Shares of several networking companies lost ground today, as a member of the extended family,

Terayon Communication Systems

(TERN)

, said fourth-quarter revenue and earnings would fall

well short of analysts' estimates because of an unexpected slowdown and canceled orders.

Shares of Terayon, which provides broadband networking systems primarily to cable companies, recently plunged $8, or 59.8%, to $5.38.

Cisco

(CSCO) - Get Report

lost $5.25, or 10.9%, to $43. Shares of

Avici Systems

(AVCI)

recently traded at $28.25, down 10.2%, or $3.19.

Avanex

(AVNX)

lost $8, or 10.6%, to $67.31, while

Sycamore Networks

(SCMR)

fell $4.69, or 8.5%, to $50.50.

Ciena

(CIEN) - Get Report

lost $7.94, or 7.9%, to $93, and

Corvis

(CORV) - Get Report

traded down $5, or 15.3%, to $27.88.

Extreme Networks

(EXTR) - Get Report

fell $16.50, or 22.8%, to $56.

Juniper Networks

(JNPR) - Get Report

held up comparatively well, losing $2.13, or 1.8%, to $127. The same couldn't be said for

Redback Networks

(RBAK)

, which followed the majority of the sector and lost $10.13, or 12.2%, to $73.