Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Secondary address

I work for a small ISP. Currently, the fastethernet interface of my 7206 router has 8 secondary addresses assigned to it. One for each /24 I route. I am running OSPF inside and BGP outside. Is there an alternative to this method? Any drawbacks?

2 REPLIES
Silver

Re: Secondary address

The largest draw back I can think of is that with all 8 /24's on one interface I assume that all the hosts on these networks are in one broadcase domain. With no separation at Layer 2 between these hosts broadcase from network 1 are heard, and might be unwanted, from network 2-8. VLAN segmentation in your switching environment will achieve Layer 2 segmentation, lessoning the Broadcast Domain size and increasing performance. Either multiple router interfaces or trunking will give you the L3 separation.

Hope this helps,

Don

New Member

Re: Secondary address

Well, I am not sure how OSPF will react for secondary IP address on the ethernet. Please check http://www.cisco.com/warp/public/105/41.html.

If your router supports trunking, go for subinterfaces.

The only thing that I remember about secondary IPs on an interface is that per to Cisco's recommendation, all routers you have on that same segment has to use a secondary address from the same subnet. I donno why though, but this is what I remember, cause I used to have the same problem.

93
Views
0
Helpful
2
Replies