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3939B + RV325 confused on how to configure

Latitude42
Frequent Contributor

3939B + RV325 confused on how to configure

3939B cable gateway has been in use for several weeks.

 

A VPN was desired by the managers. I signed up for a static IP with Comcast and purchased Cisco RV325 VPN device. The 3939B was placed in bridge mode and I went through the configraiton wizard provided by the Cisco RV325.

 

Here's a configuration question for my new topology. The setup wizard on the RV325 offers an option to pick-up the WAN static IP address, and recommended DNS addresses, directly from the ISP.  I tried this but the address it acquired was not our new static IP address at all. I am guessng  that RV325 wa simply given a dynamic IP address.  I would have thought this pick-up of the statid IP address and related kinds of goodness, upon connecting to WAN, is something Comcast would manage well over WAN. Is this something that SHOULD have worked?

 

In a larger sense I am a little lost on just how "diumb" is the 3939B in its bridge mode with the RV325 running the LAN. In other words, are there WAN configuration details that are only the concern of the 3939B.

Latitude42
Frequent Contributor

Re: 3939B + RV325 confused on how to configure

My apologies. I goofed, This does not belong under "Business Wifi". Perhaps a moderator can move it.

Trusted Forum Contributor

Re: 3939B + RV325 confused on how to configure

No, in general Comcast doesn't provide a way to "automatically" have devices configure themselves with your provisioned static subnet/settings. You will have to manually configure those on the RV325. You will also need to have the Cisco taken OUT of bridge mode; it must be in regular (non-bridge) mode for static IPs to work correctly.

Latitude42
Frequent Contributor

Re: 3939B + RV325 confused on how to configure

Both very good things to know. Not surprisingly I already backed away from the "discover my static IP"  thing, but I'll take the 3939B out of bridge mode as soon as I can. Which also means turning off  3939B DHCP server, I presume.

 

The other thing not working right is, my EnGenius wireless AP was just fine with the 3939B before I introduced RV325, but not any more. When I plug the AP into one of the RV325 LAN-side ports, the LEDs at both ends of the Ethernet run blink momentarily every few seconds but it certainly doesn't work. I suppose I could put a laptop running Wireshark on an unswitched hub common to all three and try to undersand what is going on.

 

Trusted Forum Contributor

Re: 3939B + RV325 confused on how to configure


@Latitude42 wrote:

 Which also means turning off  3939B DHCP server, I presume.


Well, if the RV325 is configured for a static IP, it shouldn't be responding to DHCP messages at all, so it shouldn't matter whether DHCP is on or off on the DPC3939B. In any case, I like to turn it off just so there are as few necessary running services as possible.

 


@Latitude42 wrote:
The other thing not working right is, my EnGenius wireless AP was just fine with the 3939B before I introduced RV325, but not any more. When I plug the AP into one of the RV325 LAN-side ports, the LEDs at both ends of the Ethernet run blink momentarily every few seconds but it certainly doesn't work. I suppose I could put a laptop running Wireshark on an unswitched hub common to all three and try to undersand what is going on.

 


Interesting. A quick flashing of the ethernet activity LEDs usually means that autonegotiation is failing on 1 or more ends. I'm assuming you've tried the basics of a different port on the RV325 and swapping the ethernet cable? If so, perhaps try a manual speed/duplex setting, if the devices are capable of doing so. (Be aware that autonegotiation must be working for the devices to run at gigabit (1000mbps) speed.) As well, ensure that the IP configuration of the EnGenius has been properly configured to be within the correct subnet of the RV325; some devices, if they are mis-configured, will bring down their ethernet interfaces.

Latitude42
Frequent Contributor

Re: 3939B + RV325 confused on how to configure

Just checking in to say I really appreciate the debugging suggestions, and I'll be investigating as soon as I can. I'm a church accidental techie and I make it to the building for these kinds of issues when I can.

Latitude42
Frequent Contributor

Re: 3939B + RV325 confused on how to configure

OK, on the Engenius wireless access point issue (no Ethernet link to RV325) it proved to be an in-wall workmanship issue.

 

The Cat6 in-wall Ethernet run is new. Before the RV325 was here, the AP worked fine going to the Comcast 3939B with a PoE injector between. The distance is about 70 feet.

 

I removed the AP from the wall and tried it on an old Cat5 Ethernet in-wall run in service since 2002. It is more like 150 feet. Running this experiment everything worked great AP -> PoE Injector -> RV325 -> 3939B -> Internet .

 

The PoE injector is not a part of the issue. The same results were exerienced when it was eliminated and the optional DC adapter was used.

 

The takeaways for the forum readers: (1) it seems CIcco 3939B is rather forgiving on marginal quality of Ethernet cabling. (2) Configuring 3939B + VPN + AP is no big deal, at least in the case of Cisco RV325 and EnGenius.

 

As for my situation, naturally I'll try crimping new RJ45 plugs first, but I sure hope I don't have to pull a new wire in the crawl spaces in summer.