New IS-IS Sub-TLVs

DE.

Intermediate System-to-Intermediate System (IS-IS) is a link-state routing protocol that is commonly used in service provider networks. Multiprotocol Label Switching Traffic Engineering (MPLS-TE) is an extension of MPLS that allows for the creation of explicit paths across an MPLS network to support traffic engineering requirements. IS-IS is one of the protocols that can be used to distribute MPLS-TE information.

Sub-TLVs (Sub-Type Length Values) are used in IS-IS to carry additional information within TLVs (Type Length Values). In the context of MPLS-TE, new IS-IS sub-TLVs were created to support the distribution of MPLS-TE information. Let's look at the options and their explanations:

A. Multitopology: This sub-TLV is used to advertise different topologies within the same IS-IS instance. It is not specifically related to MPLS-TE implementation.

B. Narrow metric: This sub-TLV is used to support finer granularity in the metric calculation. This sub-TLV is not specifically related to MPLS-TE implementation.

C. SRLG (Shared Risk Link Group): SRLG is a group of links that share the same risk of failure. The SRLG sub-TLV is used to distribute information about SRLGs. This sub-TLV is used in MPLS-TE to prevent the creation of parallel paths that share common resources.

D. Administration group: This sub-TLV is used to group interfaces into administrative groups. The purpose of this sub-TLV is to provide a way to specify the routing preferences for certain groups of interfaces. It is not specifically related to MPLS-TE implementation.

E. Maximum link bandwidth: This sub-TLV is used to distribute information about the maximum bandwidth of a link. It is used in MPLS-TE to calculate the available bandwidth on a path.

Therefore, the correct answers to the question are C. SRLG and E. Maximum link bandwidth. These sub-TLVs were created specifically to support MPLS-TE implementation in IS-IS.