D-Link DI-1750 Reference Manual page 252

Please Input the code of command to be excute(0-7): 0
input 0，Select all option ，prompt is as below:
(00)soft Soft reconfigure
(01)<cr>
Please Input the code of command to be excute(0-1): 1
input 1 and confirm it.
6.12.11 Configure synchronization between BGP and IGPs
If your autonomous system will be passing traffic through it from another autonomous system to a third
autonomous system, it is very important that your autonomous system be consistent about the routes
that it advertises. For example, if your BGP were to advertise a route before all routers in your network
had learned about the route through your IGP, your autonomous system could receive traffic that some
routers cannot yet route. To prevent this from happening, BGP must wait until the IGP has propagated
routing information across your autonomous system. This causes BGP to be synchronized with the IGP.
Synchronization is enabled by default.
In some cases, you do not need synchronization. If you will not be passing traffic from a different
autonomous system through your autonomous system, or if all routers in your autonomous system will
be running BGP, you can disable synchronization. Disabling this feature can allow you to carry fewer
routes in your IGP and allow BGP to converge more quickly. To disable synchronization, use the
following command in router configuration mode:
Synchronization (undo)
In route prompt，you must Select U or u first，prompt is as below:
(00)aggregate-address
......
(22)synchronization
......
Please Input the code of command to be excute(0-26): 22
input 22，Select synchronization option ，prompt is as below:
(00)<cr>
Please Input the code of command to be excute(0-0): 0
input 0，confirm it.
When you disable synchronization, you should also clear BGP sessions using the clear ip bgp
command.
See the "BGP Path Filtering by Neighbor Example" section at the end of this chapter for an example of
BGP synchronization.
In general, you will not want to redistribute most BGP routes into your IGP. A common design is to
redistribute one or two routes and to make them exterior routes in IGRP, or have your BGP speaker
generate a default route for your autonomous system. When redistributing from BGP into IGP, only the
routes learned using EBGP get redistributed. In most circumstances, you also will not want to
redistribute your IGP into BGP. Just list the networks in your autonomous system with network router
configuration commands and your networks will be advertised. Networks that are listed this way are
referred to as local networks and have a BGP origin attribute of "IGP." They must appear in the main IP
routing table and can have any source; for example, they can be directly connected or learned via an
IGP. The BGP routing process periodically scans the main IP routing table to detect the presence or
absence of local networks, updating the BGP routing table as appropriate. If you do perform
redistribution into BGP, you must be very careful about the routes that can be in your IGP, especially if
the routes were redistributed from BGP into the IGP elsewhere. This creates a situation where BGP is
potentially injecting information into the IGP and then sending such information back into BGP, and vice
versa.
Model Name
Command
Aggregate network
Perform IGP synchronization
- 250 -
Purpose
Disable synchronization between BGP and
an IGP.