over 篇1
L2L (站点到站点) VPN是实现企业间数据加密传输最常用的方式, 采用IPSEC协议是实现L2L VPN较为经典的VPN技术。通过在企业路由器或防火墙上配置IPSEC, 加密站点间的流量, 实现在网络层对数据的加密。然而, IPSEC VPN实际应用时也存在问题:如不支持组播协议, 站点身后网络数多造成感兴趣流增加等, 为了解决IPSEC VPN的缺陷, cisco提出通过GRE技术, 按封装包顺序不同, 出现了GRE over IPSEC或IPSEC over GRE两种方式, 本文将通过一个实例分析、比较两种技术。
1 GRE技术
GRE (通用路由封装) 定义了在任意一种网络层协议上封装任意一个其它网络层协议的隧道协议。它能够将各种网络协议 (IP协议与非IP协议) 封装到IP隧道内, 并通过IP网络在站点间建立起一个虚拟的隧道连接。
GRE是一种典型的三层隧道封装技术, 封装后的数据包主要有4个部分组成。其中内层IP头部和内层实际传递数据为封装负载。在内层IP头部之前添加一个GRE头部, 再在GRE头部之前, 添加一个全新的外层IP头部, 从而实现对原始数据包的封装, GRE封装结构图如图1所示。
GRE头部较小, 采用4个字节, 封装效率高, 但对封装的负载不提供任何安全措施, 以明文传输。采用GRE over IPSEC或IPSEC over GRE建立VPN时, GRE隧道的作用就是虚拟地把两个站点连接起来, 可以在隧道上运行动态路由协议, 支持组播的封装。而IPSEC的作用是实现数据加密、身份认证等。
2 两种技术对比
GRE over IPSEC或IPSEC over GRE哪个好呢?两种技术有什么异同点, 下面通过实例从封包方式、感兴趣流以及加密映射图配置等方面进行比较。实例网络结构图如图2所示。
2.1 封包方式
GRE over IPSEC是先把数据封装成GRE包, 然后再封装成IPSEC包。做法是在物理接口上监控, 是否有需要加密的GRE流量, 所有这两个站点间的GRE数据流将被加密封装为IPSEC包进行传递, 这样所有的数据包都会被加密, 包括隧道的建立和路由的建立和传递。
假设Site1的网络1需要与Site2的网络4通信, 那么先进行GRE封装, 然后再进行IPSEC封装, 推荐使用传输模式, 这样可以节约一个IP头部字节 (20个字节) 。GRE over IPSEC封包结构图如图3所示。
IPSEC over GRE是把需要加密的数据包先封装成IPSEC包, 然后再扔到GRE隧道里。做法是在隧道接口上监控是否有需要加密的数据流, 有则先加密封装为IPSEC包, 然后封装成GRE包进入隧道。而其他数据将不加密直接走GRE隧道, 即存在数据可能以明文方式传输。
假设Site1的网络1需要与Site2的网络4通信, 采用IPSEC over GRE, 封包结构图如图4所示。在封包结构中, 并没有出现GRE头部, 原因后续将进行说明。
2.2 感兴趣流
感兴趣流就是需要被加密传输的数据, 即需要进行保护的流量。通常用ACL (访问控制列表) 来定义感兴趣流。
对于GRE over IPSEC来说, 定义的感兴趣流是所有被GRE封装的流量, 这样做的优点就是可以减少感兴趣流的定义, 本例中ACL语句定义如下:
ip access-list extended vpn
permit gre host 202.100.1.1 host 61.128.1.1
将两个站点间被GRE封装的流量定义为感兴趣流, 包括组播流量, 如ospf路由, 这样所有的内部网络数据和组播数据都将被IPSEC封装, 实现加密传输。
而IPSEC over GRE, 定义的感兴趣流是IPSEC封装的数据, 如Site1的网络1与Site2的网络4通信, 则ACL语句定义如下:
ip access-list extended vpn
permit ip 1.1.1.0 0.0.0.255 4.4.4.0 0.0.0.255
实例中, 如所有网络间都要加密传输, 则最多需要定义9条感兴趣流。
2.3 加密映射图配置
加密映射图配置主要是匹配感兴趣流, 设置对方的Peer以及作用接口。
对于GRE over IPSEC来说, Peer通常设置为对方物理口公网地址, 本例Site1设置为61.128.1.1, Site2设置为202.100.1.1, 映射图的作用接口也为物理接口, 本例为Site1、Site2公网接口。
而IPSEC over GRE, Peer可以设置为对方物理口公网地址, 即Site1设置为61.128.1.1, Site2设置为202.100.1.1, 如图4所示。Peer也可以设置为对方的Loopback口, 那样封包中将出现GRE头部, IPSEC over GRE封包结构图, 如图5所示。假设将Peer分别设置为对方的Loopback口, 地址分别是Site1:lo11:11.11.11.1/24, Site2:lo22:22.22.22.1/24。
映射图的作用接口必须为GRE隧道接口, 本例为Site1、Site2的Tunnel 0接口。
在图5中, 由于Peer设置为对方Loopback口, 所以二次封包时外层地址为Loopback口地址, 此时由于已经不匹配感兴趣流, 故由隧道直接传输。
3 结论
不管是GRE over IPSEC或IPSEC over GRE, GRE的主要作用是实现组播数据的传输。GRE over IPSec是先GRE后IPSEC, IPSEC是最后的承载方式, 解决了IPSEC不支持组播的问题, 此方法实现了对所有GRE流量的加密传输, 减少了感兴趣流的定义, 工程应用较多, 安全性高。IPSec over GRE是先IPSEC后GRE, 此方法同样解决了IPSEC不支持组播的问题, 但感兴趣流需定义多条, 且路由流量是明文传输, 故安全性一般, 工程应用较少。
对于两种技术的应用, 可根据实际网络情况综合考虑选择。
摘要：通过一个实例对比分析两种L2L VPN技术在封包方式、感兴趣流以及加密映射图配置方面的异同点。
关键词：L2L VPN,IPSEC,GRE,对比
参考文献
[1]王隆杰, 梁广民.思科网络实验室CCNP (交换技术) 实验指南[M].北京:电子工业出版社, 2012.
over 篇2
1 安徽地震VPN网络
VPN网络是指利用互联网络, 通过建立“隧道”等相关技术手段建立连接, 以较低的费用, 实现类似于租用专线所带来的安全可靠的数据传输。VPN网络用户可以从不同的地点, 以不同的方式通过互联网络与本行业网用户进行通信。采用VPN远程接入, 不受地域限制, 可以多人同时接入。
2 GRE over IPSee VPN工作原理
2.1 IPSec VPN
IPSec VPN是目前VPN技术中使用率非常高的一种技术, 同时提供VPN和信息加密技术。IPSec在IP层提供安全服务, 用来保护一条或多条主机与主机间, 安全网关与安全网关间, 安全网关与主机问的路径, 目的是为IP提供高安全性特性。主要通过使用两大传输安全协议, 头部认证 (AH) 和封装安全负载 (ESP) 以及密钥管理程序和协议的使用来完成。
IPSec技术的优缺点是能保障数据的安全传输, 缺点是不能够对网络的组播报文进行封装, 所以常用的路由协议报文不能在IPSec协议封装隧道中传输。
2.2 GRE
GRE (Generic Routing Encapsulation) 协议是对某些网络协议 (如IP和IPX) 的数据报进行封装, 使这些被封装的数据报能够在另一个网络层协议 (如IP) 中传输。
GRE是VPN的第三层隧道协议, 在协议层之间采用了一种被称之为Tunnel (隧道) 的技术。Tunnel是一个虚拟的点对点的连接, 任实际中可以看成仅支持点对点连接的虚拟接口, 这个接口提供了一条通路使封装的数据报能够在这个通路上传输.并且在一个Tunnel的两端分别对数据报进行封装及解封装。
GRE技术的最大优点是可以对多种协议、报文进行封装, 并封装存隧道安全传输。缺点是只提供简单的隧道验证功能, 对传输的数据没有加密功能, 数据在传输的过程是不安全的。
2.3 IPSec与GRE两种技术的综合
针对IPSec和GRE技术的优缺点.综合运用IPSec和GRE技术, 利用GRE技术对数据和动态路南协议报文进行隧道封装, 通过IPSEC技术保证数据的安全性, 这样就构成了IPSec over GRE VPN技术。
3 具体的实现过程
4 结语
随着安徽防震减灾事业的不断发展, 越来越多新建台站将通过GRE over IPSec VPN技术连接到省区域中心, 它将GRE隧道技术和IPSec VPN技术进行优势互补, 将不同地区的内部网互连以达到资源共享和实现内部数据安全传输, 保证了通讯的畅通和稳定, 为安徽防震减灾事业提供了技术保障。
摘要：本文系统介绍了GRE VPN技术在安徽地震行业网络中的实现及应用, 以实现不同地域之间用户跨网络安全通信为背景, 通过构建VPN网络, 实现远程安全接人局域网, 提高了数据传输及远程维护的效率。
关键词：GRE,IPSec,安徽
参考文献
[1]刘春艳.基于IPSec的VPN网关设计与实现[J].网络安全技术与应用, 2013.
[2]王懿.VPN技术及其安全优势的分析探究[J].魅力中国, 2013.
人生没有Game Over 篇3
电影中的主人公李献计是一位患有“差时症”的病人，一直以来，他被这种奇特病症所困扰，与整个世界格格不入，直到他遇见王倩。然而，一场突如其来的意外打破了二人平静幸福的生活，无法接受现实的李献计再次陷入了差时症的漩涡当中。终于有一天，李献计获得一张可以穿越时光回到过去的游戏光盘，为了拯救失去的恋人，他不惜以卖肾为代价，打造金属手臂，只为能够打通这款游戏。在众多高人的指引下，李献计开始了一段为爱而生的超时空冒险，然而，即使可以回到过去，那份爱情是否还存在，李献计心里一样没谱……
“差时症”是《李献计》的原创。其实主观时间与客观时间的差距是一个亘古不变的哲学问题，对于时间、爱、存在、理解的质询是人类无时不刻不在面临的困境。“你做的这一切就只是为了一个女孩？”“其实就是为了自己，能从分手后的世界顺利逃走。”对，在爱情之后，时间可以缩短，也可以延长，长长短，短短长。对于爱情，对于分手，对于时间，我们也许还在不停地反复和纠结，就像你还在想着诺基亚的全键盘手机怎么还不出新款的时候，苹果却告诉你，其实你需要的是触摸。《李献计》正是如此，告诉那些花很多钱想要拍电影的人，你们不要再想什么花钱的表现时间、爱情的方式了，你们其实就只要把你们脑中的主观世界，用客观世界的方式呈现出来就好。
电影是一部诚意之作，在已有的动画作品的高度之上，敢于再进行深度加工，将一个20分钟简简单单的动画故事，讲成一个90分钟的完整的故事。说真的，最开始我是捏着一把冷汗的，但是将故事看完，我会心地走出了影院。我想，对于当年被《李献计》打动的男孩女孩们，走进影院重温这样的感动，是不会失望的。电影保留了动画最经典的故事梗概、精彩对白，使动画的婉转惆怅与积极向上的精神内核得以传承。最重要的是，动画是彻底的造梦，让你脱离现实尘嚣；电影则还原了真实的场景，演员实拍是生活，动画部分则是主观世界。
电影对动画原作最大的改编是结局。动画原作中，李献计在最后终于见到了王倩，可是那时的他為了这次相见已经在时间洪流中变成了垂暮老人，而且在无数次的穿越中，他的激情也消磨成了平静。就像我们所经历的那样，曾经以为的天长地久到最后也不过变成了一句“好久不见”。电影的改编大概还是想要让人们保有对爱情的憧憬，于是老年的李献计为了拯救他的爱情一个人等待了50年，这种荧幕上的主流爱情观打动了很多人，但真正能做到的又有几人呢？
当然也有抱憾的地方，房祖名似乎无法hold住李献计的气场，若是可以真的找一个有北京胡同气息的侃爷，像混混却又满怀深情该多好。不过因为是可爱的电影，所以那么多的电影植入也没有觉得很厌烦，你们发现有几处植入呢？
英语前缀over 篇4
overboard ad. 自船上落下,在船外
overburden vt. 使负担过重
overcame overcome的过去式
overcast a. 阴天的,阴暗的,愁闷的
overcharge vt.vi. 讨价过高,装药过多,过度充电
overcoat n.大衣
overcome vt.战胜，克服
overcrowd vi. 过度拥挤
overcrowded a. 过度拥挤的
overcrowding a. 人口过密的`
overdo v. 做理过头，过火
overdose n. (药物)过度剂量
overdraft 透支，汇款过额;透支额
overdraught 透支，透支额
overdraw vt. 透支
overdrawing 透支，超支
overdue a. 过期的,未兑的,迟到的
overeat vt. (使)吃过量
overestimate vt.过高估计
overewhelming adj.压倒一切的
overexposure n. 过度暴露
overextend v. 使…承担过多的义务
overflow vt.从…中溢出
overfulfill vt. 超额完成
overgrow vt. 在…上长满;丛生;vi. 生长过旺;长得太快
overgrown a. 发育过度的,生长过大的,不合身的
overhand a. 投下的,举手过肩而投掷的
overhang vt.悬于…之上vi.悬垂
overhaul n./v. 彻底检查，大修
overhead adv.在头上;在空中
overhear vt.偶然听到;偷听
overheat v.加热过度
overheating 市场狂热，景气过度
overjoy vt. 使大喜
overjoyed adj. 非常高兴
overland a. 陆路的,经过陆地的,陆上的
overlap vt.与…交搭 vi.重迭
overlapping adj. 相互重叠的
overlay n. 覆盖,覆盖图
overleap vt. 跳过,看漏,省略
overload vt.使超载
overlook vt.眺望;看漏;宽容
overmuch a. 过多的,过度的
overnight ad.一夜;突然
overpass n. 天桥,陆桥
overpay 付得过多
overpayment n. 多付的款项
overplus n. 剩余,过剩
overpopulation n. 人口过剩
overpower vt. 击败,打胜,克服
overprice 标价过高
overproduction n.生产过剩，过量生产
overrall a.包括一切的，全部的 n.罩衫，工装裤
overrate vt. 评价过高,高估,估价过高
overreach v. 做事过头
override v. 不理会，推翻
overriding adj. 最主要的
over 篇5
Listed banks lead in the profit list is， in some ways， heartening， indicating banks are still strong in profitability. In the past few years， the quality of their management along with their strength in innovation has made remarkable progress. However， it also reflects that the banking industry， far from serving the real economy， has instead become severely detached from it.
At the end of June， the 2，521 listed companies that have published their financial reports were seen to harvest profits of 581.3 billion yuan （$94.6 billion）， and the profits of the 16 listed banks was 17.8 percent higher than that figure. The Industrial and Commercial Bank of China alone earned 148.1 billion yuan （$24.1 billion） in the first half of the year， equivalent to 21.6 percent of the total profits of the 2，521 non-financial public companies. Such an irrational profitability structure is bound to undermine sustainable economic development in the long term.
Since social wealth is fixed during a certain period of time， the more banks take away， the less enterprises propping up the real economy can get. In this way， these enterprises will gradually lose their incentive to operate， and head toward declination and bankruptcy. This represents a vicious circle and has begun to yield negative results. Although bank profits still edge those of real enterprises， the sectors crown has shown signs of slipping. As their half-year financial reports suggest， five of the 16 listed banks have witnessed their profit growth declining to a single digit. In contrast， the 16 banks maintained an average growth above 10 percent during the same period of last year.
Moreover， the bad loans of the 16 listed banks amounted to 558 billion yuan （$90.9 billion） at the end of June， an increase of 77.2 billion yuan （$12.6 billion） in the first half. With the exception of the Bank of Ningbo， all banks saw a surge in both bad loans and their nonperforming loan ratio. Worse still， this adverse trend is not confined to listed banks. According to statistics from the China Banking Regulatory Commission， in the first half of the year， the bad loans of commercial banks increased 102.4 billion yuan （$16.7 billion）， exceeding the total added amount of 99.3 billion yuan （$16.2 billion） last year. In the second quarter， bad loans rose by 48.3 billion yuan （$7.9 billion）， marking an increase for 12 consecutive threemonth periods.endprint
Obviously， the sharp rise in bad loans mainly stems from the recession in the real economy and those enterprises affected. Bad loans caused by overcapacity， a sluggish steel trade and faltering small and micro-firms have begun to increase. The surge of bad loans will surely continue into the future if the relevant authorities dont seek solutions.
Moreover， traditional banks are becoming increasingly challenged by Internet finance. Whether it be in traditional banking services like borrowing and lending or in intermediary services like payment and money management， Internet finance has waged an all-out war against traditional brick-and-mortar banks. In the long run， it is likely business activities will be moved onto the Internet， while traditional banks are still struggling with their growing obsolescence. If they refuse to change， they are bound to perish in the wake of the overwhelming expansion of the Internet finance sector.
over 篇6
eg:相关解析：
表t_pi_part
字段idcodename
value 1222a
value 2222b
value 3 333c
给code相同的part code 添加行标，根据id 排序
select p.* ,row_number()over(partition by p.code order order by a.id desc) as row_index from t_pi_part p;
一：分析函数over
Oracle从8.1.6开始提供分析函数，分析函数用于计算基于组的某种聚合值，它和聚合函数的不同之处是
对于每个组返回多行，而聚合函数对于每个组只返回一行，
下面通过几个例子来说明其应用。
1：统计某商店的营业额。
datesale
120
215
314
418
530
规则：按天统计：每天都统计前面几天的总额
得到的结果：
DATESALESUM
----- -------- ------
12020--1天
21535--1天+2天
31449--1天+2天+3天
41867.
53097.
2:统计各班成绩第一名的同学信息
NAMECLASS S
----- ----- ----------------------
fda180
ffd178
dss195
cfe274
gds292
gf399
ddd399
adf345
asdf355
3dd378
通过：
--
select * from
(
select name,class,s,rank()over(partition by class order by s desc) mm from t2
)
where mm=1
--
得到结果：
NAMECLASS SMM
----- ----- ---------------------- ----------------------
dss1951
gds2921
gf3991
ddd3991
注意：
1.在求第一名成绩的时候，不能用row_number()，因为如果同班有两个并列第一，row_number()只返回一个结果
2.rank()和dense_rank()的区别是：
--rank()是跳跃排序，有两个第二名时接下来就是第四名
--dense_rank()l是连续排序，有两个第二名时仍然跟着第三名
3.分类统计 (并显示信息)
ABC
-- -- ----------------------
ma2
na3
ma2
nb2
nb1
xb3
xb2
xb4
hb3
select a,c,sum(c)over(partition by a) from t2
得到结果：
ABCSUM(C)OVER(PARTITIONBYA)
-- -- ------- ------------------------
hb33
ma24
ma24
na36
nb26
nb16
xb39
xb29
xb49
如果用sum，group by 则只能得到
ASUM(C)
-- ----------------------
h3
m4
n6
x9
无法得到B列值
=====
select * from test
数据:
A B C
1 1 1
1 2 2
1 3 3
2 2 5
3 4 6
---将B栏位值相同的对应的C 栏位值加总
select a,b,c, SUM(C) OVER (PARTITION BY B) C_Sum
from test
A B C C_SUM
1 1 1 1
1 2 2 7
2 2 5 7
1 3 3 3
3 4 6 6
---如果不需要已某个栏位的值分割,那就要用 null
eg: 就是将C的栏位值summary 放在每行后面
select a,b,c, SUM(C) OVER (PARTITION BY null) C_Sum
from test
A B C C_SUM
1 1 1 17
1 2 2 17
1 3 3 17
2 2 5 17
3 4 6 17
求个人工资占部门工资的百分比
SQL>select * from salary;
NAME DEPT SAL
---------- ---- -----
a 10
b 10 3000
c 10 5000
d 20 4000
SQL>select name,dept,sal,sal*100/sum(sal) over(partition by dept) percent from salary;
NAME DEPT SAL PERCENT
---------- ---- ----- ----------
a 10 2000 20
b 10 3000 30
c 10 5000 50
d 20 4000 100
二：开窗函数
开窗函数指定了分析函数工作的数据窗口大小，这个数据窗口大小可能会随着行的变化而变化，举例如下：
1：
over(order by salary) 按照salary排序进行累计，order by是个默认的开窗函数
over(partition by deptno)按照部门分区
2：
over(order by salary range between 5 preceding and 5 following)
每行对应的数据窗口是之前行幅度值不超过5，之后行幅度值不超过5
例如:对于以下列
aa
1
2
2
2
3
4
5
6
7
9
sum(aa)over(order by aa range between 2 preceding and 2 following)
得出的结果是
AASUM
---------------------- -------------------------------------------------------
110
214
214
214
318
418
522
618
722
99
就是说，对于aa=5的一行 ，sum为5-1<=aa<=5+2 的和
对于aa=2来说 ，sum=1+2+2+2+3+4=14;
又如 对于aa=9 ，9-1<=aa<=9+2 只有9一个数，所以sum=9;
3：其它：
over(order by salary rows between 2 preceding and 4 following)
每行对应的数据窗口是之前2行，之后4行
4：下面三条语句等效：
over(order by salary rows between unbounded preceding and unbounded following)
每行对应的数据窗口是从第一行到最后一行，等效：
over(order by salary range between unbounded preceding and unbounded following)
等效
over 篇7
Every May and June, female Tibetan
antelopes travel up to 300 km to reach their breeding grounds. Then, just a month after giving birth, they begin the journey to their winter pastures. Today, even though a railway and a highway cut across their migration route, the antelopes continue their annual migration.
“The Qinghai-Tibet Railway, which has been in operation for five years, has not changed the foraging, migration and breeding behaviors of Tibetan antelopes,”said Miao Xiaohua, Vice President of the Qinghai-Tibet Railway Co.
On the afternoon of July 27, nearly 40
Tibetan antelopes were observed galloping across the Qinghai-Tibet Highway and Qinghai-Tibet Railway.
When the herd approached the railway, they paused. Two adult antelopes and a fawn scurried through the passage under the railway’s Wubei Bridge. Only after seeing these front-runners were safe, did the remainder of the herd follow.
Experts say about 90 percent of migrat
ing antelopes go though the passage under Wubei Bridge, one of the 33 wildlife pas- sages along the 1,956-km-long QinghaiTibet Railway.
Life passages
The pristine natural ecological system in the Qinghai-Tibet Plateau is unique and fragile. On the freezing heights of the “Roof of the World,” the average annual temperature is 4-6 degrees Celsius. The plateau is the source of several large rivers in China including the Yellow River, the Yangtze River and the Lancang River. It is also the natural habitat of rare animals such as Tibetan antelopes, Tibetan wild donkeys and snow leopards.
Tibetan antelopes are listed as endangered animal by the World Conservation Union. In the last century they were hunted for their warm, soft and expensive wool, which is woven into the luxury fabric shahtoosh.
In the 1980s alone, rampant poaching re
duced the antelope population from 200,000 to 20,000, said the Xinhua News Agency. And numbers only recovered after the Chinese Government set up nature reserves in the Qinghai-Tibet Plateau around the turn of the 20th century.
The Qinghai-Tibet Railway cuts through the Sanjiangyuan, Qiangtang and Hoh Xil nature reserves, the Tibetan antelopes’ major natural habitat.
Even before the ground was broken for the railway, worries about its environmental impact abounded.
“We put the environment first while constructing and running the railway,” Miao said.
To minimize the disruption to wildlife,
33 migration passages have been built along the railway.
That was the first time that such “green”
passages were incorporated into a major Chinese engineering project, Miao said.
Twenty-five of the passages are in Qinghai Province and eight are in Tibet Autonomous Region, with a total length of 58.4 km, said Yang Qisen, a research fellow with the Institute of Zoology of the Chinese Academy of Sciences. Yang designed the passages following lengthy observation of animal behavior on the plateau.
In sensitive spots, the railway goes through tunnels or over bridges to avoid severing animals’ migration routes; in other places, gentlysloped overpasses have been built for animals to cross the track. At the section of the railway that travels through the area most frequently passed by migrating antelopes, many bridges were built, including 143 flyovers, each more than 100 meters long.
“In addition to building ‘green’ passages, railway employees are required to postpone or suspend ongoing projects that interfere with antelopes’ migration,” Miao said.
“These efforts have paid off. In recent years, an increasing number of Tibetan antelopes have been observed migrating,” said Xiao Penghu, deputy chief of the Hoh Xil Nature Reserve.
The number of antelopes living in the Hoh Xil Nature Reserve and its vicinity has also increased from nearly 50,000 in 2006, when the railway started operation, to about 60,000 now, Xiao said.
Gradual adaptation
“In 2003, when railroad construction in the Hoh Xil Nature Reserve began, 75 percent of Tibetan antelopes failed to migrate to their traditional breeding ground; yet over the years, they have gradually adapted to the passages along the railway,” Yang said.
Yang found by 2004, most antelopes
managed to migrate to their summer breeding ground. He observed more than 1,600 pregnant antelopes going to the breeding ground, and 2,300 returning after birth. “Not every mother and calf survive the migration,” Yang said.
On their return, Yang found approximately 96 percent of the antelopes used the passages.
Yang’s team then improved the pas
sages’ design and in 2005, he saw about 98 percent of migrating antelopes using the passages.
In 2006, 2,952 antelopes returned from their breeding ground, with 98.17 percent using the passages, Yang said in a 2008 letter to the UK-based Nature magazine.
After monitoring antelopes crossing the
Qinghai-Tibet Railway between 2004 and 2006, Yang’s findings were confirmed by researchers from the Shaanxi Institute of Zoology.
Researchers at the institute found, in
2004, Tibetan antelopes gathered near the passages and hesitated for one to two days before attempting to get through. But in 2005, most antelopes went over after hesitating for only half a day. On June 20, 2005, researchers found it only took a herd of 310 antelopes 11 minutes to go through a passage in the Hoh Xil Nature Reserve.
The success in balancing the antelopes’welfare with the construction of a massive railway has inspired designers of other large projects in China.
Builders of a railway between Yichang City in central China’s Hubei Province and Wanzhou District in Chongqing Municipality in southwest China initially planned a tunnel through the Yangtze River but later replaced it with a bridge, in order to avoid damaging the breeding grounds of the Chinese sturgeon, a highly endangered species of fish.
Greater efforts
“Since the Qinghai-Tibet Railway went into full operation, we have never slackened our environment protection efforts,” said Wang Zhiwei, a manager in the Yufeng Railroad Maintenance Co., a subsidiary of the Qinghai-Tibet Railway Co. that is responsible for maintaining the section of railway between Golmud in Qinghai to Lhasa in Tibet.
“All passenger trains running along the railway are equipped with compressed garbage and sewage collection systems. The waste collected is shipped to treatment stations in nearby cities,” said Liu Lijun, former head of a train crew working on the QinghaiTibet Railway.
“Fifteen sewage water treatment stations
have been built along the stretch of railway between Golmud and Lhasa and the stations are monitored regularly to ensure the treated water meets required standards,” Wang said. To reduce air pollution, the stations use solar power for heating and lighting.
“In the past five years, railroad maintenance companies have also planted vegetation wherever appropriate along the Qinghai-Tibet Railway. Now the ‘greened’area, which runs along 675 km, or 31 percent of the railway, totals 5.6 million square meters,” Wang said.
“Even when the railway was under construction, measures were taken to protect the area’s fragile eco-system. When tracks were laid, the turf was cut into pieces and moved to another area, where vegetation was extracted for replanting,” Yang said.
Experts say the vegetation coverage rate
in Hoh Xil has increased from less than 15 percent in 2003 to nearly 30 percent now.
“The railway is truly a green route,” Xiao said. “Since it went into operation in 2006, it has not created any environmental crisis.”
over 篇8
组网需求：
随着智能终端的普及，Android 和苹果的IOS操作系统占有电子市场的绝大份额。越来越多的客户希望利用这些手持终端设备与防火墙直接建立VPN连接，从而访问公司内部网络资源。本案例用于指导网络工程师对上述组网需求进行配置。
组网图：
移动终端通过无线与MSR三层可达，路由可达，中间不允许经过nat设备。
设备版本
Android：MIUI V5、原生安卓4.0 IOS版本：IOS 6 IOS 7 MSR版本：2209P37
四、配置步骤：
1、设备开启L2TP 功能，配置好虚模板地址以及相应的地址池，创建用户123，密码123 # l2tp enable # domain system ip pool 1 192.168.13.200 192.168.13.250 # local-user 123 password cipher 123 service-typeppp # l2tp-group 1 undo tunnel authentication allow l2tp virtual-template 0 # interface Virtual-Template0 ppp authentication-mode chap domain system pppipcp remote-address forced remote address pool 1 ip address 192.168.13.1 255.255.255.0 #
2、针对安卓手机配置IPSec： # ike proposal 1 encryption-algorithmaes-cbc 256 dh group2 sa duration 28800 # ike peer android exchange-mode aggressive proposal 1 pre-shared-key cipher 123456789 id-type name
remote-nameaaa local-name rt1 nat traversal # ipsec proposal 1 encapsulation-mode transport # ipsec policy-template android 1 ike-peerandroid proposal 1 # ipsec policy phone 1 isakmp template android # interface GigabitEthernet0/0 port link-mode route ip address 10.153.47.103 255.255.255.0 ipsec policy phone #
3、安卓客户端的配置： 名称：随便起
类型：L2TP/IPSEC PSK 服务器地址：LNS的外网地址 IPSec标示符：aaa 预共享密钥：123456789
4、针对IOS 用户的IPSec配置： # ike proposal 2 encryption-algorithm 3des-cbc dh group2 authentication-algorithm md5 sa duration 3600 # ike peer ios proposal 2 pre-shared-key cipher 456123 local-address10.153.47.103 nat traversal # ipsec proposal 2 encapsulation-mode transport esp authentication-algorithm sha1 esp encryption-algorithm aes 128 # ipsec policy-templateios 1 ike-peerios proposal 2 # ipsec policy phone 2 isakmp template ios # interface GigabitEthernet0/0 port link-mode route ip address 10.153.47.103 255.255.255.0 ipsec policy phone #
5、IOS客户端的配置：
描述：随便写
over 篇9
December 19, 2011
The Committee for Cultural Relations with Foreign Countries of DPRK
The Central Committee of the DPRK-China Friendship Association
Shocked to learn of the passing away of Kim Jong Il, the supreme leader of the Democratic People’s Republic of Korea on December 17, we felt deep grief. The CPAFFC and the China-DPRK Friendship Association express the deepest condolences to your organizations and through you to the people of the DPRK.
Comrade Kim Jong Il was a great leader of the Korean people and a close friend of the Chinese people. He had visited China many times, exchanging views on issues of common concern with the Chinese leaders, and made outstanding contributions to consolidating and developing the traditional China-DPRK friendship forged and cultivated by Chairman Mao Zedong and President Kim Il Sung. The Korean people have lost a great leader and the Chinese people a close friend. We will always remember him.
We are confident that the courageous Korean people will turn grief into strength, carry on the behests of Comrade Kim Jong Il and make continuous achievements in the struggle to build a strong and prosperous socialist country.
The Chinese People’s Association for Friendship with Foreign Countries