CCIE R&S V5.1 Written Exam: Describe Basic ISIS Network
I will be discussing Describe Basic ISIS Network as part of Layer 3 Technologies and Fundamental Routing Concepts CCIE Routing and Switching (R&S) V5.1 exam blueprint topics.
Describe Basic ISIS Network :
3.8 ISIS [for IPv4 and IPv6]
3.8.a Describe basic ISIS network
3.8.a [i] Single area, single topology
Let me summarize some of the key takeaways related to CCIE R&S V5.1 Written Exam: Implement and Troubleshoot Static Routing as relevant to CCIE Routing and Switching (R&S) V5.1 written exam blueprint topics.
- Overload bit is special bit in the IS-IS LSP used to inform the network that the advertising router is not yet ready to forward transit traffic.
- ISIS system ID is 6 bytes long
- The ISIS Attach Bit (or ATT bit) is set by L1L2 routers to notify L1 routers that they can reach the rest of the network i.e. default routing.
- Cisco IOS software allows three types of IS-IS authentication to be configured
- ISIS provides for the authentication of Hellos and Link State Packets (LSPs) through the inclusion of authentication information as part of the LSP
- IS-IS MaxAge starts at 1200 seconds by default and on reaching 0 the LSP will be remain in the Link State Database (LSD) for a period of time called the Zero Age Lifetime which has a default value of 60 seconds.
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