IBM 87302RU, Планирование и руководство по установке

Страница: 97 / 140

source port can be one of the four 10/100/1000-Mbps external ports. The target port
is where you connect a monitoring/troubleshooting device, such as a sniffer or an
RMON probe. The target port must be one of the four 10/100/1000-Mbps external
ports.
Notes:
1. Do not mirror a faster port or higher-traffic ports onto a slower port. For
example, trying to mirror the traffic from a 100-Mbps port onto a 10-Mbps port
can cause throughput problems. The port from which you are copying frames
should always support an equal or lower speed than the port to which you are
sending the copies. In addition, the target port cannot be a member of a trunk
group.
2. Port mirroring is not possible if you use the same egress and ingress target
port.
Spanning tree
The switch module supports the 801.2d Spanning Tree Protocol (STP), which
allows you to create alternative paths (with multiple switches or other types of
bridges) in your network.
Keep in mind the following considerations when configuring ports:
v Port cost can be between 1 and 65535. The lower the cost, the greater the
probability that the port will be chosen as the designated port (chosen to forward
packets).
v Port priority can be between 0 and 255. The lower the priority, the greater the
probability that the port will be chosen as the root port.
v You can choose whether to enable or disable fast STP. Enabling fast STP for a
port speeds up the time between linkup and the start of packet forwarding.
Enabling the fast STP option causes the port to skip the learning state. Instead, it
jumps from the listening state directly to the forwarding state.
v You can choose whether to enable or disable the STP state for a port.
Class of service
The switch module supports 802.1p priority queuing; four priority queues are
supported per port. The switch module provides user-programmable mapping for
the eight 802.1p priority classes (0 to 7). For the priority queue feature to take
effect, you must first enable Priority Queue Method by setting it to Weighted
Round-Robin.
Link aggregation
The switch module supports link aggregation (or port trunking), which can be used
to increase the bandwidth of a network connection or to ensure fault recovery. You
can configure up to two trunk connections (combining two to four ports into one fat
pipe) between any two BladeCenter switches or other Layer 2 switches. However,
before making any physical connections between devices, you must specify the
ports that will belong to the trunking group between switches.
Note the following considerations when planning for link aggregation:
v The ports used in a trunk must all be of the same media type (100-Mbps fiber or
1000-Mbps fiber).
v Each port can be assigned to only one trunk group, whether it is a static or
dynamic group.
v
The ports at both ends of the connection must be configured as trunk ports.
Chapter 5. Configuration considerations
83