This topic is to discuss the following lesson:
Could it be there is an error in the topology at “1. Configuration”?
I see two times 192.168.12.0/24
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That’s a typo yes. The link between R1 and R4 should be 192.168.14.0/24. I just fixed it. Thanks!
Under IBGP to IBGP I see 4.4.4.4 is advertised by R4 to R5 as IBGP route then how do we see it in R6. As per split horizon it should not be advertised. right?
Hello Rahul
The 4.4.4.4/32 network is advertised by R4 to R5, as well as from R4 directly to R6. This doesn’t violate the split horizon rule.
Remember the full mesh peering requirement in iBGP. Within AS 456, we have three peerings:
- R4 → R5
- R5 → R6
- R4 → R6
BGP is not like most IGPs where neighbors must be directly connected. iBGP peerings can take place over multiple hops. That’s why we need an underlying IGP to allow iBGP peers to reach each other to establish those peerings, even if they’re several hops away. Does that make sense?
I hope this has been helpful!
Laz