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cbulogin.et2Server is OK地暖及地暖管：PE-X管，PE-RT管
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现代地暖和管材的发展息息相关，早期地暖用钢管和铜管，钢管被淘汰了，铜管沿用至今。随着石油化学的飞速发展，合成材料日新月异，塑料管材层出不穷，地暖技术的普及，塑料管材的成功应用功不可没。上世纪七十年代初，PE-Xa管和PB-1管几乎同时跻身地暖市场，PE-Xa管拔了头魁，铜管退居第二，PB-1管屈居第三。此后又有PE-Xb管、PP-B管、PP-R管、PE-Xc管、铝塑复合管、PE-RT管和各种阻氧管先后进入地暖市场。
地暖系统对塑料管材的要求比较特殊：1)热媒为水，管材耐水性要好；2)热媒温度&60℃，管材耐热性要好；3)热媒强制循环，管材热强度要高；4)使用寿命&50年，管材耐热氧老化性、蠕变抗性要好；5)管材主要功能为换热，管材热导率要高；6)为保护系统中金属设备和部件，管材透氧率应低；7)为保证连接的可靠性，管材的记忆功能越强越好；8)为适应管材的弯曲施工，管材的弹性模量稍低为好；9)为保证管材废料容易回收，管材的热塑性越高越好。
目前在欧洲地暖市场上，PE-X管所占份额约在82%以上（包括PE-Xa管、PE-Xb管和PE-Xc管），其次为铝塑复合管（主要是PE-RT／Al／PE-RT管）和铜管。在我国地暖市场上，PE-Xa和PE-RT管约占总用量的95%以上，其次有少量PE-Xb管PB-1管。PP-B管已彻底退出地暖市场。PP-R管大约也只有瑞士一个国家的地暖工程中还有少量使用的。PB-1管在美国已然绝迹，在欧洲地暖市场上其份额占5%左右并逐年下降，在我国近年有些抬头。阻氧塑料管在欧洲是必须采用的，在我国用量逐渐增加并被普遍看好。这就是一部优胜劣汰史，也是一部地暖管的创新历史。经半个世纪的洗礼，今天主导地暖市场的纯塑料管为PE-X管和PE-RT管两种，PB-1管因无优势，对地暖市场缺乏影响力。
竞争将取决于创新，今后的若干年，地暖和地暖管又会有些什么样的创新？抛砖引玉，与同仁们分享，也欢迎讨论。
1 热塑性PE-X管
1.1 创新的缘由
PE-X管耐热性、蠕变抗性等是目前已知热水装置中用塑料管材中无与伦比的，它所具有的记忆功能又是唯一的。PE-RTⅡ管的耐热性、蠕变抗性与PE-X接近，可焊性好，废料可以热熔回收。但是，PE-X是非热塑性的，无法采用热熔焊接连接，废料无法采用热熔回收。PE-RT无记忆功能，对卡套式连接适应性差。
1.2 创新方案
低度交联PE-RT管，其耐热性、蠕变抗性不低于PE-X管，在保持热塑性的前提下，赋予其记忆功能。
1.3 关键技术
主要原料的选择和交联度的确定，能否顺利进行交联，取决于不同共聚单体。
1.4 预期效果
热塑性PE-X管耐热性、蠕变抗性与已有PE-X管相同。可焊性好，废料可热熔回收与PE-RT管相同。可称其为超级地暖管。
2 同步交联PE-Xa管挤出速度的提高
2.1 创新缘由
同步交联PE-Xa管的制造采用单管柱塞式挤出机挤出成型，设备和工艺流程都非常简单。
同步交联PE-Xa管制造，物料输送和熔体的压缩为脉冲式，管壁中存在着周期性内应力和隐形或显形&竹节&。管材挤出速度慢。
2.2 创新方案
改单管柱塞式挤出机为多管柱塞式挤出机。
2.3 关键技术
交联速度的适配，增加后交联工序，可以采用曼瑞德集团有限公司引进的红外交联箱，也可采用军星管业集团公司专利&履带模具交联装置&。
2.4 预期效果
多管柱塞式挤出机的挤出成型，使物料输送、熔体压缩频率变密，削弱因脉冲输送造成的管壁中残留有明显周期性内应力和产生&竹节&的可能，同时可成倍或数倍提高挤出速度。
3 产水交联PE-Xb管
3.1 创新缘由
PE-Xb管与PE-Xa管非常相近，耐热性好、蠕变抗性好，具有记忆功能。PE-Xb管生产过程中后交联耗能较高。
3.2 创新方案
采用产水交联PE-Xb管新技术。
3.3 关键技术
产水交联PE-Xb管配方的设计。
3.4 预期效果
产水交联PE-Xb管下线后，静置数日后即完成交联过程，不必用温水或低压蒸汽水解交联，节能效果明显。
4 微波交联后交联PE-Xa管
4.1 创新缘由
同步交联PE-Xa管受交联剂分解速度的制约，交联速度不能太高。物料推压式输送，熔体脉冲式压缩，管壁产生&竹节&，管壁中存在周期性内应力是不可避免的。引进的后交联PE-Xa制造技术和设备效率高，质量好，但受专利保护，无法复制。
4.2 创新方案
研发微波交联技术与设备。
4.3 关键技术
配方设计和交联剂的选择，微波交联炉的研发。
4.4 预期效果
引进后交联PE-Xa管生产线，高速挤出、高速交联，生产效率高，dn20PE-Xa管线速度17m／min以上，可制造dn10～dn32纯PE-Xa管、三层结构阻氧塑料管、五层结构阻氧塑料管，交联度可在线检测。产品质量稳定，不会出现&竹节&和产生周期性内应力等。微波交联后交联PE-Xa管生产线将来接近进口红外交联水平，但设备造价可望仅为进口价格的三分之一到二分之一，对加速我国PE-Xa管更新换代、达到国际先进水平发挥重要作用。
5 PE-RT／PE-X合金管
5.1 创新缘由
PE-RT耐热性、蠕变抗性、可焊性较好。
PE-RT可与PE无限相容，易被错误利用，降低PE-RT管材使用性能。
5.2 创新方案
以PE-RT／PE-X合金取代PE-RT／PE。
5.3 关键技术
交联方法与交联工艺，交联度的确定。
5.4 预期效果
PE-RT／PE-X合金性能不低于PE-RT，有可能略高于PE-RT，增加了记忆功能，成本明显低于纯PE-RT。
注：TPU管或者TPU合金管能否进入地暖市场，还取决于创新者的努力程度。
6 TLCP／PO合金阻氧塑料管
6.1 创新缘由
传统阻氧塑料管是以EVOH为阻氧材料的，EVOH属于高阻隔材料，阻氧性能好，加工容易。
EVOH耐水性差，透氧率受温度和湿度影响大，只能在夹层中应用。EVOH与PO管材间相容性差，必须借助于粘胶剂与PO管材间粘接，也因此EVOH阻氧塑料管结构复杂、废料回收困难。
6.2 创新方案
采用TLCP／PO合金做阻氧层制造阻氧塑料管。
6.3 关键技术
TLCP／PO合金的制备，PO管材涂覆TLCP／PO合金阻氧层，等离子体蚀刻技术的革新与应用。
6.4 预期效果
二层结构阻氧塑料管，结构更简单，阻氧效果更好，温度100℃以下，湿度100%以内，其透氧率不受温湿度影响，这些阻氧管的制造，可以在线完成，也可以在管材下线以后完成，废料不须分离即可热熔回收（PE-X除外），且有提高、增强管材耐热性、蠕变抗性的作用。
6.5 可以制造的二层结构阻氧塑料管，包括所有PO管材，计有：
1）PE-Xa／TLCP～PE阻氧管；
2）PE-Xb／TLCP～PE阻氧管；
3）PE-Xc／TLCP～PE阻氧管；
4）PE-RT／TLCP～PE阻氧管；
5）PB-1／TLCP～PP阻氧管；
6）PB-R／TLCP～PO阻氧管；
7）PP-H／TLCP～PP阻氧管；
8）PP-B／TLCP～PP阻氧管；
9）PP-R／TLCP～PP阻氧管；
10）PP-RCT／TLCP～PP阻氧管；
11）热塑性PE-X／TLCP～PO阻氧管（二层结构）；
12）热塑性PE-X／Si02／PE阻氧管（二层结构）。
玻璃微膜阻氧管（即Si02微膜），阻氧性能更好，工艺更为简单，价格会更加低廉。玻璃微膜阻氧管的研制近年来取得一点进展。
7 相变节能地暖
7.1 创新缘由
供电系统需要有力的调峰填谷措施，丰富的太阳能有待充分利用，建筑对环保和节能的贡献率具有巨大的潜力。
7.2 创新方案
具有强大蓄能（蓄热、蓄冷）能力的相变材料的应用，是电网调峰填谷和太阳能利用的绝好材料，节能、减排兼备。
7.3 关键技术
相变材料的选择及处理。
7.4 预期效果
以地暖为例，夜间利用谷电蓄热8h，昼间停止供电后可放热16h，使室温昼夜恒温在28℃左右。或者夏天白天蓄集太阳能，室内温度不会太高，夜间放出热量，使室内昼夜温差不致过大。
上述七项中的大部分，曼瑞德集团有限公司己申请了中国专利和国际专利（PCT），但不影响同仁们继续发挥创造才能。
创新是一个漫长的过程，创新存在一定风险，路漫漫其修远兮，吾将上下而求索。创新的结果是什么？上述初露端倪，把复杂的事情推向简单化，未来地暖系统所用塑料管材很可能是阻氧热塑性PE-X管材的天下。波谷电的利用离不开相变材料。如果不甘心喝一辈子螃蟹汤，冒创新的风险一般都是值得的，现代科学无所不能，即使是第一个吃螃蟹，风险已不再有那么恐怖。创新吧！不进则退。
作者：于东明 陈立楠；文章出自转自于东明 先生文章，文章仅仅给相关客户查阅资料用，文章源自网络，如侵犯版权，请致电，这边立刻删除~谢谢。
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截止今日，红塔地暖已经为十万多家客户提供供暖服务！
关注有惊喜好礼马上到正在初始化报价器pe-pt地暖管和pexb地暖管的区别是什么5个回答罂粟素1591、PE-RT地热管
管材无折弯记忆性，可热熔连接，热蠕动性较大，低温抗脆性好。
2、PE-XB地暖管
低温韧性好，耐高温，抗应力开裂性好，不能利用热熔连接。
漫地开花PERT耐热聚乙烯；PEXb交联聚乙烯的一种，性能比PEXa要差。
交联聚乙烯因为其无法回收利用，对环境的伤害很大。而PERT是属于国际上新开发出来的一种专门用于地板采暖的PE管材。其优越的性能逐步获得市场认可。市场销量已经远远大于交联聚乙烯。
4恬恬PERT地暖管现在是主流，便宜实用，缺点是不耐高温，这和制材有关，中密度七十多度，高密度九十度左右，PEXB主要特点就是耐高温抗低温
拓格装饰客服高PERT地暖管现在是主流，便宜实用，缺点是不耐高温，这和制材有关，中密度七十多度，高密度九十度左右，PEXB主要特点就是耐高温抗低温
宁谧青枫_3697你好，很高兴回答您的问题。pept在是主流，便宜实用，缺点是不耐高温，这和制材有关，中密度七十多度，高密度九十度左右，PEXB主要特点就是耐高温抗低温.希望我的回答可以帮到你哦。
其他回答热门问答1234567891011121314151617181920查看更多21222324252627282930相关问答1个回答徜徉吉1、PT下载 　　PT是英文Particular Transfer的缩写。 PT的中文意思是特别转让。 　　PT（Private Tracker）下载其实也是Bt下载的一种，但有两...1个回答冒泡的鱼灬1、PT下载 　　PT是英文Particular Transfer的缩写。 PT的中文意思是特别转让。 　　PT（Private Tracker）下载其实也是Bt下载的一种，但有两...1个回答心碎GFC1、PT下载 　　PT是英文Particular Transfer的缩写。 PT的中文意思是特别转让。 　　PT（Private Tracker）下载其实也是Bt下载的一种，但有两...4个回答发发5sky过载4个回答腻腻0723pt950和990都不错，是铂金的，990的含金量是99%，纯度更高，都不容易断的，只是990价格更贵，比950要贵100多块/克，一般选择时950的就很好了。1个回答小财主0703有,就是美达斯PT-43A4,PT-46A4三脚架 两个区别咯~~1个回答神化天有,就是美达斯PT-43A4,PT-46A4三脚架 两个区别咯~~4个回答鸿博家具pt950和990都不错，是铂金的，990的含金量是99%，纯度更高，都不容易断的，只是990价格更贵，比950要贵100多块/克，一般选择时950的就很好了。2个回答姜绎雯你们应该只有PT950和PT900的,太纯的不可能有在市面上卖哦3个回答虾米楼市政策铂首饰
铂也称白金。近几年，随着消费层次的不断提升，铂首饰越来越受城乡男女消费者的青睐。首饰市场中，常见的铂首饰有Pt900、 Pt950和Pt990。
①Pt900，要求铂的...双壁聚波纹管信阳市哪里有卖的
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(9)：回收利用，为节省资源，保护。二：双壁波纹管和钢带增强聚螺旋波纹管（hdpe）的主要性能、特点
（1）降板：卫生间下沉的排水参照《住宅卫生间》01sj914。具体做法是卫生间的结构楼板下层（局部）300mm作为管道敷设空间。下沉楼板采用现浇砼并做好防水层，按标高和坡度沿下层楼板敷设给、排水管道，并用焦渣等轻质材料填实作为垫层，垫层上用水泥找平后再做防水层和层面。01sj914图集指出，采用这种时，应该使用一种叫“多功能专利地漏”的管配件。现有的降板通常是指卫生间的一次防水层面，低于客厅毛坯层面。用数据来区分有：350mm，450mm不等。同层降板为：200mm，同比降板为350m
根据公司招股，报告期内，公司双壁波纹管自动化生产线分别实现销售56套、67套和84套，其中pe/pp双壁波纹管自动化生产线实现销售34套、55套和73套，而这三年中公司产销率一直是。这可以说明公司虽然一直在利用自身积累在扩充产能，销售情况也不错，但存在产能瓶颈。
金达塑胶制品目前正致力于完善产品系列，并逐步形成相关hdpe双壁波纹管的完整产品线，并以此为客户带来更为便捷的采购，在当天为您及时发货。在产品品质上，公司更是以植根于行业的精品思维为基础，致力于为客户提供品质和成本结合的产品并为客户节省更多的时间成本。
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Internet Draft
Expires: July 2003
January 2003
Terminal Independent Mobile IP (TIMIP)
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of .
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups.
other groups may also distribute working documents as Internet-
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time.
It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
The list of Internet-Draft Shadow Directories can be accessed at
All IP mobility protocols currently proposed on the IETF assume that
the mobile nodes always have a mobility-aware IP stack, which is
still a scenario that can seldom be found nowadays. Most terminals,
including the laptops and PDAs which most would benefit of the
mobility support, still use legacy IP stacks, limiting their use to
layer-2 mobility within a single IP subnet.
This document presents Terminal Independent Mobile IP (TIMIP), which
supports IP micro-mobility of all possible existing legacy IP
terminals, while fully interoperating with Mobile IP to provide
macromobility across IP subnets for all terminals.
Table of Contents
. Changes/Additions from version 00...............................
. Introduction....................................................
. Applicability...................................................
. Terminology.....................................................
. Architecture....................................................
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
. Registration....................................................
. Power-up........................................................
. Micromobility...................................................
. Macromobility..................................................
Macromobility for LMNs......................................
Macromobility for MIP terminals.............................
. Message Formats...............................................
. Generic Detection Algorithm...................................
. DHCP support for automatic registration.......................
. References....................................................
. Author's Addresses............................................
. Changes/Additions from version 00
- Precise definition of message formats used in TIMIP signaling.
- TIMIP now supports DHCP protocol for automatic registrations.
- Definition of a Generic Handoff detection procedure for use when
layer-2 does not offer sufficient information about the movement
of the Legacy Terminals.
- A exponential backoff timeout refresh behavior was added to reduce
the number of refreshes on the wireless medium.
- Several important clarifications and improvements throughout the
whole document, and other minor corrections.
. Introduction
All IP mobility protocols currently proposed on the IETF assume that
the mobile nodes always have a mobility-aware IP stack, which is
still a scenario that can seldom be found nowadays. Most terminals,
including the laptops and PDAs which most would benefit of the
mobility support, still use legacy IP stacks, limiting their use to
layer-2 mobility within a single IP subnet.
Currently, there exists evidence that the need of special mobile
stacks for the terminals may be holding the generalization of this
service, because of the effort needed to change the already existing
IP terminals for the new technology. Particularly, this need has
already been identified regarding the IP mobility deployment in
wireless technologies (see , ?Registration requests
generated on behalf of a mobile node? of [8]).
TIMIP [1] is a micromobility architecture that allows Mobile Nodes
with legacy IP stacks to roam within an IP domain, thus enabling the
IP mobility of all existing IP terminals, by explicitly not
requiring any processing related to the mobility service on the
mobile terminals. Between TIMIP domains, the movement of the
terminals is supported with custom macromobility mechanisms based on
and fully compatible with standard Mobile IP [2].
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
The main features of TIMIP are listed below, which includes both
novel and similar features of other micromobility architectures,
namely CIP [3] and HAWAII [4]:
- TIMIP does not require changes to the IP protocol stack of mobile
nodes, for both micromobility or macromobility support, thus
supporting any existing IP terminal.
- TIMIP specifically promotes the use of data link layer information
for terminal power-up and movement detection on the network side,
for detection performance. When the layer-2 does not offer
sufficient information, a generic handoff detection algorithm is
- Refreshing of routing paths is performed by data packets sent by
the mobile terminals, with refreshing being employed only when no
traffic is detected at the routers for a certain time interval
(similar to CIP).
- Routing reconfiguration during handoff within a TIMIP domain only
needs to change the routing tables of the Access Routers located
in the shortest path between the Access Points involved (similar
to HAWAII).
- Routing of data packets within a TIMIP domain does not need to
reach the Access Network Gateway, involving only the Access
Routers located in the shortest path between the sender and the
receiver (similar to HAWAII).
. Applicability
TIMIP is applicable within LANs, and possibly larger networks up to
IP domains, that form one subnet only. To provide mobility between
subnets (macromobility), Mobile IP compatible mechanisms should be
present on the Access Network Gateway of each TIMIP domain.
It is expected that the data link layer of the Access Points is able
to perform terminal power-up and movement detection, and able to
notify the TIMIP layer. If this facility is not available, a simple
handoff detection algorithm is used.
It is also assumed that the Access Routers of the TIMIP domain form
a logical tree, with the Access Network Gateway located at the top.
. Terminology
Access Network
An IP network that includes one or more Access Routers, and an
Access Network Gateway.
Access Network Gateway (ANG)
An Access Router that separates the Access Network from a third
party network.
Access Point (AP)
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An Access Router that offers layer-2 connectivity to Mobile Nodes.
This layer-2 can be based on any possible technology, and is
depicted in this document, without loss of generality, as a wireless
link, as this kind of access is the most interesting one for the use
of mobility mechanisms.
Access Router (AR)
An IP router residing in an Access Network and connected to one or
more access routers. An AR offers connectivity to Mobile Nodes by
means of IP routing. The router may include intelligence beyond
simple forwarding service offered by ordinary IP routers. Some
Access Routers can be Access Points, and one of them is the ANG.
Legacy Mobile Node (LMN)
A Mobile Node whose IP layer is not aware of mobility. The precise
requirements of the LMNs are the ones necessary for Internet Hosts,
described in [9].
Mobile Node (MN)
An IP end-node capable of changing its point of attachment to the
A range of IP addresses sharing a common prefix.
. Architecture
A TIMIP domain is an IP subnet organized as a logical tree of Access
Routers (ARs) whose root router is the Access Network Gateway (ANG).
The Access Routers can also be layer-2 Access Points (APs), which
interface directly with the MNs through the wireless medium (WM).
The architectural diagram of TIMIP is depicted in Figure 1.
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
| | -------| AR5 |-------------------|
| |--------| AR6 |----------
Figure 1: Architectural Diagram of a TIMIP domain.
As a Legacy Mobile Node (LMN) has a legacy IP stack and cannot issue
any signaling during handoff, handoff detection by the AR relies on
notification from layer-2, or from a Generic Detection Algorithm.
This notification triggers routing reconfiguration of the TIMIP
domain, leading to routing table updating at the ARs.
Registration
In order to allow attachment of an LMN to a TIMIP domain, the LMN
must be previously registered at the ANG. This is accomplished
offline through management procedures, or automatically using the
DHCP protocol (see ). For each LMN recognized in a TIMIP
domain, registration information consists on the following:
- MAC address of the LMN;
- IP Address of the LMN;
- IP address of the MIP Home A
- Authentication K
- Authentication option.
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January 2003
Mobility for IP (TIMIP)
The MIP capability parameter specifies if MIP is required, either
implemented at the ANG on behalf of legacy terminal (surrogate MIP)
or implemented at the terminal itself. If the terminal has a legacy
IP protocol stack, the next two parameters specify respectively the
IP address of its Home Agent and the authentication key to be used
between the terminal and the ANG when the authentication option is
turned on. It should be noted that TIMIP authentication is mandatory
for macromobility scenarios for both MIP and legacy terminals. The
IP address of the Home Agent is not used when the terminal
implements MIP, as the terminal itself is responsible for
registering with the Home Agent, bypassing the ANG.
Once this data is configured at the ANG, it is forwarded to the APs
(except the authentication key) so that they are able to know the IP
address of newly associated terminals based on their MAC address
provided by layer-2 as explained below.
. Power-up
When a terminal firstly appears in a TIMIP domain, a routing path is
created along the hierarchy of ARs. Consider the scenario in
Figure 1. When the MN attaches itself to AR1, the creation of the
routing path takes the following steps:
1. The MT performs a layer-2 association with an AP that belongs to
the local TIMIP domain.
2. At the AP, the IP layer is notified about the presence of the MT
in its wireless interface, by means of a primitive containing the
detected MAC address of the terminal, triggering the routing
reconfiguration procedure. This primitive can be generated
exclusively by the Layer-2 itself, or by a Generic Detection
Algorithm to be described later.
When this happens, the MAC address is matched against the
terminal registration information broadcasted by the ANG and the
respective IP address is found. As the New AP has currently no
routing table entry for the MT, the routing table is updated with
the addition of this new entry.
3. The New AP sends a TIMIP RoutingUpdate message up to the AR at
hierarchical level 2. This AR acknowledges with a
RoutingUpdateAck message, and updates its routing table
accordingly with the addition of a new entry relative to the MT.
This entry points to the source of the RoutingUpdate message ?
the AP1 - in order to specify the path through which the terminal
can be reached.
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4. Exchange of RoutingUpdate/RoutingUpdateAck messages climbs up the
hierarchy levels. At each level, the routing table is updated
with the creation of a new entry relative to the MT. This entry
always points to the source of the RoutingUpdate message in order
to specify the path through which the MT can be reached, by means
of the next node information for each terminal.
5. Exchange of RoutingUpdate/RoutingUpdateAck messages reaches the
ANG, completing the creation of the new routing path.
The MT is now reachable through the routing path established by the
above procedures. The ARs that do not belong to this path have no
routing entry for the MT. At these ARs, all packets destined to the
MT are forwarded up the hierarchy of routers by default. All packets
that arrive at an AR whose routing table has an entry to the
destination, are forwarded down the hierarchy of routers until they
reach the radio interface in which the MT is located. As thus, for
packets destined to a terminal located in the same TIMIP domain as
the source (intra-domain traffic), only in the worst case reach the
The RoutingUpdate messages are coupled with their respective
RoutingUpdateAck to ensure that the network is able to have the
correct localization information of the LMNs, even when these
signalization messages are lost. As thus, when a node does not
receive the acknowledge message of an update within a certain amount
of time (default 1 second), it automatically resends its update
message to the peer. These messages include a timestamp generated at
the New AP on the moment of detection (primitive reception). As in
TIMIP all APs are synchronized by means of the Network Time Protocol
(NTP) [5], this guarantees consistency even when the MT moves faster
than the route reconfiguration, because
It should also be noted that the routing path is soft-state and
after its establishment, it is refreshed by the data packets sent by
the LMN, being sufficient to be received for routing through the
interface that the terminal is registered. Using this facility, the
state maintaining of active terminals does not add any overhead.
Nevertheless, as the packets are routed within the TIMIP domain,
some of the ARs may not be refreshed. When this occurs, the routing
entry for the MT becomes invalid after a predefined timeout, that is
subject to a backoff procedure. The AR where the timer expired
starts to send ICMP EchoRequest messages to the terminal, filling
the source address field of the IP header with the IP address of the
ANG. This forces the MT to reply with EchoReply messages destined to
the ANG, which will refresh all the routing path within the TIMIP
If this Reply message is properly received with the current timeout,
then its value is doubled, up to
on the other
hard, if no reply is received, then the value is divided by two up
to a predefined minimum, that forces the routing entry for the LMN
to be removed.
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January 2003
Mobility for IP (TIMIP)
This basic TIMIP configuration is adequate to have micromobility in
wireless access networks where security is not an issue.
Nevertheless, just like in other unprotected IP networks, it allows
MTs to power-on with false MAC and IP addresses. In order to avoid
this, a minimal security functionality must be implemented at the MT
itself. However, this can be done in the application layer with no
need to change the IP protocol stack. When the authentication option
is used, it is assumed that the MT runs a special security
application that uses a database of authentication keys for the
different TIMIP domains in which the MT is allowed to power-up. This
database is indexed by the IP addresses of the ANGs that are the
root of the respective networks.
The authentication takes place in step 2 of the power-on procedure,
immediately after layer-2 notifies the IP layer of the AP about the
association of the MT. The AP sends an SignatureRequest message to a
well known UDP port in the MT. This message carries &IP address of
the MT, IP address of the ANG, rand, timestamp&, where rand is a
random value and the timestamp is an NTP formatted 64-bit value. The
same message is sent to the ANG.
Both the MT and the ANG answer the AP with a SignatureReply message
containing the same fields present in the SignatureRequest message,
plus its 128-bit MD5 message digest [6] calculated with the
authentication key of the MT for this network. The latter is only
known by the MT (based on the authentication key database and the IP
address of the ANG) and the ANG (based on the registration
information). The AP compares the signatures of the two
SignatureReply messages, and proceeds with the routing
reconfiguration procedures only in case there is a match.
. Micromobility
An example of handoff between two APs that belong to the same access
subnetwork is depicted in Figure 2.
Internet-draft
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January 2003
Mobility for IP (TIMIP)
| | -------| AR5 |-------------------|
(handoff)V
| |--------| AR6 |----------
Figure 2: Handoff between APs.
For the Handoff procedure, the first four steps are the exact same
as the Power-up case. The remaining steps are the following:
5. Exchange of RoutingUpdate/RoutingUpdateAck messages climbs up the
hierarchy levels, until the crossover AR (the AR that belongs
simultaneously to the old path and to the new path) is reached
(in the example above, node AR5). Now that the new routing path
is completely created, the old path must be deleted. This
procedure starts when the crossover AR sends a RoutingUpdate
message addressed to the MT through the old routing path. The AR
that receives the message realizes that the MT is no longer
accessible through it, updates its routing path by deleting the
entry that corresponds to the MT and replies with a
RoutingUpdateAck message.
6. Exchange of RoutingUpdate/RoutingUpdateAck messages goes down the
AR tree following the old path, until the Old AP is reached. At
each level, the node receives the update from its root peer, and
the each routing table is updated by deleting the entry relative
to the MT.
In a normal shared media LAN, when a terminal has a packet destined
to an address within the same IP subnet (which is known through the
analysis of the IP address prefix), it tries to obtain the MAC
address of the destination through an ARP request and send the
packet directly to it. In TIMIP, as the APs are also ARs, if the
destination is associated to a different AP, the ARP request will
never be answered.
Internet-draft
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January 2003
Mobility for IP (TIMIP)
In order to prevent this situation, the terminal is forced by
configuration (either manually or automatically by DHCP) to send all
packets to the IP Gateway of the local subnetwork through it?s
current AP. This is accomplished by setting the subnetwork mask
configuration to a special value of all bits at ?one?
(255.255.255.255), and the default GW the current ANG of this AN.
When the terminal sends an ARP request to obtain the MAC address of
the Gateway, the local AP answers with its own MAC address,
performing a proxy ARP mechanism on behalf of the ANG (as described
on standard MIP procedures [2]), which is sufficient to receive the
packets generated on the terminal for subsequent routing with the
rules depicted above.
. Macromobility
TIMIP relies on MIP to support macromobility. The ANG is the HA for
MNs whose home network is its TIMIP domain. As LMNs do not implement
MIP, the ANG implements all the needed functionality on their
behalf. On the other hand, when a foreign MN supports MIP, the ANG
acts as a Foreign Agent for the local TIMIP domain.
9.1. Macromobility for LMNs
When a MT enters a TIMIP domain different from its current location,
the terminal is locally authenticated and a routing path is created
between the terminal and the ANG. Packets are then sent/received
to/from the outside through the ANG. If the home network of the MT
is a different MIP domain, its HA must be notified so that packets
can be correctly routed through an IP tunnel established from the HA
to the FA located at the ANG.
After consulting the registration information of the MT (namely the
IP address of the HA and the MIP capability), the ANG realizes that
it is a foreign MT and that it does not implement MIP. Consequently,
the ANG must act as a surrogate MIP element on behalf of the MT,
generating all MIP signaling as the MT would (see
Firstly it has to notify the HA about the MT?s new location and
CoAddr by means of a MIP Registration Request message, which
requires authentication using the authentication key between the MT
and the HA. As the ANG does not know this key, it is the MT that
must sign the message. The ANG sends the MT an AuthenticationRequest
message containing &IP address of the ANG, IP address of the HA, MIP
Registration Request, timestamp& authenticated by the ANG with
MD5(K1, AuthenticationRequest), where K1 is the authentication key
between the MT and ANG for this TIMIP domain. The MT finds K1 in the
key database based on the IP address of the ANG and obtains the
authentication key of his home network (K2) in the key database,
based on the IP address of the HA.
Internet-draft
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January 2003
Mobility for IP (TIMIP)
It then answers with an AuthenticationReply message containing &IP
address of the ANG, IP address of the HA, MD5(K2, MIP Registration
Request), timestamp&. This message is also authenticated by the
terminal with MD5(K1, AuthenticationReply). The ANG can now send a
correctly authenticated MIP Registration Request message to the HA
adding the message digest provided by the MT as a Mobile-Home
Authentication Extension field.
The HA answers with an authenticated MIP Registration Reply message,
which has a message digest MD5(K2, MIP Registration Reply) appended
as a Mobile-Home Authentication Extension field. In order to verify
the identity of the HA, the ANG must again rely on the MT. It sends
an AuthenticationRequest message to the MT, containing &IP address
of the ANG, IP address of the HA, MIP Registration Reply (except the
Mobile-Home Authentication Extension), timestamp&, authenticated
with MD5(K1, Authentication Request).
The terminal answers with an AuthenticationReply message containing
&IP address of the ANG, IP address of the HA, MD5(K2, MIP
Registration Reply), timestamp&. If the MD5 digest of the MIP
Registration Reply provided by the MT matches that present in the
Mobile-Home Authentication Extension of the Registration Reply
message sent by the HA, the ANG can resume communication with the
After the communication with the HA is established, the ANG de-
encapsulates the tunneled IP packets that come from the HA addressed
to the MT and forwards them normally to the MT according to the
routing path established in the AR tree. Packets generated by the MT
are routed normally according to the same procedures described above
for micromobility. In this situation, the subsequent handoff between
APs within the foreign TIMIP domain are dealt with TIMIP
micromobility procedures only.
As already seen, all traffic that crosses the boundary of the TIMIP
domain must pass through the ANG, which is the IP Gateway to the
core network. Nevertheless, whenever an MT moves to a different
domain, the IP address of the ANG changes. In order to keep
consistency, the MT would have to change its IP Gateway
configuration at each handoff between TIMIP domains, as otherwise
the ARP requests to obtain the MAC address of the IP Gateway would
not be answered by the APs.
To address this situation, the MTs are configured with a well-known
ANG IP address recognized by all APs of all TIMIP domains. The
latter broadcast gratuitous ARP messages associating their own MAC
addresses with the well-known ANG IP address each time a terminal
performs an association, and performing proxy ARP for this well-
known ANG IP address as described before.
9.2. Macromobility for MIP terminals
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Terminal Independent
January 2003
Mobility for IP (TIMIP)
When the MT supports MIP but belongs to a different domain, the ANG
plays the role of FA. The MT powers-on in the same way as legacy MTs
in the TIMIP domain. Once this is completed, the MIP signaling
starts. The ANG broadcasts
[7] Router Advertisement
messages periodically, specifying its IP address as the MIP CoAddr.
In order to haste the process, the MT can request the advertisement
by broadcasting a Router Solicitation message, which is then
forwarded by the AP to the ANG.
After the MT receives a Router Advertisement message, it notifies
its HA about the CoAddr through the ANG. The HA is then able to
forward the incoming packets to the CoAddr through an IP tunnel. The
ANG de-encapsulates the IP packets and forwards them normally to the
MT according to the routing path established in the AR tree. Packets
generated by the MT are also routed normally within the TIMIP
domain. Handoff between APs within the foreign TIMIP domain are
dealt with TIMIP micromobility procedures only (see above) as the FA
is always the same (i.e. the ANG).
It should be noted that in this case it is the MT itself that
authenticates the MIP messages when communicating with the HA.
. Message Formats
In this section, we discuss the message formats for the TIMIP
messages sent between the ARs of the AN. These messages are sent on
standard ICMP protocol, extending it to special usage by the ARs,
with a private ICMP_Type that is exclusive for the use of the TIMI
Currently, there is only two message types defined ? RoutingUpdate
and RoutingUpdateAck ? to be used according the procedures outlined
on the previous sections.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ICMP_CheckSum
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Legacy Terminal Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Exclusive value for the TIMIP protocol on
each AN (official value T.B.D.)
1 (Routing Update), 2 (Routing Update Ack)
LT Address
IP of the Legacy Terminal that this update
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
refers to.
Timestamp of Detection of the LT on the AP
formatted in Network Time Protocol [5].
. Generic Detection Algorithm
The primary means of detection of the movements of the terminals is
by means of layer-2 information, that can easily be derived from the
specific mechanisms of most wireless technologies. However, when
TIMIP is to be used in technologies unable to derive such
information, a Generic detection procedure is used, that is similar
to the well known ?MAC learning? algorithm.
In this method, the AP continuously receives all messages
transmitted to the wireless medium, either by promiscuous scanning
or other means, receiving the layer-2 MAC frames with the MAC sender
information. The AP maintains a cache of known MAC stations present
in the area, which
is enough to detect the arrival of a new
station. Consequently, when a LMN connects to an AP, the first
packet it sends will be interpreted by the AP as an arrival,
triggering the primitive that launches the micro-mobility routing
procedures.
. DHCP support for automatic registration
When a LMN is roaming inside an AN, each AP already knows the
specific details about this terminal, in particular its MAC and IP
addresses. These details can be entered offline trough management
procedures, or automatically if the LMN supports the DHCP auto-
configuration protocol [10].
For this feature, the ANG implements a DHCP server that manages the
entire IP address pool of this AN, and the remaining ARs implement
DHCP relay agents functionality (thus, there exists only one DHCP
server per AN). When the terminal enters the TIMIP domain for the
first time (see Figure 1), the TIMIP power-up procedure is delayed
until the DHCP procedure is completed. This procedure uses the
standard DHCP messages (discover, offer, request and ack) through
the relay agents as defined in [10], resulting on the automatic
assignment of an IP address to the LMN.
However, the DHCP operation also provides the automatic registration
of the terminal on the network. As the LMN identifies itself with
his own MAC address, the ANG is able to add a new registration entry
to the TIMIP database containing the MAC and IP addresses, and to
broadcast this information to all ARs on the network.
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
This way, after the DHCP, the TIMIP power-up operation is able to be
performed as defined above, because all APs will have the necessary
information regarding the terminal. It should be noted that the DHCP
operation only happens when the terminal firstly enters a IP domain,
so that subsequent handoffs between APs within the TIMIP domain are
dealt with TIMIP micromobility procedures only (see Figure 2).
. References
Grilo A., Estrela P., Nunes M., Terminal Independent Mobility for
IP (TIMIP)?, IEEE Communications, Vol. 39 N?12, December 2001.
Perkins C. (Editor), "IP Mobility Support for IPv4" (Proposed
Standard), , IETF, January 2002.
A. Campbell et al, ?Design, Implementation and Evaluation of
Cellular IP?, IEEE Personal Communications, Vol. 7 N?4, August
R. Ramjee et al, ?IP-Based Access Network Infrastructure for
Next-Generation Wireless Data Networks?, IEEE Personal
Communications, Vol. 7 N?4, August 2000.
Mills D. ?Network Time Protocol (Version 3), Specification,
Implementation and Analysis?, , IETF, March 1992.
Rivest R., ?The MD5 Message-Digest Algorithm?, , IETF,
April 1992.
Deering S. (Editor), ?ICMP Router Discovery Messages?, ,
IETF, September 1991.
E. Gustafsson, ed., ?Requirements on Mobile IP from a Cellular
Perspective?, Internet draft,
, work in progress, June 1999.
R. Braden, Ed., ?Requirements for Internet Hosts -- Communication
Layers?, , October 1989
10 R. Droms, "Dynamic Host Configuration Protocol", , March
. Author's Addresses
All comments are welcome, and should be directed to the authors of
the present draft:
Pedro Estrela
Rua Alves Redol, N.9
Internet-draft
Terminal Independent
January 2003
Mobility for IP (TIMIP)
Lisboa, Portugal
pedro.estrela@inesc.pt
António Grilo
Rua Alves Redol, N.9
Lisboa, Portugal
antonio.grilo@inov.pt
Teresa Vazao
Rua Alves Redol, N.9
Lisboa, Portugal
teresa.vazao@inesc.pt
Mário Nunes
Rua Alves Redol, N.9
Lisboa, Portugal
mario.nunes@inesc.pt
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