Point-to-Point Microwave Connections cannot ping each other

[Adcom911]

Edit: issue was not related to networking. The MW interfaces where missing some settings. Problem solved!

Hello,

I have a particular situation where we have Two routers one being a 8300 and one a 2911 not able to ping each other their point-to-point Microwave connections. They can see each other via CDP neighbors but weirdly can't pin across the link to the other side. Any suggestion or help will be greatly appreciated!

8300 config

interface GigabitEthernet0/0/1
description 8300-2911 MW
bandwidth 318000
ip flow monitor NTAMonitor input
no ip address
negotiation auto
end
!
interface GigabitEthernet0/0/1.299
description 8300 MW-To-2911 Vlan 299
encapsulation dot1Q 299
ip address 10.1.4.34 255.255.255.248
ip ospf network point-to-point
mpls ip
service-policy output QOS-SHAPE
end

2911 config 

interface GigabitEthernet0/2
description 2911-8300 MW
bandwidth 318000
no ip address
ip flow monitor NTAMonitor input
duplex auto
speed auto
end

!
interface GigabitEthernet0/2.299
description 2911 -to- 83000 vlan 299
encapsulation dot1Q 299
ip address 10.1.4.33 255.255.255.248
ip ospf network point-to-point
mpls ip
service-policy output QOS-SHAPE
end

[Flavio Miranda]

@Adcom911 

 What if you remove the ip ospf network point-to-point and the mpls ip commands?

Seems they have layer2 connectivity but not layer3.

[Adcom911]

Hey @Flavio Miranda Thank you for the suggestion! I just tried that and no luck ☹. Its just very strange we can ping the MW’s IP on both sides locally and can ping the interface. So we believe that rules out anything layer one and layer 2 is fine via cdp. Just they cant ping each other is wild to me.

[Flavio Miranda]

What about the radio in between? Do they have any configuration that could prevent this? It does not make sense if those interfaces are facing each other, on the same subnet and they can not ping.

[Adcom911]

The only configuration we know is on the radio's is that there is a vlan 299 on them. The weird thing is we can reach the 8300's sides radio gui  @10.1.4.36 but we can't reach the 2911's radio gui at 10.1.4.35. The routing is across the board the same subnets. No ACL's or prefix filter list blocking anything as well. 

[Flavio Miranda]

You can reach the radio gui for 8300 from where? From the network bahind the 8300?  So, the radio have a IP address.  It is for management only or the radio do some routing?

[Adcom911]

We, can reach it from our HQ routed back here. Yes, over the network behind the 8300. 

From my understanding the radio's have management and data coming from that one link. 

[Flavio Miranda]

Sounds to me the radio might be the problem. According to your setup, if you connect both router via ethernet cable with that config, it would work.

  If you are not able to reach the radio on the 2911 side, we could assume that the problem can be on this one.  I would double check the config on the radio. Which device is it by the way?

[Adcom911]

Yea, sounds like thats the issue to me as well its something physical with the setup. On the 2911 side we did have a radio tech go out there and he was able to get on the GUI by changing his laptop IP to the gateway and screenshotted us all the settings and they are identical to the 8300's sides gui that we can reach.

I believe they are Cambium MW's 

[Adcom911]

Hey,

Thank you for the suggestion! I just tried that and no luck ☹. Its just very strange we can ping the MW’s IP on both sides locally and can ping the interface. So we believe that rules out anything layer one and layer 2 is fine via cdp. Just they cant ping each other is wild to me.

[Giuseppe Larosa]

Hello @Adcom911 ,

>> and layer 2 is fine via cdp

do you mean the Catalyst 8300 can see the Cisco 2911 as CDP neighbor over the interface connected to the RF device ?

can you check the ARP entry for the remote device ?

show arp 10.1.4.33 on the Cat8300

if you see nothing or incomplete you have an issue.

CDP uses a well known multicast address as destination that is carried by non Cisco equipment.

the 802.1Q tag 299 is probably needed and expected.

MPLS IP can add an MPLS header only for subnets that are downstream the C2911 so this should not be an issue. An MPLS label is not used for a directly connected IP address.

The two RF links may have issues in propagating frames with a broadcast destination that are needed for ARP resolution process ( ARP request)

Hope to help

Giuseppe

[Adcom911]

Hey @Giuseppe Larosa, yes they can see each other over CDP on that link. But there is no remote arp entries it looks like. They do have arp enteries for their each local MW's but not the remote side. So thats making more sense they are just not able to send frames across the link. I'll keep working with the radio side to see as this is a head scratcher to me networking wise. It should just work right? lol

Thank you, 

[Giuseppe Larosa]

Hello @Adcom911 ,

if the issue is that the RF devices are not propagating broadcast frames you can try to create static ARP entries

in global config ( check the exact syntax I'm writing on the fly)

arp <remote-IP-address> <remote-MAC-address> ARPA

this may fix your issues you need to do it on both devices

CDP frames  travel untagged and this is why you see the CDP neighbor under the main physical interface.

Hope to help

Giuseppe

[Adcom911]

Hey @Giuseppe Larosa  Ill give that a shot to make sure im doing it right do I do the IP of the remote interface and the MAC of the remote interface or the remote interface MW IP and the mac of the interface? 

[Adcom911]

@Giuseppe Larosa I belive I did it right but no luck on pings across the link

from 8300 

from 2911