ran2190 source based routing in npge

1 © Nokia Siemens Networks RAN2190 Source Based Routing in the NPGE / Michał Malcher For internal use

Network Engineering Info (NEI)Feature Deep Dive RAN2190 Source Based Routing in the NPGE

Michał Malcher

NWS Network Engineeringhttps://sharenet-ims.inside.nokiasiemensnetworks.com/Overview/D431653866

For internal use2 © Nokia Siemens Networks RAN2190 Source Based Routing in the NPGE / Michał Malcher

Change History

Issue Number Date of Issue Reason for Update

1.0 May 2011 Approved version


• Introduction

• RU20 and earlier releases

• Feature details

• User scenarios

• Parameters

• Summary

Contents


RAN2190 Source Based Routing in the NPGEIntroduction (1/3)

WCDMA Release RU30

I-HSPA System -

RNC Release RN6.0

mcRNC Release -

BTS (Ultra) -

BTS (Flexi) -

NetAct OSS5.3 CD Set1

HW Requirements RNC: NP2GE

Release Information

Common O&M Platform Feature No

BSW/ASW BSW

RAS SW Component RAN

License Control -

Supplementary O&M Information


RAN2190 Source Based Routing in the NPGEIntroduction (2/3)Brief description

• Source based routing introduces two functionalities: – 1) Local IP address based routing

In case traffic originates from an IP address which is configured to one of the NPGE's Ethernet or VLAN interfaces, ECMP routing selection is limited to routes that use this specific IP interface.

– 2) Full source based routing Routing of control and management plane traffic in NPGE card can be configured to be based on the source IP address (in difference to the usual destination IP address/subnet based routing entries). Consequently all packets carrying a source IP address from such address/subnet shall take the same configured gateway.

Motivation and benefits• Using Source Based Routing simplifies IP network configuration and maintenance for

operators using RNC site router(s), when single default route is not sufficient (using more than one Ethernet/VLAN interfaces in NPGE)

• Configuring static routes requires high maintenance effort whenever a Core Network side IP address/subnet is modified or added (related routing table updates in the RNC are required)

• Source based routing in RNC enables:– mapping of traffic to Ethernet/VLAN interfaces by looking up the source IP address (instead of

destination IP address), obsoleting the need to configure Core Network IP addresses/subnet to RNC's routing table. When performing IP addressing changes in Core Network, no related update in RNC is needed anymore,

– multiple default routes (e.g. one per VLAN),– new configuration alternatives (e.g. provisioning of multi-homed SCTP traffic to the two Ethernet

ports of the same NPGE, while allowing identical/overlapping IP addresses in the remote end)


RAN2190 Source Based Routing in the NPGEIntroduction (3/3)

Requires:

– RAN77 RNC Ethernet Physical Interface

RAN 2190RNC

RAN77


RU20 and earlier releases


• Local IP address based routing (ECMP fix)

- In earlier releases, if there were multiple routes towards identical destinations configured (incl. default routes) traffic was distributed to the IP interfaces by means of the ECMP algorithm. This might lead to traffic originating at a certain VLAN interface but being transmitted via another VLAN interface.

• Full source based routing

- Without RAN2190 routing in NPGE card in RNC is done based on destination address and associated route

RU20 and earlier releases

RNC

NPGEP 0 (WO)

GE0 10.1.1.4 /24

GE1 10.1.2.4 /24 10.1.2.2 /24

10.1.1.2 /24

SGSN

10.9.1.1 /24

Dst=10.9.1.1 Src=10.1.2.4 Data


Detailed Information about Feature


• Note, that for customer communication “Local IP address based routing” (ECMP fix) functionality should be referred as “Source based routing for user plane traffic” and “Full source based routing” functionality should be referred as “Source based routing for control/management plane”

• Source-based routing is a complementary solution to the standard routing based on destination IP subnet, which is provided as a part of basic RU10 IP transport functionality.

• In destination based routing, decision about forwarding the packet is based on destination IP address.

• Source-based routing, which takes precedence over destination based routing, makes the decision based on source IP subnet of the IP packet. The routing table consists of the source IP subnet and the gateway (next-hop) address.

RAN2190 Source Based Routing in the NPGEFeature details (1/2)


• The cRNC processes the different types of IP routes with the following priority order:

1. Source-based routes

2. Routes learned by OSPF

3. Destination based static routes (including default routes) according to configured preference

• Different source based routes with overlapping source subnets can be configured. In this case RNC selects the route based on longest prefix match.

• Source-based routing in NPGE(P) is applicable to Control Plane and Management Plane (traffic received via NPGE internal IFFE or IFAI interfaces only can be subject to source based routing)

• BFD and traceroute packets are not considered for source based routing (even if received via NPGE internal IFFE or IFAI interfaces)

RAN2190 Source Based Routing in the NPGEFeature details (2/2)


• ECMP routing with multiple VLAN interfaces

• Static routing configuration in NPGE(P):

Dst=10.9.1.1 via 10.1.1.2

Dst=10.9.1.1 via 10.1.2.2

• Both routes have the same preference

• All IP packets Src=10.1.1.4 will egress via green VLAN (GE0), all IP packets Src=10.1.2.4 will egress via red VLAN (GE1)

RAN2190 Source Based Routing in the NPGEUser scenarios (1/3)

RNC

NPGEP 0 (WO)

GE0 10.1.1.4 /24

GE1 10.1.2.4 /24 10.1.2.2 /24

10.1.1.2 /24

SGSN

10.9.1.1 /24


• Combination of traffic separation & default routes (incl. control plane)


Src=10.2.2.0/24 via 10.1.3.2

Src=10.2.3.0/24 via 10.1.4.2

Dst=default via 10.1.1.2

Dst=default via 10.1.2.2

• User Plane is subject to (fixed) ECMP routing, Control Plane is subject to source based routing (which takes precedence over default routes)


RNC

NPGEP 0 (WO)

GE0Iu-PS UP: 10.1.1.4 /24Iu-CS UP: 10.1.2.4 /24

10.1.2.2 /24 10.1.1.2 /24

10.1.4.2 /24 10.1.3.2 /24

Iu-PS CP: 10.1.3.4 /24Iu-CS CP: 10.1.4.4 /24

ICSU 0

10.2.3.1 /24

10.2.2.1 /24


• Asymmetric SCTP multi-homing


Src=10.2.2.0/24 via 10.1.1.2

Src=10.2.3.0/24 via 10.1.2.2

• Two CP addresses configured on RNC side and one CP address on SGSN side (assymetric multihoming).

• Two paths to the same destination address can be configured using source based routing

• Note that this scenario is presented for informative purposes, since it is not yet clear if asymmetric SCTP configuration is supported in the SCTP stack.


RNC

NPGEP 0 (WO)

GE0 10.1.1.4 /24

GE1 10.1.2.4 /24 10.1.2.2 /24

10.1.1.2 /24

SGSN

10.9.1.1 /24ICSU 0

10.2.3.1 /24

10.2.2.1 /24 (Control Planeaddress)


Parameters


There is one PRFILE parameter related to this feature.

• ECMP routing restriction enable/disable switch (enabled by default)

By enabling the switch local IP address based routing (ECMP fix) functionality is active.

You can manually enable PRFILE switch by executing ZWOC:2,1840:1; MML command (ZWOC:2,1840:0; command disables the switch).

Please remember that applied changes will take effect only after NPGE/NPGEP unit restart.

RAN2190 Source Based Routing in the NPGEParameters


Summary

Network Design Impact:• Interfaces Dimensioning Guideline:

– No major dimensioning impact related to the feature -> no update needed• Configuration Guideline:

– New use case covering RAN2190 can be added (alternatively current use case can also be adapted)

Network Engineering dimensioning tools impact:• ANT_3G

– No major dimensioning impact related to the feature -> no update needed

• NPS/10 (contributed by NetEng)

– New configuration options should be taken into account


THANK YOU FOR YOUR ATTENTION

ran2190 source based routing in npge

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