1. Dave Thaler dthaler@microsoft.com
A Comparison of Mobility-Related Protocols: MIP6,SHIM6, and HIP draft-thaler-mobility-comparison-01.txt
Dave Thaler
IETF 66

2. Goal of this presentation
Help those in none of the WGs understand the relationship between them
Help those in one WG understand other WGs
IETF 66

3. Disclaimers
Only work in the IETF (as WG drafts and RFCs) has been considered
There are individual submissions and IRTF drafts in addition
This is a snapshot in time, as of beginning of June 2006
This is a moving target
Only MIP6, SHIM6, and HIP have been considered so far
Other mobility-related protocols do exist (NEMO, SCTP, NETLMM, MOBIKE, etc.)
Points of comparison derived from union of the three problem statements
IETF 66

4. Terminology Name: A DNS fully-qualified domain name
Upper-layer Identifier (ULID): Address used above the mobility/multihoming layer
MIP6: “Home Address”
SHIM6: “ULID”
HIP: “Host Identity Tag (HIT)”
Locator: Address used below the mobility/multihoming layer
MIP6: “Care-of Address”
SHIM6 & HIP: “Locator”
IETF 66

5. Extension Header Order
Each protocol defines headers to go in data packets, and defines where they have to go
A hypothetical data packet with all of them, plus other headers, would look like this:
IPv6
Hdr
HbH
Opts
Type 2
Rtg Hdr
DstOpts
(HoA)
SHIM6
PEH
Frag
Hdr
ESP
(HIP)
Payload
Mobile IPv6
SHIM6
HIP
This leads to a natural layering model…
IETF 66

6. Fragmentation/reassembly
Layering
Transport layer
IPsec + HIP sub-layer
Fragmentation/reassembly
Network
Layer
SHIM6 sub-layer
MIP6 sub-layer
Routing sub-layer
Link layer
IETF 66

7. Feature Comparison 1/2 MIP SHIM6 HIP Preserve established connections
Yes
Support both ends moving simultaneously
Only within known set
Span outages No
Resolve name to locators immediately after move
IETF 66

8. Feature Comparison 2/2 MIP SHIM6 HIP Support referrals Yes
Only by name
Stable addresses
Assumed
Non-routable
Support load spreading
(monami6)
Multicast sourcing support
Not mobile No
IETF 66

9. Efficiency Considerations
MIP
SHIM6
HIP
Per-packet overhead (bytes)
0 if both home /
20/40 if src away
+ 24 if dest away
0 normally /
8 if moved
0 + IPsec transport mode (~18-29)
Connect overhead (messages)
0 if home /
6 if away
0 + 4 for IPsec key neg
Locator change overhead (messages)
2 to update HA +
6 to update peer
4 to update peer
3 to update RVS +
3 to update peer
IETF 66

10. Deployment Considerations
MIP
SHIM6
HIP
One-end benefit
Yes No
Typical deployment dependencies
Home agent
None
Rendezvous Server, New RR, IPsec
For the full security benefit of HIP, DNSSec is also needed
However, without it, it’s no worse than the others
IETF 66

11. Security Considerations
MIP
SHIM6
HIP
Control message auth check:
Minimum
On path
On path + new locator of same node
Cryptographic
Maximum
Data security
Optional
Required
IETF 66

12. Questions?
IETF 66