Cisco Support Community
Community Member

bgp issue: subdivide a large network

we have a /22 large IP segment that needs to be divided into four equal IP segments (we'll use /24 subnet mask for each segment).

our ISP is advertising the /22. what could be done on our router (who's got 4 gigabit ethernets ports) so as not to affect normal business operations ? .. or at least minimize maintenance time.

any help is very much appreciated. thanks.


Re: bgp issue: subdivide a large network

It is not related to the Ethernet issue. It is only the route summarization issue.

In normal case, if your ISP advertise /22 to the Internet, no matter what mask you are using, they will still advertise /22 to the Internet. You can check w/ your ISP for their policy.

Therefore, you can use continue to use /24 mask and advertise it to the ISP then let the ISP to summarize it for you and advertise to the Internet. Or you can summarize the routes to /22 at your router then advertise /22 route to the ISP.

It is better to work w/ ISP to determine the suitable solution. Gather the requirement or guideline from ISP and matched w/ your company policy to work out a solution.

The route summarization should not impact business operation. However, I always recommend to assign a maintenance window for any move & change activity to prevent unpredicatable issue.

Hope this helps.

CreatePlease to create content