用ADSL接入的CL用户进来看，关于MTU

DreamCat

不对啊。。CL中PPOE默认设置的是1492哦。奇怪了。楼上的需要重新启动的。

DreamCat

甭弄了，NND，1492 没问题的。别看那个站点给的结果了。最好要用自己的ADSL的GATEWAY测试MaxMTU。不然得不到结果。有时候需要连续两次才有最后结果。

QUOTE
Pinging [221.8.128.1] with 40 bytes ->bytes=40 time=32ms TTL=254Pinging [221.8.128.1] with 750 bytes ->bytes=750 time=47ms TTL=254Pinging [221.8.128.1] with 1125 bytes ->bytes=1125 time=46ms TTL=254Pinging [221.8.128.1] with 1312 bytes ->bytes=1312 time=47ms TTL=254Pinging [221.8.128.1] with 1406 bytes ->bytes=1406 time=63ms TTL=254Pinging [221.8.128.1] with 1453 bytes ->bytes=1453 time=47ms TTL=254Pinging [221.8.128.1] with 1476 bytes -> ..fragmentedPinging [221.8.128.1] with 1465 bytes ->IcmpSendEcho(): 0Pinging [221.8.128.1] with 40 bytes ->bytes=40 time=31ms TTL=254Pinging [221.8.128.1] with 750 bytes ->bytes=750 time=47ms TTL=254Pinging [221.8.128.1] with 1125 bytes ->bytes=1125 time=47ms TTL=254Pinging [221.8.128.1] with 1312 bytes ->bytes=1312 time=47ms TTL=254Pinging [221.8.128.1] with 1406 bytes ->bytes=1406 time=47ms TTL=254Pinging [221.8.128.1] with 1453 bytes ->bytes=1453 time=46ms TTL=254Pinging [221.8.128.1] with 1476 bytes -> ..fragmentedPinging [221.8.128.1] with 1465 bytes -> ..fragmentedPinging [221.8.128.1] with 1459 bytes ->bytes=1459 time=63ms TTL=254Pinging [221.8.128.1] with 1462 bytes ->bytes=1462 time=47ms TTL=254Pinging [221.8.128.1] with 1463 bytes ->bytes=1463 time=47ms TTL=254Pinging [221.8.128.1] with 1464 bytes ->bytes=1464 time=47ms TTL=254The largest possible non-fragmented packet is 1464?(1492 - 28 ICMP & IP headers).You can set your MTU to 1492

DreamCat

气死我了，白忙了半天，还以为能有什么改进的呢。那个工具真不错。建议大家都用用。

luke

刚看了篇文章说用1452比较合适~~`好像还是因线路而异的

DreamCat

嗯，MaxMTU 是最大的MTU。呵呵。两个概念。根据自己情况改吧。我这里是不用了。

DreamCat

你点两次 start  就能看到了。：）CL的论坛上也有类似的问题，我还在测试。http://www.vortech.net/phorums/read.php?8,...37353#msg-37353

DreamCat

断线？不会吧？我这里正常啊。

DreamCat

郁闷，不管怎么改还是那个样子，不过建议修改 MSS，CL设置的是1412，一般情况下MSS=MTU-40，我这里就是1492-40=1452。至于SPEEDGUID上显示的情况，我到论坛上问问吧。

DreamCat

我打错了？哪儿哦？MTU 是 1492，没错啊。MSS 在 CL 的 /etc/rc.d/rc.pppoe 里面。小心修改 MTU，麻烦啊。

QUOTE
#!/bin/sh## Coyote pppd for pppoe (DSL) Startup Script## Author: Michael Kablitz # 04-16-2001## Modified: Joshua Jackson # 05-07-2001# - Modified script to keep thousands of Coyote firewalls#   from beating the hell out of my servers with ICMP packets## Modified: Claudio Roberto Cussuol # 08-18-2004# - Removed useless pppoe test as the connection status is seted #   by ip_up/down scripts# Read in the Coyote configuration script. /etc/coyote/coyote.confcp -p /etc/ppp/options.template /etc/ppp/optionsecho "pty 'pppoe -I $IF_INET -m 1412'"           >>/etc/ppp/optionsecho "user '$PPPOE_USERNAME'"                    >>/etc/ppp/optionsif [ "$PPPOE_IDLE" != "NO" ]; then        echo "idle $PPPOE_IDLE"                  >>/etc/ppp/options        echo "demand"                            >>/etc/ppp/optionsfiecho "# Do not modify this file directly;"       >/etc/ppp/pap-secretsecho "# make changes in /etc/coyote/coyote.conf" >>/etc/ppp/pap-secretsecho "# or they will be lost upon reboot!"       >>/etc/ppp/pap-secretsecho "'$PPPOE_USERNAME' * '$PPPOE_PASSWORD' *"   >>/etc/ppp/pap-secretsln -sf /etc/ppp/pap-secrets /etc/ppp/chap-secretschmod 600 /etc/ppp/*-secretsecho "Starting pppd"ifconfig $IF_INET up mtu 1500if [ $? = 0 ] ; then        pppd &        if [ $? = 0 ] ; then  INET_UP=READY        else  INET_UP=DOWN  echo "PPP Daemon not started properly"  logger "PPP Daemon not started properly"        fielse        INET_UP=DOWN        echo "The Internet Network Interface Card is not seted properly"        logger "The Internet Network Interface Card is not seted properly"fi

DreamCat

哈哈，终于OK了。速度上来了哦。

QUOTE
TCP options string = 020405ac0103030201010402 MTU = 1492 MTU is optimized for PPoE DSL broadband. If not, consider raising MTU to 1500 for optimal throughput. MSS = 1452MSS is optimized for PPPoE DSL broadband. If not, consider raising MTU to 1500 for maximum throughput. Default Receive Window (RWIN) = 256960 RWIN Scaling (RFC1323) = 2 bits (scale factor of 4)Unscaled Receive Window = 64240 For optimum performance, consider changing RWIN to a multiple of MSS.Other values for RWIN that might work well with your current MTU/MSS: 511104 (MSS x 44 * scale factor of 8)255552 (MSS x 44 * scale factor of 4)127776 (MSS x 44 * scale factor of 2) 63888 (MSS x 44)  bandwidth * delay product (Note this is not a speed test):Your RcvWindow limits you to: 10278.4 kbps (1284.8 KBytes/s) @ 200msYour RcvWindow limits you to: 4111.36 kbps (513.92 KBytes/s) @ 500ms

DreamCat

HERE:

QUOTE
Re: How do you change the MTU with Windows Disk Creation Wizard v2.13.0Posted by: Sileet (---.dsl.skt2ca.pacbell.net)Date: October 18, 2004 07:44PMI believe I solved the issue after poking around a bit. A fairly simple change: Open /etc/rc.d/rc.pppoe through WebAdmin Edit the following line: echo "pty 'pppoe -I $IF_INET -m 1412'" >>/etc/ppp/options Change it to look like this: echo "pty 'pppoe -I $IF_INET -m 1452'" >>/etc/ppp/options I believe # value represented by this code is the MMS. "MSS (Maximum Segment Size) defines the largest segment of TCP (Transfer Control Protocol) data that the Winsock is prepared to receive. When a connection is established, the two ends agree to use the smaller of each end's value. Because headers are typically 40 bytes, MSS is usually 40 less than the MTU (Maximum Transmission Unit)." (http://www.speedguide.net/analyzer.php) So I figured I'd change that value to 40 less than 1492 (1492-40 = 1452). After I did that, my MTU was reported as 1492, and speed test now reflect my true bandwidth That said, I believe the MMS value programmed into Coyote Linux was limiting my MTU, even though it was set to 1492.