MAnual de descripcion tecnica

1. 文档名称 文档密级
BTS3900B QOS priority feature
The priority mapping ensures the transmission quality of different types of services on the IP
network. The priority mapping includes the IP layer mapping and data link layer mapping.
Priority mapping of the IP layer: The DiffServ is use. The differentiated services code
point (DSCP) may vary with services. The higher the DSCP is, the higher the service priority is.
At present, the QoS can be set according to different frame types, for example, signaling frame,
OML frame, voice frame, and data frame.
Priority mapping of the data link layer: The VLAN is used, with the support of the
IEEE802.1P/Q protocol. Similar to the DSCP, a frame type can be set to a specific VLAN Priority
and VLAN ID (indicating different VLANs).
In the IP interface board of the BSC, the service priority can be mapped to the DSCP or
VLAN priority according to the data configuration requirement. Through the IP interface, the IP
packets of different DSCPs or VLAN Priority can be transferred to the IP network. The L3 device
or L2 device of the IP network classifies IP packets according to the DSCP or VLAN Priority. The
IP packets with the higher priority are sent first. When the network congestion occurs, IP packets
with the lower priority are discarded.
1 Mapping priority in service to IP layer--Diffserv
BTS3900B supports configuring different types of data to different DSCP, which is the TOS of
the IP header.
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2. 文档名称 文档密级
The operations types of BTS3900B include:
BTS3900B OM & signal: ESL, OML, RSL, EML
BTS3900B voice & data: CS voice, CS data, PS high priority, PS low priority, and other
data types(include IPCLK IP data of clock shaking hands, DHCP, etc.)
operation type DSCP range DSCP default value
ESL 0-63 58
OML 0-63 48
RSL 0-63 46
EML 0-63 0
CS voice 0-63 38
CS data 0-63 18
PS high priority 0-63 30
PS low priority 0-63 10
other data type 0-63 18
2 Mapping from IP layer to data link layer --802.1P/Q
2.1 Introduction on 802.1Q/P
802.1Q/P specifies the implementation of VLAN, which gives the port-based VLAN model. This
is the mostly used VLAN, which uses 4B to define Tag, including 2B TPID and 2B TCI.
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3. 文档名称 文档密级
For each host supporting 802.1Q/P, it will add a 4B frame header after the source address in
former frame, which followed by Ethernet length or type.
TPID-TagProtocolIdentifier：New type defined by IEEE, showing this is a text with 802.1Q/P tap
added.
VLANIdentified(VLANID)：12 bits field, specifying VLAN ID, totally 4096. Each host that
supports 802.1Q will include this field to show which VLAN it belongs to.
CanonicalFormatIndicator(CFI)：this bit for the frame format when bus-based Ethernet
exchanging data with FDDI and Token ring network.
Priority：These 3 bits specify the priority of the frame. There are 8 levels of priority, shows which
is the first packet to send when switch congestion occurs.
2.2 Implementation mechanism of BTS3900B
BTS3900B supports mapping DSCP in IP layer to priority in Data Link layer.
service type DSCP range Vlan Priority
ESL 0-63 0-7
OML 0-63 0-7
RSL 0-63 0-7
EML 0-63 0-7
CS voice 0-63 0-7
CS data 0-63 0-7
PS high priority 0-63 0-7
PS low priority 0-63 0-7
other data 0-63 0-7
BTS3900B supports mapping DSCP in IP layer to VLAN Tag.
operation type DSCP range Vlan Tag
ESL 0-63 2-4094
OML 0-63 2-4094
RSL 0-63 2-4094
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16bit 3bit 1bit 12bit
TPID Priority CFI VID

4. 文档名称 文档密级
EML 0-63 2-4094
CS voice 0-63 2-4094
CS data 0-63 2-4094
PS high priority 0-63 2-4094
PS low priority 0-63 2-4094
Other data 0-63 2-4094
3 Ports used for BTS3900B operations
data protocol ports used by BTS
OM&signalling UDP 12288-28637
Service data UDP 4096-12287
IP clock UDP 33003
IPsec UDP 500，4500
DHCP UDP 68
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