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Community Member

WAN default gateway problem (going crazy!!!

Hello

Topology: ISP > ASR > 3750x stack>ASA

 

ASR (asr1002x-universalk9.03.12.01.S.154-2.S1-std.SPA.bin)
    I can ping out to the world
    I can ping to the DMZ switch behind this router
    I can ping to the ASA behind the DMZ switch

         interface GigabitEthernet0/0/5
         description Inside_DMZ_3750
         ip address 170.x.x.20 255.255.255.240
         standby 1 ip 170.x..17
         standby 1 priority 105
         standby 1 preempt
         standby 2 ip 170.x.x.18
         standby 2 priority 110
         standby 2 preempt
         standby 2 track 1 decrement 10
         negotiation auto
         cdp enable
         end

I am receiving the default gateway via BGP from the ISP

Gateway of last resort is 50.x.x.81 to network 0.0.0.0

           B*    0.0.0.0/0 [20/0] via 50.x.x.81, 1w0d

 

router bgp myAS#
 bgp log-neighbor-changes
 network 170.x.x.16 mask 255.255.255.240
 redistribute eigrp 171
 neighbor 50.x.x.81 remote-as ISPas#


DMZ 3750x (c3750e-universalk9-mz.122-58.SE2/c3750e-universalk9-mz.122-58.SE2.bin)
    I CANNOT ping the ASR WAN (ISP) default gateway
        my debug ip icmp DOES NOT return information on why I cannot successfully ping the ASR gateway
            Why does my debug not provide any information on failed ping
        
    I can ping the WAN interface on the ASR router
    I can ping all of the ip addresses on the ASR router
        my debug ip icmp DOES return information on why I can successfully ping these ip addresses
    I can ping the ASA behind the DMZ switch

 

    3750x interface connecting to ASR

       interface GigabitEthernet1/0/1
       description WAN ASR
       switchport trunk encapsulation dot1q
       switchport trunk native vlan 11
       switchport mode trunk
       mls qos trust dscp
       spanning-tree portfast trunk
end

ip default-gateway 170.x.x.20

 

 

sMc
2 REPLIES
Cisco Employee

Hi, Looks like issue with

Hi,

 

Looks like issue with reverse route on ISP router for LAN subnet. To confirm this you can ping to ISP gateway ip 50.x.x.81 from ASR router with source of LAN interface Gig0/0/5(170.x.x.20). If ping fails, check if ISP is accepting prefix 170.0.0.16/28 or not. I see we are originating it on ASR through BGP. Since you are able to ping other ip addresses of ASR from switch, i dont this any issue on switch or with default gateway on switch.

 

--Pls rate helpful posts--

Regards,

Akash

Community Member

Akash Thank you for the

Akash

 

Thank you for the prompt reply. I will test and report back/rate.

sMc
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