Cisco Systems 3560 Manual De Usuario
36-50
Catalyst 3560 Switch Software Configuration Guide
OL-8553-06
Chapter 36 Configuring IP Unicast Routing
Configuring BGP
Beginning in privileged EXEC mode, follow these steps to configure some decision attributes:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
router bgp autonomous-system
Enable a BGP routing process, assign it an AS number, and enter
router configuration mode.
router configuration mode.
Step 3
bgp best-path as-path ignore
(Optional) Configure the router to ignore AS path length in
selecting a route.
selecting a route.
Step 4
neighbor {ip-address | peer-group-name}
next-hop-self
next-hop-self
(Optional) Disable next-hop processing on BGP updates to a
neighbor by entering a specific IP address to be used instead of
the next-hop address.
neighbor by entering a specific IP address to be used instead of
the next-hop address.
Step 5
neighbor {ip-address | peer-group-name}
weight weight
weight weight
(Optional) Assign a weight to a neighbor connection. Acceptable
values are from 0 to 65535; the largest weight is the preferred
route. Routes learned through another BGP peer have a default
weight of 0; routes sourced by the local router have a default
weight of 32768.
values are from 0 to 65535; the largest weight is the preferred
route. Routes learned through another BGP peer have a default
weight of 0; routes sourced by the local router have a default
weight of 32768.
Step 6
default-metric number
(Optional) Set a MED metric to set preferred paths to external
neighbors. All routes without a MED will also be set to this value.
The range is 1 to 4294967295. The lowest value is the most
desirable.
neighbors. All routes without a MED will also be set to this value.
The range is 1 to 4294967295. The lowest value is the most
desirable.
Step 7
bgp bestpath med missing-as-worst
(Optional) Configure the switch to consider a missing MED as
having a value of infinity, making the path without a MED value
the least desirable path.
having a value of infinity, making the path without a MED value
the least desirable path.
Step 8
bgp always-compare med
(Optional) Configure the switch to compare MEDs for paths from
neighbors in different autonomous systems. By default, MED
comparison is only done among paths in the same AS.
neighbors in different autonomous systems. By default, MED
comparison is only done among paths in the same AS.
Step 9
bgp bestpath med confed
(Optional) Configure the switch to consider the MED in choosing
a path from among those advertised by different subautonomous
systems within a confederation.
a path from among those advertised by different subautonomous
systems within a confederation.
Step 10
bgp deterministic med
(Optional) Configure the switch to consider the MED variable
when choosing among routes advertised by different peers in the
same AS.
when choosing among routes advertised by different peers in the
same AS.
Step 11
bgp default local-preference value
(Optional) Change the default local preference value. The range
is 0 to 4294967295; the default value is 100. The highest local
preference value is preferred.
is 0 to 4294967295; the default value is 100. The highest local
preference value is preferred.
Step 12
maximum-paths number
(Optional) Configure the number of paths to be added to the IP
routing table. The default is to only enter the best path in the
routing table. The range is from 1 to 16. Having multiple paths
allows load balancing among the paths. (Although the switch
software allows a maximum of 32 equal-cost routes, the switch
hardware will never use more than 16 paths per route.)
routing table. The default is to only enter the best path in the
routing table. The range is from 1 to 16. Having multiple paths
allows load balancing among the paths. (Although the switch
software allows a maximum of 32 equal-cost routes, the switch
hardware will never use more than 16 paths per route.)
Step 13
end
Return to privileged EXEC mode.
Step 14
show ip bgp
show ip bgp neighbors
Verify the reset by checking information about the routing table
and about BGP neighbors.
and about BGP neighbors.
Step 15
copy running-config startup-config
(Optional) Save your entries in the configuration file.