Default Address Family For Show Commands; Mpls Vpn Carrier Supporting Carrier - Cisco ASR 9000 Series Configuration Manual

Default Address Family for show Commands

reflector would be configured with other route reflectors as nonclient peers (thus, all route reflectors are fully
meshed). The clients are configured to maintain iBGP sessions with only the route reflector in their cluster.
Usually, a cluster of clients has a single route reflector. In that case, the cluster is identified by the router ID
of the route reflector. To increase redundancy and avoid a single point of failure, a cluster might have more
than one route reflector. In this case, all route reflectors in the cluster must be configured with the cluster ID
so that a route reflector can recognize updates from route reflectors in the same cluster. All route reflectors
serving a cluster should be fully meshed and all of them should have identical sets of client and nonclient
peers.
By default, the clients of a route reflector are not required to be fully meshed and the routes from a client are
reflected to other clients. However, if the clients are fully meshed, the route reflector need not reflect routes
to clients.
As the iBGP learned routes are reflected, routing information may loop. The route reflector model has the
following mechanisms to avoid routing loops:
• Originator ID is an optional, nontransitive BGP attribute. It is a 4-byte attributed created by a route
• Cluster-list is an optional, nontransitive BGP attribute. It is a sequence of cluster IDs that the route has
Default Address Family for show Commands
Most of the show commands provide address family (AFI) and subaddress family (SAFI) arguments (see
RFC 1700 and RFC 2858 for information on AFI and SAFI). The Cisco IOS XR software parser provides the
ability to set the afi and safi so that it is not necessary to specify them while running a show command. The
parser commands are:
• set default-afi { ipv4 | ipv6 | all }
• set default-safi { unicast | multicast | all }
The parser automatically sets the default afi value to ipv4 and default safi value to unicast . It is necessary
to use only the parser commands to change the default afi value from ipv4 or default safi value from unicast
. Any afi or safi keyword specified in a show command overrides the values set using the parser commands.
Use the following show default-afi-safi-vrf command to check the currently set value of the afi and safi.

MPLS VPN Carrier Supporting Carrier

Carrier supporting carrier (CSC) is a term used to describe a situation in which one service provider allows
another service provider to use a segment of its backbone network. The service provider that provides the
segment of the backbone network to the other provider is called the backbone carrier. The service provider
that uses the segment of the backbone network is called the customer carrier.
A backbone carrier offers Border Gateway Protocol and Multiprotocol Label Switching (BGP/MPLS) VPN
services. The customer carrier can be either:
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.1.x
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reflector. The attribute carries the router ID of the originator of the route in the local autonomous system.
Therefore, if a misconfiguration causes routing information to come back to the originator, the information
is ignored.
passed. When a route reflector reflects a route from its clients to nonclient peers, and vice versa, it
appends the local cluster ID to the cluster-list. If the cluster-list is empty, a new cluster-list is created.
Using this attribute, a route reflector can identify if routing information is looped back to the same cluster
due to misconfiguration. If the local cluster ID is found in the cluster-list, the advertisement is ignored.
Implementing BGP
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