IPv4 and IPv6 Mobility Support Using MPLS and MP-BGP

draft-berzin-malis-mpls-mobility-00

Oleg Berzin, Andy Malis{oleg.berzin, andrew.g.malis}@verizon.com

Problem Statement• Efficiently update the network on the new L3

location of a mobile node and deliver the traffic to the node in an optimal manner, where– Optimal traffic delivery is interpreted as the delivery

of packets to the new node location following the best path between the mobile node and the correspondent node

• Packets forwarding avoids “triangular routing” in current mobile IP

– Network update process is a function of the network control plane

– Traffic delivery process is a function of the network forwarding plane

Design Criteria• Robust and Flexible Protocol Framework

– Mobility Management Control Plane Protocol and the associated functions must be placed at the intelligent network edges and allow to avoid the need to involve all nodes in the network (including the core nodes) in the network update process

– Support for mobile hosts and mobile routers– Support for IPv4 and IPv6

• Evolutionary Architecture and Implementation Approach– Mobility Management scheme should be based as much as possible on the

existing network architectures and protocol framework– Only minimal changes to the operation of mobile nodes should be expected

• Efficient Network Responsiveness– The impact on the mobile application due to the service disruption caused

by the mobile node’s movements and the associated network update and delivery processes should be reasonably minimal

• Acceptable Network Scalability and Performance– The new requirements for Mobility Management functions should not result

in decreased network scalability and performance

Previous and Related Work

a) Mobile IPv4• Triangular routing

• Optimizations require host-to-host IP tunneling

• Foreign Agent and Home Agent Registrations

• Care-of-Address• No support for Mobile Routers

b) Mobile IPv6• Triangular routing

• Optimizations require a return routability procedure, IPv6 routing header and heavy security

• Home Agent Registrations• Micro-Mobility with HMIP• Basic support for Mobile

Routers with NEMO

c) MPLS Micro-Mobility• Triangular routing

• Extension of Mobile IPv4/v6

• Home Agent Registrations• Multiple registrations with

MPLS routers• Heavy use of signaling during

original registration and during the hand-off

Proposal• Mobility Label

– MP-BGP and MPLS-based mobility management solution resulting in optimal traffic delivery (no triangular routing)

– Evolutionary architecture based on the existing widely used protocol framework (MPLS and MP-BGP)

– Support for mobile host (mobile-to-fixed, mobile-to-mobile) and mobile router communications

– Support for IPv4 and IPv6 – Increased scalability due to built-in control plane capabilities

• Main Ideas– Independence from Mobile IP – no need for HA, CoA, FA and L3 tunneling– Mobility Support Function (MSF) on the Label Edge Router (LER)

• Mobile Host/Router Discovery, Registration and Status• Mobility Label Association/De-association, Mobility Bindings• Integration with MP-BGP and Network Update Procedures• Mobile Application Priority Indication and Recognition

– Similar to label advertisement mechanism in RFC 4364 for L3 VPNs• Introduce new element (Mobility Address Family) into MP-BGP to carry Mobility Bindings

– Introduce Mobility Labels and Mobility Bindings to:• De-couple IP layer topology from the user location in the network• Associate the new user location with the fixed L3 protocol address• Use stacked MPLS labels for the identification of IP addresses and efficient traffic delivery• Indicate mobile application parameters to the network

Protocol Overview and Architecture Illustration

ArchitectureMobility Support Function

Receive Discovery from MN (Host or Router)

Reply with MSF L2/L3 Address

Receive Registration Info from MN

Mobile Router?

Assign Mobility Label to Host IPAddress

Assign Mobility Label(s) to IPPrefixes

Establish Adjacency

Create Host Mobility Binding

Generate MP-BGP UpdateNLRI with Mobility Binding

Execute Network Update

Create Router Mobility Binding

Generate MP-BGP UpdateNLRI with Mobility Binding

YesNo

Logical L3 Interfaces

L2 GroomingNetwork

Radio AccessNetwork

Network Update with Mobility Bindings• When a Mobile Node registers with a

MSF the serving LER updates the network with a Node’s Mobility Binding carrying the MPLS Label bound to the Node’s IP Address

• Four Update Methods are proposed– Unsolicited Downstream Push. Updates

are sent to all peering MSF LER’s.– Selective Downstream Push. Updates are

send to a pre-defined set of MSF LER’s (such as the Internet Gateways).

– Predictive Downstream Push. A targeted update is sent to a MSF LER node determined during the forwarding table lookup for a packet sent by a mobile node.

– Hierarchical On-Demand Distribution. The Mobility Binding update is first sent by a serving MSF LER to a set of Mobility Route Reflectors using the Selective Downstream Push. Once the Mobility Route Reflectors have been updated, all other LER nodes must explicitly request Mobility Labels from the Mobility Route Reflectors for packets destined to a mobile node.

LER2

LER1 LER3

LER4

LSR1 LSR2

MSF MSF

MSFMSF

Mobility Aware MP-BGP Sessions

Mobile Node

Mobility Bindings:{IP, Label, Priority}

Unsolicited, Selective and PredictiveNetwork Update Modes

LER2

LER1 LER3

LER4

LSR1 LSR2

MSF MSF

MSFMSFMobility Aware MP-BGP

Sessions

Mobile Node

Mobility Binding Update:{IP, Label, Priority} MRR

Mobile Node

Mobility Binding Request:{IP, Label}

Hierarchical On-Demand DistributionNetwork Update Mode

• Mobility Bindings associate Mobility Label, a Mobile Node’s IP Address or Routing Prefix and a Serving LER’s Router ID (“Origin NEXT_HOP”)

• Carried as Network Layer Reachability Information (NLRI) using MP-BGP UPDATE messages and encoded as the Address Family structure in the MP-REACH-NLRI

• New types of MP-BGP Address Families are proposed – IPv4 Mobility Address Family, IPv6 Mobility Address Family following the format in RFC 4760 – “Multi-Protocol Extensions for BGP-4”

• May contain additional information such as the Mobile Node’s priority which can be communicated during the registration process

• Two types of Mobility Binding Structures are proposed: Mobile Host Mobility Binding and Mobile Router Mobility Binding

• Traffic delivery uses stacked MPLS labels: outer infrastructure label (LER-to-LER) and inner label (Mobility Label) to identify the Mobile Node

Mobility Bindings and Traffic Delivery

Traffic delivery using stacked labels

LER1 LER2LSR1 LSR2

MP-BGP session carrying Mobility Labels

NET11

NET12

NET21

NET22

Infrastructure LSP (outer label)

Mobility LSPs (inner labels)

Summary and Next Step

• Key concept of this draft is the Mobility Label in the label stack to optimize mobile IP packet forwarding

• While MP-BGP is proposed for label distribution as in RFC 4364, we’re open to other label distribution mechanisms as well if more appropriate for the application

• Presented to solicit comments from the WG• Next step is to update the draft based on received

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