Ethernet vs. ATM Network: A Comparison Of The Two Routing Technologies
Processor speeds on the rising track,
Networks becoming a bottleneck,
We are always trying to, as we should,
To lower latency, up throughput.
But also many researchers see
Reliability as the key,
And applications sometimes miss
Good old performance that guarantees
Bounded latency, other stuff.
You'd think that Ethernet was enough,
But always striving for something best,
A brand new scheme puts it to the test.
It has advantages; time will tell
If it becomes the new standard. Well,
Let us compare the routing schemes
Of two approaches. They will seem
Divergent, mainly in one respect:
We'd look in Ethernet's written specs,
But see no mention of "routing" there.
Is it because they just didn't care
To name so process, of which they're proud,
Or simply Ethernet does not route?
Instead a broadcasting protocol
Is used, requiring that control
Of whole network is, bit by bit,
Obtained before station can transmit
Its packets. Certainly not a plus.
But once broadcasting selects to pass,
The packets will be spread all about
The Ether. There's no need to route!
In contrast, forcing the path length low,
ATM's point-to-point flow
Reduces latency, benefits
The network so when one host transmits,
The others waiting to do the same
Need not just sit there, with it to blame.
Another plus of the ATM's
The trademarked Multiple Paths
Between two hosts: should one path die,
Availability would stay high
Of both hosts, as is the case
When path's congestion puts time to waste.
Before describing advantage three,
Let's note: Ethernet is a tree
Unrooted, (which conjures up a flock
of visions; read Alexander Block.
Returning thus to the point stalled)
Ether's topology plays a role,
Ensuring there to be at most
One path between any pair of hosts.
The final point of ATM's strength
Is data being sent in fixed-length
Cell objects, while the Ether tries
To deal with varying packet size.
The gain of fixing cell length resides
In fact that easiness to provide
Performance guarantees is increased
(At least the article claims this).
By now, Ethernet's lost some pride,
But every coin has other side:
Reliability comes to play.
Let us imagine it, as we may,
That one switch router, sharp and stout,
Suddenly fails, and does not route
(Instead of routing, of work instead,
It lies there, completely dead.).
The consequences are not first-rate:
System performance degenerates,
Although the working condition lasts
Because the hosts have many paths
Between themselves. Now think what ails
The Ether, when a transceiver fails.
Like general, army stuck in the snow,
Losing a soldier: he would not know.
The bottom line: the switches need
Reliability and the speed.
Two aspects wanted, and both of which
Are claimed to rest in the banyan switch.
If ATM's claims are right, in vain
Is all resistance. Adieu. Amen.