3com 3031 Instruccion De Instalación
984
C
HAPTER
71: F
RAME
R
ELAY
Q
O
S
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Committed Burst Size (CBS): Packet traffic that frame relay network is
committed to send within the interval of a Tc. Upon network congestion, frame
relay network ensures this part of traffic could be successfully sent.
committed to send within the interval of a Tc. Upon network congestion, frame
relay network ensures this part of traffic could be successfully sent.
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Excess Burst Size (EBS): The maximum that packet traffic of frame relay
network could exceed the CBS within the interval of a Tc. Upon network
congestion, this part of excess traffic will be first discarded. Therefore, frame
relay network does not ensure this part of traffic could be certainly sent
successfully.
network could exceed the CBS within the interval of a Tc. Upon network
congestion, this part of excess traffic will be first discarded. Therefore, frame
relay network does not ensure this part of traffic could be certainly sent
successfully.
Frame Relay QoS
Implemented by V2.0
Software
The Frame Relay traffic shaping limits traffic of packets from a Virtual Circuit (VC)
and of burst packets, so that they can be transmitted at relatively average rates.
and of burst packets, so that they can be transmitted at relatively average rates.
Frame Relay traffic shaping
The Frame Relay traffic shaping can control the normal traffic size and the burst
traffic size transmitted from a PVC and enable the Frame Relay PVC to transmit
these packets at a relatively average rate.
traffic size transmitted from a PVC and enable the Frame Relay PVC to transmit
these packets at a relatively average rate.
In a Frame Relay network, the bottleneck will often occur at the boundary of
segments if the bandwidths of different segments do not match. As shown in the
following figure, Router B transmits packets to Router A at the rate of 128 kbps
whereas the maximum interface rate of Router A is only 64 kbps. In this case, the
bottleneck will occur at the place where Router A is connected to the Frame Relay
network, and thereby resulting in the congestion that prevents the data from
normal transmitting.
segments if the bandwidths of different segments do not match. As shown in the
following figure, Router B transmits packets to Router A at the rate of 128 kbps
whereas the maximum interface rate of Router A is only 64 kbps. In this case, the
bottleneck will occur at the place where Router A is connected to the Frame Relay
network, and thereby resulting in the congestion that prevents the data from
normal transmitting.
Figure 244 Frame Relay traffic shaping
If the Frame Relay traffic shaping is applied on the egress interface Serial 0 on
Router B, the interface will be able to transmit packets at 64 kbps, a relatively
average rate, so as to avoid the network congestion. Even if the congestion occurs
to the network, Router B can still transmit packets at 32 kbps.
Router B, the interface will be able to transmit packets at 64 kbps, a relatively
average rate, so as to avoid the network congestion. Even if the congestion occurs
to the network, Router B can still transmit packets at 32 kbps.
Frame Relay traffic shaping is applied on the egress interface on a router. It can
provide for the users the parameters like Committed Information Rate Allowed
(CIR ALLOW), Committed Information Rate (CIR), Committed Burst Size (CBS) and
Excess Burst Size (EBS).
provide for the users the parameters like Committed Information Rate Allowed
(CIR ALLOW), Committed Information Rate (CIR), Committed Burst Size (CBS) and
Excess Burst Size (EBS).
Frame Relay PVCs can transmit packets at the rate of CIR ALLOW and FRTS allows
the PVCs to transmit packets at a rate exceeding CIR ALLOW in case of the burst.
the PVCs to transmit packets at a rate exceeding CIR ALLOW in case of the burst.
The FRTS of our company is implemented using token bucket. The meanings of
the parameters in the protocol are modified in accordance to the actual algorithm
and fundamentals. The following figure illustrates the fundamentals of token
bucket.
the parameters in the protocol are modified in accordance to the actual algorithm
and fundamentals. The following figure illustrates the fundamentals of token
bucket.
Data flow direction
Frame-relay network
Router A
Router B
128 kbps
64 kbps
DTE
DTE
S0
S0
CIR ALLOW = 64kbps
CIR = 32kbps