bgp default-information originate

[cisc0.ameer]

Hello

this question might be looks like crazy also it's answer is much clear , problem is "Why" we use it , otherwise after giving command Can understand "Why"

in which case we use in CE router try to leak (or advertise default route) into PEs?

suppose we have MPLS VPN enabled , definitely has multiple CEs

why we have to leak default route into PEs

some assumption : 

PE-CE has eBGP peering

in both of them we mutually redistribute OSPF and BGP into each others

one side of CE routers i mean other interfaces use OSPF NEtwork

question must asked what kinds of purpose which cause we'll do this ?

thanks

[Giuseppe Larosa]

Hello cisc0.amer,

>>

in which case we use in CE router try to leak (or advertise default route) into PEs?

When the CE that we can name CE1 provides the internet connection for all the VRFs that take part in the customer VPN, so you need to inject a default route from CE1 that will be propagated via PE-CE eBGP and then via MP iBGP in AF VPNv4 to all other PE nodes importing one RT extcommunity associated to the VPNv4 default route by the PE connected to CE1.

This is an example.

Another possible option is in Central services connectivity model where you want all traffic to be sent to a central site and processed by an external CE that may be also acting as a firewall for example.

In this second scenario there is no direct communication between spoke sites and the central site use actually two VRFs to make the traffic go via an external device like a firewall for control user traffic and for logging purposes.

Hope to help

Giuseppe

[cisc0.ameer]

Hello

When the CE that we can name CE1 provides the internet connection for all the VRFs that take part in the customer VPN, 1---so you need to inject a default route from CE1 that will be propagated via PE-CE eBGP and then via MP iBGP in AF VPNv4 to all other PE nodes 2--- importing one RT extcommunity associated to the VPNv4 default route by the PE connected to CE1.

FIRST

1-for that you told , you mean we connect to internet via CE1 because of this we injected default route

THEN

2-suppose we have RR(act as VPNv4 Route-Reflector) we send this to others PE

FINALLY

3-did you mean if we used route-target e.g 100:100 for that VRF connected to CE1

we have to import that RT with extcommunity attribute via vpnv4 to all others PEs in order to achieve CE 1 for external communication(in this case Internet like that 8.8.8.8 for example)

do all three states i mentioned are correct ? 

many many thanks

and too much helpful all your answer

[Giuseppe Larosa · Accepted solution]

Hello cisc0.ameer,

your understanding is correct

the main reason to have CE1 to inject a default route is that via CE1 the customer has the internet link(s).

2) suppose we have RR(act as VPNv4 Route-Reflector) we send this to others PE

Yes this is correct too.

3)

did you mean if we used route-target e.g 100:100 for that VRF connected to CE1

we have to import that RT with extcommunity attribute via vpnv4 to all others PEs in order to achieve CE 1 for external communication(in this case Internet like that 8.8.8.8 for example)

the extcommunity RT attribute is attached to the VPNv4 route by PE1 the PE node serving CE1.

All other PE nodes that need to import the route need to have a locally defined VRF with route-target import 100:100 in order to import the default route originated by CE1 and to send it in eBGP to the local connected CE router PEx - CEx eBGP session.

So your understanding is correct also in this case.

Hope to help

Giuseppe

[cisc0.ameer]

thanks sir
too much helpful