January 4, 2010 at 06:02ASN GateWay - WiMAX Access Gateway
With this small topic, I am completing a series of articles ( one , two ) about WiMAX technology.
The article will be devoted mainly to the central device of the network: ASN-GW (which is translated into the universal Access Service Network GateWay)
ASN-GW - is the gateway between the ASN and CSN, as the name implies. Accordingly, it has interaction interfaces.
The figure below shows the layout of the device on the network with the interface designation:
Being the central node of the network, ASN-GW takes on the lion's share of all functions:
A little more about some points.
At Huawei (the equipment I'm directly dealing with), the ASN-GW is called the WASN9770. So this same WASN supports the following types of routing:
- Static
- RIP
- OSPF
- IS-IS
- BGP
The following QoS levels
are supported - Unsolicited Grant Service (UGS)
- Extended Real-Time Polling Service (ertPS)
- Real-Time Polling Service (rtPS)
- Non-Real-Time Polling Service (nrtPS)
- Best Effort (BE)
Account data can be based on both the duration of the session and the amount of traffic. Postpaid and prepaid (postpaid / prepaid) services are supported.
The WASN 9770 generates UDR files (Usage Data Record), which are then transferred to the AAA server.
In the absence of a separate DHCP server and if the IP address is not configured for AAA, WASN can take over this function.
Since a network of any structure and topology (for example, a network of another provider providing a channel) may lie between the BS and ASN-GW, the R6 interface is implemented using a VLAN or GRE tunnel
The existing AAA servers are registered on the ASN-GW, and for each domain used (the second part of the login for the MS (mobile station)), an AAA server is assigned.
It is possible to work without authentication (i.e. without using AAA). This can be used in cases, for example, when the user pays for the content, and not the traffic, as is often organized abroad.
It's about mobility: handover.
A list of neighbors for each BS is configured on the ASN-GW. In this case, BS refers to one sector, since each sector has its own BSID - the identifier of the base station and its list of neighbors, including two other sectors of this BS.
Handover triggers are configured on MS, BS and ASN-GW. The process can be initiated by the MS that detected a better signal, or the BS that detected the UL signal from the MS. A handover request is sent to the ASN-GW, which must decide in accordance with the configuration.
We are all IT specialists and understand why tracing is needed.
If I started talking about the Chinese implementation of the gateway, then I will say a few words about the iron part.
The device is placed in a 19-inch cabinet, has 10 card slots and two independent power sources.
Slots can be of three types: SRU, SPU, LPU.
The SRU (Switching and Routing Unit) performs the following functions:
Collects routing information and forms a routing table and sends it to the LPU cards and SPU
provides interaction with OMC (Operation and Maintenance Center)
performs packet switching.
There can only be two such cards that work in Hot Standby
SPU (Service Processing Unit) performs all the functions of processing incoming data.
Up to three pairs of boards can be installed. Each pair works in Hot Standby mode.
The LPU (Line interface Processing Unit) card is used to physically connect other network elements and, except for packet transmission, does not perform any functions.
Optical or electrical ports can be implemented on the board. Each of them is configured for basic needs: connecting a BS, a channel to the Internet, an AAA server, a control channel, and others.
There can be only two such cards and they are installed in the first and second slots.
In order not to overload readers, in a nutshell about managing network devices Huawei.
All are available via telnet / ssh. The interface is painfully similar to Tsiskovsky. As far as I know, Cisco and Huawei had some kind of judicial grater about this, after which Huawei changed the show to display , no to undo and made some more minor changes.
In addition, WASN and BS can be controlled through MML . Special software provides such an opportunity.
<What did I want? End this WiMAX series. I hope it was very interesting, extremely exciting and surprisingly informative>
The article will be devoted mainly to the central device of the network: ASN-GW (which is translated into the universal Access Service Network GateWay)
What is what
ASN-GW - is the gateway between the ASN and CSN, as the name implies. Accordingly, it has interaction interfaces.
The figure below shows the layout of the device on the network with the interface designation:
- R6 for communication with the BS
- R3 for communication with the CSN
- R4 for communication between different ASNs (for handover)
Functions
Being the central node of the network, ASN-GW takes on the lion's share of all functions:
- Routing
- QoS Management
- Accounting
- DHCP
- VPN
- Providing communication with the AAA server and connecting MS (Mobile Station) without authentication
- Manage current sessions and store data about connected MS
- Radio resource management
- Management of MS operating modes (sleep, idle-mode)
- Trace interfaces and equipment parameters.
A little more about some points.
Routing
At Huawei (the equipment I'm directly dealing with), the ASN-GW is called the WASN9770. So this same WASN supports the following types of routing:
- Static
- RIP
- OSPF
- IS-IS
- BGP
QoS
The following QoS levels
are supported - Unsolicited Grant Service (UGS)
- Extended Real-Time Polling Service (ertPS)
- Real-Time Polling Service (rtPS)
- Non-Real-Time Polling Service (nrtPS)
- Best Effort (BE)
Accounting
Account data can be based on both the duration of the session and the amount of traffic. Postpaid and prepaid (postpaid / prepaid) services are supported.
The WASN 9770 generates UDR files (Usage Data Record), which are then transferred to the AAA server.
DHCP
In the absence of a separate DHCP server and if the IP address is not configured for AAA, WASN can take over this function.
VPN
Since a network of any structure and topology (for example, a network of another provider providing a channel) may lie between the BS and ASN-GW, the R6 interface is implemented using a VLAN or GRE tunnel
AAA server
The existing AAA servers are registered on the ASN-GW, and for each domain used (the second part of the login for the MS (mobile station)), an AAA server is assigned.
It is possible to work without authentication (i.e. without using AAA). This can be used in cases, for example, when the user pays for the content, and not the traffic, as is often organized abroad.
Radio resource management
It's about mobility: handover.
A list of neighbors for each BS is configured on the ASN-GW. In this case, BS refers to one sector, since each sector has its own BSID - the identifier of the base station and its list of neighbors, including two other sectors of this BS.
Handover triggers are configured on MS, BS and ASN-GW. The process can be initiated by the MS that detected a better signal, or the BS that detected the UL signal from the MS. A handover request is sent to the ASN-GW, which must decide in accordance with the configuration.
Interface tracing
We are all IT specialists and understand why tracing is needed.
Iron
If I started talking about the Chinese implementation of the gateway, then I will say a few words about the iron part.
The device is placed in a 19-inch cabinet, has 10 card slots and two independent power sources.
Slots can be of three types: SRU, SPU, LPU.
The SRU (Switching and Routing Unit) performs the following functions:
Collects routing information and forms a routing table and sends it to the LPU cards and SPU
provides interaction with OMC (Operation and Maintenance Center)
performs packet switching.
There can only be two such cards that work in Hot Standby
SPU (Service Processing Unit) performs all the functions of processing incoming data.
Up to three pairs of boards can be installed. Each pair works in Hot Standby mode.
The LPU (Line interface Processing Unit) card is used to physically connect other network elements and, except for packet transmission, does not perform any functions.
Optical or electrical ports can be implemented on the board. Each of them is configured for basic needs: connecting a BS, a channel to the Internet, an AAA server, a control channel, and others.
There can be only two such cards and they are installed in the first and second slots.
In order not to overload readers, in a nutshell about managing network devices Huawei.
All are available via telnet / ssh. The interface is painfully similar to Tsiskovsky. As far as I know, Cisco and Huawei had some kind of judicial grater about this, after which Huawei changed the show to display , no to undo and made some more minor changes.
In addition, WASN and BS can be controlled through MML . Special software provides such an opportunity.
<What did I want? End this WiMAX series. I hope it was very interesting, extremely exciting and surprisingly informative>