasmOKs { ip 15 }
Syntax:
Counter
Definition:
The number of IP datagrams successfully re-assembled.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipReasmFails { ip 16 }
Syntax:
Counter
Definition:
The number of failures detected by the IP re-assembly
algorithm (for whatever reason: timed out, errors, etc).
Note that this is not necessarily a count of discarded IP
fragments since some algorithms (notably RFC 815's) can
lose track of the number of fragments by combining them
as they are received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipFragOKs { ip 17 }
Syntax:
Counter
Definition:
The number of IP datagrams that have been successfully
fragmented at this entity.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipFragFails { ip 18 }
Syntax:
Counter
Definition:
The number of IP datagrams that have been discarded
because they needed to be fragmented at this entity but
could not be, e.g., because their "Don't Fragment" flag
was set.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipFragCreates { ip 19 }
Syntax:
Counter
Definition:
The number of IP datagram fragments that have been
generated as a result of fragmentation at this entity.
Access:
read-only.
Status:
mandatory.
5.4.1. The IP Address Table The Ip Address table contains this entity's IP addressing information. OBJECT: ------- ipAddrTable { ip 20 } Syntax: SEQUENCE OF IpAddrEntry Definition: The table of addressing information relevant to this entity's IP addresses. Access: read-only. Status: mandatory. OBJECT: ------- ipAddrEntry { ipAddrTable 1 } Syntax: IpAddrEntry ::= SEQUENCE { ipAdEntAddr IpAddress, ipAdEntIfIndex INTEGER, ipAdEntNetMask IpAddress, ipAdEntBcastAddr INTEGER } Definition: The addressing information for one of this entity's IP addresses. Access: read-only.
Status:
mandatory.
OBJECT:
-------
ipAdEntAddr { ipAddrEntry 1 }
Syntax:
IpAddress
Definition:
The IP address to which this entry's addressing
information pertains.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipAdEntIfIndex { ipAddrEntry 2 }
Syntax:
INTEGER
Definition:
The index value which uniquely identifies the interface
to which this entry is applicable. The interface
identified by a particular value of this index is the
same interface as identified by the same value of
ifIndex.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipAdEntNetMask { ipAddrEntry 3 }
Syntax:
IpAddress
Definition:
The subnet mask associated with the IP address of this
entry. The value of the mask is an IP address with all
the network bits set to 1 and all the hosts bits set to
0.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipAdEntBcastAddr { ipAddrEntry 4 }
Syntax:
INTEGER
Definition:
The value of the least-significant bit in the IP
broadcast address used for sending datagrams on the
(logical) interface associated with the IP address of
this entry. For example, when the Internet standard
all-ones broadcast address is used, the value will be 1.
Access:
read-only.
Status:
mandatory.
5.4.2. The IP Routing Table
The IP Routing Table contains an entry for each route
presently known to this entity. Note that the action to be
taken in response to a request to read a non-existent entry,
is specific to the network management protocol being used.
OBJECT:
-------
ipRoutingTable { ip 21 }
Syntax:
SEQUENCE OF IpRouteEntry
Definition:
This entity's IP Routing table.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteEntry { ipRoutingTable 1 }
Syntax:
IpRouteEntry ::= SEQUENCE {
ipRouteDest
IpAddress,
ipRouteIfIndex
INTEGER,
ipRouteMetric1
INTEGER,
ipRouteMetric2
INTEGER,
ipRouteMetric3
INTEGER,
ipRouteMetric4
INTEGER,
ipRouteNextHop
IpAddress,
ipRouteType
INTEGER,
ipRouteProto
INTEGER,
ipRouteAge
INTEGER
}
Definition:
A route to a particular destination.
Access:
read-write.
Status:
mandatory.
We now consider the individual components of each route in the
IP Routing Table:
OBJECT:
-------
ipRouteDest { ipRouteEntry 1 }
Syntax:
IpAddress
Definition:
The destination IP address of this route. An entry with
a value of 0.0.0.0 is considered a default route.
Multiple such default routes can appear in the table, but
access to such multiple entries is dependent on the
table-access mechanisms defined by the network management
protocol in use.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteIfIndex { ipRouteEntry 2 }
Syntax:
INTEGER
Definition:
The index value which uniquely identifies the local
interface through which the next hop of this route should
be reached. The interface identified by a particular
value of this index is the same interface as identified
by the same value of ifIndex.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteMetric1 { ipRouteEntry 3 }
Syntax:
INTEGER
Definition:
The primary routing metric for this route. The semantics
of this metric are determined by the routing-protocol
specified in the route's ipRouteProto value. If this
metric is not used, its value should be set to -1.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteMetric2 { ipRouteEntry 4 }
Syntax:
INTEGER
Definition:
An alternate routing metric for this route. The
semantics of this metric are determined by the routing-
protocol specified in the route's ipRouteProto value. If
this metric is not used, its value should be set to -1.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteMetric3 { ipRouteEntry 5 }
Syntax:
INTEGER
Definition:
An alternate routing metric for this route. The
semantics of this metric are determined by the routing-
protocol specified in the route's ipRouteProto value. If
this metric is not used, its value should be set to -1.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteMetric4 { ipRouteEntry 6 }
Syntax:
INTEGER
Definition:
An alternate routing metric for this route. The
semantics of this metric are determined by the routing-
protocol specified in the route's ipRouteProto value. If
this metric is not used, its value should be set to -1.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteNextHop { ipRouteEntry 7 }
Syntax:
IpAddress
Definition:
The IP address of the next hop of this route.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteType { ipRouteEntry 8 }
Syntax:
INTEGER {
other(1), -- none of the following
invalid(2), -- an invalidated route
-- route to directly
direct(3), -- connected (sub-)network
-- route to a non-local
remote(4), -- host/network/sub-network
}
Definition:
The type of route.
Access:
read-write.
Status:
mandatory.
OBJECT:
-------
ipRouteProto { ipRouteEntry 9 }
Syntax:
INTEGER {
other(1), -- none of the following
-- non-protocol information,
-- e.g., manually configured
local(2), -- entries
-- set via a network management
netmgmt(3), -- protocol
-- obtained via ICMP,
icmp(4), -- e.g., Redirect
-- the remaining values are
-- all gateway routing protocols
egp(5),
ggp(6),
hello(7),
rip(8),
is-is(9),
es-is(10),
ciscoIgrp(11),
bbnSpfIgp(12),
oigp(13)
}
Definition:
The routing mechanism via which this route was learned.
Inclusion of values for gateway routing protocols is not
intended to imply that hosts should support those
protocols.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
ipRouteAge { ipRouteEntry 10 }
Syntax:
INTEGER
Definition:
The number of seconds since this route was last updated
or otherwise determined to be correct. Note that no
semantics of "too old" can be implied except through
knowledge of the routing protocol by which the route was
learned.
Access:
read-write.
Status:
mandatory.
5.5. The ICMP Group Implementation of the ICMP group is mandatory for all systems. The ICMP group contains the ICMP input and output statistics. Note that individual counters for ICMP message (sub-)codes have been omitted from this (version of the) MIB for simplicity. OBJECT: ------- icmpInMsgs { icmp 1 } Syntax: Counter Definition: The total number of ICMP messages which the entity received. Note that this counter includes all those counted by icmpInErrors. Access: read-only. Status: mandatory. OBJECT: ------- icmpInErrors { icmp 2 } Syntax: Counter Definition: The number of ICMP messages which the entity received but determined as having errors (bad ICMP checksums, bad length, etc.). Access: read-only. Status: mandatory.
OBJECT:
-------
icmpInDestUnreachs { icmp 3 }
Syntax:
Counter
Definition:
The number of ICMP Destination Unreachable messages
received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInTimeExcds { icmp 4 }
Syntax:
Counter
Definition:
The number of ICMP Time Exceeded messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInParmProbs { icmp 5 }
Syntax:
Counter
Definition:
The number of ICMP Parameter Problem messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInSrcQuenchs { icmp 6 }
Syntax:
Counter
Definition:
The number of ICMP Source Quench messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInRedirects { icmp 7 }
Syntax:
Counter
Definition:
The number of ICMP Redirect messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInEchos { icmp 8 }
Syntax:
Counter
Definition:
The number of ICMP Echo (request) messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInEchoReps { icmp 9 }
Syntax:
Counter
Definition:
The number of ICMP Echo Reply messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInTimestamps { icmp 10 }
Syntax:
Counter
Definition:
The number of ICMP Timestamp (request) messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInTimestampReps { icmp 11 }
Syntax:
Counter
Definition:
The number of ICMP Timestamp Reply messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInAddrMasks { icmp 12 }
Syntax:
Counter
Definition:
The number of ICMP Address Mask Request messages
received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpInAddrMaskReps { icmp 13 }
Syntax:
Counter
Definition:
The number of ICMP Address Mask Reply messages received.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutMsgs { icmp 14 }
Syntax:
Counter
Definition:
The total number of ICMP messages which this entity
attempted to send. Note that this counter includes all
those counted by icmpOutErrors.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutErrors { icmp 15 }
Syntax:
Counter
Definition:
The number of ICMP messages which this entity did not
send due to problems discovered within ICMP such as a
lack of buffers. This value should not include errors
discovered outside the ICMP layer such as the inability
of IP to route the resultant datagram. In some
implementations there may be no types of error which
contribute to this counter's value.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutDestUnreachs { icmp 16 }
Syntax:
Counter
Definition:
The number of ICMP Destination Unreachable messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutTimeExcds { icmp 17 }
Syntax:
Counter
Definition:
The number of ICMP Time Exceeded messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutParmProbs { icmp 18 }
Syntax:
Counter
Definition:
The number of ICMP Parameter Problem messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutSrcQuenchs { icmp 19 }
Syntax:
Counter
Definition:
The number of ICMP Source Quench messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutRedirects { icmp 20 }
Syntax:
Counter
Definition:
The number of ICMP Redirect messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutEchos { icmp 21 }
Syntax:
Counter
Definition:
The number of ICMP Echo (request) messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutEchoReps { icmp 22 }
Syntax:
Counter
Definition:
The number of ICMP Echo Reply messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutTimestamps { icmp 23 }
Syntax:
Counter
Definition:
The number of ICMP Timestamp (request) messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutTimestampReps { icmp 24 }
Syntax:
Counter
Definition:
The number of ICMP Timestamp Reply messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutAddrMasks { icmp 25 }
Syntax:
Counter
Definition:
The number of ICMP Address Mask Request messages sent.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
icmpOutAddrMaskReps { icmp 26 }
Syntax:
Counter
Definition:
The number of ICMP Address Mask Reply messages sent.
Access:
read-only.
Status:
mandatory.
5.6. The TCP Group Implementation of the TCP group is mandatory for all systems that implement the TCP protocol. Note that instances of object types that represent information about a particular TCP connection are transient; they persist only as long as the connection in question. OBJECT: ------- tcpRtoAlgorithm { tcp 1 } Syntax: INTEGER { other(1), -- none of the following constant(2), -- a constant rto rsre(3), -- MIL-STD-1778, Appendix B vanj(4) -- Van Jacobson's algorithm [15] } Definition: The algorithm used to determine the timeout value used for retransmitting unacknowledged octets. Access: read-only. Status: mandatory. OBJECT: ------- tcpRtoMin { tcp 2 } Syntax: INTEGER Definition: The minimum value permitted by a TCP implementation for the retransmission timeout, measured in milliseconds. More refined semantics for objects of this type depend upon the algorithm used to determine the retransmission timeout. In particular, when the timeout algorithm is rsre(3), an object of this type has the semantics of the LBOUND quantity described in RFC 793.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpRtoMax { tcp 3 }
Syntax:
INTEGER
Definition:
The maximum value permitted by a TCP implementation
for the retransmission timeout, measured
in milliseconds. More refined semantics for objects
of this type depend upon the algorithm used to
determine the retransmission timeout. In particular,
when the timeout algorithm is rsre(3), an object of
this type has the semantics of the UBOUND quantity
described in RFC 793.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpMaxConn { tcp 4 }
Syntax:
INTEGER
Definition:
The limit on the total number of TCP connections the
entity can support. In entities where the maximum
number of connections is dynamic, this object should
contain the value "-1".
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpActiveOpens { tcp 5 }
Syntax:
Counter
Definition:
The number of times TCP connections have made a direct
transition to the SYN-SENT state from the CLOSED
state.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpPassiveOpens { tcp 6 }
Syntax:
Counter
Definition:
The number of times TCP connections have made a direct
transition to the SYN-RCVD state from the LISTEN
state.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpAttemptFails { tcp 7 }
Syntax:
Counter
Definition:
The number of times TCP connections have made a direct
transition to the CLOSED state from either the
SYN-SENT state or the SYN-RCVD state, plus the number
of times TCP connections have made a direct transition
to the LISTEN state from the SYN-RCVD state.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpEstabResets { tcp 8 }
Syntax:
Counter
Definition:
The number of times TCP connections have made a direct
transition to the CLOSED state from either the
ESTABLISHED state or the CLOSE-WAIT state.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpCurrEstab { tcp 9 }
Syntax:
Gauge
Definition:
The number of TCP connections for which the current
state is either ESTABLISHED or CLOSE-WAIT.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpInSegs { tcp 10 }
Syntax:
Counter
Definition:
The total number of segments received, including those
received in error. This count includes segments
received on currently established connections.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpOutSegs { tcp 11 }
Syntax:
Counter
Definition:
The total number of segments sent, including those on
current connections but excluding those containing
only retransmitted octets.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpRetransSegs { tcp 12 }
Syntax:
Counter
Definition:
The total number of segments retransmitted - that is,
the number of TCP segments transmitted containing one
or more previously transmitted octets.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnTable { tcp 13 }
Syntax:
SEQUENCE OF TcpConnEntry
Definition:
A table containing TCP connection-specific
information.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnEntry { tcpConnTable 1 }
Syntax:
TcpConnEntry ::= SEQUENCE {
tcpConnState
INTEGER,
tcpConnLocalAddress
IpAddress,
tcpConnLocalPort
INTEGER (0..65535),
tcpConnRemAddress
IpAddress,
tcpConnRemPort
INTEGER (0..65535)
}
Definition:
Information about a particular current TCP connection.
An object of this type is transient, in that it ceases
to exist when (or soon after) the connection makes the
transition to the CLOSED state.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnState { tcpConnEntry 1 }
Syntax:
INTEGER {
closed(1),
listen(2),
synSent(3),
synReceived(4),
established(5),
finWait1(6),
finWait2(7),
closeWait(8),
lastAck(9),
closing(10),
timeWait(11)
}
Definition:
The state of this TCP connection.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnLocalAddress { tcpConnEntry 2 }
Syntax:
IpAddress
Definition:
The local IP address for this TCP connection.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnLocalPort { tcpConnEntry 3 }
Syntax:
INTEGER (0..65535)
Definition:
The local port number for this TCP connection.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnRemAddress { tcpConnEntry 4 }
Syntax:
IpAddress
Definition:
The remote IP address for this TCP connection.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
tcpConnRemPort { tcpConnEntry 5 }
Syntax:
INTEGER (0..65535)
Definition:
The remote port number for this TCP connection.
Access:
read-only.
Status:
mandatory.
5.7. The UDP Group Implementation of the UDP group is mandatory for all systems which implement the UDP protocol. OBJECT: ------- udpInDatagrams { udp 1 } Syntax: Counter Definition: The total number of UDP datagrams delivered to UDP users. Access: read-only. Status: mandatory. OBJECT: ------- udpNoPorts { udp 2 } Syntax: Counter Definition: The total number of received UDP datagrams for which there was no application at the destination port. Access: read-only. Status: mandatory. OBJECT: ------- udpInErrors { udp 3 } Syntax: Counter
Definition:
The number of received UDP datagrams that could not be
delivered for reasons other than the lack of an
application at the destination port.
Access:
read-only.
Status:
mandatory.
OBJECT:
-------
udpOutDatagrams { udp 4 }
Syntax:
Counter
Definition:
The total number of UDP datagrams sent from this
entity.
Access:
read-only.
Status:
mandatory.
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