Why origin is mandatory in BGP?
The ORIGIN is a well known mandatory attribute that indicates the origin of the prefix, or rather, the way in which the prefix was injected into BGP. EGP, meaning the prefix originated from the EGP protocol, which BGP replaced. INCOMPLETE, meaning the prefix originated from some unknown source.
What is origin IGP?
Origin Attribute: IGP – Indicates that the route originated on a BGP router. This route type includes any route that originated from the BGP process on a BGP-speaking router.
Which three BGP attributes are well-known and mandatory?
BGP Path Attributes
- Well-Known Mandatory (for example: Origin, AS Path, and Next Hop)
- Well-Known Discretionary (for example: Local Preference)
- Optional Transitive (for example: Community)
- Optional Non-Transitive (for example: Cluster List)
Why do you use iBGP instead of IGP?
As with everything there are trade offs; the scalability, control, and flexibility you get from iBGP means that it’s a slower converging protocol than IGPs (in general). You use BGP because you don’t want to carry your entire internet routing table in your IGP (i.e. in my case, OSPF)…
Why is iBGP route is preferred over eBGP?
Hello @AlexSimen96450, in MP BGP address family Vpnv4 on in a vrf context the i MP BGP advertisements are considered comparable with true eBGP advertisements coming from a CE in vrf. The eBGP advertisement has an AS path made of three entries “65001 65002 65003” so I suppose this is the reason why the route coming from the other PE is preferred
Why do neighbors send eBGP announcements to iBGP partners?
Neighbors, in their turn, keep these announcements, but send them only to EBGP partners, not IBGP, namely because they are obtained from IBGP partner. In other words, all BGP routers have up to date information and the possibility of loops is eliminated.
Why is eBGP configured on the link address?
Nevertheless, EBGP is frequently configured on the link address, because there usually is only one connection and in case of falling, Loopback will not be available anyway. Moreover, customization of additional routing to the ISP is not very desirable. A configuration example of such a neighbor relationship: