Hi, Before I bother you about this, I searched the archives, but I can't get it clear to me. Sorry but this has been constantly irritating me. I quess there's a big BUG in my understanding. This example is roughly from Jeff Doyle's Routing TCP/IP pp.557~565 There is a star topology frame relay network. HQ is a hub router with three branch routers BR1 , BR2 and BR3. Branch routers have only one PVC each to HQ(This is a partially meshed FR network). (point-to-point subinterfaces are not configured) Please correct me if I'm wrong! CASE 1 - UNICAST packet: Can BR1 ping to another branch router BR2?(I believe so) If it's YES, HQ is responsible for "relaying" ping to BR2. What's happening is as follows: 1. BR1 originates a ping packet and encapsulates it with its own locally significant DLCI number (for example, 200) 2. It is propagated via the established PVC through F/R Cloud to HQ with HQ's local DLCI number (for example, 100: I understand there's no direct correspondence between two DLCI numbers), 3. HQ's layer 2 (ie,F/R) strips F/R header off the received frame and examines its destination IP, then decides it doesn't belong to HQ itself. 4. HQ's layer 2 looks up its frame relay maps configured statically or dynamically(through Inverse ARP). If there is a matching entry for it, It is properly encapsulated and propagated to BR1. If there's no matching entry for it, HQ just drops it. 5. Finally BR2 receives the frame. CASE 2 - BROADCAST packet: Can BR1 send RIPv1 updates to all other branch routers BR2 and BR3 as well as to HQ. (I believe so) 1. BR1's RIP delivers RIPv1 updates to lower layer F/R, and if F/R is not configured to propagate broadcast traffic, the packet is dropped, Otherwise, if it is configured so through frame-relay map command) It is propagated to HQ as explained step 1 of case 1. But in this case destination ip is set to broadcast address 255.255.255.255. 2. In this case, HQ recognizes it as broadcast packet, so HQ replicates and propagates the broadcast traffic to each PVC except originationing PVC 3. BR2 and BR3 receives the frame. CASE 3 - BROADCAST revisited: If BR2 and B3 are directly connected, from my understanding of CASE 2, there might be a broadcast storm like what happens on LAN Switching. All of this probable misunderstanding is due to my lack of field experience. So I always try to read widely, which is the only way I can do now. Please correct my ignorance. Thanks in advance. Jaeheon Yoo _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
