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9.6 | ![]() |
BGP Attributes | |
9.6.3 | ![]() |
Next Hop behavior on multiaccess media |
Recall that a network link is considered multiaccess if more than two
hosts can potentially connect to it. Routers on a multiaccess link
share the same IP subnet and can physically access all other connected
routers in one hop. Ethernet, Frame Relay, and ATM are examples of
multiaccess media.
BGP speakers should always advertise the actual source of the route if the source is on the same multiaccess link as the speaker. In other words, RTC advertises a route learned from RTB, and RTC and RTB share a common multiaccess media. Then when RTC advertises the route, it should indicate RTB as being the source of the route. If not, routers on the same medium would have to make an unnecessary hop by way of RTC to get to a router that is sitting in the same segment. In Figure
When the media is broadcast, such as Ethernet and FDDI, physical connectivity is assumed and the next hop behavior is not an issue. However, when the media is nonbroadcast, such as Frame Relay and ATM, special care should be taken as described in the following section.
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