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Diffstat (limited to 'Documentation/networking/ieee802154.txt')
| -rw-r--r-- | Documentation/networking/ieee802154.txt | 109 |
1 files changed, 90 insertions, 19 deletions
diff --git a/Documentation/networking/ieee802154.txt b/Documentation/networking/ieee802154.txt index 23c995e6403..22bbc7225f8 100644 --- a/Documentation/networking/ieee802154.txt +++ b/Documentation/networking/ieee802154.txt @@ -4,15 +4,22 @@ Introduction ============ +The IEEE 802.15.4 working group focuses on standardization of bottom +two layers: Medium Access Control (MAC) and Physical (PHY). And there +are mainly two options available for upper layers: + - ZigBee - proprietary protocol from ZigBee Alliance + - 6LowPAN - IPv6 networking over low rate personal area networks The Linux-ZigBee project goal is to provide complete implementation -of IEEE 802.15.4 / ZigBee / 6LoWPAN protocols. IEEE 802.15.4 is a stack +of IEEE 802.15.4 and 6LoWPAN protocols. IEEE 802.15.4 is a stack of protocols for organizing Low-Rate Wireless Personal Area Networks. -Currently only IEEE 802.15.4 layer is implemented. We have choosen -to use plain Berkeley socket API, the generic Linux networking stack -to transfer IEEE 802.15.4 messages and a special protocol over genetlink -for configuration/management +The stack is composed of three main parts: + - IEEE 802.15.4 layer; We have chosen to use plain Berkeley socket API, + the generic Linux networking stack to transfer IEEE 802.15.4 messages + and a special protocol over genetlink for configuration/management + - MAC - provides access to shared channel and reliable data delivery + - PHY - represents device drivers Socket API @@ -29,15 +36,6 @@ or git tree at git://linux-zigbee.git.sourceforge.net/gitroot/linux-zigbee). One can use SOCK_RAW for passing raw data towards device xmit function. YMMV. -MLME - MAC Level Management -============================ - -Most of IEEE 802.15.4 MLME interfaces are directly mapped on netlink commands. -See the include/net/nl802154.h header. Our userspace tools package -(see above) provides CLI configuration utility for radio interfaces and simple -coordinator for IEEE 802.15.4 networks as an example users of MLME protocol. - - Kernel side ============= @@ -51,6 +49,15 @@ Like with WiFi, there are several types of devices implementing IEEE 802.15.4. Those types of devices require different approach to be hooked into Linux kernel. +MLME - MAC Level Management +============================ + +Most of IEEE 802.15.4 MLME interfaces are directly mapped on netlink commands. +See the include/net/nl802154.h header. Our userspace tools package +(see above) provides CLI configuration utility for radio interfaces and simple +coordinator for IEEE 802.15.4 networks as an example users of MLME protocol. + + HardMAC ======= @@ -59,13 +66,14 @@ net_device, with .type = ARPHRD_IEEE802154. Data is exchanged with socket family code via plain sk_buffs. On skb reception skb->cb must contain additional info as described in the struct ieee802154_mac_cb. During packet transmission the skb->cb is used to provide additional data to device's header_ops->create -function. Be aware, that this data can be overriden later (when socket code +function. Be aware that this data can be overridden later (when socket code submits skb to qdisc), so if you need something from that cb later, you should store info in the skb->data on your own. To hook the MLME interface you have to populate the ml_priv field of your -net_device with a pointer to struct ieee802154_mlme_ops instance. All fields are -required. +net_device with a pointer to struct ieee802154_mlme_ops instance. The fields +assoc_req, assoc_resp, disassoc_req, start_req, and scan_req are optional. +All other fields are required. We provide an example of simple HardMAC driver at drivers/ieee802154/fakehard.c @@ -73,8 +81,71 @@ We provide an example of simple HardMAC driver at drivers/ieee802154/fakehard.c SoftMAC ======= -We are going to provide intermediate layer implementing IEEE 802.15.4 MAC -in software. This is currently WIP. +The MAC is the middle layer in the IEEE 802.15.4 Linux stack. This moment it +provides interface for drivers registration and management of slave interfaces. + +NOTE: Currently the only monitor device type is supported - it's IEEE 802.15.4 +stack interface for network sniffers (e.g. WireShark). + +This layer is going to be extended soon. See header include/net/mac802154.h and several drivers in drivers/ieee802154/. + +Device drivers API +================== + +The include/net/mac802154.h defines following functions: + - struct ieee802154_dev *ieee802154_alloc_device + (size_t priv_size, struct ieee802154_ops *ops): + allocation of IEEE 802.15.4 compatible device + + - void ieee802154_free_device(struct ieee802154_dev *dev): + freeing allocated device + + - int ieee802154_register_device(struct ieee802154_dev *dev): + register PHY in the system + + - void ieee802154_unregister_device(struct ieee802154_dev *dev): + freeing registered PHY + +Moreover IEEE 802.15.4 device operations structure should be filled. + +Fake drivers +============ + +In addition there are two drivers available which simulate real devices with +HardMAC (fakehard) and SoftMAC (fakelb - IEEE 802.15.4 loopback driver) +interfaces. This option provides possibility to test and debug stack without +usage of real hardware. + +See sources in drivers/ieee802154 folder for more details. + + +6LoWPAN Linux implementation +============================ + +The IEEE 802.15.4 standard specifies an MTU of 128 bytes, yielding about 80 +octets of actual MAC payload once security is turned on, on a wireless link +with a link throughput of 250 kbps or less. The 6LoWPAN adaptation format +[RFC4944] was specified to carry IPv6 datagrams over such constrained links, +taking into account limited bandwidth, memory, or energy resources that are +expected in applications such as wireless Sensor Networks. [RFC4944] defines +a Mesh Addressing header to support sub-IP forwarding, a Fragmentation header +to support the IPv6 minimum MTU requirement [RFC2460], and stateless header +compression for IPv6 datagrams (LOWPAN_HC1 and LOWPAN_HC2) to reduce the +relatively large IPv6 and UDP headers down to (in the best case) several bytes. + +In Semptember 2011 the standard update was published - [RFC6282]. +It deprecates HC1 and HC2 compression and defines IPHC encoding format which is +used in this Linux implementation. + +All the code related to 6lowpan you may find in files: net/ieee802154/6lowpan.* + +To setup 6lowpan interface you need (busybox release > 1.17.0): +1. Add IEEE802.15.4 interface and initialize PANid; +2. Add 6lowpan interface by command like: + # ip link add link wpan0 name lowpan0 type lowpan +3. Set MAC (if needs): + # ip link set lowpan0 address de:ad:be:ef:ca:fe:ba:be +4. Bring up 'lowpan0' interface |