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Example: BGP Path Selection:
| Dual Homed - Dual Router | |
|---|---|
| Ingress traffic / attract traffic on one interface for a Prefix 1- set prefix length on one interface: /24 and 2 x /25 ( preferred ) |
prefix length
MED ( rarely used )
AS-PATH length2- (pre-pend)+ AS-PATH length for this prefix 3- MED ( for eBGP to #AS ) for this prefix - - If copied by intermediate AS - - ( 4- Community or ext-community ) | |
Egress traffic: |
to "force traffic on 1 interface " 1- inside set "Local Preference" | |
| Ingress traffic: Must use transitive Attributes 1- set prefix length on one interface: /24 and 2 x /25 ( preferred ) 2- (pre-pend)+ AS-PATH length for this prefix 3- MED ( for eBGP to #AS ) for this prefix - - If copied by intermediate AS - - ( 4- Community or ext-community ) |
Egress traffic: 1- inside set "Local Preference" on one interface | |
| Dual homed - Single router | |
|---|---|
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| iBGP | |
| single CPE router with 2 uplink ( RR ) | 1- loopback as soorce 2- use "from" option to differenciate the 2 uplink >> the remove will show 2 different NH ( CPE uplinks ) |
