Re: When to use BGP Was: number of CCIE [7:70151]
Were the two T1's terminating at two differant ISP's? If so BGP would be appropriate. If you have 2 T1's terminating at a single ISP in the same POP then no. What would you do if they had been terminating at a single ISP in the same POP? Or did you mean same router? Most likely simple default routes. You mean default static routes? From a pure theoretical point of view, that seems a bit dangerous to me (to have two default static route pointing to two different routers). If one of the ISP routers is not directly connected to the customer's router (because for example there is an Ethernet switch in the middle), then the customer's router won't notice even if the ISP router is powered down. Even if the two routers are directly connected, it is possible (even though with current IOS versions it is not very likely) that the interface stays up even though routing dies on the ISP router. In short, I think there is a chance of you blackholing half of your traffic. Comments? :) Thanks, Zsombor Unless your co-located with your ISP your probably not connected to an ethernet switch! Though even if serially connected, with static routes you would not know if the LAN connection on the ISP router went down effectively causing the same blackholing you refer to. Like most things there is a cost/benefit analysis. WAN links are more prone to outages than the LAN, pointing your default to the ISP WAN is simple and commonly used config. For cusomters that are more sensitive to outages may opt for dual homing to 2 ISP's using ful routing and have their WAN connections via a SHNS or SHARP configuration. Redundancy and simplicity are not bedfellows and the more your willing to spend the more redundancy can be had. Dave Though as Howard alluded to there are some exceptions where you may use BGP but not to recieve full routing but more likely to control network announcements. You could exchange same router/POP as far as routing is concerned. Dave -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=71163t=70151 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: When to use BGP Was: number of CCIE [7:70151]
Thanks, I appreciate your comments. Zsombor At 01:36 PM 6/23/2003 -0500, MADMAN wrote: Were the two T1's terminating at two differant ISP's? If so BGP would be appropriate. If you have 2 T1's terminating at a single ISP in the same POP then no. What would you do if they had been terminating at a single ISP in the same POP? Or did you mean same router? Most likely simple default routes. You mean default static routes? From a pure theoretical point of view, that seems a bit dangerous to me (to have two default static route pointing to two different routers). If one of the ISP routers is not directly connected to the customer's router (because for example there is an Ethernet switch in the middle), then the customer's router won't notice even if the ISP router is powered down. Even if the two routers are directly connected, it is possible (even though with current IOS versions it is not very likely) that the interface stays up even though routing dies on the ISP router. In short, I think there is a chance of you blackholing half of your traffic. Comments? :) Thanks, Zsombor Unless your co-located with your ISP your probably not connected to an ethernet switch! Though even if serially connected, with static routes you would not know if the LAN connection on the ISP router went down effectively causing the same blackholing you refer to. Like most things there is a cost/benefit analysis. WAN links are more prone to outages than the LAN, pointing your default to the ISP WAN is simple and commonly used config. For cusomters that are more sensitive to outages may opt for dual homing to 2 ISP's using ful routing and have their WAN connections via a SHNS or SHARP configuration. Redundancy and simplicity are not bedfellows and the more your willing to spend the more redundancy can be had. Dave Though as Howard alluded to there are some exceptions where you may use BGP but not to recieve full routing but more likely to control network announcements. You could exchange same router/POP as far as routing is concerned. Dave -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 Government can do something for the people only in proportion as it can do something to the people. -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=71201t=70151 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
