bgp (bgp-router-config)
Configures BGP router parameters
Supported in the following platforms:
Syntax
bgp [always-compare-med|bestpath|client-to-client|cluster-id|confederation|
dampening|default|deterministic-med|enable|enforce-first-as|fast-external-failover|
graceful-restart|log-neighbor-changes|neighbor|network|router-id|scan-time]
bgp [always-compare-med|deterministic-med|enable|enforce-first-as|
fast-external-failover|log-neighbor-changes]
bgp best-path [as-path [confed|ignore]|compare-router-id|med {confed {missing-as-worst}|
missing-as-worst}]
bgp client-to-client reflection
bgp cluster <IP>
bgp confederation [identifier|peers] <1-4294967295>
bgp dampening {<1-45>} {<1-20000>} <1-20000> <1-255>
bgp default [ipv4-unicast|local-preference <0-4294967295>]
bgp graceful-restart {stalepath-time <1-3600>}
bgp neighbor <IP>
bgp network import-check
bgp router-id <IP>
bgp scan-time <5-60>
Parameters
bgp [always-compare-med|deterministic-med|enable|enforce-first-as|
fast-external-failover|log-neighbor-changes]
| always-compare-med |
Enables comparison of MEDs (Multi-exit
Discriminators) received from neighbors. This option is disabled by
default. MED is a value used by BGP peers to select the best route among
multiple routes. When enabled, the MED value encoded in the route is always
compared when selecting the best route to the host network. A route with a lower
MED value is preferred over a route with a higher MED value. BGP does not
discriminate between iBGP and eBGP when using MED for route selection. This option
is mutually exclusive to the deterministic-med option.
|
| deterministic-med |
Enables selection of the best MED path from amongst all
paths advertised by neighboring ASs. This option is disabled by default. MED is
used by BGP peers to select the best route among multiple routes. When enabled,
MED route values (from the same AS) are compared to select the best route. This
best route is then compared with other routes in the BGP route table to select the
best overall route. This option is mutually exclusive to the always-compare-med
option.
|
| enable |
Starts the BGP daemon on the device (wireless controller
or service platform). BGP is disabled by default. |
| enforce-first-as |
Enforces the first AS for all BGP routes. This option is
disabled by default. When enforced, devices deny updates received from an external
neighbor that does not have the neighbor‘s configured AS at the beginning of the
received AS path parameter. This enhances security by not allowing traffic from an
unauthorized AS.
|
| fast-external-failover |
Enables immediate resetting of BGP session on the
interface once the BGP connection goes down. This option is enabled by
default. When enabled, a session is reset as soon as the direct link to an
external peer goes down. Normally, when a BGP connection goes down, the device
waits for the expiry of the duration specified in holdtime parameter before
bringing down the interface.
To configure the ‘holdtime‘, use the command in this (BGP router) configuration mode.
|
| log-neighbor-changes |
Enables logging of a BGP neighbor‘s status change
(active or not active) events. It also enables the logging of the reason for such
change in status. |
|
bgp best-path [as-path [confed|ignore]|compare-router-id|med {confed {missing-as-worst}|
missing-as-worst}]
| best-path |
Modifies the bestpath selection algorithm. The route
selection algorithm uses the following criteria when selecting the preferred route:
as-path, router-id, and med. |
| as-path [confed|ignore] |
Enables an AS path from being considered as a criteria
for selecting the preferred route
- confed – Enables comparison of path lengths (including confederation sets and
sequences) when selecting a route (EXPERIMENTAL). This option is disabled by
default.
- ignores – Disables an AS path length from being considered as a criteria for
selecting a preferred route. When, disabled the AS path length is ignored. This
option is disabled by default.
|
| compare-router-id |
Enables the use of router ID as a selection criteria
when selecting the preferred route. When enabled, the router ID is used to select
the best path between two identical BGP routes. The route with the lower router ID
is selected over a route with a higher router ID. This option is disabled by
default. |
| med {confed {missing-as-worst}|
missing-as-worst} |
Enables comparison of AS path MED value when selecting
the preferred routeMED is a value used by BGP peers to select the best route
among multiple routes. When enabled, the MED value encoded in the route is always
compared to determine the best route to the host network. A route with a lower MED
value is preferred over a route with a higher MED value.
- confed – Optional. Enables comparison of MED value among confederation paths
(EXPERIMENTAL). When enabled, you can optionally enable the treatment of AS
paths without the MED value as the least preferable route. This option is
disabled by default.
- missing-as-worst – Optional. Enables the treatment of AS paths without the
MED value as the least preferable route. This option is disabled by
default.
|
|
bgp client-to-client reflection
| client-to-client reflection |
Enables client-to-client route reflection
(EXPERIMENTAL) Route reflectors are used when all iBGP speakers are not fully
meshed. If the clients are fully meshed, the route-reflectors are not required.
This option is enabled by default.
|
|
bgp cluster <IP>
| cluster <IP> |
Enables and sets a cluster ID, in case the BGP cluster
has more than one route-reflector A cluster generally consists of a single
route-reflector and its clients. The cluster is usually identified by the router
ID of this single route-reflector. Sometimes, to increase redundancy, a cluster
might have more than one route-reflector configured. In this case, all
route-reflectors in the cluster are identified by the cluster ID (configured in
the IP format).
|
|
bgp confederation [identifier|peers] <1-4294967295>
| confederation [identifier|peers]
<1-4294967295> |
Configures AS confederation (group of ASs) parameters
(identifier and peers)
- identifier – Enables and sets a BGP confederation identifier to allow an AS to
be divided into several ASs. In other words an AS is divided into multiple ASs,
and together they form a confederation. This confederation is visible to
external routers as a single AS. The ASN is usually the confederation ID.
Specify a value from 1 - 4294967295.
Forming AS confederation reduces iBGP mesh inside an AS.
- peers – Configures the maximum number of the ASs constituting this BGP
confederation. Specify the AS number from 1 - 4294967295. Multiple ASs can be
added to the list of confederation members.
|
|
bgp dampening {<1-45>} {<1-20000>} <1-20000> <1-255>
| bgp dampening {<1-45>} {<1-20000>} <1-20000>
<1-255> |
Enables dampening and configures dampening parameters.
This option is disabled by default.Dampening minimizes the instability caused by
route flapping. A penalty is added for every flap in the flapping route. As soon
as the total penalty reaches the specified Route Suppress Limit value, the
advertisement of this route is suppressed. This penalty is delayed when the time
specified in Half Lifetime occurs. Once the penalty becomes lower than the value
specified in Start Route Reuse, the advertisement of the route is
un-suppressed.
- <1-45> – Optional. Configures the half lifetime (in minutes). A penalty
is imposed on a route that flaps. This is the time for the penalty to decrease
to half its current value. Specify a value from 1 - 45 minutes. The default is
1 minute.
- <1-20000> – Optional. Configures the route reuse value. When the penalty
for a suppressed route decays below the value specified here, the route is
un-suppressed (reused). Specify a value from 1 - 20000.
- <1-20000> – Configures the route suppress value. When a route flaps, a
penalty is added to the route. When the penalty reaches or exceeds the value
specified as the ‘maximum duration to suppress a stable route‘. Specify a
value from 1 - 20000.
The maximum duration to suppress a stable route, is the next set of
value configured in this command from 1 - 255.
- <1-255> – Configures the maximum duration, in minutes, a suppressed route
is suppressed. This is the maximum duration for which a route remains
suppressed before it is reused. Specify a value from 1 - 255 minutes.
|
|
bgp default [ipv4-unicast|local-preference <0-4294967295>]
| default |
Configures the following defaults for BGP
neighbor-related parameters: IPv4 unicast and local preference |
| ipv4-unicast |
Enable IPv4 unicast traffic for neighbors. This option
is enabled by default. |
| local-preference <0-4294967295> |
Configures a local preference for the neighbor. Higher
the value higher is the preference.
- <0-4294967295> – Specify a value from 10 - 4294967295.
|
|
bgp graceful-restart {stalepath-time <1-3600>}
| default graceful-restart {stalepath-time
<1-3600>} |
Enables graceful restart on this BGP router. This option
is disabled by default
- stalepath-time <1-3600> – Optional. Configures the maximum time, in
seconds, to retain stale paths from restarting neighbor. This is the time the
paths from a restarting neighbor are preserved. All stale paths, unless
reinstated by the neighbor after re-establishment, are deleted at the expiry of
the time specified here.
- <1-3600> – Specify a value from 1 - 3600 seconds.
|
|
bgp neighbor <IP>
| neighbor <IP> |
Configures the BGP neighbor‘s IP address and enters its
configuration mode. Use this command to configure a BGP neighbor‘s parameters.
- <IP> – Specify the IP address in the A.B.C.D format.
For BGP neighbor configuration parameters, see bgp-neighbor-config
commands.
|
|
bgp network import-check
| network import-check |
Enables checking of the existence of BGP network route
in IGP before importing |
|
bgp router-id <IP>
| |
router <IP> |
Enables the device (BGP supported wireless controller or
service platform) identified by the <IP> parameter as a router. The router‘s IP
address is configured as its ID, and uniquely identifies it. When not specified, the
IP address of the interface is configured as the router ID. This option is disabled
by default. |
|
bgp scan-time <5-60>
| scan-time <5-60> |
Configures the scanning interval, in seconds, for
updating BGP routes. This is the interval between two consecutive scans the BGP
device performs in order to validate routes in its routing table. To disable
scanning, set the value to Zero (0).
- <5-60> – Specify a value from 5 - 60 seconds. The default is 60
seconds.
|
|
Examples
nx9500-6C8809(config-profile testNX9000-router-bgp)#bgp router-id 192.168.13.13
nx9500-6C8809(config-profile testNX9000-router-bgp)#aggregate-address 116.117.118.0/24 as-set summary-only
nx9500-6C8809(config-profile testNX9000-router-bgp)#bgp neighbor 192.168.13.99
nx9500-6C8809(config-profile testNX9000-router-bgpp)#show context
router bgp
aggregate-address 116.117.118.0/24 as-set summary-only
bgp router-id 192.168.13.13
bgp neighbor 192.168.13.99
remote-as 199
maximum-prefix 9999 80 restart 50
nx9500-6C8809(config-profile testNX9000-router-bgp)#
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