Accton Technology ES4626 - Manual (Page 545)

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configuration. No parameter refers to above three parameter are configured together.
Example:
Switch(config-router)#neighbor 10.1.1.64 attribute-unchanged
Switch(config-router)# no neighbor 10.1.1.64 attribute-unchanged as-path med
13.8.3.45 neighbor as-override
Command: [no] neighbor <ip-addr> as-override
Function: Use this command to replace the previous AS number with its own AS number
when transmitting the BGP route in the VRF.
Parameter: IP address of neighbors, shown in dotted decimal notation
Command Mode: vrf mode
Usage Guide: When BGP receives remote routing messages, it will check the AS path
whether its AS number exists, if yes, the route will be considered as circuit and cleared.
However in VPN environment there may be two or more CE with the same AS number on
the PE link. As the EBGP is required between private network and public network, routes
step across public network will be considered circuit and unable to reach the partner.
Under this circumstance we can configure the as-override attribute of the CE neighbor on
the VRF address-family of BGP on PE, replacing the remote as number with the global
as number, so that CE will not filter this route due to discovering its own as number.
Example:
In CE1-PE1-P-PE2-CE2 environments, as numbers of two CE are all 200, as number of
area P is 100.
After typical environment is configured, the CE1 route will be restrained on CE 2 due to
as number, the debugging messages shows:
Prefix 11.1.1.0/24 denied due to as-path contains our own AS.
Prefix 20.1.1.0/24 denied due to as-path contains our own AS
Now configure on PE2 as follows
Switch(config)# router bgp 100
Switch(config)#address-family ipv4 vrf DC1
Switch(config-router-af)#neighbor 15.1.1.70 as-override
Switch(config-router-af)#exit-address-family
The route is successfully transmitted to CE2 after refresh, on CE2 shown:
Switch#show ip bgp
BGP table version is 5, local router ID is 100.1.1.70
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete