📄 rfc2954.txt
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rapidly the end user can inject data into the network.
Bc - The Committed Burst Size (Bc) is the maximum amount of
subscriber data (expressed in bits) that the network agrees to
transfer, under normal conditions, during a time interval Tc.
Rehbehn & Fowler Standards Track [Page 6]
RFC 2954 Frame Relay Service MIB October 2000
Be - The Excess Burst Size (Be) is the maximum amount of subscriber
data (expressed in bits) in excess of Bc that the network will
attempt to deliver during the time interval Tc. This data (Be) is
delivered in general with a lower probability than Bc.
CIR - The Committed Information Rate (CIR) is the subscriber data
rate (expressed in bits/second) that the network commits to deliver
under normal network conditions. CIR is averaged over the time
interval Tc (CIR = Bc/Tc).
DLCI - Data Link Connection Identifier
Logical Port - This term is used to model the frame relay "interface"
on a device.
NNI - Network to Network Interface
Permanent Virtual Connection (PVC) - A virtual connection that has
its end-points and bearer capabilities defined at subscription time.
Time slot (E1) - An octet within the 256-bit information field in
each E1 frame is defined as a time slot. Time slots are position
sensitive within the 256-bit information field. Fractional E1 service
is provided in contiguous or non-contiguous time slot increments.
Time slot (DS0) - An octet within the 192-bit information field in
each DS1 frame is defined as a time slot. Time slots are position
sensitive within the 192-bit information field. Fractional DS1
service is provided in contiguous or non-contiguous time slot
increments.
UNI - User to Network Interface
N391 - Full status (status of all PVCs) polling counter
N392 - Error threshold
N393 - Monitored events count
T391 - Link integrity verification polling timer
T392 - Polling verification timer
nT3 - Status enquiry timer
nN3 - Maximum status enquiry counter
Rehbehn & Fowler Standards Track [Page 7]
RFC 2954 Frame Relay Service MIB October 2000
2.5. Relation to Other MIBs
2.5.1. System Group
Use the System Group of the SNMPv2-MIB [27] to describe the Frame
Relay Service (FRS) agent. The FRS agent may be monitoring many
frame relay devices in one network. The System Group does not
describe frame relay devices monitored by the FRS agent.
sysDescr: ASCII string describing the FRS agent.
Can be up to 255 characters long. This field is
generally used to indicate the network providers
identification and type of service offered.
sysObjectID: Unique OBJECT IDENTIFIER (OID) for the
FRS agent.
sysUpTime: Clock in the FRS agent; TimeTicks
in 1/100s of a second. Elapsed type since
the FRS agent came on line.
sysContact: Contact for the FRS agent.
ASCII string of up to 255 characters.
sysName: Domain name of the FRS agent, for example,
acme.com
sysLocation: Location of the FRS agent.
ASCII string of up to 255 characters.
sysServices: Services of the managed device. The value "2",
which implies that
the frame relay network is providing
a subnetwork level service, is recommended.
2.5.2. Interfaces Table (ifTable, ifXtable)
This specifies how the Interfaces Group defined in the IF MIB [26]
shall be used for the management of frame relay based interfaces, and
in conjunction with the Frame Relay Service MIB module. This memo
assumes the interpretation of the evolution of the Interfaces group
to be in accordance with: "The interfaces table (ifTable) contains
information on the managed resource's interfaces. Each sub-layer
below the internetwork layer of a network interface is considered an
interface." Thus, the ifTable allows the following frame relay-based
interfaces to be represented as table entries:
Rehbehn & Fowler Standards Track [Page 8]
RFC 2954 Frame Relay Service MIB October 2000
- Frame relay interfaces in equipment (e.g., switches, routers or
networks) supporting frame relay. This level is concerned with
generic frame counts and not with individual virtual connections.
In accordance with the guidelines of ifTable, frame counts per
virtual connection are not covered by ifTable, and are considered
interface specific and covered in the Frame Relay Service MIB module.
In order to interrelate the ifEntries properly, the Interfaces Stack
Group shall be supported.
Some specific interpretations of ifTable for frame relay follow.
Object Use for the generic Frame Relay layer
====== =============================================
ifIndex Each frame relay port is represented by an
ifEntry.
ifDescr Description of the frame relay interface.
ASCII string describing the UNI/NNI logical
port. Can be up to 255 characters long.
ifType The value allocated for Frame Relay Service
is equal to 44.
ifMtu Set to maximum frame size in octets for this
frame relay logical port.
ifSpeed Peak bandwidth in bits per second available
for use. This could be the speed of the
logical port and not the access rate. Actual
user information transfer rate (i.e., access
rate) of the UNI or NNI logical port in bits
per second (this is not the clocking speed).
For example, it is 1,536,000 bits per second
for a DS1-based UNI/NNI logical port and
1,984,000 bits per second for an E1-based
UNI/NNI logical port.
ifPhysAddress The primary address for this logical port
assigned by the frame relay interface
provider. An octet string of zero length if
no address is used for this logical port.
ifAdminStatus The desired administrative status of the
frame relay logical port.
Rehbehn & Fowler Standards Track [Page 9]
RFC 2954 Frame Relay Service MIB October 2000
ifOperStatus The current operational status of the Frame
Relay UNI or NNI logical port.
ifLastChange The value of sysUptime at the last
re-initialization of the logical port. The
value of sysUpTime at the time the logical
port entered its current operational state.
If the current state was entered prior to the
last re-initialization of the local network
management subsystem, then this object
contains a zero value.
ifInOctets The number of received octets. This counter
only counts octets from the beginning of the
frame relay header field to the end of user
data.
ifInUcastPkts The number of received unerrored, unicast
frames.
ifInDiscards The number of received frames discarded.
Specifically, frames discarded due to ingress
buffer congestion and traffic policing.
ifInErrors The number of received frames that are
discarded because of an error. Specifically,
frames that are too long or too short, frames
that are not a multiple of 8 bits in length,
frames with an invalid or unrecognized DLCI,
frames with an abort sequence, frames with
improper flag delimitation, and frame that
fail FCS.
ifInUnknownProtos The number of packets discarded because of an
unknown or unsupported protocol. For Frame
Relay Service interfaces, this counter will
always be zero.
ifOutOctets The number of transmitted octets. This
counter only counts octets from the beginning
of the frame relay header field to the end of
user data.
ifOutUcastpkts The number of unerrored, unicast frames sent.
ifOutDiscards The number of frames discarded in the egress
direction. Possible reasons are as follows:
policing, congestion.
Rehbehn & Fowler Standards Track [Page 10]
RFC 2954 Frame Relay Service MIB October 2000
ifOutErrors The number of frames discarded in the egress
direction because of an error. Specifically,
frames that are aborted due to a transmitter
underrun.
ifName This variable is not applicable for Frame
Relay Service interfaces, therefore, this
variable contains a zero-length string.
ifInMulticastPkts The number of received unerrored, multicast
frames.
ifInBroadcastPkts This variable is not applicable for Frame
Relay Service interfaces, therefore, this
counter is always zero.
ifOutMulticastPkts The number of sent unerrored, multicast
frames.
ifOutBroadcastPkts This variable is not applicable for Frame
Relay Service interfaces, therefore, this
counter is always zero.
ifHCInOctets Only used for DS3-based (and greater) Frame
Relay logical ports. The number of received
octets. This counter only counts octets
from the beginning of the frame relay header
field to the end of user data.
ifHCOutOctets Only used for DS3-based (and greater) Frame
Relay logical ports. The number of
transmitted octets. This counter only counts
octets from the beginning of the frame relay
header field to the end of user data.
ifLinkUpDownTrapEnable Set to true(1). It is recommended that the
underlying physical layer notifications be
disabled since both are not required.
Notifications are enabled at the frame relay
service layer specifically because PVC
notifications are not to be sent if the frame
relay interface fails. Without a
linkUp/linkDown notification, the management
station would receive no notification of the
failure.
Rehbehn & Fowler Standards Track [Page 11]
RFC 2954 Frame Relay Service MIB October 2000
ifHighSpeed Set to the user data rate of the frame relay
logical port in millions of bits per second.
If the user data rate is less than 1 Mbps,
then this value is zero.
ifPromiscuousMode Set to false(2).
ifConnectorPresent Set to false(2).
Frame relay network service interfaces support the Interface Stack
Group. Frame relay network service interfaces do not support any
other groups or objects in the Interfaces group of the IF MIB.
2.5.3. Stack Table for DS1/E1 Environment
This section describes by example how to use ifStackTable to
represent the relationship of frame relay service to ds0 and
ds0Bundles with ds1 interfaces [20].
Example: A frame relay service is being carried on 4 ds0s of a ds1.
+---------------------+
| Frame Relay Service |
+---------------------+
|
+---------------------+
| ds0Bundle |
+---------------------+
| | | |
+---+ +---+ +---+ +---+
|ds0| |ds0| |ds0| |ds0|
+---+ +---+ +---+ +---+
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