 SentinelPremium
join:2001-02-07
Florida
kudos:1 | reply to boondoggle
Re: RWIN, MTU, MSS in NIC vs RT314? As far as I know you set the Rwin & MTU on the workstation PC and the MTU & RWIN on the router you don't touch unless you are PPPoE. If you are cable you don't adjust the settings in the router. Leave the MTU as Auto on the PC's and set your RWIN. That should be it.
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~AL~ |
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 bbarreraPremium,MVM
join:2000-10-23
Sacramento, CA
kudos:1
 ·SureWest Internet
| Speed up FTP firmware updates boonie, your MSS=1460 and RWIN are set in PC's TCP/IP stack and are configured using DrTCP program (on tweak section of this website) or manually editing registry.
The router has it's own TCP/IP stack, and is only used when connecting to the router's internal servers (HTTP, FTP, Telnet). I changed router's TCP MSS and Window after reading a post a couple of months ago (from DrTCP I think). The reason? To speed up FTP firmware updates -- with these tweaks uploading the firmware via FTP should only take ~2 seconds. The default MSS (512) and TCP Receive Window (2xMSS) slow the firmware upload process. I don't notice any speed difference with telnet or web interface.
To change "Router to Internet MSS" you must issue the command "ip adj wanif0 1452." This specific tweak is used for PPPoE, because router's default for PPPoE is MSS=1400 and MTU=1440. It expires after PPPoE session is dropped, and there is a new command in latest Zyxel firmware to make it persistant (ip adjmss 1452).
I don't recommend this, but if you want to tweak MTU for Ethernet/cable modem just replace wanif0 with enif1. For Ethernet encapsulation you can check interfaces with command "ip ifconfig" or "ip ifconfig enif0" or "ip ifconfig enif1."
Checkout this great FAQ on tweaking:
»Tweaking FAQ |
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AOTMA
join:2001-04-13
Florissant, MO | I'm using my RT311 with PPPoE, and when I type ip ifconfig I get the following:
enif0: mtu 1500
wanif0: mtu 1492
Does this mean my MSS is not the default 1400? |
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 DrTCPYours trulyPremium,ExMod 1999-04
join:1999-11-09
Round Rock, TX | You guys are confusing a lot of settings. The first post confused the MSS/Window settings for the internal TCP stack for telnet/ftp/web connections to the router itself with PC settings. These settings are not used when communicating with remote sites.
You found the interface MTU settings alright but additionally there is a separate TCP MSS limit of 1400 despite MTU of interface is 1492 (maximum MSS is 1452). Note that this for TCP connections only and when using PPPoE.
It works like this: If the MSS option in TCP connection establishment packets is greater than the limit set router modifies it down to 1400. Router does it to both SYN and SYN-ACK packets so both sides think the other side has a lower MSS and adjusts its send packet size accordingly. In other words, router is fooling both ends to achieve smaller packet size. UDP or ICMP does not carry MSS in header so they are not bound by this operation.
You can adjust MSS limit via:
ip adj wanif0 1452
This command is only effective after PPPoE connected.
Upcoming firmware has "ip adjmss 1452" command which sets the default MSS and it can be added to autoexec.net to make it permanent. |
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| I wrote GearMinder, and want to upgrade the software to enter the
MSS limit adjustment automatically every time it renews the WAN.
How can I tell that the command was entered properly? In other
words, what config screens do I view to verify the command?
Thank you.
Dr. Edward Cheung - Author of GearMinder
»www.edcheung.com |
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bbarreraPremium,MVM
join:2000-10-23
Sacramento, CA
kudos:1 Reviews:
·SureWest Internet
| Here is a menu 24.8 session, typing "ip adj wanif0" will tell you current MSS on WAN:
314>
314> ip adj wanif0
adjust TCP mss on wanif0 to 1400
314>
314> ip adj wanif0 1452
adjust TCP mss on wanif0 to 1452
314>
314> ip adj wanif0
adjust TCP mss on wanif0 to 1452
314> |
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| Thank you!
»www.edcheung.com |
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