Brian HixenbaughNetwork Managment
My Home Network
My Plan…N.A.S. (1 TB External Hard Drive)
Connects to Router via Ethernet (Has IP Address)
Stores movies, television shows, etc.Laptop Connected to TV (Downstairs)
Wirelessly stream content from N.A.S. or Internet
Display on televisionRoommate’s Laptop (iPhone, etc.)
Independently use Internet or N.A.S. as well
It Works! (Almost)Need to Implement QoS (Quality of Service)
Router Inspects Packets – Prioritizes Video, VoIP
Low Priority – P2PImprove Radio Performance
Increase TX power, Increase Beacon IntervalExpensive Commercial Routers Offer These
FeaturesCheap home routers can offer these features as
well with replacement software!
Embedded SystemsA Router is a “Mini” Computer with:
CPURAMHard Drive (Flash Chip)
Open Source Software Can Replace Factory Software to Provide More FeaturesOpenWRTTomatoDD-WRT
Netgear WGR614
DD-WRT
“Flashing” New SoftwareSimilar to a PC
Boot program (CFE)Kernal (linux!)Software (dd-wrt)
Upload via Router’s Web GUI (Ethernet)Software not always compatible with all makes
& models of routersFlash memory locations can be differentThere can be problems!
Bricked
Fix a Brick with JTAGJoint Test Action Group or Boundary-Scan
IEEE Standard for communicating with embedded systems
Allows issuing commands directly to ProcessorAllows directly programming Flash Memory
Allows a PC to Communicate for DebuggingRequires parallel port on PC, special interface
device, and communication software
Common Firmware EnvironmentCFE contains information for Ethernet (MAC
addr.)Also contains information to boot Kernal
If damaged, must be replaced by JTAGCFE is small (~128k) but JTAG is slow – can take
5-10 minutes to uploadKernal & software are much larger (2-3MB) not
practical to send via JTAGOnce CFE is uploaded and running, remaining
software can be quickly flashed via Ethernet using TFTP (Trivial File Transfer Protocol)
No Happy EndingCould not
successfully reload factory softwarePossible hardware
problems (bad flash chip, CPU)
Still a Brick!