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(Flow Acceleration and Cut-Through Forwarding)
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Note the following screenshot of a Linksys EA6200 with a Note the following screenshot of a Linksys EA6200 with a
-[[Image:Linksys-ea6200-CTF-FA.png]]+[[Image:Linksys-ea6200-CTF-FA.png| left | 280px]]
==Hardware Modifications== ==Hardware Modifications==

Revision as of 07:38, 29 May 2021



NVRAM (non-volatile RAM) also called flash space is the place where the permanent settings are stored. This includes

You can run the following commands using Command Line:

  • Show the whole NVRAM content:
nvram show
  • Show NVRAM content containing the pattern <search_pattern> (useful for quickly finding things in NVRAM):
nvram show | grep <search_pattern>
Replace <replace_pattern> with what you are actually looking for. This can simply be a word or a regular expression
  • Show value of a certain variable:
nvram get <variable_name>
  • Change variable value in RAM only:
nvram set <variable_name>="<value>"
(Quotes not needed for numeric/boolean values, needed for texts like or 443 8080 or sometext).
Now you can play with the new settings or test user scripts but this new value will be lost after reboot unless you do nvram commit.
  • Delete a variable (and its value). Useful when you made a typo in <variable_name> above:
nvram unset <variable_name>
  • Save all changed variables to NVRAM:
nvram commit

Reboot the router for new settings in NVRAM to go into effect.

  • To erase the nvram block when running DD-WRT:
erase nvram
  • To erase nvram in the Broadcom CFE (bootloader):
nvram erase
  • These are often confused!


/* boardflags */

  1. define BFL_BTCOEXIST 0x0001 /* This board implements Bluetooth coexistance */
  2. define BFL_PACTRL 0x0002 /* This board has gpio 9 controlling the PA */
  3. define BFL_AIRLINEMODE 0x0004 /* This board implements gpio13 radio disable indication */
  4. define BFL_ENETROBO 0x0010 /* This board has robo switch or core */
  5. define BFL_CCKHIPWR 0x0040 /* Can do high-power CCK transmission */
  6. define BFL_ENETADM 0x0080 /* This board has ADMtek switch */
  7. define BFL_ENETVLAN 0x0100 /* This board has vlan capability */
  8. define BFL_AFTERBURNER 0x0200 /* This board supports Afterburner mode */
  9. define BFL_NOPCI 0x0400 /* This board leaves PCI floating */
  10. define BFL_FEM 0x0800 /* This board supports the Front End Module */
  11. define BFL_EXTLNA 0x1000 /* This board has an external LNA */
  12. define BFL_HGPA 0x2000 /* This board has a high gain PA */
  13. define BFL_BTCMOD 0x4000 /* This board' BTCOEXIST is in the alternate gpios */


BCM3303 v0.7 clock frequencies: (todo...)

MIPS/CPU Backplane Comment

BCM3303 v0.8 clock frequencies:

MIPS/CPU Backplane Comment
183 91
188 94
197 98
200 100
206 103
212 106
216 108
217 109
225 113
238 119
240 120
250 125

Flow Acceleration and Cut-Through Forwarding

As Internet Bandwidth speeds available to the end users have continued to increase, manufacturers have had to increase speed and power of routers to keep up with the higher network speeds. This has 2 negative consequences, first is that powerful router CPU's at high clock speeds are much more expensive, and second that more powerful hardware increases heat production which shortens the life of the equipment. Adding a cooling fan can help this but it decreases router reliability because the fan can fail causing the router to overheat.

Broadcom corporation has tackled this problem by adding special hardware into it's chips that helps distribute the processing of packets in the router. Instead of the primary CPU handling all packet delivery within the router, many packets can be moved directly from interface to interface without the primary CPU being involved in all of the packet handling. This technology, abbreviated CTF and FA, is built into a Broadcom-proprietary kernel module that was officially incorporated into dd-wrt in May of 2021. CTF works with many Broadcom chips while FA works with the Northstar line of Broadcom chips. FA is more specifically for Network Address Translation.

Once dd-wrt is loaded on your router, click Status and look at the router CPU. If it is a newer Broadcom CPU you should have CTF. If it is Broadcom and an ARM chip then you can check this list to see if your CPU is a Northstar CPU If it is, you will get both FA and CTF.

Note the following screenshot of a Linksys EA6200 with a

Hardware Modifications

Hardware Modifications (mods) are not necessarily DD-WRT specific or compatible.