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PoE, Comcast Modems, and Service Outages
by Aaron de Bruyn 31 Mar '22

31 Mar '22

I just got off the phone with a Comcast tech, and wanted to double-check my sanity. Somehow in the last 6 months I've managed to reach the exact same rep twice when dealing with an outage or a degraded service event. I asked him to remotely reboot the modem because there was high packet loss. Both times I've talked with him, he noted the high packet loss, started to reboot the modem, and then asked me point-blank if we had any PoE switches on our network. When I said "yes", he said I needed to disable PoE because it messes with the Comcast modems and he can see "buildups" in his graphs that show power is "leaking" to the Comcast modem every 24 hours. For reference, our setup is: Internal Network ←→ PoE Switch ←→ My Router (FreeBSD Box) ←→ Comcast Modem I told him the Comcast modem isn't plugged into the PoE Switch, it's plugged into My Router (FreeBSD box) and My Router does not negotiate PoE+ and the switch shows PoE isn't being send to My Router's LAN port. While the switch is capable of outputting old-school 24v PoE, it must be specifically turned on for a port, and it's not enabled or used anywhere on the networks I manage. When provided with that information, the Comcast tech still insisted that the switch was sending PoE to My Router and it was "leaking through" to the Comcast modem and that's why every 4-6 weeks the Comcast modem needs to be reset. The tech insisted that switches that *are* PoE-capable *always* send PoE even if the device doesn't request it or negotiate it. Attempts to explain the difference between the old 24-volt PoE and PoE+/++ were met with arguing that he's been in the industry for decades and I don't know what I'm talking about...and that all my problems would go away if I just disabled PoE everywhere on the switch. Again, I double-checked the port and said "It's not sending PoE to my router, but even if I were, I highly doubt PoE would leak through a PCI card to the opposite side of the chassis to the on-board NIC and out to your modem". He insisted it happened "all the time" and he had previously fried equipment by plugging it into a PoE switch. He insisted that he's also handled quite a few calls relating to this magic PoE problem over the years and Comcast has internal tools that show graphs of how much PoE power "builds up" inside their modems and he "can see a buildup in my router that resets every 24 hours". I didn't have the heart to tell him that I manage about 40 networks that have Comcast connections...and they *all* have identical FreeBSD boxes acting as their router, and they are *all* using the exact same PoE switches at every location with all ports set to PoE+...and we only have degraded service or outages after ~30 days at ~3 locations. Slightly off-topic, but if I call Comcast about outages or degraded service and any *other* tech but this guy answers, they all say "you need to unplug your Comcast modem and plug it back in once every 3-4 weeks" and they act like it's normal to reboot the modems every few weeks. In fact, last week I wanted Comcast to check on a modem setting at one location and they said the modem had been up for over 127 days and it should be rebooted. I said "it's up and working fine, why would I reboot it?". Anyways, am I insane for thinking the tech was flat-out wrong? I mean...occasionally some really bizarre stuff happens in IT...but this seems extremely far-fetched and contrary to everything I know about the PoE standard. -A

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MAP-T (was: Re: V6 still not supported)
by Jared Brown 31 Mar '22

31 Mar '22

Most IPv6 transition mechanisms involve some form of (CG)NAT. After watching a NANOG presentation on MAP-T, I have a question regarding this. Why isn't MAP-T more prevalent, given that it is (almost) stateless on the provider side? Is it CPE support, the headache of moving state to the CPE, vendor support, or something else? NANOG 2017 Mapping of Address and Port using Translation MAP T: Deployment at Charter Communications https://www.youtube.com/watch?v=ZmfYHCpfr_w - Jared

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CGNAT scaling cost (was Re: V6 still not supported)
by Jared Brown 31 Mar '22

31 Mar '22

An oft-cited driver of IPv6 adoption is the cost of scaling CGNAT or equivalent infrastructure for IPv4. Those of you facing costs for scaling CGNAT, are your per unit costs rising or declining faster or slower than your IPv4 traffic growth? I ask because I realize I am not fit to evaluate the issue on a general level, as, most probably due to our insignificant scale, our CGNAT marginal costs are zero. This is mainly because our CGNAT solution is oversized to our needs. Even though scaling up our currently oversized system further would lower per unit costs, I understand this may not be the case outside our bubble. - Jared

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Sling.com and/or Dish Network Contact.
by Anthony Leto 30 Mar '22

30 Mar '22

Sorry for the spam, is there anyone that has a contact for Sling.com or Dish? If so, can you contact me off-list. Thanks Anthony Leto

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ATT DNS contact
by nanog＠fleish.org 30 Mar '22

30 Mar '22

Hi all, Apologies for the spam, but if anyone has a contact for AT&T that can help with DNS on the list could you please reach out to me off list? I’m seeing failures to send messages to @txt.att.net addresses due to a bogus DNS failure on your end: host mx3b.txt.att.net <http://mx3b.txt.att.net/>[166.216.152.132] said: 554 5.1.0 <REDACTED> has no MX or A record (in reply to MAIL FROM command) However, the <REDACTED> domain does have a valid, published MX record. Adding a root A record for the domain allowed me to work around the issue, but shouldn’t be necessary. Thanks, Todd

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Re: PoE, Comcast Modems, and Service Outages
by Livingood, Jason 30 Mar '22

30 Mar '22

> I asked him to remotely reboot the modem because there was high packet loss. FWIW, as a customer (assuming residential), you can login to the website and check for area outages/impairments at https://www.xfinity.com/support/status-map. You can also use the Xfinity app to remotely reboot your cable modem, run diagnostics/check for outages, etc. See https://www.xfinity.com/support/articles/check-service-outage > Both times I've talked with him, he noted the high packet loss, started to reboot the modem, and then asked me point-blank if we had any PoE switches on our network. High packet loss typically suggests an RF impairment of some type. I don’t know how to explain the PoE comment but am happy to look at your connection if you want to email me off-list. > I said "it's up and working fine, why would I reboot it?". In some cases a reboot will trigger a pull of the latest firmware, which might include security fixes, performance improvements, and other changes. Jason

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Re: V6 still not supported
by Jared Brown 30 Mar '22

30 Mar '22

Doug McIntyre wrote: > > Jared Brown wrote: > > > Owen DeLong via NANOG wrote: > > > When your ISP starts charging $X/Month for legacy protocol support > > > > Out of interest, how would this come about? > > It already happens, more along the lines of "Business Class" vs. "Residential Class". > > Ie. for Residential Class, you may get put onto CGNAT, and have no control over that. > > While on x level of Business Class, you get to opt out of CGNAT, and potentially even have a > static IP address assigned to your connection. I find this example to be somewhat contrived. Both classes have access to IPv4 and thus there is no surcharge for "legacy protocol support". Furthermore these are not operator services nor are the prices for these services tightly coupled to actual production costs. - Jared

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Internet Storm Center says Russia hijacking Twitter's BGP
by Jay R. Ashworth 29 Mar '22

29 Mar '22

https://isc.sans.edu/diary/rss/28488 -- Jay R. Ashworth Baylink jra(a)baylink.com Designer The Things I Think RFC 2100 Ashworth & Associates http://www.bcp38.info 2000 Land Rover DII St Petersburg FL USA BCP38: Ask For It By Name! +1 727 647 1274

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Budget news: Proposed Puerto Rico FEMA distribution center (warehouse)
by Sean Donelan 29 Mar '22

29 Mar '22

Program Change 1 – Caribbean Area Office and Warehouse Support: Description The FY 2023 Budget includes an increase of $1.4M for the staffing and operational costs of the Puerto Rico Distribution Centers (DC). Staff will manage readiness, disaster response operations and the distribution of commodities for the FEMA DCs in Puerto Rico. [...] As a result of lesson learned responding during the 2017 and 2018 hurricane seasons, analysis of observed maritime parameters has determined the requirement for one week of supply necessary to bridge a tailored disaster supply chain from CONUS. [...] To meet these readiness targets, the sites require staffing that are prepared to respond to all future major declarations, in lieu of being temporarily funded by a single, current major disaster declaration. This will allow sustained continuity of disaster support within the Caribbean. Organization structure of these facilities are based on models used at other FEMA distribution centers. https://www.dhs.gov/sites/default/files/2022-03/Federal%20Emergency%20Manag… Reminder: The annual president's budget proposal is mostly imaginary. The traditional joke is Congress tosses it in the trash bin immediately after the press conference. Nevertheless, its good to see some of the problems after the 2017/2018 caribbean hurricanes mentioned. In 2017/2018 took over a month to get the disaster response supply chain from CONUS to the island territories (PR/USVI) working in spite of many heroic efforts at the time.

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Routes to twitter via 8359 8359 8342
by Drew Weaver 28 Mar '22

28 Mar '22

Is anyone else seeing this route destined for Twitter in the US being directed through 8359 announced by 8342? 104.244.42.0/24 Just curious, replies off list welcome. -Drew

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