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
•
Main Ideas
– 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
– 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
•
Introduce new element (Mobility Address Family) into MP-BGP to carry Mobility Bindings
•
•
•
•
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
– Similar to label advertisement mechanism in RFC 4364 for L3 VPNs
– Introduce Mobility Labels and Mobility Bindings to:
Protocol Overview and Architecture Illustration
Mobility Support Function
Architecture
Receive Discovery from MN (Host or Router)
Reply with MSF L2/L3 Address
Receive Registration Info from MN
No
Yes
Mobile Router?
Assign Mobility Label to Host IP
Address
Establish Adjacency
Create Host Mobility Binding
Assign Mobility Label(s) to IP
Prefixes
Generate MP-BGP Update
NLRI with Mobility Binding
Create Router
Mobility Binding
Generate MP-BGP Update
NLRI with Mobility Binding
Execute Network Update
Logical L3
Interfaces
L2 Grooming
Network
Radio Access
Network
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.
Mobility Bindings:
{IP, Label, Priority}
MSF
LER1
Mobile
Node
LSR1
MSF
LER3
MSF
LER4
MSF
LSR2
LER2
Mobility Aware MP-BGP
Sessions
Unsolicited, Selective and Predictive
Network Update Modes
Mobility Binding Request:
{IP, Label}
Mobility Binding Update:
Mobile
MRR
{IP, Label, Priority}
Node
MSF
LER1
Mobile
Node
LSR1
MSF
LER3
MSF
LER4
MSF
LSR2
LER2
Mobility Aware MP-BGP
Sessions
Hierarchical On-Demand Distribution
Network Update Mode
Mobility Bindings and Traffic Delivery
•
•
•
•
•
•
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 – “MultiProtocol 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
MP-BGP session carrying Mobility Labels
NET21
NET11
LER1
LSR1
LSR2
NET12
LER2
NET22
Infrastructure LSP
(outer label)
Mobility LSPs (inner labels)
Traffic delivery using stacked 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
comments