ASN GateWay - WiMAX Access Gateway
With this small topic, I am completing a series of articles ( one , two ) on WiMAX technology.
The article will be devoted mostly to the central device of the network: ASN-GW (which is translated to the human Access Service Network GateWay)
ASN-GW is the gateway between the ASN and CSN networks, as the name implies. Accordingly, it has interaction interfaces.
The figure below shows the layout of the device on the network with the designation of interfaces:
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Being the central node of the network, ASN-GW assumes the lion’s share of all functions:
A little more about some points.
In Huawei (the equipment I am dealing with directly), the ASN-GW is called 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)
Accounting data can be based on the duration of the session, and the amount of traffic. Postpaid and prepaid (postpaid / prepaid) services are supported.
WASN 9770 generates UDR-files (Usage Data Record), which are then transmitted to the AAA server.
In the absence of a separate DHCP server and, if the issuance of the IP address is not configured on AAA, WASN can take over this function.
Since between a BS and an ASN-GW there may be a network of any structure and topology (for example, a network of another provider providing a channel), the R6 interface is implemented using a VLAN or GRE tunnel
The existing AAA servers are registered on the ASN-GW and an AAA server is assigned for each domain used (the second part of the login for the MS (mobile station)).
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 traffic, as is often organized abroad.
It's about mobility: handover.
On the ASN-GW, a list of neighbors is configured for each BS. In this case, BS refers to one sector, since each sector has its own BSID - base station identifier and its list of neighbors, including two other sectors of this BS.
Handover triggers are configured on the MS, BS and ASN-GW. The process may be initiated by an MS that detects a better signal, or a BS that detects a UL signal from an MS. A handover request is sent to the ASN-GW, which must decide in accordance with the configuration.
We are all IT users and understand why traces are 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, it has 10 card slots and two independent power sources.
Slots can be of three types: SRU, SPU, LPU.
SRU (Switching and Routing Unit) performs the following functions:
Collects routing information and generates a routing table and sends it to the LPU and SPU cards
provides interaction with OMC (Operation and Maintenance Center)
performs packet switching
There can be only two such boards that work in the Hot Standby mode.
SPU (Service Processing Unit) performs all the functions of processing incoming data.
Up to three pairs of cards can be installed. Each pair works in Hot Standby mode.
The LPU (Line interface Processing Unit) is used to physically connect other network elements and, besides sending packets, does not perform any functions.
The board can be implemented optical or electrical ports. Each of them is configured for immediate needs: BS connection, channel to the Internet, AAA server, control channel and others.
There can be only two such boards and they are installed in the first and second slots.
In order not to load readers much, in a few words about the management of Huawei network devices.
All of them are available via telnet / ssh. The interface is painfully similar to tsiskovsky. As far as I know, Cisco and Huawei had some kind of litter on the subject, after which Huawei changed the show to display , no to undo and made some other minor changes.
In addition, WASN and BS can be managed through MML . Special software provides such an opportunity.
<What did I want? End this article with a WiMAX cycle. I hope it was very interesting, extremely exciting and surprisingly informative>
The article will be devoted mostly to the central device of the network: ASN-GW (which is translated to the human Access Service Network GateWay)
What is what
ASN-GW is the gateway between the ASN and CSN networks, as the name implies. Accordingly, it has interaction interfaces.
The figure below shows the layout of the device on the network with the designation of interfaces:
- R6 for communication with BS
- R3 to communicate with the CSN network
- R4 for communication between different ASNs (for handover)
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Functions
Being the central node of the network, ASN-GW assumes the lion’s share of all functions:
- Routing
- QoS management
- Accounting
- DHCP
- VPN
- Providing communication with AAA server and connecting MS (Mobile Station) without authentication
- Management of current sessions and storage of data on connected MS
- Radio Resource Management
- Management of MS operation modes (sleep, idle-mode)
- Tracing interfaces and hardware parameters.
A little more about some points.
Routing
In Huawei (the equipment I am dealing with directly), the ASN-GW is called 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
Accounting data can be based on the duration of the session, and the amount of traffic. Postpaid and prepaid (postpaid / prepaid) services are supported.
WASN 9770 generates UDR-files (Usage Data Record), which are then transmitted to the AAA server.
DHCP
In the absence of a separate DHCP server and, if the issuance of the IP address is not configured on AAA, WASN can take over this function.
VPN
Since between a BS and an ASN-GW there may be a network of any structure and topology (for example, a network of another provider providing a channel), the R6 interface is implemented using a VLAN or GRE tunnel
AAA server
The existing AAA servers are registered on the ASN-GW and an AAA server is assigned for each domain used (the second part of the login for the MS (mobile station)).
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 traffic, as is often organized abroad.
Radio Resource Management
It's about mobility: handover.
On the ASN-GW, a list of neighbors is configured for each BS. In this case, BS refers to one sector, since each sector has its own BSID - base station identifier and its list of neighbors, including two other sectors of this BS.
Handover triggers are configured on the MS, BS and ASN-GW. The process may be initiated by an MS that detects a better signal, or a BS that detects a UL signal from an MS. A handover request is sent to the ASN-GW, which must decide in accordance with the configuration.
Interface tracing
We are all IT users and understand why traces are 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, it has 10 card slots and two independent power sources.
Slots can be of three types: SRU, SPU, LPU.
SRU (Switching and Routing Unit) performs the following functions:
Collects routing information and generates a routing table and sends it to the LPU and SPU cards
provides interaction with OMC (Operation and Maintenance Center)
performs packet switching
There can be only two such boards that work in the Hot Standby mode.
SPU (Service Processing Unit) performs all the functions of processing incoming data.
Up to three pairs of cards can be installed. Each pair works in Hot Standby mode.
The LPU (Line interface Processing Unit) is used to physically connect other network elements and, besides sending packets, does not perform any functions.
The board can be implemented optical or electrical ports. Each of them is configured for immediate needs: BS connection, channel to the Internet, AAA server, control channel and others.
There can be only two such boards and they are installed in the first and second slots.
In order not to load readers much, in a few words about the management of Huawei network devices.
All of them are available via telnet / ssh. The interface is painfully similar to tsiskovsky. As far as I know, Cisco and Huawei had some kind of litter on the subject, after which Huawei changed the show to display , no to undo and made some other minor changes.
In addition, WASN and BS can be managed through MML . Special software provides such an opportunity.
<What did I want? End this article with a WiMAX cycle. I hope it was very interesting, extremely exciting and surprisingly informative>
Source: https://habr.com/ru/post/79926/
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