多热备路由器协议与交换机的操作流程

　　一、连接方法

　　两个路由器与两个不同的交换机端口连接，HSRP和MSHRP使用IP多点传送数据报来确保在其它路由器故障时，其中的一个路由器可以用作备份。一个或多个NT服务与交换机端口、而不是路由器使用的两个端口连接。

　　二、问题分析

　　当NT服务器与交换机连接时，它向交换机发送一个IGMP连接消息(指定思科的HSRP/MSHRP地址224.0.0.2)，这是加入该多点传送组的唯一的一个交换机端口，因为思科路由器从来没有加入这个组(它们只是使用多点传送地址)。随后，交换机停止向其它端口转发，包括路由器。对交换机而言，这是正确的IGMP行为，问题在于思科路由器不再互相接收HSRP/MSHRP数据包，因此协议无法正常工作。

　　三、对于这种情况的规避方法

　　(1)配置惠普交换机封锁或转发各个端口上的IP多点传送流量，不考虑IGMP。

　　(2)在直接连接两个(M)HSRP路由器的端口的交换机IGMP配置中指定Forward (与Auto或Blocked)相反。

　　这个变化使交换机在这些端口之间转发所有的多点传送流量。

　　注：这是一个交换机IGMP配置项，而不是交换机流量/安全性过滤器。

　　x

　　.........following with all English text ....

　　[A5551807/TRAK-ACTIVE/English] A5551807

　　思科: interoperability of HSRP and MSHRP w/ NT 5.0 and HP AdvanceStack

　　Problem Description

　　How does the 思科Hot Standby Routing Protocol (HSRP) or Multiple Hot

　　Standby Router Protocol (MSHRP) interoperate with Microsoft NT 5.0, and

　　HP AdvanceStack or ProCurve switch, with Interior Group Management

　　Protocol (IGMP)?

　　Solution

　　Two routers are connected to two different switch ports. HSRP and MSHRP

　　use IP multicast datagrams to ensure that one of the routers is available as a backup in case the other router goes down. One or more NT servers are connected to switch ports other than the two used by the routers.

　　When the NT server is connected to the switch, it sends an IGMP join

　　message to the switch (specifying 思科's HSRP/MSHRP address 224.0.0.2).

　　At this point, this is the only switch port joined to that multicast group, since 思科routers never perform a join to this group (they simply use the multicast address). Subsequently, the switch stops forwarding to the other ports, including those to the routers.

　　This is correct IGMP behavior on the part of the switches.

　　The problem is that the 思科routers no longer receive each other's HSRP/MSHRP packets, so the protocol cannot work properly.

　　Use these steps as a work-around for this behavior:

　　1. Configure HP switches to block or forward IP multicast traffic on individual ports, regardless of IGMP.

　　2. Specify Forward (as opposed to Auto or Blocked) in the switch's IGMP configuration on the ports which directly connect the two (M)HSRP routers.

　　This change causes the switch to forward all multicast traffic between those ports.

　　Note: This is a switch IGMP configuration item, not a switch Traffic/Security filter.