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Configuring the next hop attribute – H3C Technologies H3C S7500E Series Switches User Manual

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Network NextHop MED LocPrf PrefVal Path/Ogn

*>i 10.0.0.0 3.3.3.3 50 0 200e

* i 10.0.0.0 2.2.2.2 50 0 300e

* i 1.1.1.1 60 0 200e

Note that, in this case, BGP load balancing cannot be implemented because load balanced routes

must have the same AS-path attribute.

Follow these steps to enable the comparison of MED of routes from each AS:

To do…

Use the command…

Remarks

Enter system view

system-view

Enter BGP view

bgp as-number

Enable the comparison of MED of routes

from each AS

bestroute compare-med

Optional

Not enabled by default

Enable the comparison of MED of routes from confederation peers

Follow these steps to enable the comparison of MED of routes from confederation peers:

To do…

Use the command…

Remarks

Enter system view

system-view

Enter BGP view

bgp as-number

Enable the comparison of MED of routes

from confederation peers

bestroute med-confederation

Optional

Not enabled by default

The MED attributes of routes from confederation peers are not compared if their AS-path attributes

contain AS numbers that don’t belong to the confederation. For example, there are three routes:

AS-path attributes of them are 65006 65009, 65007 65009 and 65008 65009, and MED values of them

are 2, 3, and 1. Because the third route contains an AS number that does not belong to the

confederation, the first route becomes the optimal route.

Configuring the Next Hop Attribute

By default, when advertising routes to an iBGP peer/peer group, a BGP router does not set itself as the

next hop. However, to ensure a BGP peer can find the correct next hop in some cases, you need to

configure the router as the next hop for routes sent to the peer.

For example, as shown in the figure below, Router A and Router B establish an eBGP neighbor

relationship, and Router B and Router C establish an iBGP neighbor relationship. When Router B

advertises a network learned from Router A to Router C, if Router C has no route to IP address