How does route aggregation work?
The route aggregation methodology helps minimize the number of routing tables in an IP network by consolidating selected multiple routes into a single route advertisement. This approach is in contrast to non-aggregation routing, in which every routing table contains a unique entry for each route.
What is BGP Multipath relax?
Configures Border Gateway Protocol (BGP) to treat two BGP routes as equal cost even if their AS-paths differ, as long as their AS-path lengths and other relevant attributes are the same.
How do you load balance the traffic in BGP?
To configure the BGP peer sessions:
- Configure the BGP group.
- Enable the BGP group to use multiple paths.
- Configure the load-balancing policy.
- Apply the load-balancing policy.
- Configure the local autonomous system (AS) number.
What is auto summarization in BGP?
auto-summary (BGP) BGP automatically summarizes routes to classful network boundaries when this command is enabled. Route summarization is used to reduce the amount of routing information in routing tables. Automatic summarization applies to connected, static, and redistributed routes.
What is Multihome BGP?
Multihoming is the practice of connecting your company’s network and IT infrastructure to two or more providers via the Border Gateway Protocol (BGP), the primary routing protocol used on the internet.
What is route aggregation and how it can be useful in Internet?
Route aggregation lets you take several specific routes and combine them into one inclusive route. Route aggregation can reduce the number of routes a given protocol advertises. The aggregates are activated by contributing routes.
Can BGP do ECMP?
Unlike most routing protocols, BGP only selects a single best path for each prefix. It doesn’t do ECMP (Equal Cost Multi-Path Routing) by default but it is possible to enable this.
What is Ebgp multihop in BGP?
EBGP multihop enables a neighbor connection between two EBGP peers that do not have a direct connection. The default behavior for an EBGP connection is to peer over a single physical hop using the physical interface address of the peer.
What is BGP maximum paths?
The maximum-paths command allows you to configure BGP to install multiple paths in the RIB for multipath load sharing. BGP uses the best path algorithm to select a single multipath as the best path and advertise the best path to BGP peers.
What is BGP ECMP?
BGP (Border Gateway Protocol) [RFC4271] employs tie-breaking logic to select a single best path among multiple paths available, known as BGP best path selection. At the same time, it is a common practice to allow for “equal-cost multipath” (ECMP) selection and programming of multiple next-hops in routing tables.
How does BGP choose the best path?
BGP Table 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.
- For EBGP-received routes, prefer the current active route.
What is BGP route aggregation?
What is BGP Route Aggregation. Route Aggregation (RA) also known as BGP Route Summarization is a method to minimize the size of the routing table, announcing the whole address block received from the Regional Internet Registry (RIR) to other ASes.
What is the as set option in BGP?
The option as-set allows AS path loop detection for BGP, as a router does not install a route into its BGP table when it detects its own AS in the AS PATH attribute update. Adding the as-set option ensures that the aggregate route 70.36.0.0/20 will be shown as originating from R1 (AS3695).
How do I inject a component route into the BGP table?
Note: A component route can be injected into the BGP table of a router via the network command, redistributed from the IGP protocols or learned by another BGP peer. The BGP table of the router R3 is shown on Picture 7.
How do I include an as set in an aggregate route?
To include an AS set in our aggregate route, append the as-set keyword to the aggregate-address command: This configuration generates an aggregate route with an AS path containing the AS set of 10 and 20, since the aggregate contains routes originating from those autonomous systems.