DELL S50V User Manual
Border Gateway Protocol IPv4 (BGPv4) | 217
Next Hop
The Next Hop is the IP address used to reach the advertising router. For EBGP neighbors, the Next-Hop
address is the IP address of the connection between the neighbors. For IBGP, the EBGP Next-Hop address
is carried into the local AS. A Next Hop attribute is set when a BGP speaker advertises itself to another
BGP speaker outside its local AS. It can also be set when advertising routes within an AS. The Next Hop
attribute also serves as a way to direct traffic to another BGP speaker, rather than waiting for a speaker to
advertise.
address is the IP address of the connection between the neighbors. For IBGP, the EBGP Next-Hop address
is carried into the local AS. A Next Hop attribute is set when a BGP speaker advertises itself to another
BGP speaker outside its local AS. It can also be set when advertising routes within an AS. The Next Hop
attribute also serves as a way to direct traffic to another BGP speaker, rather than waiting for a speaker to
advertise.
FTOS 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.
determine a router as the next hop for a BGP neighbor.
Multiprotocol BGP
MBGP for IPv6 unicast is supported on platforms
e c
MBGP for IPv4 Multicast is supported on platform
c e
s
Multiprotocol Extensions for BGP (MBGP) is defined in IETF RFC 2858. MBGP allows different types of
address families to be distributed in parallel. This allows information about the topology of 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.
address families to be distributed in parallel. This allows information about the topology of 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.
Implementing BGP with FTOS
Advertise IGP cost as MED for redistributed routes
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.
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.
FTOS 8.3.1.0 and later support configuring 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 IGP cost.
By using the
redistribute
command in conjunction with the
route-map
command, you can specify whether a
peer advertises the standard MED or uses the IGP cost as the MED.
Note the following when configuring this functionality:
Note: 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. Therefor, You
cannot redistribute Multiprotocol BGP routes into BGP.
reachability information (NLRI), but you cannot connect Multiprotocol BGP with BGP. Therefor, You
cannot redistribute Multiprotocol BGP routes into BGP.