10G Core Routing Switch User Manual
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If the physical link and the lower layer protocol are normal, please check the OSPF parameters configured on the
interface. The parameters should be the same parameters configured on the router adjacent to the interface. The
same area ID should be used, and the networks and the masks should also be consistent. (The p2p or virtually
linked segment can have different segments and masks.) Ensure that the dead timer on the same interface is at
least four times the value of the hello timer.
If the network type is broadcast or NBMA, there must be at least one interface with a priority greater than zero.
If an area is set as the STUB area, to which the routers are connected. The area on these routers must be also set
as the STUB area.
The same interface type should be adopted for the neighboring routers.
If more than two areas are configured, at least one area should be configured as the backbone area (that is to say,
the area ID is 0).
Ensure the backbone area to connect with all the areas.
The virtual links cannot pass through the STUB area.
Troubleshooting globally:
If OSPF cannot discover the remote routes yet in the case that the above steps are correctly performed, proceed to
check the following configurations.
If more than two areas are configured on a router, at least one area should be configured as the backbone area.
As shown in the following figure: RTA and RTD are configured to belong to only one area, whereas RTB (area0 and
area1) and RTC (area1 and area 2) are configured to belong to two areas. In which, RTB also belongs to area0, which is
compliant with the requirement. However, none of the areas to which RTC belongs is area0. Therefore, a virtual link
should be set up between RTC and RTB. Ensure that area2 and area0 (backbone area) is connected.
Figure
OSPF areas
The backbone area (area 0) cannot be configured as the STUB area and the virtual link cannot pass through the
STUB area. That is, if a virtual link has been set up between RTB and RTC, neither area1 nor area0 can be
configured as a stub area. In the above figure, only area 2 can be configured as stub area.
Routers in the STUB area cannot redistribute the external routes.
Backbone area must guarantee the connectivity of all nodes.
IP Multicast Protocol
IP Multicast Overview
Problems with Unicast/Broadcast
The constant development of the Internet and increasing interaction of versatile data,voice and vedio information over
the network, has promoted the emergence of new services like e-commerce, network conference, online auction,
vedio on demand (VoD),and tele-education. These services require higher information security and greater rewards.
I. Unicast
