Cabletron Systems SSIM-R8-02 Specifikace stáhnout pdf (Strana 194)

BGP Configuration Examples

174 Enterasys Xpedition User Reference Manual

For example, in Figure 15, routers XP12, XP13, and XP14 have the following line in

their CLI configuration files:

• The value of the set-pref option should be consistent with the import policy in the

network.

The metric value should be set high enough to avoid conflicts between BGP routes and

IGP or static routes. For example, if the import policy sets GateD preferences ranging

from 170 to 200, a set-pref metric of 170 would make sense. You should set the metric

high enough to avoid conflicts between BGP routes and IGP or static routes.

Multi-Exit Discriminator Attribute Example

Multi-Exit Discriminator (MED) is a BGP attribute that affects the route selection process.

MED is used on external links to discriminate among multiple exit or entry points to the

same neighboring AS. All other factors being equal, the exit or entry point with a lower

metric should be preferred. If received over external links, the MED attribute may be

propagated over internal links to other BGP speakers within the same AS. The MED

attribute is never propagated to other BGP speakers in neighboring autonomous systems.

Figure 16 shows a sample BGP configuration where the MED attribute has been used.

Figure 16. Sample BGP Configuration (MED Attribute)

/jointfilesconvert/276250/bgp set peer-group as901 set-pref 100

Physical Link

Legend:

Peering Relationship

Information Flow

AS 64752

10.200.12.15/24

10.200.12.4/24

10.200.12.0/24

10.200.12.6/24

AS 64751

172.16.200.4/24

172.16.200.6/24

XP4

XP6

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Cabletron Systems SSIM-R8-02 Specifikace Strana 194