OSPF抓包分析Word格式.docx

1、Router-ID 必须不同Area-ID 、Authentication、Network mask、Hellointerval、RouterDeadInterval 必须相同卷一中指出还会比对option value 字段其实如果区域类型不匹配，OSPF邻居关系也无法建立。但是在Hello报文中，我们并没有直观的看到区域类型的相关信息。关于区域类型的信息究竟隐藏在Hello包的什么位置呢？hello包中并没有直观体现区域类型，而是从external routing capablilty和 NSSAsupported 的角度间接体现了区域类型。从邻居关系建立的角度来讲，区域只有三种：常规区域、

2、stub area、NSSA area 。至于另外两种完全区域从配置上看也很明了，仅仅是只在ABR上配置stub 或者NSSA的时候加后缀参数no-summary 来阻止3型lsa进入该区域而已。接口的区域类型对于stub 、totally stub；nssa、totally nssa本来也就是不一致的。所以并不影响邻居关系的建立。Hello报文的信息如下（摘自卷一）：Router ID of the originating router.（必须不匹配）Area ID of the originating router interface.（必须匹配）Address mask of the o

3、riginating interface.（必须匹配）Authentication type and authentication information for the originating interface.（必须匹配）HelloInterval of the originating interface.（必须匹配）RouterDeadInterval of the originating interface.（必须匹配）Router Priority.DR and BDR.Five flag bits signifying optional capabilities.（必须匹配？）R

4、outer IDs of the originating routers neighbors. This list contains only routers from which Hellos were heard on the originating interface within the last RouterDeadIntervalWhen a router receivesa Hello from a neighbor, it will verify that the Area ID, Authentication, Network Mask, HelloInterval, RouterDeadInterval, andOptions valuesmatch the values configured on the receiving interface. If they do not, the packet is dropped and no adjacency is established. （摘自 卷一）