Header Compression for Communication exceed 6LoWPAN

20091029

outline

• Problem statement and analysis

• Solution 1-the existing technical

• Solution 2-Header Compression base on binding table

Problem statement and analysis(1/2)

• packet transportation within 6LoWPAN– Source and destination IPv6 addresses in adaptation

layer header use MAC addresses, e.g. 7 octet. Reference to RFC4994

• 6LoWPAN nodes communicate to nodes outside– The source IPv6 address prefix, the prefix and

interface identifier of destination IPv6 address would not be omitted, for a total 24 octet.

Problem statement and analysis(2/2)

• In the 6LoWPAN applications, more scenarios is the communication among nodes within and out of 6lowpan.

• The cost reduction is to be further addressed, in case a 6LoWPAN node sends a IPv6 package to an IP address outside.

Solution 1• twice-NAT

FE80::1:1:1:1FE80::2:2:2:2

FE80::3:3:3:3

402::0/128 202::234:89

www.huawei.com

1. Send a DNS request

Q=www.huawei.com

NAT table

FE80::A:A:A:A=202::234:89

2.Gateway DNS request

Q=www.huawei.com

R=202::234:893.Router reply

R=FE80::A:A:A:A

4.Connection request source IP: FE80::3:3:3:3

Dest IP: FE80::A:A:A:A

FE80::1:1:1:1=402::1

FE80::2:2:2:2=402::2

FE80::3:3:3:3=402::3

5.Translation request source IP: 402::3

dest IP: 202::234:89

7.Translation reply source IP: FE80::A:A:A:A

Dest IP: FE80::3:3:3:3

6.Connection reply source IP: 202::234:89

Dest IP: 402::3

Save 16 byte prefix when use 64-bit extended address

The allocation of internal address to

external equipment of 6loWPAN and management

will be Complex.

FE80::7:7:7:7

Reference to: IPv6 Global to Link-layer ADdress Translation for 6LoWPAN Overhead Reducing Zimmermann, A.; Sa Silva, J.; Sobral, J.B.M.; Boavida, F.;

Solution 2

The mechanism to use 16bits short address to identify 6LoWPAN nodes;

A binding table with scheme of 16bit short address, PAN id, binding id, identifier of external node and binding expiration, maintained by edge routerNOTE: information already stored in edge router.

Edge gateway converts inner identifiers and outer identifiers when communication.

Solution 2

1. When a node A within the PAN communicate to nodes outside PAN，the packet is sent to the edge router with 16bits short address and identifier of destination (IP address or host name).

6LoWPAN edge router uses above binding table to maintain the connections with nodes out of 6LoWPAN.

A static mapping or DNS query mechanism are used to establish the binding table

FE80::1:1:1:1 FE80::2:2:2:2

FE80::3:3:3:3

402::0/128

202::234:89

www.huawei.comFE80::7:7:7:7

64bit MAC

address

16bit short address

PAN

ID

binding

ID

external device

binding expiration

IPHC Encoding Extension

2. Node A uses16-bit short address and sends a request extension to DAM fields of LOWPAN_IPHC Encoding.

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+| 0 | 1 | 1 | TF |NH | HLIM |CID|SAC| SAM | M |DAC| DAM |+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+LOWPAN_IPHC Encoding

DAM=10 no use of binding ID DAM=11 use of binding ID, In accordance with the indication to use binding ID, following 1 octet is to indicate

binding ID

3. When node A using binding identifier, edge router fetches the binding table with 16-bit short address and binding ID, and encapsulates data packets sending to the corresponding node out of 6lowpan.

If M=1 and DAC=1 00: 48 bits.

01: reserved. 10: reserved 11: reserved

From Ietf-6lowpan-hc

binding table scheme(4/4)

the maintenance of binding table as node move In the same subnet prefix within the different PAN

FE80::1:1:1:1FE80::2:2:2:2

FE80::3:3:3:3

402::0/128 202::234:89

www.huawei.com

402::1:0/128FE80::9:9:9:9

FE80::f:f:f:f

FE80::3:3:3:3

64bit MAC

address

16bit short address

PAN

ID

Binding

ID

external

device

binding period

3:3:3:3 3 1 1 202::234:89 100

64bit MAC

address

16bit short address

PAN

ID

Binding

ID

external

device

binding period

3:3:3:3 8 2 1 202::234:89 100

Compare of two solution

header MAC header adaptation header

field Source addr Dest addr source IP dest IP

Twice-NAT 3:3:3:3(64bit)

7:7:7:7(64bit)

0bit A:A:A:A(64bit)

Binding-table

3(16bit) 0(16bit) 0bit 0bit

FE80::1:1:1:1 FE80::2:2:2:2

FE80::3:3:3:3

402::0/128

202::234:89

www.huawei.com

FE80::7:7:7:7

Compare to solution 1,the Binding-table solution can reduce 160 bits.

Phy header MAC header Adaptation header IP payload

Consideration next steps

• Extension to LOWPAN_IPHC Encoding in page 8 is possible to define alternative methods .

Thanks!