BGP Messages and Neighbor States
The desired state for BGP neighbors is the established state. In that state, the routers have formed a TCP connection, and they have exchanged Open messages, with the parameter checks having passed. At this point, topology information can be exchanged using Update messages. Table 12-3 lists the BGP neighbor states, along with some of their characteristics. Note that if the IP addresses mismatch, the neighbors settle into an active state. Table 12-3 BGP Neighbor States
Hello packets are sent to multicast MAC-layer addresses to determine whether other systems are running IS-IS. There are three types of hello packets in IS-IS: one for point-to-point interfaces, one for level 1 routers, and one for level 2 routers. The hellos sent to level 1 and level 2 routers are given to different multicast addresses. Therefore, a level 1 router connected to a common wire where a level 2 router resides does not see level 2 hellos, and vice versa. ..
IGMPv1 Host Membership Report Functions
Hosts use IGMPv1 Host Membership Report message to reply to IGMP Queries and inform the router(s) of their desire to receive multicasts. Multicast hosts use IGMPv1 Host Membership Report messages to communicate to a local router for which multicast groups they want to receive traffic. In IGMPv1, a host sends an IGMPv1 Host Membership Report under the following two conditions: ■ When a host receives an IGMPv1 Query from a local router, it is supposed to send an IGMPv1 Hos..
If you have several physical interfaces on your router that you want to treat as a single dialer, particularly for PPP multilink channel bonding, you can create a logical dialer interface: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#interface BRI0/0 Router1(config-if)#encapsulation ppp Router1(config-if)#dialer pool-member 1 Router1(config-if)#isdn switch-type basic-ni Router1(config-if)#isdn spid1 8005551234..
Selecting the Appropriate Area Types
In the Introduction to this chapter, we talked about the various types of OSPF areas. You can configure these different types areas by using the appropriate keywords on the area command. For a Stubby Area, use the stub keyword: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#router ospf 55 Router1(config-router)#area 100 stub Router1(config-router)#exit Router1(config)#end Router1# To configure a Totally Stubby..
