You can configure the Sun to do round-robin, but not a Cisco switch.
Depending on the switch, the Cisco's can do MAC, IP, layer 4 ports (with
PFC2 module in switch). Whether you do MAC, IP or Port hashing, they all
result in a single path from one machine to the server, however the
total number of clients should be statistically balanced. None of the
cisco switches support round-robin. 

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a
0080094714.shtml


>From SUN TRUNKING documentation:

Trunking Policies

The four supported trunking policies used in the Sun Trunking 1.2.1
software are
MAC, Round Robin, IP Destination, and IP Source+Destination. With these
policies,
if a link fails, the traffic goes to the next available link. The
policies are defined
below.

MAC
 Is the default policy used by the Sun Trunking 1.2.1 software. MAC is
the
preferred policy to use with switches. Most trunking-capable switches
require
using the MAC-hashing policy, but check your switch documentation.

 Uses the last three bits of the MAC address of both the source and
destination.
For two ports, the MAC address of the source and destination are first
XORed:
Result = 00, 01, which selects the port.

 Favors a large population of clients. For example, this ensures that 50
percent of
the client connections will go through one of two ports in a two-port
trunk.

 Is required by most trunking-capable switches.

Round Robin

 Round Robin is the preferred policy with a Back to Back connection,
used
between the output of a transmitting device, and the input of an
associated
receiving device.
 Uses each network interface of the trunk in turn, as a method of
distributing
packets over the assigned number of trunking interfaces.
 May have an impact on performance since the temporal ordering of
packets is not
observed.

IP Destination Address
 Uses the four bytes of the IP Destination address to determine the
transmission
path.

 If a trunking interface host has one IP source address, and it is
necessary to
communicate to multiple IP clients connected to the same router, then
the IP
Destination Address policy is the preferred policy to use.

IP Source Address/IP Destination Address
 Connects the source server to the destination, based on where the
connection
originated or terminated.
 Uses the four bytes of the source and destination IP addresses to
determine the
transmission path.

The primary use of the IP Source/IP Destination Address policy occurs
where
you use the IP virtual address feature to give multiple IP addresses to
a single
physical interface. For example, you might have a cluster of servers
providing
network services, in which each service is associated with a virtual IP
address
over a given interface. If a service associated with an interface fails,
the virtual IP
address migrates to a physical interface on a different machine in the
cluster. In
such an arrangement, the IP Source Address/IP Destination Address policy
gives
you a greater chance of using more, different links within the trunk
than would
the IP Destination Address policy.


----
Matthew Huff           | One Manhattanville Rd
Director of Operations | Purchase, NY 10577
OTA LLC                | Phone: 914-460-4039 
http://www.otaotr.com  | Fax:   914-460-4139    

> -----Original Message-----
> From: Darren Dunham [mailto:ddunham AT TAOS DOT COM] 
> Sent: Wednesday, July 07, 2004 10:43 AM
> To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> Subject: Re: [Networker] Sun Trunking
> 
> 
> > It works fine, just keep in mind that if you are going from 
> one host 
> > to just one other host, it will only use 1 of the 4 links.
> 
> Even if you turn on round robin?
> 
> You'd still want a few streams to maximize the pipe, but it 
> should use all the links.
> 
> --
> Darren Dunham                                           
> ddunham AT taos DOT com
> Senior Technical Consultant         TAOS            
> http://www.taos.com/
> Got some Dr Pepper?                      
>      San Francisco, CA bay area
>          < This line left intentionally blank to confuse you. >
> 
> --
> Note: To sign off this list, send a "signoff networker" 
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> 

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