Hello guys !
Im trying to config 3 AS BGP with OSPF, but I have no idea how to config the Default routes in the ASBR Routers.
i want to ping from VMX1 ( Lo0: 10.100.100.1) to the destination VMX6 ( lo0: 10.100.100.6).
I need your help please , thanks
You don't need default routes in ASBRs.
In fact, the whole internet operates without default routes, and it's called Default Free Zone (DFZ) for a reason.
As for pinging between VMX loopbacks, You only need to announce specific /32 prefixes between AS, with nexthop-self export policy on ASBRs.
should it work without IBGP? because I just configered OSPF and EBGP. VMX1 has only OSPF
maybe you can explain to me in which scenario should I have IBGP + OSPF.
It will work without IBGP.
But if You are interested in best practices, then, on a very high level :
1/ Your IGP should ideally contain only loopbacks, less ideally loopbacks+link subnets
2/ Your customer routes should be in IBGP
3/ You should advertise Your summarized customer routes and Your own summarized infra routes (DNS subnets, company portal, etc) over EBGP to the outside world.
Anything else is good for lab practicing/exam prep only.
I tried many times but its still docent work!! can you please write the correct configuration for ASBRs, it will help me und will be helpful for others.
Here is the simple example R-6 config for You.
Assuming VMX6 lo0.0 IP address is 203.0.113.6 and R-6 lo0.0 IP address is 198.51.100.66, then
set routing-options autonomous-system 64544
set protocols bgp group EBGP peer-as 64533
set protocols bgp group EBGP neighbor 10.100.46.1
set protocols bgp group EBGP export PL-VMX6-LPBK
set protocols bgp group IBGP type internal
set protocols bgp group IBGP local-address 198.51.100.60
set protocols bgp group IBGP neighbor 203.0.113.6 ## VMX6 lo0.0 IP address
set protocols bgp group IBGP export PL-NHS
set policy-options policy-statement PL-NHS then next-hop self
set policy-options policy-statement PL-NHS then accept
set policy-options policy-statement PL-VMX6-LPBK term 1 from route-filter 203.0.113.6/32 exact
set policy-options policy-statement PL-VMX6-LPBK term 1 then accept
thanks for your response. Hin: R-6 and VMX6 are one Router ( RE+ FPE ) but anyway I will apply your configuration on VMX2 in AS 64522.
i have one more question please, what if there too many Routers in AS must I config a routing policy on ASBR ( from route-filter xx.xx.xx.xx/32 exact ) for each Router? thanks
You must configure BGP export policy saying "from route-filter X.Y.Z.W/NN" everywhere where You want to inject a route into BGP.
So, if "X.Y.Z.W/NN" isn't in BGP - check with "show route protocol bgp X.Y.Z.W/NN" it should be empty if route is not in BGP - then please configure BGP export policy.