Where once the networking stocks tended to trade together, the notion now has clearly sunk in that many of the companies operate in very different spheres. And they're being treated accordingly.

"What we're seeing in general is that investors are starting to segment out these companies a little more by what their market is and who they're selling to," said analyst Steve Kammen with

CIBC World Markets.

After reporting earnings that were in line with expectations yesterday,

Extreme Networks

(EXTR) - Get Extreme Networks, Inc. Report

, which specializes in corporate networking, got no love today.

Thomas Weisel

analyst Mark Edelen downgraded the stock to buy from strong buy, largely because of slowing economics. Extreme's higher-end networking products are seen as vulnerable to a slowdown in corporate information-technology budgets. (Weisel has done underwriting for Extreme.)

Extreme was down $5.38, or 11.2%, to $42.50 on the downgrade.

Sharing some product overlap and some of the same vulnerability,

Foundry Networks

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also finished down, dropping 19 cents, or 1.1%, to $17.25.

Despite

beating Street estimates for earnings and revenue,

Redback Networks

(RBAK)

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, which makes subscriber management systems for DSL networks, got pasted with four downgrades. Analysts zeroed in on much lower gross margins and the usual suspect, a slowing economy.

CIBC's Kammen, who downgraded Redback last week, said there also may be some slowing in its business growth with the crippling of DSL resellers such as

Covad

(COVD)

and

NorthPoint

(NPNT)

. "It's no longer pedal to the metal. Now, it's just above the speed limit," said Kammen. (His firm has done no underwriting for Redback.) And

Robertson Stephens

analyst Paul Johnson also wrote that with a recent run-up in the stock -- Redback has gained 42.6% on the month before today -- it was approaching its fair value.

Redback fell $7.69, or 15.8%, to $40.88.

Juniper Networks

(JNPR) - Get Juniper Networks, Inc. (JNPR) Report

continued its own run-up -- 33% since the beginning of the month -- with a very healthy report this week. Juniper's network routers have done extremely well competing with the

Mother of All Networkers

,

Cisco Systems

(CSCO) - Get Cisco Systems, Inc. Report

. Juniper was still cruising off a report that took it up 6.4% yesterday; it finished up 44 cents, or 0.3%, to $136.63 today. Cisco was up $2.88, or 7.4%, to $41.88.