比较老的运营商运维竞赛题.doc

<p>一、 综合题（共2小题，每题20分，共40分）
1、 某省干网组网图如下：

其中RA、RB、RC、RD均为NE40-8，LSWA、LSWB、LSWC、LSWD均为S8505，四台路由器均运行在AS100内，IGP应用IS-IS协议，每台路由器的互联接口和Loopback 0接口都在IS-IS中进行了宣告，各地除了提供普通宽带上网业务以外，还需要承载运营商的视频会议系统，系统要求所有会议终端都需要在同一个网段内。视频会议系统分支节点接入时，携带特定的Vlan id在MA5200F上终结，MA5200F上应用CAMS做用户认证。各地的普通宽带业务承载在“公网”上，其中RA、RD上都有对外的Internet连接，并且与外网运行EBGP。
1）在初期的网络规划中，决定采用MPLS-VPN的形式承载视频会议系统，为满足系统要求，采用L2形式还是L3形式？（3分）
&amp; 答案： L2形式
&amp; 知识点：8011产品
&amp; 试题出处：8011产品操作手册
&amp; 难度：中
2）在配置MA5200F时，MA5200F支持在PORTVLAN下配置用户为哪些接入类型（access-type，至少回答三种）？ 本方案中需要配置为哪种？（5分）
&amp; 答案：
interface、layer2-subscriber、layer3-subscriber、vlan-lease-line、relay-lease-line、pppoe-lease-line、system-reserved；（每回答出一种，得1分，共3分）
本方案中需要配置为layer2-subscriber或者vlan-lease-line方式。（每回答出一种，得1分，共2分）
&amp; 知识点：MA5200产品
&amp; 试题出处：MA5200产品操作手册
&amp; 难度：中
3）由于每个会议终端都应用特定的Vlan id，并且随着业务量的增加，会议终端的数目也会有所增加，为了使NE40上的配置比较便于维护，并且新增会议终端不需调整所有NE40配置，本方案中除了应用MPLS-VPN以外，还需要应用什么技术？（3分）
&amp; 答案： QinQ
&amp; 知识点：8011产品
&amp; 试题出处：8011产品操作手册
&amp; 难度：中
4）在CAMS上打开用户认证的调试信息，可能出现哪些种类的radius报文，各是什么作用？（3分）
&amp; 答案：code 1 认证请求；code 2 认证通过；code 3 认证拒绝（每回答出一种，得1分，共3分）
&amp; 知识点：CAMS产品
&amp; 试题出处：CAMS产品操作手册
&amp; 难度：中
5）RA下挂网络中，所有普通宽带客户应用220.0.0.0/23网段地址；RB下挂网络中，所有普通宽带客户应用220.0.2.0/23网段地址；RC下挂网络中，所有普通宽带客户应用220.0.4.0/23网段地址；RD下挂网络中，所有普通宽带客户应用220.0.6.0/23网段地址。为了有效的利用链路资源，并确保整个网络的可靠性，客户要求正常情况下，RA、RB下挂网络的回程流量通过RA的对外连接回程；RC、RD下挂网络的回程流量通过RD的对外连接回程。任何一条对外链路故障，剩下的一条需要承载所有的流量。在保证对外网发布的路由条目尽量少的情况下，需要在RA、RD上应用什么样的路由配置？（6分）
&amp; 答案：
在RA上手工发布220.0.0.0/22、220.0.0.0/21两个网段的路由（2分），并在本地配置对应的黑洞路由；（1分）
在RD上手工发布220.0.4.0/22、220.0.0.0/21两个网段的路由（2分），并在本地配置对应的黑洞路由。（1分）
注意：本问如果回答更改BGP的MED属性，可以得2分。如果没有作聚合扣2分。
&amp; 知识点：8011产品
&amp; 试题出处：8011产品操作手册
&amp; 难度：中

2、 某城域网拓扑如下图所示：

RA、RB、RC、RD为城域网骨干设备（NE40），Loopback 0地址分别为：1.1.1.1/32、1.1.1.2/32、1.1.1.3/32、1.1.1.4/32。骨干设备之间互通OSPF协议，运行在area 0中；骨干设备下挂网络根据不通情况运行OSPF（非0 area）或者静态路由。A、B、C、D四个接入点都承载普通宽带业务，并且RA、RD以L3 MPLS-VPN的方式为一个企业大客户提供A、D接入点之间的互通服务，A点应用10.0.0.0/24网段、D点应用10.1.0.0/24网段。以下是这个网络运行过程中出现的一些问题，请分别定位：
1）网络建设过程中，D点下挂S3526E，S3526E下挂多个2403H作为小区接入设备，S3526E连接不同2403H的接口属于不同的Vlan，并且在S3526E上建立相应的Vlan-if接口，作为2403H下挂用户的网关，同时2403H的管理地址也在这个网段内。为了对每个2403H不同接口接入的用户进行隔离，在每个2403H上应用了Isolate-user-vlan技术，但是实施完成后，发现网管系统无法管理到每个2403H，请给出可行的解决方案。（3分）
&amp; 答案：将2403H上行口的PVID更改为管理Vlan的Vlan id。（3分）
&amp; 知识点：低端交换机
&amp; 试题出处：产品配置手册
&amp; 难度：中
2）小区用户上网速度很慢，在S3526E上查看路由表信息，发现有1000条左右的OSPF路由信息（其中包括默认路由），请定位问题原因，并给出解决方案。（4分）
&amp; 答案：S3526最长匹配的路由表只有16条，多余的路由会上送CPU进行软件转发，导致上网速度慢。（2分）可以通过在OSPF协议中进行路由过滤，只接收默认路由。（2分）
&amp; 知识点：低端交换机
&amp; 试题出处：产品规格、配置手册
&amp; 难度：中
3）一次客户反映RA和RB之间的链路中断后，A、D节点的大客户业务无法互通，但是其他业务都正常。下面是客户收集到的信息，请根据这些信息判断故障原因，并给出解决的办法。（4分）
在RA上执行disp bgp vpn all rout 显示如下：</p><ra>disp bgp vpn all rout &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Flags: &nbsp; # - valid &nbsp; &nbsp; &nbsp; ^ - active &nbsp; &nbsp; &nbsp;I - internal &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; D - damped &nbsp; &nbsp; &nbsp;H - history &nbsp; &nbsp; S - aggregate suppressed &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;In/out &nbsp; &nbsp; As &nbsp;
&nbsp; &nbsp;Dest/mask &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Next-hop &nbsp; &nbsp; &nbsp; &nbsp;Med &nbsp; &nbsp; &nbsp; &nbsp;Local-pref &nbsp; &nbsp; label &nbsp; &nbsp; path
----------------------------------------------------------------------------
&nbsp; &nbsp;Route Distinguisher:100:1 (VPN instance:vpn-1) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
#^ &nbsp;10.0.0.0/24 &nbsp; &nbsp; &nbsp; &nbsp; 0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;16/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
#^I 10.1.0.0/24 &nbsp; &nbsp; &nbsp; &nbsp; 1.1.1.4 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;100 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0/18 &nbsp; &nbsp;

在RD上执行disp bgp vpn all rout 显示如下：<rd>disp bgp vpn all rout &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Flags: &nbsp; # - valid &nbsp; &nbsp; &nbsp; ^ - active &nbsp; &nbsp; &nbsp;I - internal &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; D - damped &nbsp; &nbsp; &nbsp;H - history &nbsp; &nbsp; S - aggregate suppressed &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;In/out &nbsp; &nbsp; As &nbsp;
&nbsp; &nbsp;Dest/mask &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Next-hop &nbsp; &nbsp; &nbsp; &nbsp;Med &nbsp; &nbsp; &nbsp; &nbsp;Local-pref &nbsp; &nbsp; label &nbsp; &nbsp; path
----------------------------------------------------------------------------
&nbsp; &nbsp; &nbsp;Route Distinguisher:100:1 (VPN instance:vpn-1) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
#^ &nbsp;10.1.0.0/24 &nbsp; &nbsp; &nbsp; &nbsp; 0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;18/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
#^I &nbsp;10.0.0.0/24 &nbsp; &nbsp; &nbsp; &nbsp; 1.1.1.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;100 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0/16 &nbsp;
&nbsp;
在RA上执行disp mpls lsp 显示如下：<ra>disp mpls lsp &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Total: &nbsp; 1 Record(s) Matched &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;ID &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: &nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;I/O-Label &nbsp; &nbsp; : &nbsp;---/3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;In-Interface &nbsp;: &nbsp;---------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Out-Interface : &nbsp;GigabitEthernet1/0/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Prefix/Mask &nbsp; : &nbsp;1.1.1.3/32 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Next-Hop &nbsp; &nbsp; &nbsp;: &nbsp;192.168.0.6 &nbsp;
&nbsp;
在RC上执行disp mpls lsp 显示如下：<rc>disp mpls lsp &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Total: &nbsp; 1 Record(s) Matched &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;ID &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: &nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;I/O-Label &nbsp; &nbsp; : &nbsp;---/3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;In-Interface &nbsp;: &nbsp;---------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Out-Interface : &nbsp;GigabitEthernet1/0/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Prefix/Mask &nbsp; : &nbsp;1.1.1.1/32 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Next-Hop &nbsp; &nbsp; &nbsp;: &nbsp;192.168.0.5 &nbsp; &nbsp;

在RB上执行disp mpls lsp 显示如下：<rb>disp mpls lsp &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Total: &nbsp; 1 Record(s) Matched &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;ID &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: &nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;I/O-Label &nbsp; &nbsp; : &nbsp;---/3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;In-Interface &nbsp;: &nbsp;---------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Out-Interface : &nbsp;GigabitEthernet1/0/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Prefix/Mask &nbsp; : &nbsp;1.1.1.4/32 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Next-Hop &nbsp; &nbsp; &nbsp;: &nbsp;192.168.0.14 &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
在RD上执行disp mpls lsp 显示如下：<rd>disp mpls lsp &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Total: &nbsp; 1 Record(s) Matched &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;ID &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: &nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;I/O-Label &nbsp; &nbsp; : &nbsp;---/3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;In-Interface &nbsp;: &nbsp;---------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Out-Interface : &nbsp;GigabitEthernet1/0/0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Prefix/Mask &nbsp; : &nbsp;1.1.1.2/32 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;Next-Hop &nbsp; &nbsp; &nbsp;: &nbsp;192.168.0.13
&amp; 答案：RB与RC之间没有启动LDP协议。（2分）
可以在RB与RC之间的互连接口上启动LDP协议，使网络可靠性更好。（2分）
&amp; 知识点：8011产品
&amp; 试题出处：产品配置手册
&amp; 难度：中
4）某天在网管系统上发现RC与下挂NE05之间的POS链路上流量异常（封装PPP协议），比正常时大很多，在NE05上打开调试信息发现有大量目的地址为210.1.1.3，TTL=0的报文，请分析问题原因，并给出合适的解决方案。（3分）
&amp; 答案：由于封装PPP，所以RC和NE05上会产生210.1.1.1/32、210.1.1.2/32、210.1.1.0/29的路由信息，对于目的地址为210.1.1.3的数据包，在两台设备上都是匹配210.1.1.0/29，导致在两台设备之间成环。（2分）
可以通过调整互连接口地址掩码为30位来解决。（1分）
&amp; 知识点：8070产品
&amp; 试题出处：产品配置手册
&amp; 难度：中
5）一次日常维护过程中，工程师发现A点S8016 telnet响应特别慢，应用“display system-bucket”命令查看，下行FE接口板的多个系统漏桶都有大量丢包，并且不停增长，同时在RB下挂的S6506上无法ping通S8016，但是在RA上可以ping通S8016，检查S8016连接RA的接口，发现地址掩码被更改为29位了，请根据以上信息，判断S8016 telnet响应慢和无法被S6506 ping通的原因，并分别给出解决方案。（6分）
&amp; 答案：系统漏桶有大量丢包，说明有很多上送CPU处理的报文，导致CPU繁忙，所以telnet响应慢。（2分）正常的网络中不应该有大量的主机报文，说明下挂网络中有用户染毒，发出大量的病毒报文，可以通过调整有丢包的系统漏桶大小来解决。（1分）
S8016无法被S6506 ping通是因为在S6506上ping S8016，虽然ICMP request报文可以正常到达S8016，但是由于ICMP报文源地址为210.1.1.134，对应ICMP reply报文目的地址， S8016的上行接口地址为210.1.1.130/29，会发送ARP请求，由于这个广播域中没有设备回应，所以ICMP reply报文不会被转发，导致无法ping通。（2分）将S8016上行接口地址更改为30位掩码即可解决。（1分）
&amp; 知识点：8011产品、中低端交换机产品
&amp; 试题出处：产品配置手册
&amp; 难度：中

二、 综合题（共2小题，合计30分）
1、 某宽带城域网DSLAM设备经过S8016二层汇聚后通过ISN 8850接入到Internet，接入层的DSLAM设备使用了MA5100、MA5105和MA5300。MA5100都使用LAND接入到S8016，MA5300通过ISU单板的GE口接入到S8016。组网图如下：

问题一、MA5100_B通过LAND的IPDSLAM模式上行到S8016，通过该单板上行的所有ADSL用户经常出现无法正常拨号、无法打开网页或者上网速度慢等问题，请问在MA5100_B上可能存在什么问题？需要如何处理？(3&#39;)
答：
问题原因：由于LAND单板逻辑处理存在异常导致（2分）
处理方法：需要将升级H511LAND到B06D081版本（1分）

问题二、MA5100_A开局时使用MA5103V100R005版本，共有ADSL用户30个左右，同时在该LAND单板中接入若干专线用户。ADSL用户使用小区VLAN方式上行，都使用2M带宽，分配固定IP地址，S8016的三层接口地址作为用户网关，专线用户通过DHCP Server获取IP地址。但设备开通一段时间后经常有部分ADSL用户反馈：上网中断，将计算机重启、网卡禁用再启用可以恢复，如果不做处理，隔一段时间也可以自行恢复。后查明发现是部分用户擅自更改IP地址，导致地址冲突。请根据上述描述回答以下问题：
1)、为什么出现地址冲突，而用户侧计算机却没有提示？（2’）
答：
1、 用户更改IP地址后，会向同一网段的计算机中发送ARP探测报文，来确定是否有地址相同的用户。（1’）
2、 由于MA5100_A下的用户使用的是小区VLAN，用户之间是隔离的，导致ARP探测报文无法被其他用户收到，从而无法发现有相同的地址。（1’）

2)、为什么重启计算机或者网卡禁用后可以恢复（2’）
答：
1、 出现故障时，在S8016上建立了IP地址和错误用户MAC的对应关系，导致正常用户无法上网。
2、 当正常用户重启计算机后，会向网络发送ARP报文，使得在S8016上重新建立IP地址和正确用户MAC地址的对应关系，业务恢复正常。
3)、请提供简单有效的方法，找出擅自更改IP地址的用户所在的ADSL端口。（2’）
答：
1、 出现问题时，首先在8016上找出故障用户的ARP表项，确定目前该地址对应的MAC地址。（1’）
2、 在MA5100_A上使用Show location 命令，输入MAC地址，就可以找到该用户对应的ADSL端口。（1’）
注：问题一主要是为了找到用户的MAC地址，其他方法也可。
问题三：某运营商为了更好的开展业务，向企业提供了专线互联业务，请根据MA5300V100R005版本 Samrt VLAN的实现原理，回答以下问题：

B

C
主控板
EADA
D

E
EVDA
SmartVlan 2
A
F
普通 Vlan 3

1）、Smart VLAN 2包括端口B、C、D、E，普通VLAN 3包含端口A、F,
问端口B、C、D、E下的用户是否可以互通？(1’)
答：不可以
2）、组网如问题一描述情况，端口A、B下的用户是否可以互通？(1’)
答：不可以
3）、如果Samrt vlan 2只包含C、D 两个用户端口，普通VLAN 3包含A、B、E、F四个端口，那么A、B下的用户是否可以互通？简述原因。(2’)
答：不可以(1’)
原因：EADA单板的核心交换芯片是逻辑，逻辑上各端口之间本身就是隔离的，但与上行口是互通的。因此，在同一块EADA单板上的ADSL用户在同一个普通VLAN也不能互通。(1’)
4）、组网如问题3描述的情况，则E、F下的用户是否可以互通，并简述原因？(2’)
答：可以(1’)
原因：EVDA单板的核心交换芯片是以太网交换芯片，在同一块EVDA单板上的VDSL用户在同一个普通VLAN是通过以太网交换芯片实现互通。(1’)
&amp; 知识点：MA5100、MA5300故障处理、MA5100预警、MA5100、MA5300数据配置。
&amp; 试题出处：MA5100、MA5300故障处理手册，MA5100、MA5300配置手册，预警。
&amp; 难度：高

2、 一台ISN8850设备位于某运营商城域网会聚层，通过ATM接口和ETHERNET接口接入若干DSLAM，单GE上行，提供PPPOE/PPPOEOA的业务方式，并使用RADIUS认证和计费。
1）近期该运营商对PPP用户下线原因进行了统计，发现8850上报的CODE=4报文的49号属性中，大部分值都是“2（lost-carrier）”。
问题：请说明“2（lost-carrier）”的含义以及导致该现象的原因（二种以上），并由此说明8850维护PPP链路的方式。（5分）
3）随着业务的发展，该运营商要求8850提供双GE负荷分担上行。单GE更改为双GE上行后，可能会由于8850与RADIUS服务器配合的原因而产生一个隐患。问题：请问该隐患是什么？并给出解决该隐患的两种方法。（5分）
&amp; 答案：
问题一：下线原因是2（lost-carrier）则表明是8850发送PPP ECHO REQUEST报文没有得到用户的响应，于是8850将用户主动下线。（1分）
当8850与用户间链路不稳定、用户直接断开网线或者掉电关机都会导致该现象。（2分）
8850维护PPP链路的方法就是每隔40S发送一次PPP ECHO REQUEST报文，连续三次得不到用户侧响应，就会将该PPP链路删除。（2分）
问题三：改为双GE上行后，可能会导致8850与RADIUS SERVER通信的报文源地址发生改变，如果RADIUS SERVER上只定义了一个NAS-IP，则会认为是非法报文而丢弃。（2分）
处理方法一是在RADIUS SERVER上绑定两个NAS-IP，包括8850的两个GE接口地址；（1分）
二是升级为V500R005B02，将8850的LOOPBACK地址与RADIUS协议绑定，并将RADIUS SERVER上对应的NAS-IP也更改为LOOPBACK地址。（2分）
&amp; 知识点：ISN8850故障定位方法、ISN8850巡检及整改指导
&amp; 试题出处：ISN8850智能IP业务交换机《故障处理手册》、ESR设备技术支持质量检查及巡检标准、宽带ESR产品整改指导书
&amp; 难度：高</rd></rb></rc></ra></rd></ra>