Table of Contents
What is ECMP used for?
Equal-cost multipath (ECMP) is a network routing strategy that allows for traffic of the same session, or flow—that is, traffic with the same source and destination—to be transmitted across multiple paths of equal cost.
What is ECMP in Cisco?
Equal Cost Multi-Path or ECMP is a routing strategy where packets towards a single destination IP address are load-balanced over multiple best paths with equal metrics.
Does BGP use 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 ECMP in OSPF?
The ECMP feature allows OSPF to add routes with multiple next-hop addresses and with equal costs to a given destination in the forwarding information base (FIB) on the routing switch.
Does OSPF support ECMP?
What is ECMP hashing?
For ECMP, the hashing algorithm determines how incoming traffic is forwarded to the next-hop device. The hashing algorithm makes hashing decisions based on values in various packet fields, as well as on the hash seed value.
What is ECMP in BGP?
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.
What is an ECMP group?
An ECMP group is a list of unique next hops that are referenced by multiple ECMP routes. An ECMP route counts as a single route with multiple next hops.
What is OSPF ECMP?
What are the trade-offs between ECMP and lag?
Tradeoffs between ECMP and LAG include speed to failure detection, scalability, supported network protocols and ease of use. Newer options include Multipath TCP (MPTCP) which performs load balancing at the transport layer, enabling multiple subflows that take unique paths for the same traffic flow.
What is the difference between ECMP and lag and DLB?
For ECMP, you can configure DLB globally, whereas for LAG, you configure it for each aggregated Ethernet interface. You can apply DLB on selected ether-type (IPv4, IPv6, and MPLS) based on configuration. If you don’t configure any ether-type, then DLB is applied to all EtherTypes.
Is multicast traffic supported in the lag bundle?
Multicast traffic is not supported. Aggregated interfaces are supported, but consistent load balancing is not supported among members of the link aggregation (LAG) bundle. Traffic from active members of the LAG bundle might be moved to another active member when one or more member links fail.
Does consistent load balancing apply when modifying an ECMP?
Consistent load balancing does not apply when you add a new ECMP path or modify an existing path in any way. To add a new path with minimal disruption, define a new ECMP group without modifying the existing paths. In this way, clients can be moved to the new group gradually without terminating existing connections.