> hi john, > > is the /29 address-block assigned by ISPA and staticall routed to > you only by ISPA? > Does the connectivity problem only exist from networks that you reach > preferrably through ISPB? >
Yes, the /29 block is assigned by ISPA from their address space and it's statically routed to me by them. No, the connectivity issue occurs for both networks reachable through ISPA or ISPB. > If so, then could it be that ISPB has packet filters applied > that drop packets with the source of the /29 network? To ISPB traffic from > the /29 network looks like illegal traffic since the packets have a source > IP other than the networks you announce with BGP. > I don't think ISPB has any packet filters blocking my /29 subnet, because this /29 subnet is part of the whole ISPA address space, and ISPB has a route to this ISPA address space... Thanks, john > regards > > Reinhold > > > > On Sun, Nov 30, 2008 at 08:32:39PM +0200, mm-tech wrote: >> Hi guys, >> >> I'm having this weird issue with BGP and I was wondering if you could >> help. >> >> Topology: >> - 2 X cisco 1800 series routers, both connected to 2 different ISPs: >> Router1 -> ISPA and RouterB -> ISPB >> - Router1 and Router2 are directly connected >> - on Router1 receiving only the default route from ISPA >> - on Router2 receiving customer routes from ISPB >> - announcing a /23 address block through both ISPA and ISPB (91.195.X.X) >> >> The connectivity with ISPA is being done using a /30 subnet >> (interconnected subnets): ISPA(172.28.164.17/30) -> >> router1(172.28.164.18/30). Also, I have a /29 public address space on >> router1 (62.217.X.X) routed through the /30 subnet. The default gw for >> Router1 received via eBGP is 62.217.w.w and I have added a static route >> for it: >> ip route 62.217.w.w 255.255.255.255 172.28.164.17 >> >> That's how ISPA has it's network configured and I cannot change >> anything. >> >> The connectivity with ISPB is simple: only a /32 ip address on Router2: >> 89.149.X.X >> >> BGP config Router1: >> >> router bgp myASN >> no synchronization >> bgp router-id 62.217.X.X >> bgp log-neighbor-changes >> network 91.195.X.0 mask 255.255.254.0 >> neighbor 62.217.X.X remote-as ASN_ISPA >> neighbor 62.217.X.X ebgp-multihop 8 >> neighbor 62.217.X.X soft-reconfiguration inbound >> neighbor 62.217.X.X filter-list 10 out >> neighbor 91.195.y.1 remote-as myASN >> neighbor 91.195.y.1 next-hop-self >> no auto-summary >> >> ip as-path access-list 10 permit ^$ >> >> BGP config Router2: >> >> router bgp myASN >> no synchronization >> bgp router-id 89.149.X.X >> bgp log-neighbor-changes >> network 91.195.X.0 mask 255.255.254.0 >> neighbor 89.149.X.X remote-as ASN_ISPB >> neighbor 89.149.X.X filter-list 10 out >> neighbor 91.195.z.1 remote-as myASN >> neighbor 91.195.z.1 next-hop-self >> no auto-summary >> >> ip as-path access-list 10 permit ^$ >> >> 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 >> >> _______________________________________________ >> 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/
