Layer 3 / Diffserv - Siemens HiPath 8000 Administrator's Manual

Administration via Local Phone
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--- Administration
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--- Network
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--- QoS
|--- Layer 2
|--- Layer 2 voice
|--- Layer 2 signalling
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--- Layer 2 default
3.3.1.2

Layer 3 / Diffserv

Diffserv assigns a class of service to an IP packet by adding an entry in the IP header.
Traffic flows are classified into 3 per-hop behavior groups:
1. Default
Any traffic that does not meet the requirements of any of the other defined classes is placed
in the default per-hop behaviour group. Typically, the forwarding has best-effort forwarding
characteristics. The DSCP (Diffserv Codepoint) value for Default is „0 0 0 0 0 0".
2. Expedited Forwarding (EF referred to RFC 3246)
Expedited Forwarding is used for voice (RTP streams) by default. It effectively creates a
special low-latency path in the network. The DSCP (Diffserv Codepoint) value for EF is
„1 0 1 1 1 0".
3. Assured Forwarding (AF referred to RFC 2597)
Assured forwarding is used for signaling messages by default (AF31). It is less stringent
than EF in a multiple dropping system. The AF values are containing two digits X and Y
(AFXY), where X is describing the priority class and Y the drop level.
Four classes X are reserved for AFXY: AF1Y (high priority), AF2Y, AF3Y and AF4Y (low
priority).
Three drop levels Y are reserved for AFXY: AFX1 (low drop probability), AFX2 and AFX3
(High drop probability). In the case of low drop level, packets are buffered over an extended
period in the case of high drop level, packets are promptly rejected if they cannot be for-
warded.
Data required
• Layer 3: Activates or deactivates QoS on layer 3.
Value range: „Yes", „No".
• Layer 3 voice: Sets the CoS (Class of Service) value for voice data (RTP streams).
Value range: „AF11", „AF12", „AF13", „AF21", „AF22", „AF23", „AF31", „AF32", „AF33",
„AF41", „AF42", „AF43", „EF", „CST").
A31003-01010-M11-1-7619, 29/01/2007
HiPath 8000 - OpenStage 60/80, Administrator Manual
administration.fm
Administration
IP Network Parameters
3-9