Re: Route-map question [7:34431]
Hunt, You are correct, there is nothing filtering the routes entering from Router B, without local preference set higher on 10.1.1.1 (Router A?) for the routes, nothing will prevent AS 202 from being used for other destinations as well. More confusing to me is the configuration. I read the question as if Router B should only be used for packets _originating_ from AS 202, which should use the T1 connection. In this case an outbound filter would be appropriate, along with a community tag of no-export. Even if this the reverse is true (which the configuration seems to indicate), the as-path access-list is only setting local preference for the AS 300 destination! It seems like the following access-list should have been used: ip as-path access-list 1 permit ^202$ Then again, perhaps I have just totally misunderstood the question. Either way, I hope that this helps. - Tom On Mon, 04 Feb 2002 23:43:41 -0500, Hunt Lee wrote: > I have a Route-Map question that I'm very confused about: > > The scenario is from Caslow (p840), it is as follows: > > Company A has a full T3 connection to the Internet thru the ISP > AAA-101.NET. Company B has a T1 connection to the Internet thru the ISP > BBB-202.Net. Company A acquires Company B, but Company A wants to keep > both Internet connections, with the exception of packets originating > from the AS of BBB-202.Net (BBB-202.Net's AS is 202). All traffic > originating from AS 202 will use the T1 Internet connection. > > Caslow states in order to do this, the following configs should be used > on RouterB > > router bgp 1000 > neighbor 10.1.1.1 remote-as 1000 > neighbor 172.16.1.100 remote-as 202 > neighbor 172.16.1.100 route-map AS-200-IN in > > no ip classless > ip as-path access-list 1 permit _300$ > > route-map AS-200-IN permit 10 > match as-path 1 > set local-preference 200 > > route-map AS-200-IN permit 20 > > What I don't understand is: > > With the "set local-preference 200" statement, it directs the traffic > (routes coming from AS 202 / neighbor 172.16.1.100) to go out via Router > B. However, what makes the router not passing any other routes (not from > AS 200)? Wouldn't they still be able to go out thru Router B as well? In > consideration that the local preference has not been changed on the > router. > > Any help will be greatly appreciated. > > Best Regards, > Hunt Lee > System Engineer > WebCentral > misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=34474&t=34431 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-map question [7:34431]
Thanks so much for your helpful explanation Tom :) Hunt ""Tom Martin"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hunt, > > You are correct, there is nothing filtering the routes entering from > Router B, without local preference set higher on 10.1.1.1 (Router A?) for > the routes, nothing will prevent AS 202 from being used for other > destinations as well. > > More confusing to me is the configuration. > > I read the question as if Router B should only be used for packets > _originating_ from AS 202, which should use the T1 connection. In this > case an outbound filter would be appropriate, along with a community tag > of no-export. > > Even if this the reverse is true (which the configuration seems to > indicate), the as-path access-list is only setting local preference for > the AS 300 destination! It seems like the following access-list should > have been used: > > ip as-path access-list 1 permit ^202$ > > Then again, perhaps I have just totally misunderstood the question. Either > way, I hope that this helps. > > - Tom > > > On Mon, 04 Feb 2002 23:43:41 -0500, Hunt Lee wrote: > > > I have a Route-Map question that I'm very confused about: > > > > The scenario is from Caslow (p840), it is as follows: > > > > Company A has a full T3 connection to the Internet thru the ISP > > AAA-101.NET. Company B has a T1 connection to the Internet thru the ISP > > BBB-202.Net. Company A acquires Company B, but Company A wants to keep > > both Internet connections, with the exception of packets originating > > from the AS of BBB-202.Net (BBB-202.Net's AS is 202). All traffic > > originating from AS 202 will use the T1 Internet connection. > > > > Caslow states in order to do this, the following configs should be used > > on RouterB > > > > router bgp 1000 > > neighbor 10.1.1.1 remote-as 1000 > > neighbor 172.16.1.100 remote-as 202 > > neighbor 172.16.1.100 route-map AS-200-IN in > > > > no ip classless > > ip as-path access-list 1 permit _300$ > > > > route-map AS-200-IN permit 10 > > match as-path 1 > > set local-preference 200 > > > > route-map AS-200-IN permit 20 > > > > What I don't understand is: > > > > With the "set local-preference 200" statement, it directs the traffic > > (routes coming from AS 202 / neighbor 172.16.1.100) to go out via Router > > B. However, what makes the router not passing any other routes (not from > > AS 200)? Wouldn't they still be able to go out thru Router B as well? In > > consideration that the local preference has not been changed on the > > router. > > > > Any help will be greatly appreciated. > > > > Best Regards, > > Hunt Lee > > System Engineer > > WebCentral > > misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=34703&t=34431 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-map question [7:34431]
Tom, Can you please elaborate how the outbound filter with the community tag of no-export would help... as I'm still not too clear what it will achieve. And sorry for the stupid question... Thanks again. Best Regards, Hunt Lee ""Tom Martin"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I read the question as if Router B should only be used for packets > _originating_ from AS 202, which should use the T1 connection. In this > case an outbound filter would be appropriate, along with a community tag > of no-export. > On Mon, 04 Feb 2002 23:43:41 -0500, Hunt Lee wrote: > > > I have a Route-Map question that I'm very confused about: > > > > The scenario is from Caslow (p840), it is as follows: > > > > Company A has a full T3 connection to the Internet thru the ISP > > AAA-101.NET. Company B has a T1 connection to the Internet thru the ISP > > BBB-202.Net. Company A acquires Company B, but Company A wants to keep > > both Internet connections, with the exception of packets originating > > from the AS of BBB-202.Net (BBB-202.Net's AS is 202). All traffic > > originating from AS 202 will use the T1 Internet connection. > > > > Caslow states in order to do this, the following configs should be used > > on RouterB > > > > router bgp 1000 > > neighbor 10.1.1.1 remote-as 1000 > > neighbor 172.16.1.100 remote-as 202 > > neighbor 172.16.1.100 route-map AS-200-IN in > > > > no ip classless > > ip as-path access-list 1 permit _300$ > > > > route-map AS-200-IN permit 10 > > match as-path 1 > > set local-preference 200 > > > > route-map AS-200-IN permit 20 > > > > What I don't understand is: > > > > With the "set local-preference 200" statement, it directs the traffic > > (routes coming from AS 202 / neighbor 172.16.1.100) to go out via Router > > B. However, what makes the router not passing any other routes (not from > > AS 200)? Wouldn't they still be able to go out thru Router B as well? In > > consideration that the local preference has not been changed on the > > router. > > > > Any help will be greatly appreciated. > > > > Best Regards, > > Hunt Lee > > System Engineer > > WebCentral > > misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=35358&t=34431 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Route-map question [7:34431]
Tom, Can you please elaborate how the outbound filter with the community tag of no-export would help... as I'm still not too clear what it will achieve. And sorry for the stupid question... Thanks again. Best Regards, Hunt Lee WebCentral ""Tom Martin"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hunt, You are correct, there is nothing filtering the routes entering from Router B, without local preference set higher on 10.1.1.1 (Router A?) for the routes, nothing will prevent AS 202 from being used for other destinations as well. More confusing to me is the configuration. I read the question as if Router B should only be used for packets _originating_ from AS 202, which should use the T1 connection. In this case an outbound filter would be appropriate, along with a community tag of no-export. Even if this the reverse is true (which the configuration seems to indicate), the as-path access-list is only setting local preference for the AS 300 destination! It seems like the following access-list should have been used: ip as-path access-list 1 permit ^202$ Then again, perhaps I have just totally misunderstood the question. Either way, I hope that this helps. - Tom Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=35374&t=34431 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
