Monitoring and support backdoors are common and pervasive in most networking gear. This isn't something that should be considered lightly.

There's been some hullaboo about Chinese manufacturers putting backdoor access into their devices, Huawei Technologies and ZTE Corporation particularly: http://www.infosecisland.com/blogview/21930-China-Has-Backdo...

Legally mandated backdoors exist on Cisco gear as well: http://www.forbes.com/2010/02/03/hackers-networking-equipmen...