Route Recursion; Sharing Of Routing Information; Displaying And Maintaining A Routing Table - H3C S5500-EI series Operation Manual

Operation Manual – IP Routing-GR Overview
H3C S5500-EI Series Ethernet Switches
II. Route backup
Route backup can help improve network reliability. With route backup, you can
configure multiple routes to the same destination, expecting the one with the highest
priority to be the main route and all the rest backup routes.
Under normal circumstances, packets are forwarded through the main route. When the
main route goes down, the route with the highest priority among the backup routes is
selected to forward packets. When the main route recovers, the route selection process
is performed again and the main route is selected again to forward packets.

1.2.5 Route Recursion

The nexthops of some BGP routes (except EBGP routes) and static routes configured
with nexthops may not be directly connected. To forward the packets, the outgoing
interface to reach the nexthop must be available. Route recursion is used to find the
outgoing interface based on the nexthop information of the route. Link-state routing
protocols, such as OSPF and IS-IS, do not need route recursion because they obtain
nexthop information through route calculation.

1.2.6 Sharing of Routing Information

As different routing protocols use different routing algorithms to calculate routes, they
may find different routes. In a large network with multiple routing protocols, it is required
for routing protocols to share their routing information. Each routing protocol has its
own route redistribution mechanism. For detailed information, refer to the description
about route redistribution in each routing protocol.

1.3 Displaying and Maintaining a Routing Table

Display brief information
about the active routes in
the routing table
Display information about
routes to the specified
destination
Display information about
routes with destination
addresses in the specified
range
Display information about
routes permitted by an
IPv4 basic ACL
To do...
display ip routing-table
[ verbose | | { begin | exclude |
include } regular-expression ]
display ip routing-table
ip-address [ mask-length |
mask ] [ longer-match ]
[ verbose ]
display ip routing-table
ip-address1 { mask-length |
mask } ip-address2
{ mask-length | mask }
[ verbose ]
display ip routing-table acl
acl-number [ verbose ]
Use the command...
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Chapter 1 IP Routing Overview
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