IBM 8275-416, Руководство пользователя

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802.3x flow control
The switch supports 802.3x flow control, which, when enabled, allows the
transmission of data frames to be inhibited for a specified period of time. The
default for 802.3x flow control is
Disabled . 802.3x flow control is valid only when the
port is in full-duplex mode.
Broadcast storm recovery
The switch detects broadcast storms and automatically blocks broadcast traffic to
minimize the impact of the broadcast storm on the rest of the network. You can
enable or disable this function at a switch level. For all broadcast frames received
by the switch, the broadcast storm recovery operation depends on port speed and
is described as follows:
1. If the Broadcast Storm Recovery Mode is
Enable
, and if the broadcast traffic on
a 10 Mbps Ethernet port exceeds 20% of the link speed, then the switch blocks
the broadcast traffic on the port until the broadcast traffic is returned to 10% or
below.
2. If the Broadcast Storm Recovery Mode is Enable , and if the broadcast traffic on
a 100 Mbps Ethernet port exceeds 5% of the link speed, then the switch blocks
the broadcast traffic on the port until the broadcast traffic is returned to 2.5% or
below.
3. Broadcast Storm Recovery is not supported on 1000 Mbps Ethernet ports.
4. If Broadcast Storm Recovery Mode is Disable , the switch does not block the
broadcast traffic on the Ethernet port.
5. The switch issues a trap message when traffic exceeds a port’s broadcast
threshold and when it returns to or below the port’s recovery threshold.
Forwarding database
The switch port MAC addresses are stored in the forwarding database. An address
learned by the switch is removed from the forwarding database after a period of
time if no frames have been received from that address. The default value for the
aging period is 300 seconds (5 minutes), but it can be configured by the user. The
time values range from 10 seconds to 600 seconds.
The switch forwarding database stores 12 000 entries. When the database is full,
no new entries are learned until an existing entry ages out. All frames with unknown
destination addresses are multicast to all ports in the appropriate VLAN.
Virtual local area networks (VLANs)
The switch supports VLANs. “Appendix E. Introduction to Virtual LANs (VLANs)” on
page 117 provides an introduction to VLANs. It describes concepts and terminology,
as well as, the benefits of using VLANs. The switch is manageable only through the
ports which are members of the Default VLAN (VLAN 1).
Figure 36 on page 54 and Figure 37 on page 55 show examples of the panels and
descriptions of the parameters used to configure VLANs.
Self Learning IP
Self Learning IP is a configurable function of the switch that learns where IP
addresses are in the network so that packets normally sent from one host to
another through a router can bypass the router and be sent directly to the
destination host address. Self Learning IP is most effective when the switch is used
to “front” the router (the switch is positioned logically between the router and the
networks to which it belongs). Because of this strategic vantage point in the network
(Figure 1 on page 3), the switch has visibility to all packets flowing to and from the
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8275-416 User’s Guide