IP Routing Use Cases

Answers

  1. No, it is not turned on by default. You need to turn it on by entering the nsf command within IGP configuration mode.

  2. NSF-aware means that the device can participate in an NSF restart by virtue of understanding the GR LSA, but might not undertake the restart itself. NSF-capable routers, on the other hand, can both understand GR LSA and can also undergo an NSF restart. Cisco ASR 1000 is an NSF-aware and -capable device.

  3. ERSPAN stands for Encapsulated Remote SPAN, which essentially encapsulates the SPAN-ed traffic inside a GRE header so that it can be routed across a Layer 3 domain. This enables data capturing on one device on a given set of interfaces and direction, whereas monitoring station could be placed several L3 hops away on another device (such as Cisco ASR 1000). Cisco Catalyst 6500, 7600, Nexus, and ASR 1000 are the only platforms that support ERSPAN.

  4. The RP IOS package for ASR1000-RP2 and most of the underlying software infrastructure has been extended to 64 bits, hence it can therefore address beyond 4 GB DRAM.

  5. No, the Cisco ASR 1000 does not require any software RTU licenses for these basic features. Hence, they can be used as long as they are available in the given IOS image.

  6. DCI stands for data center interconnect, which is a common way to extend Layer 2 or Layer 3 connectivity across the data centers. The ASR 1000 can be used at this time for p2p connectivity across two data centers for IP and MPLS transport types. EoMPLS can be used to extend the L2 connectivity and VLANs across the DCI WAN link. The ASR 1000 has a unique feature known as Remote Port Shutdown, which functions similar to GSR. So, to avoid traffic blackholing and to allow faster convergence, as soon as a pseudowire goes down, the router switches off the port laser to let the peer port (customer edge [CE]) know that the link has gone down, which immediately goes to down/down. This proves handy to achieve extremely fast convergence end to end. As soon as the pseudowire comes back up, it turns the laser on, signaling the CE port that it can resume traffic via the given EoMPLS PE. This feature is enabled by default and does not require any additional configuration.

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