10-21-2010 03:04 AM - edited 03-06-2019 01:39 PM
Why the maximum total no 8 port(cable) can be loggicaly bundled in etherchannel?
10-21-2010 03:13 AM
Hello,
I'm not 100% sure about this, but I think the number is 8 ports, due to load-balancing formula. The port is selected using a Cisco-proprietary hash algorithm, based on source or destination MAC addresses, IP addresses or TCP and UDP port numbers. The hash function gives a number between 0 and 7, and the following table shows how the 8 numbers are distributed among the 2 to 8 physical ports. In the hypothesis of real random hash algorithm, 2, 4 or 8 ports configurations lead to fair load-balancing, whereas other configurations lead to unfair load-balancing:
Number of Ports | Load Balancing |
---|---|
8 | 1:1:1:1:1:1:1:1 |
7 | 2:1:1:1:1:1:1 |
6 | 2:2:1:1:1:1 |
5 | 2:2:2:1:1 |
4 | 2:2:2:2 |
3 | 3:3:2 |
2 | 4:4 |
I hope this helps you!
Cheers,
Calin
03-12-2024 02:19 PM
The limit of eight ports in an EtherChannel bundle is a restriction imposed by some network hardware and protocols. It's not a fundamental limitation of EtherChannel itself but rather a practical constraint based on implementation and design considerations.
Here are a few reasons why this limit might exist:
Protocol Limitations: Some EtherChannel protocols, like PAgP (Port Aggregation Protocol) and LACP (Link Aggregation Control Protocol), may have limitations on the maximum number of ports allowed in a bundle. For instance, some implementations might support up to 8 ports per bundle.
Hardware Constraints: Switch hardware may have limitations on the number of ports that can be aggregated into a single logical bundle due to processing power, memory, or other hardware-specific factors. Even if the protocol supports more ports, the hardware might not.
Efficiency and Management: Managing large EtherChannel bundles with a high number of ports can become complex and may not provide significant benefits in terms of bandwidth aggregation beyond a certain point. It's often more efficient to deploy multiple smaller EtherChannel bundles rather than a single large one.
Network Design: From a network design perspective, having too many ports in a single EtherChannel bundle can lead to a lack of redundancy and increase the risk of a single point of failure. Distributing ports across multiple smaller bundles provides better fault tolerance and scalability.
03-12-2024 03:17 PM - edited 03-12-2024 03:17 PM
Hello,
For both LACP and PAgP you can bundle 16 ports into an etherchannel, however only 8 ports will be active. So if one of the 8 ports goes down the Etherchannel process will pick a new port to take its place keeping 8 ports in the bundle and active.
Hope that helps
-David
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