3Com 7700 Configuration Manual page 138

130 C 5: R P
HAPTER OUTING
O
ROTOCOL PERATION
Perform the following configurations in BGP view.
Table 112 Configuring the Sub-AS of the Confederation
Operation
Configure a confederation consisting of which
sub-ASs
Cancel the specified sub-AS in the
confederation
By default, no autonomous system is configured as a member of the
confederation.
Configuring the Nonstandard AS If it is necessary to perform the
interconnection with the devices whose implementation mechanism is different
from that of RFC1965, you must configure all the routers in the confederation.
Perform the following configurations in BGP view.
Table 113 Configuring the Nonstandard AS
Operation
Configure AS confederation attribute
compatible with nonstandard router
Cancel AS confederation attribute compatible
with nonstandard router
By default, the configured confederation is consistent with RFC1965.
Configuring BGP Route Dampening
The main possible reason for an unstable route is the intermittent disappearance
and re-emergence of the route that formerly existed in the routing table, and this
situation is called the flapping. When flapping occurs, the update packet will be
propagated on the network repeatedly, which will occupy much bandwidth and
much processing time of the router. We have to find measures to avoid it. The
technology controlling unstable route is called route dampening.
The dampening divides the route into the stable route and unstable route, the
latter of which shall be suppressed (not to be advertised). The history performance
of the route is the basis to evaluate the future stability. When the route flapping
occurs, penalty will be given, and when the penalty reaches a specific threshold,
the route will be suppressed. With time going, the penalty value will decrease
according to power function, and when it decreases to certain specific threshold,
the route suppression will be eliminated and the route will be re-advertised.
Perform the following configurations in BGP view.
Table 114 Configuring BGP Route Dampening
Operation
Configure BGP route dampening
Clear route attenuation information and
eliminating the suppression of the route
Command
confederation peer-as as-number-1 [ ...
as-number-n ]
undo confederation peer-as [ as-number-1
] [ ...as-number-n ]
Command
confederation nonstandard
undo confederation nonstandard
Command
dampening [ half-life-reachable
half-life-unreachable reuse suppress ceiling ] [
route-policy route-policy-name ]
reset dampening [ network-address [ mask ]
]