Module08 Network Planning Training

7/27/2019 Module08 Network Planning Training

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Confidential & Proprietary 3

Typical IP-RAN Physical Network Topology Definitions

A Fully loaded DO-RNC will have eight BIO TM 10/100 Mbit/secEthernet interfaces connected directly to Aggregation router ports.

The Aggregation router will aggregate the backhaul links andconnecting the DO-RNC to the data center Ethernet

DO-EMS server attached to the data center Ethernet (or to an optionalmanagement Ethernet LAN.

Two AAA server functions (the access network AAA server (AN-AAA) and the core network AAA server (CN-AAA)), implemented inone or two devices.

DO-RNCs require access to the AN-AAA server. PDSNs requireaccess to the CN-AAA server. If the PDSN is separated from the datacenter LAN by an additional firewall router, the firewall mustimplement a secure path through for the PDSN to reach the CN-AAAserver, or the CN-AAA server must be co-located with the PDSN onthe external side of the firewall router.

PDSN connected to the data center Ethernet and to the Internet.


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Understanding DO-RNC IP Address Requirements

A fully loaded DO-RNC has the following IP addressrequirements:

Eight IP-capable BIO TM Ethernet interfaces which eachis configured to reside on different IP subnets. This has adirect impact on the physical network topology of the datacenter and on the IP address and subnet design.

One virtual node IP address, defined with a /32 mask (255.255.255.255 in dot decimal notation), that is notassociated with any physical interface. Used for Abis communications for all traffic (user traffic,

signaling, and control ) between the DO-RNC and the BSNE,transmitted out the BIO TM Ethernet ports, NEVER out the SCEthernet ports.

Used for communication between DO-RNC & DO-EMS.


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Understanding BSNE IP Address Requirements

A fully loaded BSNE has the following IP addressrequirements:

Four T1/E1 backhaul interfaces, each configured ondifferent IP subnets. This has a direct impact on the

physical network topology of the data center and on the IPaddress and subnet design.

One virtual node IP address, defined with a /32 mask (255.255.255.255 in dot decimal notation), that is notassociated with any physical interface. Used for Abis communications for all traffic (user traffic,

signaling, and control ) between the DO-RNC and the BSNE,transmitted out over each T1/E1 backhaul interface.

Used for communication between BSNE & DO-EMS.


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Understanding Public IP Addressing

Public IP addresses are guaranteed to be unique (like atelephone number) throughout the entire global Internet.

Allocated for use by controlling regulatory authorities. Need to acquire a range of public IP addresses to operate

the IP-RAN, IF your PDSN does not have a NAT function,which provides dynamic IP address assignment to ATs

Ensure the range allocated for this purpose is large enoughto accommodate the maximum number of ATs that youexpect to connect to the public Internet at any given time.


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Understanding Private IP Addressing

Used for internal IP-RAN network, appropriatelyarranged into subnets according to the physicalnetwork topology.

The numbers of the subnets in your IP plan islimited by the overall size of your privateaddresses available

If possible, use 10.X.X.X range providing almost17 million IP addresses.

Other available private IP address ranges are asfollows: 172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255


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Segmenting DO-RNC Domains

The DO-RNC consists of two physical domains thatcorrespond to two groups of front-side chassis slots. Front side chassis slots 1 to 6 correspond to domain A, front side

chassis slots 11 to 16 correspond to domain B. These slots contain BIO modules and RNSM modules in a one-to-

two ratio (one BIO module for every two RNSM modules).

BSNE homes to a specific RNSM module. Cannot determine in advance which RNSM module, and therefore

which domain, an BSNE will be homed to. Has a consequence for ECMP egress load balancing. Minimize the forward direction traffic that originates in an RNSM

module homed in one domain from being transmitted out a BIOTM Ethernet interface that resides in the other domain. Thisminimizes inter-domain backplane traffic and increases DO-RNCefficiency.


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Segmenting DO-RNC Domains (Contd)

Forward direction user traffic IP datagram will first check for routes that correspond to subnets in the same domain asthe RNSM module to which the BSNE is homed to. If there are any valid routes in this domain, the IP datagram is

transmitted accordingly. If there are no valid routes in this domain, routes corresponding to

subnets in the other domain are checked. Recommend installing appropriate static routes for both

domains to prevent unnecessary inter-domain traffic. Install static routes for all BSNE backhaul IP addresses such that

efficient egress load balancing occurs regardless of which domain particular BSNEs are homed to.


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Load Balancing Forward Direction Abis Traffic

All forward direction Abis traffic i.e. from DO-RNCs to BSNE, to a particular BSNE should egress through one BIO TM Ethernet interface

All forward direction Abis traffic to all BSNEs should be load balanced acrossall BIO TM Ethernet interfaces.

Avoid other available BIO TM Ethernet interfaces underutilized when allforward direction traffic only uses one or a few BIO TM Ethernet interfaces

The DO-RNC topology manager tracks and load balances forward directiontraffic among the currently available backhaul links

Source IP: Node IP address of the DO-RNC to which the BSNE is homed Destination IP: IP address of the BSNE backhaul interface selected by

Topology Manager Use ECMP resolves multiple equal cost routes predictably to a single route

based on the source IP address, the destination IP address, and the number of available routes with the same metric within the DO-RNC domain. uses the round robin selection mechanism to cycle among the currently

available links, thus achieving basic load balancing over the backhaullinks.


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Load Balancing Reverse Direction A10 Traffic

Reverse direction A10 traffic i.e. from DO-RNC to PDSN is load balancedon egress from the DO-RNC among appropriate BIO TM Ethernetinterfaces. Source IP address: PCF IP address Destination IP address: PDSN IP address

Recommend to use static routes in combination with ECMP to distributePCF Load balancing

If there are eight BIO TM Ethernets on the DO-RNC, eight correspondingPCFs, and two PDSNs, there are 16 possible PCF-to-PDSN IPrelationships. For each of these, you will need to install two static routes (

primary & secondary) for a total of 32 static routes.

Note:Reverse direction traffic consumes far less bandwidth (approximately 1/8) thandoes forward direction traffic under normal circumstances. Therefore, load

balancing reverse connections is not as critical to overall performance as load

balancing Forward direction Abis traffic


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Planning for Maximum Backhaul Delay

Maximum delay of Backhaul links between each BSNEand the DO-RNC SHOULD NOT be higher than 50milliseconds (ms) Round-Trip. Any higher delay could cause protocol inefficiencies and poor

utilization of backhaul link bandwidth. Can cause to lose Abis packets, thus retransmission which wastes

network bandwidth and processing cycles. Use PING utility to measure it


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EMS System Planning (Contd)

Server capacity and maintenance. Data collection (network element statistics) is collecting various statistics

from network elements at periodic intervals. Both the extent of datacollected and time period at which they are uploaded to the server areconfigured and therefore directly affect server disk resource requirements(and the quantity of network bandwidth consumed for the task).

Fault management is event and alarm collection, correlation, and display.Fault management provides the ability to suppress the collection of eventsand alarms based on selected levels of severity.

Both server log files and network element log files are stored on the DO-EMS server. You can configure the severity of events that are logged, aswell as how often network element log files are uploaded to the server and

how long they are stored before being deleted. These choices impactserver resource utilization and requirements.

Server maintenance includes server database and file system backup andrecovery plans. How often files are backed up and deleted from the server

disk directly impacts the average available server disk space.


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EMS System Planning (End)

Server availability planning. The main criteria is cost and availability requirements. If minimal

interruption to visibility of network elements is important, the

warm-standby, redundant DO-EMS server option can be deployed.If cost is the most important consideration, the standalone optionmay be appropriate.

The redundant option consists of two servers (one active, onestandby) sharing a RAID disk system and accessible through asingle IP address.


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Thank You

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Module08 Network Planning Training