温馨提示！由于新浪微博认证机制调整，您的新浪微博帐号绑定已过期，请重新绑定！&&|&&
0、更新缓存1、依次打开“后台 -& 工具 -& 云平台诊断工具 – 手动修改站点ID/KEY”，清空站点ID和站点通信KEY，将状态改为“尚未开通云平台”，提交。（切勿使用“更换站点KEY”和“同步站点信息”，这些操作都是徒劳的） 2、打开“http://domain/admin.php?action=cloud&operation=open”，来到“Discuz!云平台”的“开通Discuz!云平台”版块，点击“我要开通”，弹出提示框“您即将转向Discuz!云平台（）完成开通流程”，点击“继续”，接下来会提示站点URL重复注册，根据他的步骤操作（目的是为了验证操作者的FTP权限）。
可以从data/log/XXXX_SMTP.php查看详细错误信息如果是PASSWORD - 535 Error: authentication failed，有可能是SMTP 身份验证密码不正确，此密码不是邮箱登陆的密码，而是开启smtp时会给你一个它系统生成的密码，要用它生成的密码才可以！
0x:未授予用户在此计算机上的请求登录类型. 这个意思 是你没权访问目标主机。解决方法：开始运行gpedit.msc，打开组策略，找到“计算机配置”--“Windows设置”--“安全设置”--“本地策略”，点“用户权限分配”，在右边的策略中找到“拒绝从网络访问这 台计算机”，把guest删除、保存即可。
&& && 一开始都可能会遇到这个问题：打开Android SDK Manager的时候底下会看到有fetching dl-…字样，是android SDK Manager在从dl-拉XML数据，从而知道所有的SDK包。 &&&& && 这个dl-域名经常会访问不了，具体原因不可说。不过天朝的有些东西不喜欢域名里面带ssl，因为一般带ssl或者地址是https协议的都“居心不良”，所以。。。
原因可能是归档日志占满了FLASH_RECOVERY_AREA 的空间。select * from v$flash_recovery_area_查看FLASH_RECOVERY_AREA 占用空间解决方法1：先手工删除D:\oracle\product\10.2.0\flash_recovery_area里面的日志，然后用户用rman进入把归档日志删除
最后登录加载中...
this.p={b:2,ua:-1, ub:'-1000',us:'他', friendstatus:'none',followstatus:'unFollow',hmcon:'0',aShowT:'0',guideId:6};
积分 ${data.totalScore} 分，距离下一等级还有 ${data.nextGradeNeedScore}分
心情随笔列表加载中...
this.p={b:2,n:5,r:'/chenyidragon@126/blog/#m=1&c=',mset:'000',mcon:'',srk:-100};
{if defined('fl')&&fl.length>0} {list fl as x}
${x.content|xescape:x.id,x.moveFrom} ${x.publishTime|xtime}
{if x.moveFrom&&x.moveFrom=='wap'} && {/if} {if x.moveFrom&&x.moveFrom=='mobile'} && {/if}
{/list} {else} 暂无心情随笔记录！ {/if}
博友列表加载中...
this.p={b:2,m:0};
发现好博客
列表加载中...
this.p={b:2,cn:12,ct:12};
列表加载中...
this.p={b:2,cn:15};
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& & & & & &
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{list x.l as y}
{/list} {/list}
{if defined('wl')} {list wl as x}{/list} {/if}在win7系统电脑上安装网络打印机报错,其中打印机连接到XP系统的电脑上（打印机已经共享）,并且其他安装XP_百度知道
在win7系统电脑上安装网络打印机报错,其中打印机连接到XP系统的电脑上（打印机已经共享）,并且其他安装XP
baidu://a.jpg" />&nbsp直接添加“网络打印机”时.hiphotos.baidu，选择使用新端口。报错信息为“登录失败.后来我在网络搜了一篇文章
com/zhidao/wh%3D600%2C800/sign=/zhidao/wh%3D450%2C600/sign=0f7a16af94cad1c8d0eefb3f/d1a20cf431adcbef493d7886adaf2edda3cc9f20.jpg" target="_blank" title="点击查看大图" class="ikqb_img_alink"><img class="ikqb_img" src="http://h.com/zhidao/wh%3D600%2C800/sign=992a9b63fc1f152fb9f2/d1a20cf431adcbef493d7886adaf2edda3cc9f20，无法加入域.baidu，加入域试试吧,并且其他安装XP系统的电脑都能正常共享此打印机，但其他XP电脑都在域里面.hiphotos.hiphotos。2://b.baidu，还是不行://h、后来发现这台win7电脑是家庭版的./zhidao/pic/item/8bfc09fa513d2697c50d。不知道是否与这有关系.jpg" esrc="http、在win7系统电脑上安装网络打印机报错.com/zhidao/wh%3D450%2C600/sign=29ba3f4430adcbeff02eb/8bfc09fa513d2697c50d.hiphotos.hiphotos。明天找人把win7系统换了吧。<a href="/zhidao/pic/item/d1a20cf431adcbef493d7886adaf2edda3cc9f20.hiphotos.baidu://b,其中打印机连接到XP系统的电脑上（打印机已经共享）://h，但我把那台连结打印机的XP电脑改成了与win7电脑一个组.jpg" esrc="http.baidu.baidu
提问者采纳
建议你去找售后服务
提问者评价
到有时间让售后处理一下吧！！我们单位的有几台XP电脑也是同样情况。
其他类似问题
34人觉得有用
为您推荐：
win7系统的相关知识
其他2条回答
你需要在XP系统上把这个打印机的win7驱动装上，这样共享win7系统才能装上驱动
安装驱动时最后一步报错。
给你个链接，你用这个方法试试行不行
等待您来回答
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出门在外也不愁你现在的位置：& > &
网络共享错误提示:找不到网络路径.
网络共享错误提示:找不到网络路径.
你的情况属于下面列出的第10类。网管人员可以打印出来备用。 局域网共享问题全方位解决
声明：这不是共享组建教程，而是问题解决。如果你对共享一直搞不清，那么你可以花一至几小时的时间来看这篇文章，我相信以后共享问题你基本上都能解决。
看过了很多人写共享教程，看过了更多人写共享问题解决。可是，我到最后还是决定写。原因之一是大多数教程都是把解决方案写在一起，经典与仅来宾两个模式的解决方案混在一起。让出问题的人不知道是哪里出问题了，原因之二是因为这也是网络教程要写到的，所以，那就一起解决了吧。如果有某些问题没提到请指点。
局域网共享我们这里就以网上邻居能够访问的共享为准。不考虑&#92;&#92;计算机名&#92;或&#92;&#92;IP&#92;来访问的共享。因为这个访问模式透过了工作组和用户匿名共享枚举，所以在&#92;&#92;计算机名&#92;或&#92;&#92;IP&#92;能访问在网上邻居可能不能访问。而从网上邻居能访问它必然也能访问。从现在开始一个一个问题来解决吧：
问题以你打开网上邻居到“查看工作组计算机”到访问“某一主机”失败而出现的错误框来列出，所以只要你对照你的错误框，就可能在这里找到你的问题的答案。问题列表：根据你在客户端访问共享的错误到下面找答案吧。（由于2000没有仅来宾模式，所以一些要用到仅来宾的方法不能在2000系统上使用）1：错误提示框为如图1：网络不存在或尚未启动2：错误提示框为如图2：此工作组的服务器列表当前无法使用3：错误提示框为如图3：Windows无法找到网络路径……请与网络管理员联系4：错误提示框为如图4：登录失败：未授予用户在此计算机上的请求登录类型5：错误提示框为如图5：拒绝访问6：提示框为如图6：弹出密码输入框，并且用户名不能改，默认为“Guest”。7：提示框为如图7：弹出输入用户名和密码输入框.8：错误提示框为如图8：用户账户限制，可能的原因包括不允许空密码……9：我没看到自己或他人：进入工作组，只有自己或是看不到自己，或看不到共享机子10：提示框为如图10：找不到网络路径＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝以下是问题解决方案：＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝1：错误提示框为如图1：网络不存在或尚未启动这是因为你的Workstation服务没有启动，如果这个服务没有启动的话，那么你的工作组将无效，所以解决的方法就是在开始—运行—输入—Services.msc 回车。拉到最下面，把Workstation改为“自动”，然后“启用”，再点应用即可以解决问题。如图所示：92：错误提示框为如图2：此工作组的服务器列表当前无法使用这是因为你的Computer Browser服务没有启动。这个服务是不一定要启动的，不过同一工作组内最少要有一台机子启动此服务，主要功能是维护网络上计算机的更新列表。如果出现此错误对话框，解决方法为：开始—运行—输入—Services.msc 回车。找到Computer Browser服务把它设置为“自动”，“启用”。再点应用即可以解决问题。如图所示：10如果没有找到Computer Browser这个服务。说明你的本地连接没有安装“Microsoft 网络客户端”请在网上邻居右键—属性--本地连接—右键属性—添加—客户端-- Microsoft 网络客户端。就可以了。如果出现“本地计算机上的Compu......
网络共享错误提示:找不到网络路径. ……
你的情况属于下面列出的第10类。网管人员可以打印出来备用。 局域网共享问题全方位解决 声明:这不是共...
网络共享错误提示:找不到网络路径. ……
可能共享已被取消。
win7本地连接共享总显示出现错误,怎么解决? ……
win7本地连接2共享无线网络连接2出...
加入家庭组时提示:家庭组遇到错误,访问网络共享计算机提示:登录失败禁用当前的账户。 ……
点启动家庭组疑难解答 检查一下故障范围 针对修复后,重启计算机 重新加入 ,注意密码要正确。
网络共享和中心出现错误代码0X,怎么解决啊。 ……
点击开始菜单,在搜索栏中输入“services.msc”(输入时不要打引号),并按下回车。如果此时弹...
win7系统 设置宽带连接网络共享 出现错误 无法启用共享访问 错误代码:0x800704cf .有... ……
0X800704cf这个错误代码多数是出现在突然不能访问网络位置上了,这时若在设备管理器设置显示隐藏...
win7系统 设置宽带连接网络共享 出现错误 无法启用共享访问 错误代码:0x:未指... ……
你在“控制面板”/“管理工具”中找到“服务”，将Windows FireWall服务设置为启用并为自...
win7系统 设置宽带连接网络共享 出现错误 无法启用共享访问 错误代码:0x:未指... ……
你是通过何种方法打开局域网保护的?是利用的路由器中的相应的保护功能还是防火墙?如果是路由器中的,则是...
电脑无法共享网络,在宽带连接设置共享的时候选择了,后面就说无法启用共享,错误代码:1061 ……
电脑无法共享网络,在宽带连接设置共享的时候选择了,后面就说无法启用共享,错误代码:错...
网络共享问题 找不到工作组的一台电脑 ……
一、先用百度搜一个“局域网共享工具”,在两台电脑上都设置“不需要密码验证共享”; 二、检查两台电脑的...
你的情况属于下面列出的第10类。网管人员可以打印出来备用。 局域网共享问题全方位解决 声明:这不是共...
共享被取消了,或者是网络设置不好,你查看一下两台计算机是不是在同一个计算机工作组内,不在的话,设置成...
一、 控制面板——管理工具——服务——server:设置为启动 二、 网络连接——本地连接——安装:...
默认情况下,WindowsXP的本地安全设置要求进行网络访问的用户全部采用来宾方式。同时,在Wind...
局域网共享是个头疼的问题,只要找到的正确的设置方法,其实也很简单。原版也需要设置,否则也不能进行共享...
错误代码:0x情况描述:在局域网内访问有VISTA和Win7操作系统PC时,出现报错...
一、先用百度搜一个“局域网共享工具”,在两台电脑上都设置“不需要密码验证共享”; 二、检查两台电脑的...
你在做共享的主机看一下IP地址 应该是使用的动态IP然后ip地址改变了 所以没有路径了 \\改变的I...
提示这个是因为系统找不到主机,原因可能是两个方面,一是防火墙规则,二是功能缺失。 先看防火墙设置,你...
你可能感兴趣的内容？Network Working Group
L. Mamakos
Request for Comments: 2516
Category: Informational
UUNET Technologies, Inc.
RedBack Networks, Inc.
R. Wheeler
RouterWare, Inc.
February 1999
A Method for Transmitting PPP Over Ethernet (PPPoE)
Status of this Memo
This memo provides information for the Internet community.
not specify an Internet standard of any kind.
Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1999).
All Rights Reserved.
The Point-to-Point Protocol (PPP) [1] provides a standard method for
transporting multi-protocol datagrams over point-to-point links.
This document describes how to build PPP sessions and encapsulate PPP
packets over Ethernet.
Applicability
This specification is intended to provide the facilities which are
defined for PPP, such as the Link Control Protocol, Network-layer
Control Protocols, authentication, and more.
These capabilities
require a point-to-point relationship between the peers, and are not
designed for the multi-point relationships which are available in
Ethernet and other multi-access environments.
This specification can be used by multiple hosts on a shared,
Ethernet to open PPP sessions to multiple destinations via one or
more bridging modems.
It is intended to be used with broadband
remote access technologies that provide a bridged Ethernet topology,
when access providers wish to maintain the session abstraction
associated with PPP.
Mamakos, et. al.
Informational
Transmitting PPP Over Ethernet
February 1999
This document describes the PPP Over Ethernet encapsulation that is
being deployed by RedBack Networks, RouterWare, UUNET and others.
1. Introduction
Modern access technologies are faced with several conflicting goals.
It is desirable to connect multiple hosts at a remote site through
the same customer premise access device.
It is also a goal to
provide access control and billing functionality in a manner similar
to dial-up services using PPP.
In many access technologies, the most
cost effective method to attach multiple hosts to the customer
premise access device, is via Ethernet.
In addition, it is desirable
to keep the cost of this device as low as possible while requiring
little or no configuration.
PPP over Ethernet (PPPoE) provides the ability to connect a network
of hosts over a simple bridging access device to a remote Access
Concentrator.
With this model, each host utilizes it's own PPP stack
and the user is presented with a familiar user interface.
control, billing and type of service can be done on a per-user,
rather than a per-site, basis.
To provide a point-to-point connection over Ethernet, each PPP
session must learn the Ethernet address of the remote peer, as well
as establish a unique session identifier.
PPPoE includes a discovery
protocol that provides this.
2. Conventions
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [2].
3. Protocol Overview
PPPoE has two distinct stages.
There is a Discovery stage and a PPP
Session stage.
When a Host wishes to initiate a PPPoE session, it
must first perform Discovery to identify the Ethernet MAC address of
the peer and establish a PPPoE SESSION_ID.
While PPP defines a
peer-to-peer relationship, Discovery is inherently a client-server
relationship.
In the Discovery process, a Host (the client)
discovers an Access Concentrator (the server).
Based on the network
topology, there may be more than one Access Concentrator that the
Host can communicate with.
The Discovery stage allows the Host to
discover all Access Concentrators and then select one.
Discovery completes successfully, both the Host and the selected
Access Concentrator have the information they will use to build their
point-to-point connection over Ethernet.
Mamakos, et. al.
Informational
Transmitting PPP Over Ethernet
February 1999
The Discovery stage remains stateless until a PPP session is
established.
Once a PPP session is established, both the Host and
the Access Concentrator MUST allocate the resources for a PPP virtual
interface.
4. Payloads
The following packet formats are defined here.
The payload contents
will be defined in the Discovery and PPP sections.
An Ethernet frame is as follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DESTINATION_ADDR
(6 octets)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SOURCE_ADDR
(6 octets)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ETHER_TYPE
(2 octets)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The DESTINATION_ADDR field contains either a unicast Ethernet
destination address, or the Ethernet broadcast address (0xffffffff).
For Discovery packets, the value is either a unicast or broadcast
address as defined in the Discovery section.
For PPP session
traffic, this field MUST contain the peer's unicast address as
determined from the Discovery stage.
The SOURCE_ADDR field MUST contains the Ethernet MAC address of the
source device.
The ETHER_TYPE is set to either 0x8863 (Discovery Stage) or 0x8864
(PPP Session Stage).
Mamakos, et. al.
Informational
Transmitting PPP Over Ethernet
February 1999
The Ethernet payload for PPPoE is as follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SESSION_ID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The VER field is four bits and MUST be set to 0x1 for this version of
the PPPoE specification.
The TYPE field is four bits and MUST be set to 0x1 for this version
of the PPPoE specification.
The CODE field is eight bits and is defined below for the Discovery
and PPP Session stages.
The SESSION_ID field is sixteen bits.
It is an unsigned value in
network byte order.
It's value is defined below for Discovery
The value is fixed for a given PPP session and, in fact,
defines a PPP session along with the Ethernet SOURCE_ADDR and
DESTINATION_ADDR.
A value of 0xffff is reserved for future use and
MUST NOT be used
The LENGTH field is sixteen bits.
The value, in network byte order,
indicates the length of the PPPoE payload.
It does not include the
length of the Ethernet or PPPoE headers.
5. Discovery Stage
There are four steps to the Discovery stage.
When it completes, both
peers know the PPPoE SESSION_ID and the peer's Ethernet address,
which together define the PPPoE session uniquely.
The steps consist
of the Host broadcasting an Initiation packet, one or more Access
Concentrators sending Offer packets, the Host sending a unicast
Session Request packet and the selected Access Concentrator sending a
Confirmation packet.
When the Host receives the Confirmation packet,
it may proceed to the PPP Session Stage.
When the Access
Concentrator sends the Confirmation packet, it may proceed to the PPP
Session Stage.
All Discovery Ethernet frames have the ETHER_TYPE field set to the
value 0x8863.
Mamakos, et. al.
Informational
Transmitting PPP Over Ethernet
February 1999
The PPPoE payload contains zero or more TAGs.
A TAG is a TLV (type-
length-value) construct and is defined as follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_LENGTH
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_VALUE ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_TYPE is a sixteen bit field in network byte order.
Appendix A
contains a list of all TAG_TYPEs and their TAG_VALUEs.
TAG_LENGTH is a sixteen bit field.
It is an unsigned number in
network byte order, indicating the length in octets of the TAG_VALUE.
If a discovery packet is received with a TAG of unknown TAG_TYPE, the
TAG MUST be ignored unless otherwise specified in this document.
This provides for backwards compatibility if/when new TAGs are added.
If new mandatory TAGs are added, the version number will be
incremented.
Some example Discovery packets are shown in Appendix B.
5.1 The PPPoE Active Discovery Initiation (PADI) packet
The Host sends the PADI packet with the DESTINATION_ADDR set to the
broadcast address.
The CODE field is set to 0x09 and the SESSION_ID
MUST be set to 0x0000.
The PADI packet MUST contain exactly one TAG of TAG_TYPE Service-
Name, indicating the service the Host is requesting, and any number
of other TAG types.
An entire PADI packet (including the PPPoE
header) MUST NOT exceed 1484 octets so as to leave sufficient room
for a relay agent to add a Relay-Session-Id TAG.
5.2 The PPPoE Active Discovery Offer (PADO) packet
When the Access Concentrator receives a PADI that it can serve, it
replies by sending a PADO packet.
The DESTINATION_ADDR is the
unicast address of the Host that sent the PADI.
The CODE field is
set to 0x07 and the SESSION_ID MUST be set to 0x0000.
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The PADO packet MUST contain one AC-Name TAG containing the Access
Concentrator's name, a Service-Name TAG identical to the one in the
PADI, and any number of other Service-Name TAGs indicating other
services that the Access Concentrator offers.
If the Access
Concentrator can not serve the PADI it MUST NOT respond with a PADO.
5.3 The PPPoE Active Discovery Request (PADR) packet
Since the PADI was broadcast, the Host may receive more than one
The Host looks through the PADO packets it receives and
chooses one.
The choice can be based on the AC-Name or the Services
The Host then sends one PADR packet to the Access
Concentrator that it has chosen.
The DESTINATION_ADDR field is set
to the unicast Ethernet address of the Access Concentrator that sent
The CODE field is set to 0x19 and the SESSION_ID MUST be
set to 0x0000.
The PADR packet MUST contain exactly one TAG of TAG_TYPE Service-
Name, indicating the service the Host is requesting, and any number
of other TAG types.
5.4 The PPPoE Active Discovery Session-confirmation (PADS) packet
When the Access Concentrator receives a PADR packet, it prepares to
begin a PPP session.
It generates a unique SESSION_ID for the PPPoE
session and replies to the Host with a PADS packet.
DESTINATION_ADDR field is the unicast Ethernet address of the Host
that sent the PADR.
The CODE field is set to 0x65 and the SESSION_ID
MUST be set to the unique value generated for this PPPoE session.
The PADS packet contains exactly one TAG of TAG_TYPE Service-Name,
indicating the service under which Access Concentrator has accepted
the PPPoE session, and any number of other TAG types.
If the Access Concentrator does not like the Service-Name in the
PADR, then it MUST reply with a PADS containing a TAG of TAG_TYPE
Service-Name-Error (and any number of other TAG types).
In this case
the SESSION_ID MUST be set to 0x0000.
5.5 The PPPoE Active Discovery Terminate (PADT) packet
This packet may be sent anytime after a session is established to
indicate that a PPPoE session has been terminated.
It may be sent by
either the Host or the Access Concentrator.
The DESTINATION_ADDR
field is a unicast Ethernet address, the CODE field is set to 0xa7
and the SESSION_ID MUST be set to indicate which session is to be
terminated.
No TAGs are required.
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When a PADT is received, no further PPP traffic is allowed to be sent
using that session.
Even normal PPP termination packets MUST NOT be
sent after sending or receiving a PADT.
A PPP peer SHOULD use the
PPP protocol itself to bring down a PPPoE session, but the PADT MAY
be used when PPP can not be used.
6. PPP Session Stage
Once the PPPoE session begins, PPP data is sent as in any other PPP
encapsulation.
All Ethernet packets are unicast.
The ETHER_TYPE
field is set to 0x8864.
The PPPoE CODE MUST be set to 0x00.
SESSION_ID MUST NOT change for that PPPoE session and MUST be the
value assigned in the Discovery stage.
The PPPoE payload contains a
PPP frame.
The frame begins with the PPP Protocol-ID.
An example packet is shown in Appendix B.
7. LCP Considerations
The Magic Number LCP configuration option is RECOMMENDED, and the
Protocol Field Compression (PFC) option is NOT RECOMMENDED.
implementation MUST NOT request any of the following options, and
MUST reject a request for such an option:
Field Check Sequence (FCS) Alternatives,
Address-and-Control-Field-Compression (ACFC),
Asynchronous-Control-Character-Map (ACCM)
The Maximum-Receive-Unit (MRU) option MUST NOT be negotiated to a
larger size than 1492.
Since Ethernet has a maximum payload size of
1500 octets, the PPPoE header is 6 octets and the PPP Protocol ID is
2 octets, the PPP MTU MUST NOT be greater than 1492.
It is RECOMMENDED that the Access Concentrator ocassionally send
Echo-Request packets to the Host to determine the state of the
Otherwise, if the Host terminates a session without sending
a Terminate-Request packet, the Access Concentrator will not be able
to determine that the session has gone away.
When LCP terminates, the Host and Access concentrator MUST stop using
that PPPoE session.
If the Host wishes to start another PPP session,
it MUST return to the PPPoE Discovery stage.
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8. Other Considerations
When a host does not receive a PADO packet within a specified amount
of time, it SHOULD resend it's PADI packet and double the waiting
period. This is repeated as many times as desired.
If the Host is
waiting to receive a PADS packet, a similar timeout mechanism SHOULD
be used, with the Host re-sending the PADR.
After a specified number
of retries, the Host SHOULD then resend a PADI packet.
The ETHER_TYPEs used in this document (0x8863 and 0x8864) have been
assigned by the IEEE for use by PPP Over Ethernet (PPPoE).
these values and the PPPoE VER (version) field uniquely identify this
UTF-8 [5] is used throughout this document instead of ASCII.
supports the entire ASCII character set while allowing for
international character sets as well.
See [5] for more details.
9. Security Considerations
To help protect against Denial of Service (DOS) attacks, the Access
Concentrator can employ the AC-Cookie TAG.
The Access Concentrator
SHOULD be able to uniquely regenerate the TAG_VALUE based on the PADR
SOURCE_ADDR.
Using this, the Access Concentrator can ensure that the
PADI SOURCE_ADDR is indeed reachable and can then limit concurrent
sessions for that address.
What algorithm to use is not defined and
left as an implementation detail.
An example is HMAC [3] over the
Host MAC address using a key known only to the Access > Concentrator.
While the AC-Cookie is useful against some DOS attacks, it can not
protect against all DOS attacks and an Access Concentrator MAY employ
other means to protect resources.
While the AC-Cookie is useful against some DOS attacks, it can not
protect against all DOS attacks and an Access Concentrator MAY employ
other means to protect resources.
Many Access Concentrators will not wish to offer information
regarding what services they offer to an unauthenticated entity.
that case the Access Concentrator should employ one of two policies.
It SHOULD never refuse a request based on the Service-Name TAG, and
always return the TAG_VALUE that was sent to it.
Or it SHOULD only
accept requests with a Service-Name TAG with a zero TAG_LENGTH
(indicating any service).
The former solution is RECOMMENDED.
10. Acknowledgments
This document is based on concepts discussed in several forums,
including the ADSL forum.
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Copious amounts of text have been stolen from RFC 1661, RFC 1662 and
11. References
[1] Simpson, W., Editor, "The Point-to-Point Protocol (PPP)", STD 51,
RFC 1661, July 1994
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[3] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed-Hashing
for Message Authentication", RFC 2104, February 1998.
[4] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700,
October 1994.
See also: http://www.iana.org/numbers.html
[5] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998.
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Appendix A
TAG_TYPES and TAG_VALUES
0x0000 End-Of-List
This TAG indicates that there are no further TAGs in the list. The
TAG_LENGTH of this TAG MUST always be zero.
Use of this TAG is
not required, but remains for backwards compatibility.
0x0101 Service-Name
This TAG indicates that a service name follows.
The TAG_VALUE is
an UTF-8 string that is NOT NULL terminated. When the TAG_LENGTH
is zero this TAG is used to indicate that any service is
acceptable.
Examples of the use of the Service-Name TAG are to
indicate an ISP name or a class or quality of service.
0x0102 AC-Name
This TAG indicates that a string follows which uniquely identifies
this particular Access Concentrator unit from all others. It may
be a combination of trademark, model, and serial id information,
or simply an UTF-8 rendition of the MAC address of the box.
not NULL terminated.
0x0103 Host-Uniq
This TAG is used by a Host to uniquely associate an Access
Concentrator response (PADO or PADS) to a particular Host request
(PADI or PADR).
The TAG_VALUE is binary data of any value and
length that the Host chooses.
It is not interpreted by the Access
Concentrator.
The Host MAY include a Host-Uniq TAG in a PADI or
If the Access Concentrator receives this TAG, it MUST
include the TAG unmodified in the associated PADO or PADS
0x0104 AC-Cookie
This TAG is used by the Access Concentrator to aid in protecting
against denial of service attacks (see the Security Considerations
section for an explanation of how this works).
The Access
Concentrator MAY include this TAG in a PADO packet.
receives this TAG, it MUST return the TAG unmodified in the
following PADR.
The TAG_VALUE is binary data of any value and
length and is not interpreted by the Host.
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0x0105 Vendor-Specific
This TAG is used to pass vendor proprietary information.
first four octets of the TAG_VALUE contain the vendor id and the
remainder is unspecified.
The high-order octet of the vendor id
is 0 and the low-order 3 octets are the SMI Network Management
Private Enterprise Code of the Vendor in network byte order, as
defined in the Assigned Numbers RFC [4].
Use of this TAG is NOT RECOMMENDED.
To ensure inter-operability,
an implementation MAY silently ignore a Vendor-Specific TAG.
0x0110 Relay-Session-Id
This TAG MAY be added to any discovery packet by an intermediate
agent that is relaying traffic.
The TAG_VALUE is opaque to both
the Host and the Access Concentrator.
If either the Host or
Access Concentrator receives this TAG they MUST include it
unmodified in any discovery packet they send as a response.
PADI packets MUST guarantee sufficient room for the addition of a
Relay-Session-Id TAG with a TAG_VALUE length of 12 octets.
A Relay-Session-Id TAG MUST NOT be added if the discovery packet
already contains one.
In that case the intermediate agent SHOULD
use the existing Relay-Session-Id TAG.
If it can not use the
existing TAG or there is insufficient room to add a Relay-
Session-Id TAG, then it SHOULD return a Generic-Error TAG to the
0x0201 Service-Name-Error
This TAG (typically with a zero-length data section) indicates
that for one reason or another, the requested Service-Name request
could not be honored.
If there is data, and the first octet of the data is nonzero, then
it MUST be a printable UTF-8 string which explains why the request
was denied.
This string MAY NOT be NULL terminated.
0x0202 AC-System-Error
This TAG indicates that the Access Concentrator experienced some
error in performing the Host request.
(For example insufficient
resources to create a virtual circuit.)
It MAY be included in
PADS packets.
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If there is data, and the first octet of the data is nonzero, then
it MUST be a printable UTF-8 string which explains the nature of
the error.
This string MAY NOT be NULL terminated.
0x0203 Generic-Error
This TAG indicates an error.
It can be added to PADO, PADR or
PADS packets when an unrecoverable error occurs and no other error
TAG is appropriate.
If there is data then it MUST be an UTF-8
string which explains the nature of the error.
This string MUST
NOT be NULL terminated.
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Appendix B
The following are some example packets:
A PADI packet:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0xffffffff
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Host_mac_addr
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Host_mac_addr (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ETHER_TYPE = 0x8863
| v = 1 | t = 1 |
CODE = 0x09
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SESSION_ID = 0x0000
LENGTH = 0x0004
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_TYPE = 0x0101
TAG_LENGTH = 0x0000
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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A PADO packet:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Host_mac_addr
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Host_mac_addr (cont)
| Access_Concentrator_mac_addr
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Access_Concentrator_mac_addr (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ETHER_TYPE = 0x8863
| v = 1 | t = 1 |
CODE = 0x07
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SESSION_ID = 0x0000
LENGTH = 0x0020
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_TYPE = 0x0101
TAG_LENGTH = 0x0000
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TAG_TYPE = 0x0102
TAG_LENGTH = 0x0018
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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A PPP LCP packet:
The PPP protocol value is shown (0xc021) but the
PPP payload is left to the reader.
This is a packet from the Host to
the Access Concentrator.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Access_Concentrator_mac_addr
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Access_Concentrator_mac_addr(c)|
Host_mac_addr
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Host_mac_addr (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ETHER_TYPE = 0x8864
| v = 1 | t = 1 |
CODE = 0x00
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SESSION_ID = 0x1234
LENGTH = 0x????
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PPP PROTOCOL = 0xc021
PPP payload
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Louis Mamakos
UUNET Technologies, Inc.
3060 Williams Drive
Fairfax, VA
United States of America
UUNET Technologies, Inc.
3060 Williams Drive
Fairfax, VA
United States of America
Jeff Evarts
UUNET Technologies, Inc.
3060 Williams Drive
Fairfax, VA
United States of America
Mamakos, et. al.
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David Carrel
RedBack Networks, Inc.
1389 Moffett Park Drive
Sunnyvale, CA
United States of America
Dan Simone
RedBack Networks, Inc.
1389 Moffett Park Drive
Sunnyvale, CA
United States of America
Ross Wheeler
RouterWare, Inc.
3961 MacArthur Blvd., Suite 212
Newport Beach, CA
United States of America
Mamakos, et. al.
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Full Copyright Statement
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