• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 390
  • Last Modified:

cannot ping back

Can the experts help me in understanding this? I have 2 sites (A & B)  connecting through a MPLS network. A can ping B. But B cannot ping A. Why? If A can ping B then B should have a route back to A. Correct?

I checked the BGP route on my two routers and they have a route to each other. When I do the traceroute to A from B router, I see that it stops at the 3rd hop, I believe that is the PE MPLS router.
0
leblanc
Asked:
leblanc
1 Solution
 
SouljaCommented:
Looks like your ISP is blocking ICMP in one of the directions or is disabling TTL propagation.
0
 
BigPapaGottiCommented:
If B is able to Reply to A's Ping request what this tells me is that it does have a route back to reach A. But since this is not working when originated from B this tells me that something on A's side is not allowing the ping to come through. Check your ACL's and Firewalls to see if icmp is being denied?

Have you tried any other sort of network testing such as trying to telnet to a webserver on port 80. This would help in troubleshooting to tell you whether or not icmp is being blocked by and ACL but web traffic on port 80 is being allowed.

Let me know what you find and I hope this helps.
0
 
Thomas GrassiSystems AdministratorCommented:
run a traceroute  and post results
0
The new generation of project management tools

With monday.com’s project management tool, you can see what everyone on your team is working in a single glance. Its intuitive dashboards are customizable, so you can create systems that work for you.

 
Matt WilliamsCommented:
try a traceroute to see at which point the ping is failing
0
 
leblancAccountingAuthor Commented:
This is a private MPLS network and I am not sure what they have within their network. I can only see my 2 routers. I already opened a ticket. I just want to get your thoughts on this. So it looks like something is blocking the ping

I have the sniffer in A and I don't see the ping coming from B on the WAN interface of A.
0
 
SouljaCommented:
Okay, if you can only see your routers, then they are have TTL Propogation disabled. This prevents you from seeing the hops withing their cloud.
0
 
nader alkahtaniNetwork EngineerCommented:
I apply with BigPapaGotti in when he said "Check your ACL's and Firewalls to see if icmp is being denied?"

you should ping A from B then post ping output to analyze that
you should use pingpath
0
 
leblancAccountingAuthor Commented:
I found out that the provider does not have the route pointed to us.
0

Featured Post

Take Control of Web Hosting For Your Clients

As a web developer or IT admin, successfully managing multiple client accounts can be challenging. In this webinar we will look at the tools provided by Media Temple and Plesk to make managing your clients’ hosting easier.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now