Re: Etherchannel load balancing?

src-mac ,dst-mac

Src-dst-ip

Options are diff on 3550 switch and 3560 .its related with switch .
for more info ,check cisco doc cd .

Rsharma
Sent by blackberry

On 5/29/09, Evan Weston <evan_weston_at_hotmail.com> wrote:
> G'day all,
>
> I have a question about the logic used by Etherchannel load balancing.
>
>
> I have this exert from the CCNP book:
>
> ----8<----8<----8<----8<----8<----8<----8<
> Traffic in an EtherChannel is distributed across the individual bundled
> links in a deterministic
> fashion; however, the load is not necessarily balanced equally across all
> the links. Instead, frames
> are forwarded on a specific link as a result of a hashing algorithm. The
> algorithm can use source IP
> address, destination IP address, or a combination of source and destination
> IP addresses, source
> and destination MAC addresses, or TCP/UDP port numbers. The hash algorithm
> computes a binary
> pattern that selects a link number in the bundle to carry each frame.
>
> If only one address or port number is hashed, a switch forwards each frame
> by using one or more
> low-order bits of the hash value as an index into the bundled links. If two
> addresses or port
> numbers are hashed, a switch performs an exclusive-OR (XOR) operation on one
> or more loworder
> bits of the addresses or TCP/UDP port numbers as an index into the bundled
> links.
>
> For example, an EtherChannel consisting of two links bundled together
> requires a 1-bit index. If
> the index is 0, link 0 is selected; if the index is 1, link 1 is used.
> Either the lowest-order address bit
> or the XOR of the last bit of the addresses in the frame is used as the
> index. A four-link bundle
> uses a hash of the last 2 bits.
> ----8<----8<----8<----8<----8<----8<----8<
>
>
> Now things Im not sure about:
> In an etherchannel running a dot1q trunk the only options I can use are
> src-mac and dst-mac correct? Or is there a better way to get more throughput
> over etherchannels running dot1q trunks?
>
> Also am I right to say that the logic isn't that great? It just comes down
> to a 1bit even or odd number based on either the source or destination mac
> of the flow depending on what method I have selected?
>
>
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Received on Fri May 29 2009 - 12:43:41 ART