User guide

September 2009
Page 42 of 79 OmniSwitch 6400/6850/6855/9000/9000E—Release 6.4.2.R01
PVST+ Interoperability
The current Alcatel-Lucent 1x1 Spanning Tree mode has been extended to allow all user ports on an
OmniSwitch to transmit and receive either the standard IEEE BPDUs or proprietary PVST+ BPDUs.
An OmniSwitch can have ports running in either 1x1 mode when connecting to another OmniSwitch,
or PVST+ mode simultaneously.
• It is mandatory that all the Cisco switches have the Mac Reduction Mode feature enabled.
• Priority values can only be assigned in multiples of 4096 to be compatible with the Cisco
MAC Reduction mode.
• In a mixed OmniSwitch and Cisco environment, it is highly recommended to enable PVST+
mode on all OmniSwitches in order to maintain the same root bridge for the topology.
• Alcatel-Lucent’s PVST+ interoperability mode is not compatible with a switch running in
PVST mode.
• The same default path cost mode, long or short, must be configured the same way on all
switches.
Quality of Service (QoS)
Alcatel-Lucent’s QoS software provides a way to manipulate flows coming through the switch based
on user-configured policies. The flow manipulation (generally referred to as Quality of Service or QoS)
may be as simple as allowing/denying traffic, or as complicated as remapping 802.1p bits from a Layer
2 network to ToS values in a Layer 3 network. QoS can support up to 2048 policies and it is hardware-
based on the first packet. OmniSwitch 6850/9000/9000E switches support 8 queues per port.
QoS is implemented on the switch through the use of policies, created on the switch or stored in
PolicyView. While policies may be used in many different network scenarios, there are several typical
types:
• Basic QoS—includes traffic prioritization and bandwidth shaping
• 802.1p/ToS/DSCP—includes policies for marking and mapping
• Addded support for DSCP Ranges
• Policy Based Routing (PBR)—includes policies for redirecting routed traffic
• Access Control Lists (ACLs)—ACLs are a specific type of QoS policy used for Layer 2,
Layer 3/4, and multicast filtering.
Auto-Qos Prioritization for NMS Traffic
This feature can be used to enable the automatic prioritization of NMS traffic—SSH (TCP Port 22),
Telnet (TCP Port 23), WebView (HTTP Port 80) and SNMP (TCP port 161)—that is destined for the
switch. Prioritization maximizes access for NMS traffic and helps to reduce the potential for DoS
attacks.
Note: When automatic NMS prioritization is enabled, QoS policies that specify priority are not
applied to the NMS traffic. Other QoS policies, however, are applied to this type of traffic as usual.
If a policy specifies rate limiting, then the policy with the lowest rate limiting value is applied.
Auto-Qos Prioritization on IP Phones
This feature is used to automatically enable the prioritization of IP phone traffic. The traffic can be
assigned a priority value or, if set to trusted mode, the IP phone packet is used to determine the
priority. IP phone traffic is identified by examining the source MAC address of the packet received on
the port. If the source MAC falls within one of the Alcatel-Lucent ranges below, the Auto-QoS feature
automatically sets the priority.