Interworking with the DS

4.3.15.5.11 Interworking with the DS

A mesh BSS might contain one or more mesh gates that connect to one or more distribution systems. A
mesh gate can announce its presence in the mesh BSS by sending Gate Announcement frames. Alternatively
a mesh gate can announce its presence in the mesh BSS by sending HWMP Path Selection frames with the
RANN element or the PREQ element indicating mesh gate announcement, when it is configured as a root
mesh STA. Typically a mesh gate announces its presence when it is collocated with a portal or it has access

to a portal. Gate announcements allow mesh STAs to select the appropriate mesh gate and build a path
towards it. It should be noted that, when multiple mesh gates that have access to the same DS are present in
the mesh BSS, proper configuration is necessary.
When a mesh gate has access to IEEE 802 STAs outside the mesh BSS, the mesh gate acts as a proxy for the
IEEE 802 STAs outside the MBSS. Such a mesh gate is called a proxy mesh gate. The details of the proxy
functionality are described in 13.11.3.
The details of the mesh BSS interworking are described in 13.11.
4.3.15.5.12 Intra-mesh congestion control
Intra-mesh congestion control is used to provide flow control over the multi-hop communication. Intra-mesh
congestion control is useful to mitigate wasteful wireless medium utilization caused by buffer overflow at
mesh STAs. Intra-mesh congestion control consists of three main mechanisms: local congestion monitoring
and congestion detection, congestion control signaling, and local rate control. The details of the intra-mesh
congestion control are described in 13.12.
4.3.15.5.13 Emergency service support in mesh BSS
Depending on regulations, emergency services support might be mandated over the mesh network. In this
case the Beacon and Probe Response frames inform whether a mesh STA supports emergency services,
advertising to other mesh STAs that mesh peering for emergency services is possible. If a mesh STA
subsequently requires emergency services, an emergency indication is then set within the Mesh Peering
Open frame. Mesh STAs that support emergency services, accept peering from other mesh STAs requiring
emergency services, transferring frames to an emergency server (such as a PSAP).