User guide

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XTREME
W
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OFTWARE
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13-9
BGP F
EATURES
IGP S
YNCHRONIZATION
You can configure an AS to be a transit AS, so that it can pass traffic through from one
AS to a third AS. When you configure a transit AS, it is important that the routes
advertised by BGP are consistent with the routes that are available within the AS using
its interior gateway protocol. To ensure consistency, BGP should be synchronized with
the IGP used within the AS. This will ensure that the routes advertised by BGP are, in
fact, reachable within the AS. IGP synchronization is enabled by default.
U
SING
T
HE
L
OOPBACK
I
NTERFACE
If you are using BGP as your interior gateway protocol, you may decide to advertise the
interface as available, regardless of the status of any particular interface. The loopback
interface can also be used for EBGP multihop. Using the loopback interface eliminates
multiple, unnecessary route changes.
OSPF
TO
BGP R
OUTE
R
E
-D
ISTRIBUTION
Both BGP and OSPF can be enabled simultaneously on the switch. Route re-distribution
allows the switch to exchange routes, including static routes, between the two routing
protocols.
Exporting routes from OSPF to BGP, and from BGP to OSPF, are discreet configuration
functions. To run OSPF and BGP simultaneously, you must first configure both
protocols and then verify the independent operation of each. Then you can configure
the routes to export from OSPF to BGP and the routes to export from BGP to OSPF.