What metric does BGP use?
metric is the primary metric on all routes sent to peers. It can be a value in the range from 0 through 4,294,967,295 (2 32 – 1). The following optional settings are also supported: minimum-igp —Sets the metric to the minimum metric value calculated in the interior gateway protocol (IGP) to get to the BGP next hop.
What is IGP metric in BGP?
RFC 7311 defines an optional non-transitive BGP attribute called the Accumulated IGP Metric Attribute (AIGP). As we know, IGP stands for Interior Gateway Protocol and represents a group of routing protocols that run within a single administrative domain.
What are the path selection criteria for BGP?
The following parameters are followed for BGP’s path selection:
- Prefer the highest local-preference value.
- Prefer the shortest AS-path length.
- Prefer the lowest origin value.
- Prefer the lowest MED value.
- Prefer routes learned from an EBGP peer over an IBGP peer.
- Prefer best exit from AS.
How do I use show IP in BGP neighbors?
To display information about the TCP and BGP connections to neighbors, use the show ip bgp neighbors command in EXEC mode. Syntax Description address (Optional) Address of the neighbor whose routes you have learned from. If you omit this argument, all neighbors are displayed.
What is locally originated in BGP?
1 Answer. Locally injected routes will always have a next hop of 0.0. 0.0 which means this is local to the router itself (connected), or learned from an IGP and injected into BGP with the ‘network’ command. These local routes will always have a weight of 32768 (highest) and will always be preferred.
What is IGP and EGP?
An interior gateway protocol (IGP) is a routing protocol that is used to exchange routing information within an autonomous system (AS). In contrast, an Exterior Gateway Protocol (EGP) is for determining network reachability between autonomous systems and makes use of IGPs to resolve routes within an AS.
What administrative distance BGP uses for Ibgp and Ebgp?
Some vendors have a preference (distance) of 20 for external BGP (EBGP) and a distance of 200 for internal BGP (IGBP). Junos OS uses the same value (170) for both EBGP and IBGP.
What is the best router select path?
A primary function of a router is to determine the best path to use to send packets. To determine the best path, the router searches its routing table for a network address that matches the destination IP address of the packet.
What is the difference between internal and external BGP?
EBGP is used between autonomous systems. It is used and implemented at the edge or border router that provides inter-connectivity for two or more autonomous system….Difference between EBGP and IBGP :
| SR.NO | EBGP | IBGP |
|---|---|---|
| 2 | It runs between two BGP routers in different autonomous system. | It runs between two BGP routers in the same autonomous system. |
What is the difference between BGP and IGP on PE1?
BGP table on PE1 has two (almost) identical entries, the only difference being the IGP metric toward the BGP next hop. The path with the lower IGP metric is selected.
What do the > and < mean in BGP?
The > means that this entry has been selected as the best path. The next hop is 0.0.0.0. The next hop of 0.0.0.0 means that this network originated on this router, that makes sense since I used the network command on R4 to advertise this network into BGP. Further to the right you see metric, local preference and weight.
What is AIGP in BGP?
AIGP is a non-transitive attribute that includes the accumulated IGP metric. BGP routers advertise this AIGP metric to neighbors in other ASes. This allows BGP routers to select the best path based on the end-to-end IGP metric.
Why does BGP use EIGRP instead of OSPF when calculating best paths?
When calculating BGP best paths, BGP takes IGP metric from the IP routing table and it just so happens that a good EIGRP metric is higher than a not-so-good OSPF metric, and so a BGP next hop learned by OSPF is preferred over a BGP next hop learned by EIGRP. Please note that this behavior is not IGP-specific.