Hi again, I've solved it by marking the default route coming from the iBGP neighbor w/ a local-preference of 90 and now the correct route is the default one. Is there any other more elegant solution to this issue?
thanks, john > Hi, > > Yes, I'm still trying to find out more details about rpf... > > But now, I ran into another issue: router1 is preferring the default route > from router2. In other words, once the iBGP relationship is established, > the default route (62.217.x.x) from router1 becomes router2's IP address > (91.195.X.1). Everything works fine, but all the traffic goes out through > router2. > > Do you know how can I fix this issue? I want router1 to keep its default > route after the iBGP comes up. > > Thanks, > john > >> hi, >> >> perhaps rather than just turn it off outright, investigate rpf loose? >> >> that will still allow you to have asymmetric traffic flows and drop >> traffic from bogon address space. >> >> you may still find you get some packet loss where icmp echo replies are >> returned from mpls interfaces that arent advertised, depending on your >> upstream/peer networks, but imho for the most part it works just fine. >> >>> -----Original Message----- >>> From: [EMAIL PROTECTED] [mailto:cisco-nsp- >>> [EMAIL PROTECTED] On Behalf Of mm-tech >>> Sent: Thursday, 4 December 2008 5:30 PM >>> To: [EMAIL PROTECTED] >>> Cc: [email protected] >>> Subject: Re: [c-nsp] bgp weird issue >>> >>> Hi guys, >>> >>> I've finally solved out the mystery with that /29 subnet being blocked >>> after the iBGP relationship came up. >>> It was because of the "ip verify unicast reverse-path" option enabled >>> on >>> Router1 on the interfaces connecting the router to the ISPA. >>> I had this option enabled to prevent ip spoofing, but it seems that it >>> affects in a negative way iBGP, BGP being a unicast protocol. >>> >>> Thanks, >>> john >>> >>> >> Hello John: >>> >> >>> >> >>> >> On 11/30/08 10:32 AM, "mm-tech" <[EMAIL PROTECTED]> wrote: >>> >> >>> >> <snip> >>> >> >>> >>> The issue is after I configure the iBGP relationship between >>> Router1 >>> >>> and >>> >>> Router2: connectivity to the 62.217.X.X/29 subnet on Router1 is >>> lost. >>> >>> It >>> >>> cannot be pinged anymore from outside. The 91.195.X.X/23 is >>> announced >>> >>> correctly through both ISPs and any IP in this /23 subnet is >>> pingable >>> >>> from >>> >>> outside. They only problem is with the 62.217.X.X/29 block that >>> becomes >>> >>> unreachable after configuring the iBGP relationship and I don't >>> >>> understand >>> >>> why this is happening. >>> >>> >>> >>> Sorry for the long post and I hope you'll give me some hints -:) >>> >>> >>> >>> Thanks, >>> >>> John >>> >>> >>> >> >>> >> How is the /29 configured on router 1? If it's being statically >>> routed >>> >> from >>> >> your ISP, then you need to have it in your IGP somehow. Something >>> >> simple >>> >> would be: >>> >> >>> >> Interface x/x >>> >> Ip address 62.217.x.x 255.255.255.248 >>> >> >>> >> Router ospf 10 >>> >> Redistribute connected subnets >>> >> >>> >> More information is needed, I'm afraid. >>> >> >>> >> Regards, >>> >> >>> >> Mike >>> >> >>> >> >>> > Yes, the /29 subnet is configured on Router1 on a SVI interface. I >>> haven't >>> > tried to put this /29 into my IGP. I'll try that and I'll let you >>> know >>> > guys. >>> > >>> > Iy you need more info, please let me know... >>> > >>> > Thanks, >>> > john >>> > >>> > >>> >>> >>> _______________________________________________ >>> cisco-nsp mailing list [email protected] >>> https://puck.nether.net/mailman/listinfo/cisco-nsp >>> archive at http://puck.nether.net/pipermail/cisco-nsp/ >> > > > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
