Specifications

100 Implementing IBM System Networking 10Gb Ethernet Switches
2.8.7 VLAN maps
A VLAN map (VMAP) is an ACL that can be assigned to a VLAN or VM group rather than to a
switch port, as with regular ACLs. A VMAP is useful in a virtualized environment where traffic
filtering and metering policies must follow virtual machines (VMs) as they migrate
between hypervisors.
Individual VMAP filters are configured in the same fashion as regular ACLs, except that
VLANs cannot be specified as a filtering criteria (which is unnecessary, because the VMAP is
assigned to a specific VLAN or associated with a VM group VLAN).
2.8.8 Storm-control filters
This feature is available only for Top of Rack IBM System Networking switches.
IBM System Networking RackSwitch provides filters that can limit the number of the following
packet types transmitted by switch ports:
򐂰 Broadcast packets
򐂰 Multicast packets
򐂰 Unknown unicast packets (destination lookup failure)
Broadcast storms
Excessive transmission of broadcast or multicast traffic can result in a broadcast storm. A
broadcast storm can overwhelm your network with constant broadcast or multicast traffic, and
degrade network performance. Common symptoms of a broadcast storm are slow network
response times and network operations timing out.
Unicast packets whose destination MAC address is not in the forwarding database are
unknown unicasts. When an unknown unicast is encountered, the switch handles it like a
broadcast packet and floods it to all other ports in the VLAN (broadcast domain). A high rate
of unknown unicast traffic can have the same negative effects as a broadcast storm.
2.9 Quality of Service
You can use Quality of Service (QoS) features to allocate network resources to
mission-critical applications at the expense of applications that are less sensitive to such
factors as time delays or network congestion. You can configure your network to prioritize
specific types of traffic, ensuring that each type receives the appropriate QoS level.
2.9.1 QoS overview
QoS helps you allocate guaranteed bandwidth to the critical applications, and limit bandwidth
for less critical applications. Applications such as video and voice must have a certain amount
of bandwidth to work correctly; using QoS, you can provide that bandwidth when necessary.
Also, you can put a high priority on applications that are sensitive to timing out or that cannot
tolerate delay, by assigning their traffic to a high-priority queue.
By assigning QoS levels to traffic flows on your network, you can ensure that network
resources are allocated where they are needed most. You can use QoS features to prioritize
network traffic, providing better service for selected applications.