NEtwork MObility (NEMO)
description
Transcript of NEtwork MObility (NEMO)
NEtwork MObility (NEMO)
Houcheng Lee
Main Idea
• NEMO works by moving the mobility functionality from Mobile IP mobile nodes to a mobile router. The router is able to change its attachment point to the Internet in a manner that is transparent to attached nodes
Goals – RFC4886• Migration Transparency• Performance Transparency and Seamless Mobility• Network Mobility Support Transparency• Operational Transparency• Arbitrary Configurations• Local Mobility and Global Mobility• Scalability• Backward Compatibility• Secure Signaling• Location Privacy• IPv4 and NAT Traversal• Minimal Impact on Internet Routing
Requirements – RFC 4886
1. The solution must be implemented at the IP layer level
2. The solution must set up a bi-directional tunnel between a MR and its HA (MRHA tunnel)
3. All traffic between MNN and CN msut transit through the bi-directional MRHA tunnel
4. MNNs must be reachable at a permanent IP address and name
5. The solutions must maintain continuous sessions
Requirements – RFC 4886
6. The solution must not require modifications to any node other than MRs and Has
7. Support fixed nodes, mobile hosts, and mobile routers in the mobile network
8. Must allow MIPv6-enabled MNNs to use a mobile network link as either a home link or a foreign link
9. Must ensure backward compatibility10. Solution will behave the same way if NEMO is
nested.
Requirements – RFC 488611. Arbitrary levels of recursive mobile networks must be supported12. The solution must function for multihomed MRs and multihomed
mobile networks as defined in RFC 488513. NEMO support signaling over the bi-directional must be
minimized14. Signaling messages between the HA and the MR must be
secured15. The solution must ensure transparent continuation of routing and
management operations over the bi-directional tunnel16. When one egress interface fails, the solution may preserve
sessions established through another egress interface17. The solution should have a minimal impact on the global Internet
routing system
Basic Support – RFC3963
Basic Support - Introduction
• An extension to Mobile IPv6 (MIPv6)• compatible with Mobile IPv6
– e.g. a NEMO-compliant HA can operate as a Mobile IPv6 HA
• satisfies the goals and requirements identified in “Network Mobility Support Goals and Requirements” (RFC4886)
• NEMO ensures session continuity for all the nodes in the MN, even as the MR changes its point of attachment to the Internet
• NEMO provides connectivity and reachability for all nodes in the MN as it moves
Basic Support - Introduction
• Definition of a MR extends that of a Mobile IPv6 Mobile Node, by adding routing capability routing between its point of attachment and a subnet that moves with the MR
• proposes a bi-directional tunnel between the MR and its HA.
• Tunnel is set up when the MR sends a Binding Update to its HA successfully
• All traffic between MNN and CN passes through the HA• Basic support does not place any restriction on the
number of levels for nested mobility, but significant overhead is expected
Basic Support - Overview
• A mobile Network is a network segment or subnet that can move and attach to arbitrary points in the routing infrastructure
• The Mobile Router is the default gateway for the Mobile Network
• A Mobile Network can comprise of nested subnets, but the overhead is heavy
• A Mobile Router has a unique registered Home Address with its Home Agent. The Home Address is configured from a prefix aggregated and advertised by its Home Agent.
Basic Support - Overview
• When Mobile Router acquires a Care-of Address from Foreign Agent, it sends a Binding Update to its Home Agent, and Home Agent creates a cache entry binding the Mobile Router’s Home Address to its Care-of Address.
• If the Mobile Router Seeks to act as a Mobile Router and provide connectivity to nodes in the Mobile Network, it indicates this to the Home Agent by setting a flag (R) in the Binding Update
• Mobile Router MAY include information about one or multiple Mobile Network Prefix in the Binding Update
Basic Support - Overview
• The Home Agent acknowledges the Binding Update by sending a Binding Acknowledge to the Mobile Router. A positive acknowledgement with the Mobile Router Flag (R) set means that the Home Agent has set up forwarding for the Mobile Network.
• Once the binding process finishes, a bi-directional tunnel is established between the Home Agent and the Mobile Router, and the end points of the tunnel are the MR’s CoA and HA’s address.
• The packets sourced from MN are sent to HA through the reverse-tunnels which is done by using IP-in-IP encapsulation, and then HA decapsulates the packets and forward it to the CN.
Basic Support - Overview
• Before MR decapsulates the packets sent from HA via tunnel, MR has to check whether the Source address on the outer IPv6 header is the Home Agent’s address, but this check is not necessary if the packet is protected by IPsec in tunnel mode.
• The MR and HA can run a routing protocol through the bi-directional tunnel. In this case, the MR need not include prefix information in the Binding Update. Instead the HA uses the routing protocol updates to set up forwarding for the Mobile Network. The MR should be configured not to send any routing protocol messages on its egress interface when it is away from he home link and connected to a visited link.
Basic Support - Overview
MR acts as
Mobile Host
HABinding Update
Get CoA
create cache entry
MR’s Home Address CoA
Basic Support - Overview
MR acts as
Mobile RouterHA
Binding Update with flag (R)Get CoA
implicit mode – No Network Prefix Option in the Binding Update
explicit mode – include one or more (multiple prefix information options on)
Mobile Network Prefix Options
Basic Support - Overview
MR HA
Binding Acknowledgement set to 0 (Binding Update accepted)
with Mobile Router Flag (R)
once finishes, a bi-directional tunnel is established
MR’s CoA HA’s address
Basic Support - Overview
MR HA
src address
from Mobile Network
reverse-tunnels
using IP-in-IP encapsulation
CN
decapsulates and forward
Basic Support - Overview
MR HA
MNN
CN
tunnel MR CoA
decapsulates and check (for Security Considerations)
1. src address is HA’s address (NOT necessary if IPsec)
2. inner IPv6 header belongs to a prefix used in MNDROP
Basic Support - Overview
MR HA
run an intra-domain routing protocol (e.g RIPng and OSPF)
through the bi-directional tunnel
HA uses the routing protocol updates to
set up forwarding for the MNMR should be configured NOT
to send any routing protocol messages
on its egress interface
Dynamic Routing Protocols
Basic Support – Message Formats
• Binding Update
• A new flag (R) (Mobile Router Flag) is included in the Binding Update to indicate to the HA whether the Binding Update is coming from a MR not from a mobile node
• Other Mobility options are defined in RFC3775 “Mobility Support in IPv6”
Basic Support – Message Formats
• Binding Acknowledgement
• A new flag (R) is included in the Binding Acknowledgement to indicate that the Home Agent that processed the corresponding Binding Update supports MR
• New Binding Acknowledge status values– 140 Mobile Router Operation not permitted– 141 Invalid Prefix– 142 Not Authorized for Prefix– 143 Forwarding Setup failed (prefixes missing)
Basic Support – Message Formats
• Mobile Network Prefix Option
• The Mobile Network Prefix Option is included in the Binding Update to indicate the prefix information for the MN to the HA. An alignment of 8n+4 is required.
Basic Support – MR Operation
• MN can act in 2 ways– Mobile Host
• HA doesn’t maintain prefix information related to MH• maintain a cache entry related to the MH’s Home Address
– Mobile Router• both prefix information and cache entry are maintained
• Mobile Router Flag (R) is used to represented these 2 modes
• MR maintains a Binding Update List. It is one entry per each destination to which MR sending Binding Updates
Basic Support – MR Operation
• Sending Binding Updates – if MR is not running a routing protocol, 2 modes are used to tell HA which prefixes belong
to the MR
1. Implicit:MR does not include a Mobile Network Prefix Option in the Binding Update. HA uses other mechanism to determine the Mobile Network Prefix(es) owned by the MR
2. Explicit:MR includes one or more Mobile Network Prefix Options in the Binding Update
• if the Mobile Router Flag is set, the Home Registration Flag (H) must be set
Basic Support – MR Operation
• Receiving Binding Acknowledgements– 0 (Binging Update accepted) and the Mobile Router
Flag (R) is set to 1– If (R) not set, MR assumes that HA doesn’t support
Mobile Routers– Then MR performs Dynamic Home Agent Address
Discovery again to discover HA that supports– MR MUST de-register with the HA before attempting
registration with another– Status of Binding Acknowledgement status is set to a
value between 128 and 139
Basic Support – MR Operation
• Establishment of Bi-directional Tunnel– After a successful Binding Acknowledgement is
received, the MR sets up its endpoint of the bi-directional tunnel
– The bi-directional tunnel is created by merging 2 unidirectional tunnels as described in RFC2473
– CoA of MR and HA’s address are the two ends of the bi-directional tunnel
– A MR uses the Tunnel Hop Limit normally assigned to routers (RFC2473)
Basic Support – MR Operation
• Neighbor Discovery for Mobile Router– When the MR is at home, it MAY be configured to send Router
Advertisements and to reply Router Solicitations on the interface attached to the home link
– The value of the Router Lifetime field SHOULD be set to 0 to prevent other nodes from configuring the MR as the default router
– MR SHOULD NOT do any of the above when on the visited link– MR MUST NOT ignore Router Advertisements received on the
egress interface. The received Router Advertisements MAY be used for address configuration, default router selection, or movement detection
Basic Support – MR Operation
• Multicast Groups for Mobile Router– When at home, the MR joins the multicast group All
Routers Address with scopes 1 interface-local (on the home-advertising interface), and 2 link-local, on any of it egress interface.
– When in a visited network, MR MUST NOT join the above multicast groups
Basic Support – MR Operation
• Returning Home– When returning home, MR MUST de-register with its
HA– MR MUST implement and follow the returning-home
procedures defined for a mobile node in RFC3775– MR might start behaving as a router on its egress
interface• MR may send Router Advertisement but the lifetime should
be set to 0 to prevent being picked as a default router• MR may join the All Routers Address multicast group• MR may send routing protocol messages on its egress
interface if it is configured to run a dynamic routing protocol
– When the HA removes a binding cache entry, it deletes all associated Mobile Network Prefix routes
Basic Support – HA Operation
• HA MUST satisfy all the requirement listed in section 8.4 of RFC 3775
• Data Structure– Binding Cache
• HA maintains Binding Cache Entries for each MR currently registered with the HA
• might also need to store Mobile Network Prefixes associated with a MR in the corresponding Binding Cache Entry
• HA also stores the status of the Mobile Router Flag (R) in the Binding Cache entry
Basic Support – HA Operation
– Prefix Table• HA should prevent a MR from claiming Mobile
Network Prefixes belonging to another MR• HA maintains a Prefix Table and verifies the prefix
information provided by the MR against Prefix Table entries
• Not required if running a dynamic routing protocol• In explicit mode, Prefix Tables are used by Has
when they process Binding Updates• Each entry contains:
– The Home Address of the Mobile Router– The Mobile Network Prefix of the MR associated with HA
Basic Support – HA Operation
• Mobile Network Prefix Registration– The HA processes the Binding Updates as described
in section 10.3.1 of RFC 3775– The Home Registration (H) Flag MUST be set– Relaxes RFC 3775 requires that the HA in the Binding
Update be configured from a prefix advertised on the home link, but rejects the Binding Updates only if the HA does not belong to the prefix that the HA is configured to serve
– Check if there is a duplicated one in cache entry, otherwise send acknowledgement with code 139
Basic Support – HA Operation
• Advertising Mobile Network Reachability– To receive packets meant for the Mobile Network, the
HA advertises reachability to the Mobile Network– If the Home link is configured with an aggregated
prefix and the Mobile Network Prefix is aggregated under that prefix, then the routing changes related to the Mobile Network maybe restricted to the Home link
– If the HA receives routing updates through a dynamic routing protocol from the Mobile Router, HA can be configured to propagate those routes on the relevant interface
Basic Support – HA Operation
• Establishment of Bi-directional Tunnel– Must be capable of the following operations:
1. HA can tunnel packets meant for the Mobile Network prefix to the Mobile Router’s current location, the CoA
2. The HA can accept packets tunneled by the Mobile Router with the src address of the outer IPv6 header set to the Mobile Router’s CoA
Basic Support – HA Operation
• Forwarding Packets– when HA receives a data packets destined for the
MN, it MUST forward the packet to the MR through the bi-directional tunnel
– Utilize the routing table, the Binding Cache or a combination to route packets to the Mobile Network
– Two examples• HA maintains a route to the MN Prefix with the next hop set
to the MR’s HA• HA maintains a route to the MN Prefix with the outgoing
interfaces set to the bi-directional tunnel interfaces
Basic Support – HA Operation
• Sending Binding Acknowledgements– HA sets the status code in the Binding
Acknowledgement to 0 (accepted)– code 140 means HA is not configured to support
Mobile Routers– code 141 means one or more prefixes received in the
Binding Update are invalid– code 142 means not authorized to use this Home
Address to forward packets– code 143 means Forward Setup failed
Basic Support – HA Operation
• Mobile Network Prefix De-registration– HA deletes the Binding Cache Entry for the
MR’s Home Address and stops proxying the Home Address
– HA removes the bi-directional tunnel and stops forwarding packets to the Mobile Network.
Basic Support – Modification to Dynamic Home Agent Address Discovery
• Extends the Dynamic Home Agent Address Discovery (DHAAD) defined in RFC 3775, so that MR only attempts registration with HA that support them
1. Modified Dynamic Home Agent Discovery Address Request
2. Modified Dynamic Home Agent Discovery Address Request
3. Modified Home Agent Information option
Basic Support – Support for Dynamic Routing Protocols• An alternative way to set up the forward
between HA and MR is run an intra-domain routing protocol such as RIPng and OSPF through the bi-directional tunnel.
• So the MR can continue running the same routing protocol that it ran when attached to the home link.
Basic Support – Support for Dynamic Routing Protocols• This feature is useful. Routing changes
can propagate to HA and MR quickly
• When the MR returns to the home link, it runs a routing protocol by sending routing updates through its egress interface, and stop sending routing updates when in a visited link.
Home Network - Introduction
• In NEMO, the Home Network can encompass much more than the Home Link
• Home Network can spans the Home Link and all the Links that the MRs carry with them
• Provided examples aim at illustrating the NEMO Basic Support
• Five different organizations of the Home Network
Home Network - Introduction
1. MIPv6 Home Network• the Home Network is with Mobile IP
2. NEMO Extend Home Network• the Home Network only subnet of a larger
aggregation that encompasses the Mobile Networks.
• When at home, a Mobile Router performs normal routing between the Home Link and the Mobile Networks
Home Network - Introduction
3. NEMO Aggregated Home Network• the Home Network overlaps with the Mobile
Networks• When at home, a MR acts as a bridge
between the Home Link and the MNs
4. Virtual Home Network• No physical Home Link for the MRs to come
back home
Home Network - Introduction
5. NEMO Mobile Home Network• A global Home Network is advertised to the
infrastructure by a head Home Agent (HA) and further subnetted into MNs
• Each subnet is owned by a MR that registers it in a NEMO fashion while acting as a Home Agent for that network.
• In all cases, the Home Agents collectively advertise only the aggregation of the MNs. The subnetting is kept within the Has and the MRs, not to advertised by means of routing protocols to other parties
Home Network – General Expectations
• NEMO extends the concept of home so that it is not only a flat subnet composed of Home Addresses but an aggregation that is itself subnetted in Mobile and Home Networks
Route Optimization
Multihoming
Applications - Airplanes
Applications - Automobiles
Applications - Personal Area Networks (PANs)
Terminology1. Access Router (AR)2. Care-of Address (CoA)3. Correspondent Node (CN)4. Foreign Agent (FA)5. Home Agent (HA)6. Home Network (HN)7. Mobility Agent (MA)8. Mobility Network Node (MNN)9. Mobile Node (MN)10. Mobile Router (MR)11. Mobile Netowrk Prefix
• An IPv6 prefix delegated to a Mobile Router and advertised in the Mobile Network. More than one Mobile Network Prefix could be advertised in a Mobile Network
12. Prefix Table• A list of Mobile Network Prefixes indexed by the Home Address of a Mobile Router. The Home Agent
manages and uses Prefix Table to determine which Mobile Network Prefixes belong to a particular Mobile Router
Reference1. E.Perera, V.Sivaraman, and A.Seneviratne, “Survey on Network Mobility Support”, ACM
SIGMOBILE Mobile Computer and Communications Review, Volume 8, Number 2, 20042. Paul Moceri, “Enabling Network Mobility: A Survey of NEMO”3. Devarapalli, V.,R. Wakikawa, A. Petrescu P. Thubert. “RFC 3963: Network Mobility (NEMO)
Basic Support Protocol,” IETF, NEMO Working Group, January, 20054. Leung, K.,G.Dommety, V.Narayana, A. Petrescu. “IPv4 Network Mobility (NEMO) Basic
Support Protocol,” IETF, NEMO Working Group, February 24, 20065. C. Perkins, Ed. “RFC 3344: IP Mobility Support for IPv4,” IETF Network Working Group,
August, 20026. Ernst, T. “Network Mobility Support Goals and Requirements,” NEMO Working Group,
Internet-Draft, October 24, 20057. Ernst, T.,H-Y. Lach. “Network Mobility Support Terminology,” NEMO Working Group, March 6,
20068. Ng, C., F. Zhao, M. Watari, P. Thubert. “Netowrk Mobility Route Optimization Solution Space
Analysis,” IETF, NEMO Working Group, Febraruy 10, 20069. Ng. C.,F. Zhao, M. Watari, P. Thubert. “Network Mobility Route Optimization Problem
Statement,” IETF, NEMO Working Group, December 28, 200510. Ng. C., E. Paik, T. Ernst, M. Bagnulo, “Analysis of Multihoming in Network Mobility Support,”
IETF, NEMO Working Group, February 23, 200611. “Nautilus6 – Network Mobility Website,” 2005. Nautilus6, WIDE, April, 200612. “Nautilus6 – NEPL Enhancement Website,” November 11, 2005. Nautilus6, WIDE, April 2006
Reference - RFC
1. RFC 3963: draft-ietf-nemo-basic-support
2. RFC 4887: draft-ietf-nemo-home-network-models
3. RFC 4980: draft-ietf-nemo-multihoming-issues
4. RFC 4886: draft-ietf-nemo-requirements
5. RFC 4888: draft-ietf-nemo-ro-problem-statement
6. RFC 4889: draft-ietf-nemo-ro-space-analysis
7. RFC 4885: draft-ietf-nemo-terminology
8. RFC 3775: Mobility Support in IPv6
9. RFC 3776: Using IPsec to Protect Mobile IPv6 Signaling between Mobile Nodes and Home Agents
END
Thanks