Which of the following two statements about Cisco NSF and SSO are the most relevant to thenetwork designer？ （）

• A、 You can reduce outage 1 to 3 seconds by using SSO in Layer 2 environment or Cisco NSF with SSO in a Layer 3 environment.
• B、 SSO and NSF each require the device to either be graceful restart-capable or graceful-aware.
• C、 In a fully redundant topology adding redundant supervisor a with NSF and SSO may causelonger convergence times than single supervisors with turned IGP times
• D、 The primary deployment scenario for Cisco NSF with SSO is in the Distribution and Corelayers.
• E、 Cisco NSF-aware neighbor relationship are independent of any turned IGP times