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Questions tagged [ecmp]

For questions about Equal-cost multi-path routing (ECMP), where it is a routing strategy where next-hop packet forwarding to a single destination can occur over multiple "best paths" which tie for top place in routing metric calculations.

0
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1answer
43 views

Regarding ECMP hashing

Assume we have a following topology. R1 represents Router1, R2 represents Router2, R3 represents Router3 and R4 represents Router4. Src represents the source Server. Dest represents the destination. ...
3
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1answer
531 views

Juniper SRX BGP based ECMP not working as expected

Overview I am trying to setup BGP based ECMP to two end servers that sit on separate subnets/VLANs and advertise out the same IP address to a SRX firewall. The end nodes are linux boxes running BIRD ...
3
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1answer
1k views

Using ECMP for switching in Layer 2

Equal-cost multi-path (ECMP) is a routing strategy that gives several benefits such as load balancing (as far as I know it is mostly implemented in routers). Suppose there exists a set of switches, ...
4
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1answer
362 views

L3 leaf-spine architecture and DHCP ip assignment

Background: we are planning to have a L3 leaf spine network with TOR(redundant mlag) and spine switch. Each TOR is on a specific subnet and run bgp with spine. Now, what is the recommendation to run ...
3
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2answers
1k views

Example of ECMP uses hashing technique

Can someone provide me an example of how Equal-cost multi-path routing uses hashing to decided which packet goes to which? I apologize for that but all I found online are just a definition of ECMP.
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2answers
3k views

Why are my equal cost LSP's not load balancing equally when using auto-bandwidth?

First, I'm adding this question and answering myself because this type of behavior was absolutely no where to be found, hopefully it will help someone. Problem: We use auto bandwidth to handle the ...
0
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1answer
160 views

How do ECMP and OSPF collaborate within Cisco's MSDC network?

Reading the MSDC design guide, it was indicated that OSPF is used for the routing and ECMP for supporting equal cost paths. Who does the actual routing, is it OSPF using ECMP or the other way arround? ...
3
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1answer
4k views

load-balancing on congestion, OSPF over MPLS

I have a network of routers with two clients at both ends, as shown in the Figure below. All the routers use OSPF routing protocol over IP, and the three routers inside the "MPLS backbone" subnetwork ...
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1answer
516 views

ECMP between next-hops with different route prefix length

I have a basic question about ECMP, say I have a /20 route and also a /16 route to a host, and both are reachable, can ECMP load-balance between different prefix length or is it like, hardware first ...
15
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2answers
8k views

BGP multipath with different ASNs feasible for production networks?

on Cisco (this command is hidden for some reason) #bgp bestpath as-path multipath-relax The default BGP behavior only installs only routes with exact the same AS_PATH into RIB. With multipath-relax, ...
18
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6answers
10k views

Best practice for the combination of HSRP and ECMP

The combination of ECMP (or other causes of asymmetric paths) and HSRP is broken by default in Cisco IOS; the default behaviour with this design floods unicast traffic excessively. What is the best-...
11
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3answers
1k views

Two Cisco ASA 5525-X as Internet Gateways without Layer 2

Add another reason to hate NAT to the list. I'm bringing up two Internet egress points in our corporate network. The edge devices will be ASA 5525-X firewalls. Traditionally you would put these into ...
16
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4answers
5k views

Why does this router fail to use multiple, equal-cost routes from OSPF?

A Brocade router running NetIron 5.2, and a Dynamips emulation running IOS 12.4 both fail to dependably use equal cost paths in what seems to be a very simple configuration. I say "dependably" because ...