Users Guide

Enabling Neighbor Graceful Restart
BGP graceful restart is active only when the neighbor becomes established. Otherwise, it is disabled.
Graceful-restart applies to all neighbors with established adjacency.
With the graceful restart feature, Dell Networking OS enables the receiving/restarting mode by default. In Receiver-Only mode, graceful
restart saves the advertised routes of peers that support this capability when they restart. This option provides support for remote peers
for their graceful restart without supporting the feature itself.
You can implement BGP graceful restart either by neighbor or by BGP peer-group. For more information, refer to the Dell Networking OS
Command Line Interface Reference Guide
.
• Add graceful restart to a BGP neighbor or peer-group.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} graceful-restart
• Set the maximum restart time for the neighbor or peer-group.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} graceful-restart [restart-time time-in-seconds]
The default is 120 seconds.
• Local router supports graceful restart for this neighbor or peer-group as a receiver only.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} graceful-restart [role receiver-only]
• Set the maximum time to retain the restarting neighbor’s or peer-group’s stale paths.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | peer-group-name} graceful-restart [stale-path-time time-in-seconds]
The default is 360 seconds.
Filtering on an AS-Path Attribute
You can use the BGP attribute, AS_PATH, to manipulate routing policies.
The AS_PATH attribute contains a sequence of AS numbers representing the route’s path. As the route traverses an AS, the ASN is
prepended to the route. You can manipulate routes based on their AS_PATH to aect interdomain routing. By identifying certain ASN in the
AS_PATH, you can permit or deny routes based on the number in its AS_PATH.
AS-PATH ACLs use regular expressions to search AS_PATH values. AS-PATH ACLs have an “implicit deny.” This means that routes that do
not meet a deny or match lter are dropped.
To congure an AS-PATH ACL to lter a specic AS_PATH value, use these commands in the following sequence.
1 Assign a name to a AS-PATH ACL and enter AS-PATH ACL mode.
CONFIGURATION mode
ip as-path access-list as-path-name
2 Enter the parameter to match BGP AS-PATH for ltering.
CONFIG-AS-PATH mode
{deny | permit} filter parameter
This is the lter that is used to match the AS-path. The entries can be any format, letters, numbers, or regular expressions.
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Border Gateway Protocol IPv4 (BGPv4)