ping things [7:66155]
I can ping from router A through various hops to router F. Therefore the packet'knows' how to reach F - and also how to find a path back to A by reply. However from router F I cannot ping router A. As the ping works in the first case - ie it knows the path back from F to A - how come it doesnt work in the 2nd ? The path is 'clean' ie no firewalls, access lists or any filtering. Puzzled. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66155&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
Orlando Palomar Jr CCIE#11206 wrote: > > You have a routing problem. Check your routing tables > thouroughly. I'm sure you're missing some networks. > > The reason you're able to ping one-way is because you're using > different sets of source and destination IP addresses when > pinging from router A to router F, as compared to pinging from > router F to router A. The ping reply from router F uses the same addresses as the ping from router F to router A. Why would the reply work but not the ping? Or maybe the ping from router F to router A fails because the reply from router A doesn't get back. But that would be weird too. Why would router A be able to send a ping but not a reply? He needs to find out which fails and where, with debugs or sniffers. He could still have a routing problem, but it would have to be a weird one if these results are consistent. He says no firewalls or access lists, but it sure sounds like a firewall or access list to me. Priscilla > > Use the extended ping command to see what I mean. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66162&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
You have a routing problem. Check your routing tables thouroughly. I'm sure you're missing some networks. The reason you're able to ping one-way is because you're using different sets of source and destination IP addresses when pinging from router A to router F, as compared to pinging from router F to router A. Use the extended ping command to see what I mean. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66160&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
Several thoughts: A standard ping uses as its source address the address of the exit interface. Extended ping can use the address of any interface on that router. Do a trace to see where it fails. Check the routing tables of the various routers. Somewhere a route is missing. For example - suppose routers A and F each have a LAN segment and a WAN interface. A standard ping from either would use its WAN interface address. Now on one end (say A)the LAN network isn't in the routing table. From A you can ping F (maybe both LAN and WAN); but F can only ping the WAN interface of A - not the LAN. Let us know your results. > -Original Message- > From: Peter P [mailto:[EMAIL PROTECTED] > Sent: Tuesday, March 25, 2003 8:56 AM > To: [EMAIL PROTECTED] > Subject: ping things [7:66155] > > > I can ping from router A through various hops to router F. > Therefore the packet'knows' how to reach F - and also how to > find a path > back to A by reply. However from router F I cannot ping router A. > As the ping works in the first case - ie it knows the path > back from F to A > - how come it doesnt work in the 2nd ? The path is 'clean' ie > no firewalls, > access lists or any filtering. Puzzled. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66168&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ping things [7:66155]
At 02:55 PM 3/25/2003 +, Peter P wrote: >I can ping from router A through various hops to router F. >Therefore the packet'knows' how to reach F - and also how to find a path >back to A by reply. However from router F I cannot ping router A. >As the ping works in the first case - ie it knows the path back from F to A >- how come it doesnt work in the 2nd ? The path is 'clean' ie no firewalls, >access lists or any filtering. Puzzled. A cannot reach the interface from which the ping in sourced on F most likely. Try controlling your source addresses and see if that points you in the right direction. Pete Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66174&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
At 04:35 PM 3/25/2003 +, Priscilla Oppenheimer wrote: >Orlando Palomar Jr CCIE#11206 wrote: > > > > You have a routing problem. Check your routing tables > > thouroughly. I'm sure you're missing some networks. > > > > The reason you're able to ping one-way is because you're using > > different sets of source and destination IP addresses when > > pinging from router A to router F, as compared to pinging from > > router F to router A. > >The ping reply from router F uses the same addresses as the ping from router >F to router A. Why would the reply work but not the ping? In many cases the ping is directed to a router loopback which I assumed and likely Orlando did as well. >Or maybe the ping from router F to router A fails because the reply from >router A doesn't get back. But that would be weird too. Why would router A >be able to send a ping but not a reply? He needs to find out which fails and >where, with debugs or sniffers. > >He could still have a routing problem, but it would have to be a weird one >if these results are consistent. > >He says no firewalls or access lists, but it sure sounds like a firewall or >access list to me. > >Priscilla > > > > > > Use the extended ping command to see what I mean. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66175&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ping things [7:66155]
do a traceroute from F to A and see what it says and email it to this list... Larry Letterman Network Engineer Cisco Systems - Original Message - From: Peter P To: [EMAIL PROTECTED] Sent: Tuesday, March 25, 2003 6:55 AM Subject: ping things [7:66155] I can ping from router A through various hops to router F. Therefore the packet'knows' how to reach F - and also how to find a path back to A by reply. However from router F I cannot ping router A. As the ping works in the first case - ie it knows the path back from F to A - how come it doesnt work in the 2nd ? The path is 'clean' ie no firewalls, access lists or any filtering. Puzzled. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66183&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
At 04:35 PM 3/25/2003 +, Priscilla Oppenheimer wrote: >Orlando Palomar Jr CCIE#11206 wrote: > > > > You have a routing problem. Check your routing tables > > thouroughly. I'm sure you're missing some networks. > > > > The reason you're able to ping one-way is because you're using > > different sets of source and destination IP addresses when > > pinging from router A to router F, as compared to pinging from > > router F to router A. > >The ping reply from router F uses the same addresses as the ping from router >F to router A. Why would the reply work but not the ping? In many cases the ping is directed to a router loopback which I assumed and likely Orlando did as well. >Or maybe the ping from router F to router A fails because the reply from >router A doesn't get back. But that would be weird too. Why would router A >be able to send a ping but not a reply? He needs to find out which fails and >where, with debugs or sniffers. > >He could still have a routing problem, but it would have to be a weird one >if these results are consistent. > >He says no firewalls or access lists, but it sure sounds like a firewall or >access list to me. > >Priscilla > > > > > > Use the extended ping command to see what I mean. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66204&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
OK If I use the loopback addr then I can see ext trace going right way. Now I need to make the rtr use this addr as the source Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66237&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
I can reach my end node by declaring the loopback address as the source. By default the router is using the seril i/f address. Unless I use the loopback as the source it dont work. So I need to understand how to fix this - I imagine the intervening hops are where the trouble lies Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66244&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
Type in ping, press return and follow the on screen prompts. This will allow you to use ping in extended mode to specify the source address or interface. Steve Wilson Network Engineer -Original Message- From: Peter P [mailto:[EMAIL PROTECTED] Sent: 26 March 2003 11:16 To: [EMAIL PROTECTED] Subject: RE: ping things [7:66155] OK If I use the loopback addr then I can see ext trace going right way. Now I need to make the rtr use this addr as the source Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66241&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ping things [7:66155]
The reason it doesn't work is someone somewhere doesn't have a route to your loopback interface. Dave Peter P wrote: > I can reach my end node by declaring the loopback address as the source. By > default the router is using the seril i/f address. Unless I use the loopback > as the source it dont work. So I need to understand how to fix this - I > imagine the intervening hops are where the trouble lies -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 I would rather have a German division in front of me than a French one behind me." --- General George S. Patton Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66264&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
At 12:55 PM 3/26/2003 +, Peter P wrote: >I can reach my end node by declaring the loopback address as the source. By >default the router is using the seril i/f address. Unless I use the loopback >as the source it dont work. So I need to understand how to fix this - I >imagine the intervening hops are where the trouble lies Make the serial interface reachable. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66260&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ping things [7:66155]
Type in ping, press return and follow the on screen prompts. This will allow you to use ping in extended mode to specify the source address or interface. Steve Wilson Network Engineer -Original Message- From: Peter P [mailto:[EMAIL PROTECTED] Sent: 26 March 2003 11:16 To: [EMAIL PROTECTED] Subject: RE: ping things [7:66155] OK If I use the loopback addr then I can see ext trace going right way. Now I need to make the rtr use this addr as the source Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66477&t=66155 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
