Multiprotocol Bgp; Implement Bgp; Additional Path (Add-Path) Support; Advertise Igp Cost As Med For Redistributed Routes - Dell C9000 Series Networking Configuration Manual

Hide thumbs Also See for C9000 Series:

Table of Contents

The system allows you to set the next hop attribute in the CLI. Setting the next hop attribute lets you

determine a router as the next hop for a BGP neighbor.

Multiprotocol BGP

Multiprotocol extensions for BGP (MBGP) is defined in IETF RFC 2858. MBGP allows different types of address

families to be distributed in parallel.

MBGP allows information about the topology of the IP multicast-capable routers to be exchanged separately

from the topology of normal IPv4 and IPv6 unicast routers. It allows a multicast routing topology different

from the unicast routing topology.

It is possible to configure BGP peers that exchange both unicast and multicast network layer

reachability information (NLRI), but you cannot connect multiprotocol BGP with BGP. Therefore, you

cannot redistribute multiprotocol BGP routes into BGP.

The following sections describe how BGP is implemented on the switch.

The add-path feature reduces convergence times by advertising multiple paths to its peers for the same

address prefix without replacing existing paths with new ones. By default, a BGP speaker advertises only the

best path to its peers for a given address prefix. If the best path becomes unavailable, the BGP speaker

withdraws its path from its local RIB and recalculates a new best path. This situation requires both IGP and

BGP convergence and can be a lengthy process. BGP add-path also helps switchover to the next new best

path when the current best path is unavailable.

Advertise IGP Cost as MED for Redistributed

When using multipath connectivity to an external AS, you can advertise the MED value selectively to each

peer for redistributed routes. For some peers you can set the internal/IGP cost as the MED while setting

others to a constant pre-defined metric as MED value.

Use the set metric-type internal command in a route-map to advertise the IGP cost as the MED to

outbound EBGP peers when redistributing routes. The configured set metric value overwrites the default

By using the redistribute command with the route-map command, you can specify whether a peer

advertises the standard MED or uses the IGP cost as the MED.

Border Gateway Protocol IPv4 (BGPv4)