Router Advertisements for Routing between Moving Networks

draft-petrescu-autoconf-ra-based-routing-00.txtPresenter: Alexandru Petrescu

IETF 78 Maastricht29 July 2010, AUTOCONF Working Group

Slide 1

Outline

• Problems: once addresses and prefixes are assigned – how to update routing tables.

• ICMPv6 extension• Topology and Message Exchange Diagrams• Conceptual Algorithm on MR3; scalability• Recent remarks (from AUTOCONF, MEXT and

private).• Implementation

Slide 2

Problem

Slide 3

MR1

LFN1

MR2

LFN2

?Routing tables?

Self-formed link-local addresses

Prefixespre-configured

ICMPv6 Extension Router Advertisement is a message format defined in [RFC4861] as an ICMPv6 message. The document [RFC5175] proposes an option for RA extensibility: IPv6 Router Advetisement Flags Option. We propose to reserve bit 16 for Mobile Network Prefixes.

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |M| Bit fields available ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... for assignment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

'M' - Mobile Network Prefix present. Set to 1 if this Router Advertisement contains a Mobile Network Prefix.

If the RA Flags Option contais the flag M, and set to 1, then the Router Advertisement MUST contain a Route Information Option [RFC4191] followed optionally by a Source-Link Layer Address Option [RFC4861]. (If this SLLAO option is used then it avoids the necessity of doing NS/NA exchange for the link-local address of the Gateway entry in the data structure mentioned earlier.)

Slide 4

Topology and Message Exchange Diagrams MR-to-MR

2001:db8:3::/64

egressegress

MR1Net1

LFN11

MR3Net3

LFN31

WiFiessid: “V3”channel: 9mode: managed

fe80::MR1_egress

2001:db8:1::/64

fe80::MR3_egress

fe80::MR1_ingress fe80::MR3_ingress

eth0 eth0

2001:db8:2::/64

egress

MR2Net2

LFN21

WiFiessid: “V2”channel: 9mode: managed

fe80::MR2_egress

fe80::MR2_ingress

eth0

WiFiessid: “V1”channel: 9

mode: managed

SimultaneousMLD“JOIN”

MR1 MR2 MR3

RA1:

RA3:

RA2:

Phase 1

Phase 2

Simultaneous power-upof 3 MRs.

Slide 5

WiFiessid: “V2V”channel: 3mode: ad-hoc

Slide 6

More Message Exchange DiagramsMR1 MR2 MR3

MLD “JOIN”

RA1:

RA3:

RA2:

RS

MR1 MR2 MR3

RA1 used for deletionMNP1, flag ‘D’, or lifetime ‘0’

Upon receipt of this RA,MR2 and 3 delete theirroutes for MNP1 fromtheir routing tables.

MR1 MR2 MR3

RA1:

RA2:

RS

Timeout

Deletion

Renewal, eventually

Arrival of MR3 in a settingof MR1 and MR2.

Timed out expirationand deletion.

Explicitdeletion.

Slide 7

Conceptually – an Algorithm on MR3

(1)Send an RA containing the prefix(es) allocated to its subnets to which the ingress interfaces are connected

(2) "Join" the all-routers multicast address with link-scope, on its egress interface

(3) Send a Router Solicitation (RS) on its egress interface requesting RAs from MR1 and MR2

(4) Receive their special RAs: RA1 and RA2

(5) For each received RA, extract the source address and the prefixes and insert the corresponding number of routing table entries; these entries will help reach the LFNs in the moving networks of MR1 and MR2.

Slide 8

Scalability

Dst prefix Gateway Dev

2001:db8:2::/64 fe80::MR2_egress egress

2001:db8:3::/64 fe80::MR3_egress egress

2001:db8:n::/64 fe80::MRn_egress egress

2001:db8:1::/64 « connected » ingress

Routing table on MR1

MR1

LFN11

MR2

LFN12LFN1n

LFN21

LFN22LFN2m

MR3

LFN21

LFN22LFN2m

MRn

LFN11

LFN12LFN1n

Number of entries equals thenumber of Mobile Routersat the scene.

Dst prefix Gateway Dev

2001:db8:1::/64 « connected » eth0

default fe80::MR1_ingress eth0

Routing table on LFN11Number of entries is constant.

Slide 9

Security

• Example risk: attacker MR claims towards other MRs that it owns the MNP of a victim MR – victim MR no longer receives its traffic.

• More threats.• Is SeND appropriate.• Certificates when PKI infrastructure is absent.• Ongoing work.

Slide 10

• Bug in distinctor of prefixes (/64 instead of /24)• Use of distinctive ESSIDs on egress and ingress interfaces• Use of link-local addresses (notation, pertinence)• Address spoofing mode not good• How is MNP provided initially?• Addressing model not new and inline with IPv6 addressing arch• Collective « we » look at addres/prefix autoconf w/o restrictions for packet relaying

via same interface• Is this multi-hop?• Adapted to MEXT or AUTOCONF? [Teco, Chris, Ulrich, Henning, ThomasC –

discussion above]• Concept of prefix ownership, SeND• Is MR2 relaying between 1 and 3 (if so packet rcvd on multiple paths?)• Specifics on Route Deletion, RS used for.• Have I checked AODV and similar [Antti]

Remarks from AUTOCONF and MEXT WGs

Slide 11

• Wrong email address of a co-author• Need to separate the addressing model from

protocol

Private Remarks

Slide 12

Implementation• Extensions to ICMP Router

Advertisements sent on the egress interface

• Implementation on linux with radvd 1.4

• Packet Dissectors for Wireshark, for the packet formats

• Link-layer security on egress using WPA-NONE PSK TKIP/AES (yes, it is secure); and WEP too some times.

Slide 13

More on the Addressing Model

Slide 14

Slide 15

• Thanks in advance to the note takers!

Comments

Slide 16