GE ML1200 instruction manual Broadcast Storms

CHAPTER 9: PORT MIRRORING AND SETUPPORT MIRRORING AND SETUP

Back pressure and flow control (continued)

ML1200(device)## show port

Keys: E	= Enable		D	= Disable
H	= Half Duplex		F	=	Full Duplex
M	= Multiple VLAN's		NA =		Not Applicable
LI	=	Listening	LE =		Learning
F	=	Forwarding	B	=	Blocking

Port Name Control Dplx Media Link Speed Part Auto VlanID GVRP STP

-------------------------------------------------------------------------------

1	B1	E	H	10Tx	UP	10	No	E	1	-	-
2	B2	E	H	10Tx	DOWN	10	No	E	1	-	-
3	JohnDoe	E	H	10Tx	DOWN	10	No	E	1	-	-
4	JaneDoe	E	H	10Tx	DOWN	10	No	E	1	-	-
5	B5	E	F	100Tx	UP	100	No	E	1	-	-
6	B6	E	H	10Tx	DOWN	10	No	E	1	-	-

ML1200(device)## show port=11

Configuration details of port 11

--------------------------------------------------

Port Name	: JohnDoe
Port Link State	: DOWN
Port Type	: TP Port
Port Admin State	: Enable
Port VLAN ID	: 1
Port Speed	: 10Mbps
Port Duplex Mode	: half-duplex
Port Auto-negotiation State	: Enable
Port STP State	: NO STP
Port GVRP State	: No GVRP
Port Priority Type	: None
Port Security	: Enable
Port Flow Control	: Enable
Port Back Pressure	: Enable
Port Link Loss Alert	: Enabled

Note that the flow control and back pressure is shown as enabled for the specific port. The global show port command does not provide this detail. The back pressure and flow control parameters are global – i.e., the same for all ports.

9.3.4Broadcast Storms

One of the best features of the MultiLink ML1200 Managed Field Switch is its ability to keep broadcast storms from spreading throughout a network. Network storms (or broadcast storms) are characterized by an excessive number of broadcast packets being sent over the network. These storms can occur if network equipment is configured incorrectly. Storms can reduce network performance and cause bridges, routers, workstations, servers and PCs to slow down or even crash.

The MultiLink ML1200 Managed Field Switch is capable of detecting and limiting storms on each port. A network administrator can also set the maximum rate of broadcast packets (frames) that are permitted from a particular interface. If the maximum number is exceeded, a storm condition is declared. Once it is determined that a storm is occurring on an interface, any additional broadcast packets received on that interface will be dropped until the storm is determined to be over. The storm is determined to be over when a one- second period elapses with no broadcast packets received.

MULTILINK ML1200 MANAGED FIELD SWITCH – INSTRUCTION MANUAL 9–7