An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks Martin Herrmann Chair for Network Architectures and Services Department for Computer Science Technische Universit¨ at M¨ unchen May 15, 2013 Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 1
Outline Motivation a.k.a. ”The Old Header” 1 IEEE 802.11 2 The new Header Structure 3 Evaluation 4 Conclusion 5 Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 2
Motivation a.k.a. ”The Old Header” What is a Wireless (Coded) Mesh-Network? Nodes in the network are connected wirelessly Many different possible routes = ⇒ reliability Combining packets using finite field arithmetic Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 3
Motivation a.k.a. ”The Old Header” What is a Wireless (Coded) Mesh-Network? Nodes in the network are connected wirelessly Many different possible routes = ⇒ reliability Combining packets using finite field arithmetic Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 3
Motivation a.k.a. ”The Old Header” What is a Wireless (Coded) Mesh-Network? Nodes in the network are connected wirelessly Many different possible routes = ⇒ reliability Combining packets using finite field arithmetic Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 3
Motivation a.k.a. ”The Old Header” The old moep80211 Header Octets 2 2 6 6 6 2 6 MAC 1 MAC 2 MAC 3 MAC 4 Frame Duration / SEQ Control ID (SA) (DA) (TA) (RA) Octets 2 2 2 4 2 – 128 2 2 ≀≀ Payload Frame Frame Generation Ethertype Rank Info Coefficients Length Disc. Info SEQ ≀≀ Octets 0 - 2162 4 ≀≀ Frame Body FCS ≀≀ Very large (36 – 172 Bytes), not all information is always of interest Different versions for different purposes, no efficient way for assembling the header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 4
Motivation a.k.a. ”The Old Header” The old moep80211 Header Octets 2 2 6 6 6 2 6 MAC 1 MAC 2 MAC 3 MAC 4 Frame Duration / SEQ Control ID (SA) (DA) (TA) (RA) Octets 2 2 2 4 2 – 128 2 2 ≀≀ Payload Frame Frame Generation Ethertype Rank Info Coefficients Length Disc. Info SEQ ≀≀ Octets 0 - 2162 4 ≀≀ Frame Body FCS ≀≀ Very large (36 – 172 Bytes), not all information is always of interest Different versions for different purposes, no efficient way for assembling the header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 4
Motivation a.k.a. ”The Old Header” The old moep80211 Header Octets 2 2 6 6 6 2 6 MAC 1 MAC 2 MAC 3 MAC 4 Frame Duration / SEQ Control ID (SA) (DA) (TA) (RA) Octets 2 2 2 4 2 – 128 2 2 ≀≀ Payload Frame Frame Generation Ethertype Rank Info Coefficients Length Disc. Info SEQ ≀≀ Octets 0 - 2162 4 ≀≀ Frame Body FCS ≀≀ Very large (36 – 172 Bytes), not all information is always of interest Different versions for different purposes, no efficient way for assembling the header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 4
Outline Motivation a.k.a. ”The Old Header” 1 IEEE 802.11 2 The new Header Structure 3 Evaluation 4 Conclusion 5 Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 5
IEEE 802.11 Why use IEEE 802.11? moep80211 is based on IEEE 802.11 and cannot access the physical medium by itself Advantage: can be used with existing wireless hardware Disadvantage: having to ”deal” with the IEEE 802.11 header Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 HT QoS Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 6
IEEE 802.11 Why use IEEE 802.11? moep80211 is based on IEEE 802.11 and cannot access the physical medium by itself Advantage: can be used with existing wireless hardware Disadvantage: having to ”deal” with the IEEE 802.11 header Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 HT QoS Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 6
IEEE 802.11 Why use IEEE 802.11? moep80211 is based on IEEE 802.11 and cannot access the physical medium by itself Advantage: can be used with existing wireless hardware Disadvantage: having to ”deal” with the IEEE 802.11 header Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 HT QoS Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 6
IEEE 802.11 Why use IEEE 802.11? moep80211 is based on IEEE 802.11 and cannot access the physical medium by itself Advantage: can be used with existing wireless hardware Disadvantage: having to ”deal” with the IEEE 802.11 header Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 HT QoS Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 6
IEEE 802.11 Problems due to the IEEE 802.11 header Frame format must adhere to the basic IEEE 802.11 structure A receiver must still be able to differentiate between moep80211 and regular frames Changing of some fields is not possible or causes problems elsewhere = ⇒ presence of unnecessary information Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 QoS HT Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 7
IEEE 802.11 Problems due to the IEEE 802.11 header Frame format must adhere to the basic IEEE 802.11 structure A receiver must still be able to differentiate between moep80211 and regular frames Changing of some fields is not possible or causes problems elsewhere = ⇒ presence of unnecessary information Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 QoS HT Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 7
IEEE 802.11 Problems due to the IEEE 802.11 header Frame format must adhere to the basic IEEE 802.11 structure A receiver must still be able to differentiate between moep80211 and regular frames Changing of some fields is not possible or causes problems elsewhere = ⇒ presence of unnecessary information Octets 2 2 6 6 6 2 Frame Duration / MAC 1 MAC 2 MAC 3 SEQ (RA) (TA) (SA) Control ID Octets 6 2 4 0 – 7951 4 MAC 4 QoS HT Payload FCS (DA) Control Control Figure: Generic IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 7
Outline Motivation a.k.a. ”The Old Header” 1 IEEE 802.11 2 The new Header Structure 3 Evaluation 4 Conclusion 5 Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 8
The new Header Structure Basic idea The old structure was complicated and not very efficient. Performance and expandability are improved by using following concepts: Use of a generic header that contains the basic information Adding of extension headers where special information is necessary Moving the frame discriminator into the third address field of the IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 9
The new Header Structure Basic idea The old structure was complicated and not very efficient. Performance and expandability are improved by using following concepts: Use of a generic header that contains the basic information Adding of extension headers where special information is necessary Moving the frame discriminator into the third address field of the IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 9
The new Header Structure Basic idea The old structure was complicated and not very efficient. Performance and expandability are improved by using following concepts: Use of a generic header that contains the basic information Adding of extension headers where special information is necessary Moving the frame discriminator into the third address field of the IEEE 802.11 header Martin Herrmann: An Extendable Link Layer Frame Format for Wireless Coded Mesh Networks 9
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