Thanks Jeff, that makes sense... Without the sham link, the customer routers never even sees the routes coming in from the PE. With the sham link, they are advertised from the PE to CE as type 1 or type 2 LSA's, so we can adjust the cost of the backdoor path and/or MPLS path to control how traffic is routed.
Doug -------- Original Message -------- Subject: Re: [OSL | CCIE_RS] OSPF behavior with MPLS VPN, backdoor link, no sham link From: Jeff Andiorio <[email protected]> Date: Mon, November 19, 2012 10:42 am To: Michael Davis - Webquor <[email protected]> Cc: "[email protected]" <[email protected]>, "[email protected]" <[email protected]> This link does call out the PE will not create a Type3 LSA if Type 1 is received from the site. http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/L3VPNCon.html Jeff On Thu, Nov 15, 2012 at 4:40 PM, Michael Davis - Webquor <[email protected]> wrote: > Thanks Doug that seems to make sense. I will give your gns3 topology a go > > Sent from my iPhone > > On 15/11/2012, at 11:36 PM, "[email protected]" <[email protected]> wrote: > >> Actually, I mean the OSPF routes (originating from the remote customer >> site, advertised across the back-door link to the local CE, and then >> advertised to the local PE) have an AD of 110, while the BGP routes >> (advertised via OSPF from the remote site CE to the the remote PE, then >> redistributed into BGP and advertised to the local PE) have an AD of >> 200. So the PE selects the OSPF routes to insert into the VRF routing >> table, and the BGP routes never get re-distributed. >> >> Here's a link to the GNS3 topology I'm using for this. Have a quick >> look, it will make much more sense than my rambling on... >> http://gns3vault.com/MPLS/advanced-mpls-vpn.html >> >> Thanks, >> >> Doug >> >> >> >> >> -------- Original Message -------- >> Subject: Re: [OSL | CCIE_RS] OSPF behavior with MPLS VPN, backdoor >> link, no sham link >> From: Steve Storniak <[email protected]> >> Date: Thu, November 15, 2012 7:23 am >> To: "[email protected]" <[email protected]>, >> "[email protected]" <[email protected]> >> >> Did you mean local CE routes (internal) have high priority over BGP >> routes(external) per ospf route selection process? >> >> >> >> Steve >> >> >> From: [email protected] <[email protected]>; >> To: <[email protected]>; >> Subject: Re: [OSL | CCIE_RS] OSPF behavior with MPLS VPN, backdoor >> link, no sham link >> Sent: Thu, Nov 15, 2012 11:05:13 AM >> >> Specifying the both external and internal types when re-distributing >> into MP-BGP doesn't seem to make a difference. Since they are all >> internal routes, the distribution works without specifying the route >> types, as evidenced by the Type 3 LSA's and O IA routes showing up when >> I shut down the back-door link. >> >> But I think I have the answer... Here's an excerpt from "sh ip bgp vpnv4 >> vrf MELON" from the PE router that connects to one customer site, let's >> call it "Customer Site A". This was taken while the back-door link was >> up: >> >> *> 12.12.12.12/32 192.168.23.2 111 32768 ? >> * i 5.5.5.5 11 100 0 ? >> >> And here an excerpt from "show ip route vrf MELON" for the same route: >> >> O 12.12.12.12 [110/111] via 192.168.23.2, 00:00:04, Ethernet0/3 >> 13.0.0.0/32 is subnetted, 1 subnets >> >> 192.168.23.2 is the CE router at "Customer Site A", while 5.5.5.5 is the >> PE router loopback that connects to "Customer Site B" and 12.12.12.12 is >> the loopback of the CE router at "Customer Site B". >> >> Only active routes, present in the VRF's routing table, are >> re-distributed. Since the OSPF routes from the local CE have a lower AD >> than the BGP routes from the other site, the OSPF routes are active in >> the VRF's routing table, not the BGP routes. So the BGP routes from the >> other site coming across the MPLS VPN never get redistributed into OSPF, >> so the LSA's don't get created. >> >> Does this sound correct? >> >> Doug >> >> >> >> >> -------- Original Message -------- >> Subject: Re: [OSL | CCIE_RS] OSPF behavior with MPLS VPN, backdoor >> link, no sham link >> From: Greg Chisholm <[email protected]> >> Date: Wed, November 14, 2012 8:21 pm >> To: [email protected] >> >> On 11/14/2012 05:12 PM, [email protected] wrote: >>> I'm working on a sham link lab, and came across some behavior I don't >>> understand. I've got the MPLS L3VPN built, and routes are being learned >>> across it properly. Everything is in area 0, and I've used the same >>> process ID for the vrf on both PE's. I do not have the sham link >>> configured yet, so all traffic is going over the back-door link. >>> >>> The thing I don't understand is that there are no Type3 LSA's anywhere, >>> not on the CE routers, nor on the PE vrf's. I only see type 1 and Type 2 >>> LSA's. If I shut down the back-door link, the Type 3's show up, along >>> with the O IA routes as expected. >>> >>> I would think that while the back-door is up, we would see the Type 2 >>> LSA's coming across the back-door link, as well as the Type 3 LSA's >>> being redistributed from MP-BGP. >>> >>> What am I missing? >>> >>> Thanks, >>> >>> Doug >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >>> Are you a CCNP or CCIE and looking for a job? Check out >>> www.PlatinumPlacement.com >>> >>> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> >> Look at your redistribution in BGP, you need to specify the types of >> OSPF routes with redistribute ospf >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, >> please visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, >> please visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
