Dell MX5108n OS10 Enterprise Edition User Guide for PowerEdge MX IO Modules Re - Page 297

Timers, Neighbor soft-reconfiguration, soft-reconfiguration

Page 297 highlights

View dampened paths OS10# show ip bgp dampened-paths BGP local router ID is 80.1.1.1 Status codes: s suppressed, S stale, d dampened, h history, * valid, > best Origin codes: i - IGP, e - EGP, ? - incomplete Network From Reuse Path d* 3.1.2.0/24 80.1.1.2 00:00:12 800 9 8 i d* 3.1.3.0/24 80.1.1.2 00:00:12 800 9 8 i d* 3.1.4.0/24 80.1.1.2 00:00:12 800 9 8 i d* 3.1.5.0/24 80.1.1.2 00:00:12 800 9 8 i d* 3.1.6.0/24 80.1.1.2 00:00:12 800 9 8 i Total number of prefixes: 5 Timers To adjust the routing timers for all neighbors, configure the timer values using the timers command. If both the peers negotiate with different keepalive and hold time values, the final hold time value is the lowest values received. The new keepalive value is one-third of the accepted hold time value. • Configure timer values for all neighbors in ROUTER-NEIGHBOR mode. timers keepalive holdtime - keepalive - Time interval in seconds, between keepalive messages sent to the neighbor routers (1 to 65535, default 60). - holdtime - Time interval in seconds, between the last keepalive message and declaring the router dead (3 to 65535, default 180). View nondefault values OS10# show running-configuration ... neighbor 32.1.1.2 remote-as 103 timers 61 181 no shutdown Neighbor soft-reconfiguration BGP soft-reconfiguration allows for fast and easy route changes. Changing routing policies requires a reset of BGP sessions or the TCP connection, for the policies to take effect. Resets cause undue interruption to traffic due to the hard reset of the BGP cache, and the time it takes to re-establish the session. BGP soft-reconfiguration allows for policies to apply to a session without clearing the BGP session. You can perform a soft-reconfiguration on a per-neighbor basis, either inbound or outbound. BGP soft-reconfiguration clears the policies without resetting the TCP connection. After configuring soft-reconfiguration, use clear ip bgp to make the neighbor use soft reconfiguration. When you enable soft-reconfiguration for a neighbor and you execute the clear ip bgp soft in command, the update database stored in the router replays and updates are re-evaluated. With this command, the replay and update process triggers only if a route-refresh request is not negotiated with the peer. If the request is negotiated after using the clear ip bgp soft in command, BGP sends a route-refresh request to the neighbor and receives all the peer's updates. To use soft reconfiguration, or soft reset without preconfiguration, both BGP peers must support the soft route refresh capability. The soft route refresh advertises in the OPEN message sent when the peers establish a TCP session. To determine whether a BGP router supports this capability, use the show ip bgp neighbors command. If a router supports the route refresh capability, the Received route refresh capability from peer message displays. Layer 3 297

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View dampened paths
OS10# show ip bgp dampened-paths
BGP local router ID is 80.1.1.1
Status codes: s suppressed, S stale, d dampened, h history, * valid, > best
Origin codes: i - IGP, e - EGP, ? - incomplete
Network
From
Reuse
Path
d*
3.1.2.0/24
80.1.1.2
00:00:12
800 9 8 i
d*
3.1.3.0/24
80.1.1.2
00:00:12
800 9 8 i
d*
3.1.4.0/24
80.1.1.2
00:00:12
800 9 8 i
d*
3.1.5.0/24
80.1.1.2
00:00:12
800 9 8 i
d*
3.1.6.0/24
80.1.1.2
00:00:12
800 9 8 i
Total number of prefixes: 5
Timers
To adjust the routing timers for all neighbors,
configure
the timer values using the
timers
command. If both the peers negotiate with
different
keepalive and hold time values, the
final
hold time value is the lowest values received. The new keepalive value is one-third of the
accepted hold time value.
Configure
timer values for all neighbors in ROUTER-NEIGHBOR mode.
timers
keepalive holdtime
keepalive
— Time interval in seconds, between keepalive messages sent to the neighbor routers (1 to 65535, default 60).
holdtime
— Time interval in seconds, between the last keepalive message and declaring the router dead (3 to 65535, default
180).
View nondefault values
OS10# show running-configuration
...
neighbor 32.1.1.2
remote-as 103
timers 61 181
no shutdown
Neighbor
soft-reconfiguration
BGP
soft-reconfiguration
allows for fast and easy route changes. Changing routing policies requires a reset of BGP sessions or the TCP
connection, for the policies to take
effect.
Resets cause undue interruption to
traffic
due to the hard reset of the BGP cache, and the time it takes to re-establish the session. BGP
soft-reconfiguration
allows for policies to apply to a session without clearing the BGP session. You can perform a
soft-reconfiguration
on a
per-neighbor basis, either inbound or outbound. BGP
soft-reconfiguration
clears the policies without resetting the TCP connection. After
configuring
soft-reconfiguration,
use
clear ip bgp
to make the neighbor use soft
reconfiguration.
When you enable
soft-reconfiguration
for a neighbor and you execute the
clear ip bgp soft in
command, the update database
stored in the router replays and updates are re-evaluated. With this command, the replay and update process triggers only if a route-refresh
request is not negotiated with the peer. If the request is negotiated after using the
clear ip bgp soft in
command, BGP sends a
route-refresh request to the neighbor and receives all the peer’s updates.
To use soft
reconfiguration,
or soft reset without
preconfiguration,
both BGP peers must support the soft route refresh capability. The soft
route refresh advertises in the OPEN message sent when the peers establish a TCP session. To determine whether a BGP router supports
this capability, use the
show ip bgp neighbors
command. If a router supports the route refresh capability, the
Received route
refresh capability from peer
message displays.
Layer 3
297