HP FlexFabric 12900E Series Configuration Manual page 205

When a BGP speaker sends a received route to an EBGP peer, it sets the address of the

sending interface as the NEXT_HOP.
When a BGP speaker sends a route received from an EBGP peer to an IBGP peer, it does

not modify the NEXT_HOP attribute. If load balancing is configured, BGP modifies the
NEXT_HOP attribute for the equal-cost routes. For load balancing information, see
load balancing."
Figure 51 NEXT_HOP attribute
AS 200
1.1.2.1/24
D = 8.0.0.0
Next_hop = 1.1.2.1
•
MED (MULTI_EXIT_DISC)
BGP advertises the MED attribute between two neighboring ASs, each of which does not
advertise the attribute to any other AS.
Similar to metrics used by IGPs, MED is used to determine the optimal route for traffic going into
an AS. When a BGP router obtains multiple routes to the same destination but with different
next hops, it considers the route with the smallest MED value as the optimal route. As shown in
Figure 52, traffic from AS 10 to AS 20 travels through Router B that is selected according to
MED.
Figure 52 MED attribute
D = 9.0.0.0
Next_hop = 2.1.1.1
MED = 0
Router A
D = 9.0.0.0
Next_hop = 3.1.1.1
MED = 100
AS 10
D = 8.0.0.0
Next_hop = 1.1.1.1
1.1.1.1/24
EBGP
EBGP
AS 300
IBGP
D = 8.0.0.0
Next_hop = 1.1.2.1
MED = 0
Router B
2.1.1.1
EBGP
IBGP
EBGP
3.1.1.1
Router C
MED = 100
193
AS 100
8.0.0.0
IBGP
9.0.0.0
Router D
IBGP
AS 20
"BGP