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> I'm not a CCNA, but I play one at work.
That's OK - I am not a certified Solaris admin, or certified for anything
else for that matter (though some suggest I am certifiable - why are they
laughing when they say that?).
> > It would be nice if it could work across multiple switches, so if a
> > single switch failed, you would not lose connectivity (I think the
> > adaptive failover can do this, but that does not improve bandwidth).
>
> No it wouldn't be nice because it would put a tremendous burdon on the
> link connecting the switches. If you are lucky, this link is 1Gb/sec, much
> slower than back planes which or 10Gb/sec and up. In general, you don't
> want to "load balance" your switches. Keep as much as you can on the same
> back plane.
OK, so if I want the HA features, then use on switch at a time. I
wonder if there is any way to have redundant (failover) bonded channels.
In other words, can I have a bonded channel (say, four ports - don't
put them all on one card by the way) on Catalyst 6500 A and another bonded
channel (another four ports) on Catalyst 6500 B, and then failover from
A to B should A go down? This is really not a Cisco question, but a
Linux question. I think the answer is probably no, but I was pleasantly
surprised yesterday, so I am going to be greedy and try again today.
> > Even so, in a Cisco Catalyst chassis with multiple blades and redundant
> > supervisor cards (and power supplies, obviously), this might be a decent
> > HA/performance solution. I'll have to look at the back of those big
> > Ciscos and see if they have multiple power cables. I find it amusing
> > that a Sun 4500 can have four power supplies (and a 450 can have two),
> > but since they have a single power cord, one clumsy person can take
> > the system down quite easily. In my experience, that kind of thing
> > happens far more often than equipment failure. HA is all about
> > attention to details.
>
> Any Cisco chassis' (4000s, 5000s, and 6000s) have multiple power supplies,
> each with its own power chord.
That is an excellent design decision. The more recent Sun servers have
also started doing that (ie 220R, 420R, 280R, E250 even).
> > So, are there any Cisco Fast EtherChannel experts out there? Can
> > FEC run across multiple switches, or at least across multiple Catalyst
> > blades? I guess I can go look it up, but if somebody already knows,
> > I don't mind saving myself the trouble.
>
> Fast EtherChannel cannot run across multiple switches. A colleague spent
> weeks of our time proving that.
It's refreshing to know this is practice, not theory. Be sure to thank
your colleague for determining this so thoroughly. ;)
> In short, each switch will see a distinct link, for a total of two, but
> your server will think it has one big one. The switches will not talk to
> each other to bond the two links and you don't want them to for the reason
> I stated above. Over multiple blades, that depends on your
> switch. Do a "show port capabilities" to find out; it will list the ports
> that can be grouped into an FEC group.
Thanks again for the info.
--
John Cronin
mailto: `echo NjsOc3@xxxxxxxxxxx | sed 's/[NOSPAM]//g'`
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