3Com Router User Manual

Configure Frame Relay257
Perform the following configurations in interface view.
Ta b l e 296   Configure Frame Relay Compression on multipoint interface
By default, Frame Relay payload compression is disable.
On the 3Com Router, both the Frame Relay main interfaces and sub-interfaces can 
be multipoint interfaces.
Enable/Disable TCP/IP 
Header Compression on 
InterfacesFrame Relay supports TCP/IP header compression. Only when the packet format of 
Frame Relay interface is nonstandard, can TCP/IP header...

258CHAPTER 17: CONFIGURING FRAME RELAY
Configure Frame Relay 
QoSQuality of Service (QoS) is a set of technologies adopted to meet the users 
requirements in throughput, delay jitter, delay and packet loss ratio. Briefly 
speaking, QoS technologies provides network services of different qualities for 
different requirements.
On a Frame Relay interface, the user can use the general QoS to provide the 
services, such as traffic policing, traffic shaping, congestion management, and 
congestion avoidance....

Configure Frame Relay QoS259
Figure 82   Frame Relay traffic shaping
If the Frame Relay traffic shaping is applied on the outgoing 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.
Frame Relay traffic shaping is applied on the outgoing interface on a router. It can 
provide for the users the parameters...

260CHAPTER 17: CONFIGURING FRAME RELAY
notification (BECN) flag bit is 1, indicating that the congestion has occurred to the 
network, and the transmit rate of the PVC will be lowered to CIR.
Frame Relay Queueing Management
To ensure that the packets on the PVCs can be transmitted at an average rate in 
the process of Frame Relay traffic shaping, a queueing mechanism should be 
adopted to manage the packets. Generally, except that the Frame Relay interface 
owns one interface queue, the Frame Relay PVC...

Configure Frame Relay QoS261
Figure 85   Frame Relay traffic policing
As shown in the above figure, Router A at the user side transmits packets at 192 
kbps to Router B at the switching side. However, Router B only wants to provide 
the 64 kbps bandwidth for Router A. In this case, you need to configure the Frame 
Relay traffic policing at the DCE side of Router B.
Frame Relay traffic policing can only be applied on the DCE interface on a router. It 
can monitor the traffic transmitted from the DTE side....

262CHAPTER 17: CONFIGURING FRAME RELAY
Frame Relay Congestion Management
Frame Relay congestion management can process the Frame Relay packets 
whenever there is network congestion. It will discard the packets that are marked 
with the DE flag bit. At the same time, it will notify other devices on the network 
about the congestion. 
Frame Relay congestion management is applied at the output interface on a Frame 
Relay switched device. If there is no congestion, the router will normally forward 
the Frame...

Configure Frame Relay QoS263
Ta b l e 299   Create/Delete a Frame Relay class
By default, no Frame Relay class is created.
After creating the Frame Relay class using this command, the user will enter the 
frame relay class view under which you can configure the parameters like CIR.
2Associate the Frame Relay class with the Frame Relay interface or a PVC
Please configure the association between a Frame Relay class and an interface in 
interface view, and configure the association between a 
Frame Relay...

264CHAPTER 17: CONFIGURING FRAME RELAY
■Configure the parameters of Frame Relay class
1Enable the Frame Relay traffic shaping
Perform the following configurations in synchronous serial interface view.
Ta b l e 301   Enable/Disable the Frame Relay traffic shaping
By default, the Frame Relay traffic shaping is not enabled on the interface.
The function of Frame Relay traffic shaping is applied on the outgoing interfaces 
on a router. Usually it is applied at the DTE end on a Frame Relay network.
2Create a...

Configure Frame Relay QoS265
Numerically, the value of CBS should not be less than CIR ALLOW, otherwise, the 
large packets may not be sent.
Configure Frame Relay 
Traffic PolicingFrame Relay traffic policing configuration includes:
■Enable the Frame Relay traffic policing
■Create a Frame Relay class
■Associate the Frame Relay class with the Frame Relay interface or a PVC
Configure the parameters of Frame Relay class for Frame Relay traffic policing
1Enable the Frame Relay Traffic Policing
Perform the...

266CHAPTER 17: CONFIGURING FRAME RELAY
Configure Frame Relay 
Congestion 
ManagementThere are two ways to set the congestion threshold. One is to configure the 
congestion threshold for a PVC in a specified 
Frame Relay class, another is to 
configure the congestion threshold for the overall interface in interface view. The 
router determines whether there is congestion on the interface according to the 
ratio that the current queue length on the Frame Relay interface or PVC occupies 
the total queue...