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azdeltawye
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Friday, September 16th, 2022 8:20 PM

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Cannot ping Comcast gateway IP after maintenance outage

Hello,

I experienced a problem this morning after a planned Xfinity maintenance outage. After the outage, I rebooted the Modem and my router pulled a new WAN IP address (DHCP), however, the IPv4 Gateway monitor in my router was showing 100% loss and I could not get out to the internet via IPv4.

The IPv6 interface, however, seemed to be working fine.

Looking at the router logs I noticed this message repeating many times:

Sep 16 05:38:00 	kernel 		arpresolve: can't allocate llinfo for 71.226.124.1 on igb0

I attempted to ping the Comcast GW (71.226.124.1) from my phone via LTE but got 100% packet loss result.

Does this mean the Comcast gateway is down?

Investigating further, I looked at the router: Status/Interfaces/WAN and observed that Comcast has me allocated on a /22 subnet. So I manually changed the Gateway monitor IP in my router to 71.226.126.1 which is on the same /24 block as my WAN IP.

Now the gateway monitor is green (no packet loss) and I can access the internet via IPv4.

Looking at the router logs again, I am periodically seeing this message:

/interfaces.php: Removing static route for monitor 71.226.126.1 and adding a new route through 71.226.124.1

Should I call Comcast/Xfinity and get a trouble ticket started?

BTW - also posted this question on the Netgate forums:

https://forum.netgate.com/topic/161391/arpresolve-can-t-allocate-llinfo-for-gw_ip-on-igb0

Question

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Updated 

3 years ago

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XfinityThomasA

Official Employee

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2.3K Messages

3 years ago

@azdeltawye - Hello. Thank you for your detailed message and for commenting here on the Xfinity Forums. I know I'd be wondering that same thing too! Had you tried using the Xfinity My Account app to troubleshoot your Xfinity services? 

 

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azdeltawye

Contributor

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68 Messages

@XfinityThomasA​ 

Thanks for the reply. Yeah the Xfinity 'My Account' app does not provide any information about the upstream Comcast/Xfinity network other than an outage map, if there is an outage..

Perhaps you did not understand my question. What I am asking/concerned about is why my IPv4 default gateway (first hop) is not responding to ICMP requests (ping). I have been a Comcast/Xfinity internet customer for six years and over that time period have had a handful of different external IP address assigned to me. All of which, with the exception of this latest one, the default gateway (first hop) have responded to ICMP requests (ping).

Why is this default gateway (71.226.124.1) different? Is there a problem with it? Has Comcast changed their policy on responding to ICMP requests?

The answers to the above questions will help me decide how to configure my router's gateway monitoring feature going forward.

Thanks.

(edited)

3 years ago

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