Got it, thanks for your help.
From: Adam Booth [mailto:[email protected]] Sent: Wednesday, October 12, 2011 8:48 AM To: Bill Riley Cc: [email protected] Subject: Re: [OSL | CCIE_RS] IPExpert Vol1 6.9 Hi Bill, It's because of routing and the next-hop selection due to the longest match and because PPP links by default install a host route for its adjacent peer Virtual-Access Interfaces inherit information from Virtual-Templates If we use this basic configuration: hostname R1 interface Virtual-Template1 ip address 10.1.124.1 255.255.255.0 interface Serial0/0 no ip address encapsulation frame-relay frame-relay interface-dlci 102 ppp Virtual-Template1 hostname R2 interface Virtual-Template1 ip address 10.1.124.2 255.255.255.0 interface Serial0/0 no ip address encapsulation frame-relay frame-relay interface-dlci 201 ppp Virtual-Template1 frame-relay interface-dlci 204 ppp Virtual-Template1 hostname R4 interface Virtual-Template1 ip address 10.1.124.4 255.255.255.0 interface Serial0/0 no ip address encapsulation frame-relay frame-relay interface-dlci 402 ppp Virtual-Template1 R1#sh ip route | b Gateway Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.124.2/32 is directly connected, Virtual-Access2 C 10.1.124.0/24 is directly connected, Virtual-Access2 R2#sh ip route | b Gateway Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks C 10.1.124.4/32 is directly connected, Virtual-Access3 C 10.1.124.1/32 is directly connected, Virtual-Access2 C 10.1.124.0/24 is directly connected, Virtual-Access2 is directly connected, Virtual-Access3 R4#sh ip route | b Gateway Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.124.2/32 is directly connected, Virtual-Access2 C 10.1.124.0/24 is directly connected, Virtual-Access2 If we were to consider the decisions made for a packet travelling from R1 to R4 (e.g. on R1 we go ping 10.1.124.4) At R1 10.1.124.4 is best (only) matched by 10.1.124.0/24 via Virtual-Access2 - so the packet goes through the PPP link hitting R2 At R2 10.1.124.4 is best matched by 10.1.124.4/32 via Virtual-Access3 - so the packet goes through the PPP link R4 The return of the ping is similar At R4 10.1.124.1 is best (only) matched by 10.1.124.0/24 via Virtual-Access2 - so the packet goes through the PPP link hitting R2 At R2 10.1.124.1 is best matched by 10.1.124.1/32 via Virtual-Access2 - so the packet goes through the PPP link hitting R1 Hope that's of some help. Cheers, Adam On Wed, Oct 12, 2011 at 10:41 PM, Bill Riley <[email protected]> wrote: Yes they are on the same subnet. When I do a trace route it does go to the HUB first and then to the spoke so it is not direct. Still trying to understand why it does that. Is it just inherent in the PPPoFR configuration? From: Adam Booth [mailto:[email protected]] Sent: Tuesday, October 11, 2011 5:22 PM To: Bill Riley Cc: [email protected] Subject: Re: [OSL | CCIE_RS] IPExpert Vol1 6.9 Hi Bill, I will assuming that on your routers the virtual-templates exist on the same subnet. If you do a show ip route on each of the routers you will see a connected route for the network the virtual-template is associated with and a /32 route for the direct peer through the virtual-access interface Connectivity between spokes occurs via the hub and requires routing and relies on longest match rules and the ppp peer neighbor routes. For spoke to spoke, the spoke will send traffic to the hub, which then will have an exact match for the other spoke due to the ppp neighbor route and be able to select the appropriate virtual-access to reach the other spoke. If you perform a traceroute between spokes even though these are on the same subnet, you will see the hub as a hop to reach the other spoke. Cheers, Adam On Wed, Oct 12, 2011 at 5:39 AM, Bill Riley <[email protected]> wrote: Why is it when I configure the DLCI's using PPP I get a fully meshed network and can ping all the spoke sites even though the local DLCI is only setup to reach the hub site of R2? _______________________________________________ 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 _______________________________________________ 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
