Huawei Quidway NetEngine80E Configuration Manual page 964

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
BGP routing table entry information of 10.1.4.0/30:
From: 10.1.3.2 (10.1.3.2)
Route Duration: 00h03m18s
Relay IP Nexthop: 0.0.0.0
Relay IP Out-Interface: GigabitEthernet0/0/2
Original nexthop: 10.1.3.2
Qos information : 0x0
AS-path Nil, origin incomplete, MED 0, localpref 100, pref-val 0, valid, internal,
pre 255, not preferred for router ID
Not advertised to any peer yet
The preceding command output shows that the route learned from Router C becomes the optimal
route because it has a smaller router ID than the route learned from Router D.
the attribute comparison of the routes learned from Router C and Router D.
Table 8-27 Attribute comparison of the routes learned from Router C and Router D
Route Attribute
PrefVal
Local_Pref
Route type
AIGP
AS_Path
Origin
MED
Peer type
IGP cost
Cluster_List
Router ID
MED
MED attributes of routes can be configured as required to control traffic forwarding path for the
purpose of load balancing.
The MED attribute is transmitted only within an AS or between two neighboring ASs. The AS
that receives the MED attribute does not advertise it to a third AS.
Similar to the cost used by an IGP, the MED is used to determine the optimal route when traffic
enters an AS. When a BGP peer learns multiple routes that have the same destination address
but different next hop addresses from EBGP peers, the route with the smallest MED value is
selected as the optimal route if all the other attributes are the same.
Table 8-28
Issue 02 (2014-09-30)
Route Learned
from Router C
0
100
Learned from a peer
-
-
Incomplete
0
IBGP
-
-
10.1.2.2
lists two methods used to modify the MED value.
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Route Learned
from Router D
0
100
Learned from a peer
-
-
Incomplete
0
IBGP
-
-
10.1.3.2
8 BGP Configuration
Table 8-27 shows
Comparison
The same.
The same.
The same.
The same.
The same.
The same.
The same.
The same.
The same.
The same.
The route learned
from Router C is
optimal.
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