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#1
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IP6 Address
Can someone explain why my modem and ipconfig give me two different IP6
addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem -- David E. Ross http://www.rossde.com/ "President Donald Trump said on Tuesday [11 December] that U.S. authorities had 'caught 10 terrorists', ... but four government sources said there was no recent evidence of terrorism suspects being caught along the border." Reuters News I think Trump is the primary source of the fake news he condemns. |
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#2
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IP6 Address
David E. Ross wrote:
Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem When logging into the web server internal to the modem to look at devices, are you looking at the LAN-side (aka intranet) IPv6 address the modem's DHCP server assigned to the device (or what the router reports if the host uses if using static addressing), or are you looking at its WAN-side IP address (the public address that all external/Intranet hosts will see)? https://www.google.com/search?q=what%27s+my+ip+address Does that public IP address match on either the IPv6 addresses you noted above? If so, that's the WAN-side IPv6 address of your router, not the LAN-side IPv6 address of your intranet host. When I go into my modem and click on the device listing for my host, its IPv6 address, local link IPv6 address, and MAC/physical address match what "ipconfig /all" reports on my host. Do you have multiple NICs in your host? I don't have bother Ethernet (wired) and wi-fi in my host, so I can't see how the modem reports the different IP and MAC addresses for each NIC but I assume they would be different. The PC came with a wi-fi daughtercard but I removed it because it's a desktop, doesn't move, I prefer the simplicity and security of a wired connection, and anything wireless that wants to connect to my PC can do it through a wi-fi connect through the modem. |
#3
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IP6 Address
KenW Wrote in message:
On Thu, 13 Dec 2018 10:33:00 -0800, "David E. Ross" wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem How does anyone knew what he was BRIEFED on or what he was told ? You that pick on Trump should be shot. KenW Are you having a mental breakdown? If so, you should be shot. -- ----Android NewsGroup Reader---- http://usenet.sinaapp.com/ |
#4
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IP6 Address
Nil wrote:
KenW Wrote in message: On Thu, 13 Dec 2018 10:33:00 -0800, "David E. Ross" wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem How does anyone knew what he was BRIEFED on or what he was told ? You that pick on Trump should be shot. KenW Are you having a mental breakdown? If so, you should be shot. https://www.reuters.com/article/us-u...-idUSKBN1OB05Y "President Donald Trump said on Tuesday that U.S. authorities had “caught 10 terrorists,” citing it as a reason for why the United States should build a wall on its Mexican border, but four government sources === said there was no recent evidence of terrorism suspects being caught along the border. " My guess is, rogue strawberry pickers. They're the worst. Paul |
#5
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IP6 Address
On 12/14/2018 3:04 AM, Paul wrote:
Nil wrote: KenW***************** Wrote in message: On Thu, 13 Dec 2018 10:33:00 -0800, "David E. Ross" wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem How does anyone knew what he was BRIEFED on or what he was told ? You that pick on Trump should be shot. KenW Are you having a mental breakdown? If so,* you should be shot. https://www.reuters.com/article/us-u...-idUSKBN1OB05Y ** "President Donald Trump said on Tuesday that U.S. authorities *** had “caught 10 terrorists,” citing it as a reason for why *** the United States should build a wall on its Mexican border, but ***** four government sources*** === *** said there was no recent evidence of terrorism suspects being *** caught along the border. ** " My guess is, rogue strawberry pickers. They're the worst. ** Paul Especially the toddlers, Trump was scared they might eat a couple of his strawberries. Rene |
#6
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IP6 Address
On 12/13/2018 3:44 PM, VanguardLH wrote:
David E. Ross wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem When logging into the web server internal to the modem to look at devices, are you looking at the LAN-side (aka intranet) IPv6 address the modem's DHCP server assigned to the device (or what the router reports if the host uses if using static addressing), or are you looking at its WAN-side IP address (the public address that all external/Intranet hosts will see)? https://www.google.com/search?q=what%27s+my+ip+address Does that public IP address match on either the IPv6 addresses you noted above? If so, that's the WAN-side IPv6 address of your router, not the LAN-side IPv6 address of your intranet host. When I go into my modem and click on the device listing for my host, its IPv6 address, local link IPv6 address, and MAC/physical address match what "ipconfig /all" reports on my host. Do you have multiple NICs in your host? I don't have bother Ethernet (wired) and wi-fi in my host, so I can't see how the modem reports the different IP and MAC addresses for each NIC but I assume they would be different. The PC came with a wi-fi daughtercard but I removed it because it's a desktop, doesn't move, I prefer the simplicity and security of a wired connection, and anything wireless that wants to connect to my PC can do it through a wi-fi connect through the modem. Configuration: Windows 7 Ultimate SP1 (x64) Motorola MB7220 V1.0 cable modem with firmware version 7220-5.7.1.9 Modem accessed through a Netgear N300 Wireless Router WNR2000v5 When I logon to the modem and request the advanced display, I can see the following: IPv6 Address 2605:e000:c04:7b:e855:8b57:644f:706d Selecting the circled "i" for more information, I get: IPv6 Address: Assigned to your cable modem by your cable provider. The assignment is referred to as a Lease. IPv6 is a newer, longer style of IP Address. Your cable provider may assign an IPv4 Address, an IPv6 Address, or both. Note: Both IP6 addresses are "owned" by Spectrum, which is my ISP for connecting to the Internet. (When connected, I use a different ISP for E-mail and hosting my Web site.) -- David E. Ross http://www.rossde.com/ "President Donald Trump said on Tuesday [11 December] that U.S. authorities had 'caught 10 terrorists', ... but four government sources said there was no recent evidence of terrorism suspects being caught along the border." Reuters News I think Trump is the primary source of the fake news he condemns. |
#7
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IP6 Address
David E. Ross wrote:
On 12/13/2018 3:44 PM, VanguardLH wrote: David E. Ross wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem When logging into the web server internal to the modem to look at devices, are you looking at the LAN-side (aka intranet) IPv6 address the modem's DHCP server assigned to the device (or what the router reports if the host uses if using static addressing), or are you looking at its WAN-side IP address (the public address that all external/Intranet hosts will see)? https://www.google.com/search?q=what%27s+my+ip+address Does that public IP address match on either the IPv6 addresses you noted above? If so, that's the WAN-side IPv6 address of your router, not the LAN-side IPv6 address of your intranet host. When I go into my modem and click on the device listing for my host, its IPv6 address, local link IPv6 address, and MAC/physical address match what "ipconfig /all" reports on my host. Do you have multiple NICs in your host? I don't have bother Ethernet (wired) and wi-fi in my host, so I can't see how the modem reports the different IP and MAC addresses for each NIC but I assume they would be different. The PC came with a wi-fi daughtercard but I removed it because it's a desktop, doesn't move, I prefer the simplicity and security of a wired connection, and anything wireless that wants to connect to my PC can do it through a wi-fi connect through the modem. Configuration: Windows 7 Ultimate SP1 (x64) Motorola MB7220 V1.0 cable modem with firmware version 7220-5.7.1.9 Modem accessed through a Netgear N300 Wireless Router WNR2000v5 When I logon to the modem and request the advanced display, I can see the following: IPv6 Address 2605:e000:c04:7b:e855:8b57:644f:706d Selecting the circled "i" for more information, I get: IPv6 Address: Assigned to your cable modem by your cable provider. The assignment is referred to as a Lease. IPv6 is a newer, longer style of IP Address. Your cable provider may assign an IPv4 Address, an IPv6 Address, or both. Note: Both IP6 addresses are "owned" by Spectrum, which is my ISP for connecting to the Internet. (When connected, I use a different ISP for E-mail and hosting my Web site.) I'm assuming from your description that you have a separate router and cable modem, not a combination modem that has a built-in router. If they are separate, you have the config without the enclosing "combo". .-----------combo(router+modem)------------. |.-----router-----. | host:IP---||--LANsideIP | .------modem------.| || WANsideIP --|---|---WANsideIP || |'----------------' | ISPsideIP --||---ISP | '-----------------'| '------------------------------------------' There's the IP address of your intranet host. There's the IP address on the LAN-side of your router. There's the IP address on the WAN-side of your router. (*) There's the IP address on the WAN-side of the modem. (*) There's the IP address on the ISP-side of the modem. (*) You won't see this in a combo (router+modem). Unless you configured your host with a static IP address, it is dynamically assigned by the DHCP server internal to the router. The router's WAN-side IP address gets dynamically assigned by the modem's internal DHCP server. The ISP-side IP address for the modem gets assigned by your ISP's DHCP server. I found your cable modem at with pics: https://www.amazon.com/MOTOROLA-Cert.../dp/B019ZY1ZWS The backside has only 1 Ethernet port, so it is usable with only a single intranet host or you connect it to a router to hookup multiple intranet hosts. Since it appears you are using a separate router, my guess is: - The WAN-side IP address of your router comes from the cable modem's internal DHCP server. - The ISP-side IP address of the cable modem comes from the ISP's DHCP server. - Both those IP addresses come from your ISP's IP pool. - They need not be the same. The cable modem's IP address allows tech to access the cable modem, like when provisioning it, not something beyond it. They probably don't care/support what you have on the other side of their modem. Since the router and modem are separate network devices, they each need an IP address on their interface to connect to each other. The WAN-side IP address of the router connects to the WAN-side IP address of the modem. ..---router----. |--LANsideIP | .----modem----. | WANsideIP--|---|--WANsideIP | '-------------' |ISPsideIP --| '-------------' Does your router report the modem's WAN-side IP address? If your router is configured for dynamic IP address assigned (from the modem's internal DHCP server), it should list what is its "gateway" IP address (where to find the modem but its IP address). |
#8
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IP6 Address
On 12/14/2018 3:07 PM, VanguardLH wrote:
David E. Ross wrote: On 12/13/2018 3:44 PM, VanguardLH wrote: David E. Ross wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem When logging into the web server internal to the modem to look at devices, are you looking at the LAN-side (aka intranet) IPv6 address the modem's DHCP server assigned to the device (or what the router reports if the host uses if using static addressing), or are you looking at its WAN-side IP address (the public address that all external/Intranet hosts will see)? https://www.google.com/search?q=what%27s+my+ip+address Does that public IP address match on either the IPv6 addresses you noted above? If so, that's the WAN-side IPv6 address of your router, not the LAN-side IPv6 address of your intranet host. When I go into my modem and click on the device listing for my host, its IPv6 address, local link IPv6 address, and MAC/physical address match what "ipconfig /all" reports on my host. Do you have multiple NICs in your host? I don't have bother Ethernet (wired) and wi-fi in my host, so I can't see how the modem reports the different IP and MAC addresses for each NIC but I assume they would be different. The PC came with a wi-fi daughtercard but I removed it because it's a desktop, doesn't move, I prefer the simplicity and security of a wired connection, and anything wireless that wants to connect to my PC can do it through a wi-fi connect through the modem. Configuration: Windows 7 Ultimate SP1 (x64) Motorola MB7220 V1.0 cable modem with firmware version 7220-5.7.1.9 Modem accessed through a Netgear N300 Wireless Router WNR2000v5 When I logon to the modem and request the advanced display, I can see the following: IPv6 Address 2605:e000:c04:7b:e855:8b57:644f:706d Selecting the circled "i" for more information, I get: IPv6 Address: Assigned to your cable modem by your cable provider. The assignment is referred to as a Lease. IPv6 is a newer, longer style of IP Address. Your cable provider may assign an IPv4 Address, an IPv6 Address, or both. Note: Both IP6 addresses are "owned" by Spectrum, which is my ISP for connecting to the Internet. (When connected, I use a different ISP for E-mail and hosting my Web site.) I'm assuming from your description that you have a separate router and cable modem, not a combination modem that has a built-in router. If they are separate, you have the config without the enclosing "combo". .-----------combo(router+modem)------------. |.-----router-----. | host:IP---||--LANsideIP | .------modem------.| || WANsideIP --|---|---WANsideIP || |'----------------' | ISPsideIP --||---ISP | '-----------------'| '------------------------------------------' There's the IP address of your intranet host. There's the IP address on the LAN-side of your router. There's the IP address on the WAN-side of your router. (*) There's the IP address on the WAN-side of the modem. (*) There's the IP address on the ISP-side of the modem. (*) You won't see this in a combo (router+modem). Unless you configured your host with a static IP address, it is dynamically assigned by the DHCP server internal to the router. The router's WAN-side IP address gets dynamically assigned by the modem's internal DHCP server. The ISP-side IP address for the modem gets assigned by your ISP's DHCP server. I found your cable modem at with pics: https://www.amazon.com/MOTOROLA-Cert.../dp/B019ZY1ZWS The backside has only 1 Ethernet port, so it is usable with only a single intranet host or you connect it to a router to hookup multiple intranet hosts. Since it appears you are using a separate router, my guess is: - The WAN-side IP address of your router comes from the cable modem's internal DHCP server. - The ISP-side IP address of the cable modem comes from the ISP's DHCP server. - Both those IP addresses come from your ISP's IP pool. - They need not be the same. The cable modem's IP address allows tech to access the cable modem, like when provisioning it, not something beyond it. They probably don't care/support what you have on the other side of their modem. Since the router and modem are separate network devices, they each need an IP address on their interface to connect to each other. The WAN-side IP address of the router connects to the WAN-side IP address of the modem. .---router----. |--LANsideIP | .----modem----. | WANsideIP--|---|--WANsideIP | '-------------' |ISPsideIP --| '-------------' Does your router report the modem's WAN-side IP address? If your router is configured for dynamic IP address assigned (from the modem's internal DHCP server), it should list what is its "gateway" IP address (where to find the modem but its IP address). It is almost dinner time. After dinner, I will reconfigure to have my PC connect directly to the modem without the router. That can be only temporary because my wife's PC also connects to the router to reach the modem and then to the Internet. This is described at http://www.rossde.com/computer/LAN.html. I generally avoid combination devices -- router-modem, printer-scanner, etc -- because subcomponents rarely fail together. I am concerned that Southern California Edison's momentary spike might cause only the router part of a router-modem to fail. If that happens with separate modem and router, I could still connect directly to the modem until I can replace the router. This indeed happened. -- David E. Ross http://www.rossde.com/ "President Donald Trump said on Tuesday [11 December] that U.S. authorities had 'caught 10 terrorists', ... but four government sources said there was no recent evidence of terrorism suspects being caught along the border." Reuters News I think Trump is the primary source of the fake news he condemns. |
#9
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IP6 Address
On 12/14/2018 5:29 PM, I previously wrote:
It is almost dinner time. After dinner, I will reconfigure to have my PC connect directly to the modem without the router. That can be only temporary because my wife's PC also connects to the router to reach the modem and then to the Internet. This is described at http://www.rossde.com/computer/LAN.html. I generally avoid combination devices -- router-modem, printer-scanner, etc -- because subcomponents rarely fail together. I am concerned that Southern California Edison's momentary spike might cause only the router part of a router-modem to fail. If that happens with separate modem and router, I could still connect directly to the modem until I can replace the router. This indeed happened. Oops! The modem only accepts outgoing ethernet cable while the PCs are connected to the router with USB LAN cables. I have a long ethernet cable I can run from the modem to my PC. Since the modem and router are in the attic, however, that is something I have to wait until daylight to try (maybe Sunday). -- David E. Ross http://www.rossde.com/ "President Donald Trump said on Tuesday [11 December] that U.S. authorities had 'caught 10 terrorists', ... but four government sources said there was no recent evidence of terrorism suspects being caught along the border." Reuters News I think Trump is the primary source of the fake news he condemns. |
#10
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IP6 Address
On 12/14/18 7:29 PM, David E. Ross wrote:
[snip] I generally avoid combination devices -- router-modem, printer-scanner, etc -- because subcomponents rarely fail together. I am concerned that Southern California Edison's momentary spike might cause only the router part of a router-modem to fail. If that happens with separate modem and router, I could still connect directly to the modem until I can replace the router. This indeed happened. A printer-scanner does make it easy to make copies. Other than that, I avoid combination devices too, ESPECIALLY modem router. A modem (I have cable) is under the control of your ISP. A router is a part of YOUR network, and the ISP shouldn't have anything to do with that. -- 11 days until the winter celebration (Tue Dec 25, 2018 12:00:00 AM for 1 day). Mark Lloyd http://notstupid.us/ "SENILE.COM found. Out Of Memory." |
#11
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IP6 Address
On Sat, 15 Dec 2018 10:55:29 -0600, Mark Lloyd
wrote: On 12/14/18 7:29 PM, David E. Ross wrote: [snip] I generally avoid combination devices -- router-modem, printer-scanner, etc -- because subcomponents rarely fail together. I am concerned that Southern California Edison's momentary spike might cause only the router part of a router-modem to fail. If that happens with separate modem and router, I could still connect directly to the modem until I can replace the router. This indeed happened. A printer-scanner does make it easy to make copies. Not for me. My scanner software (Canon) has a setting for making copies, and it goes straight from the scanner to my default printer. Other than that, I avoid combination devices too, ESPECIALLY modem router. A modem (I have cable) is under the control of your ISP. A router is a part of YOUR network, and the ISP shouldn't have anything to do with that. I avoid and recommend against *all* combination devices. If one part of a combination device fails, I don't want to have replace all parts. The only exception for my recommendation against them is for someone who has very little desk space for his equipment. For someone like that, a combo printer-scanner and combo router-modem might make sense. |
#12
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IP6 Address
On Fri, 14 Dec 2018 19:16:17 -0800, "David E. Ross"
wrote: On 12/14/2018 5:29 PM, I previously wrote: It is almost dinner time. After dinner, I will reconfigure to have my PC connect directly to the modem without the router. That can be only temporary because my wife's PC also connects to the router to reach the modem and then to the Internet. This is described at http://www.rossde.com/computer/LAN.html. Oops! The modem only accepts outgoing ethernet cable To put it another way, the modem has a single LAN-side Ethernet port and a single WAN-side coax connector. Both are bidirectional, as they would have to be. while the PCs are connected to the router with USB LAN cables. USB LAN cables? Do you mean USB-to-Ethernet adapters, like this? https://www.amazon.com/Cable-Matters.../dp/B00ET4KHJ2 If not, what's a USB LAN cable? Anyway, it probably doesn't matter since you're connected to the router via Ethernet and the router is connected to the modem via Ethernet, so it all becomes pretty simple, as I'll describe below. I have a long ethernet cable I can run from the modem to my PC. Since the modem and router are in the attic, however, that is something I have to wait until daylight to try (maybe Sunday). It's probably much easier than that. There should be no need to run a second cable. Go to the router and determine which LAN Ethernet cable is coming from your PC. Disconnect that cable from the router. Disconnect the Ethernet cable from the modem. Plug in 'your' Ethernet cable directly to the modem. Now you're connected directly to the modem, bypassing the router. Do the reverse to put it all back how it was. You'll have to power cycle the modem so it can learn your MAC address, and I recommend power cycling your PC, as well, although "ipconfig /release /renew" should also do the trick. -- Char Jackson |
#13
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IP6 Address
On Fri, 14 Dec 2018 17:07:18 -0600, VanguardLH wrote:
David E. Ross wrote: On 12/13/2018 3:44 PM, VanguardLH wrote: David E. Ross wrote: Can someone explain why my modem and ipconfig give me two different IP6 addresses? 2605:e000:141e:c49f:8d8a:a676:3154:e70f (IP6) per IPConfig 2605:e000:c04:7b:e855:8b57:644f:706d (IP6) per modem When logging into the web server internal to the modem to look at devices, are you looking at the LAN-side (aka intranet) IPv6 address the modem's DHCP server assigned to the device (or what the router reports if the host uses if using static addressing), or are you looking at its WAN-side IP address (the public address that all external/Intranet hosts will see)? https://www.google.com/search?q=what%27s+my+ip+address Does that public IP address match on either the IPv6 addresses you noted above? If so, that's the WAN-side IPv6 address of your router, not the LAN-side IPv6 address of your intranet host. When I go into my modem and click on the device listing for my host, its IPv6 address, local link IPv6 address, and MAC/physical address match what "ipconfig /all" reports on my host. Do you have multiple NICs in your host? I don't have bother Ethernet (wired) and wi-fi in my host, so I can't see how the modem reports the different IP and MAC addresses for each NIC but I assume they would be different. The PC came with a wi-fi daughtercard but I removed it because it's a desktop, doesn't move, I prefer the simplicity and security of a wired connection, and anything wireless that wants to connect to my PC can do it through a wi-fi connect through the modem. Configuration: Windows 7 Ultimate SP1 (x64) Motorola MB7220 V1.0 cable modem with firmware version 7220-5.7.1.9 Modem accessed through a Netgear N300 Wireless Router WNR2000v5 When I logon to the modem and request the advanced display, I can see the following: IPv6 Address 2605:e000:c04:7b:e855:8b57:644f:706d Selecting the circled "i" for more information, I get: IPv6 Address: Assigned to your cable modem by your cable provider. The assignment is referred to as a Lease. IPv6 is a newer, longer style of IP Address. Your cable provider may assign an IPv4 Address, an IPv6 Address, or both. Note: Both IP6 addresses are "owned" by Spectrum, which is my ISP for connecting to the Internet. (When connected, I use a different ISP for E-mail and hosting my Web site.) I'm assuming from your description that you have a separate router and cable modem, not a combination modem that has a built-in router. If they are separate, you have the config without the enclosing "combo". .-----------combo(router+modem)------------. |.-----router-----. | host:IP---||--LANsideIP | .------modem------.| || WANsideIP --|---|---WANsideIP || |'----------------' | ISPsideIP --||---ISP | '-----------------'| '------------------------------------------' There's the IP address of your intranet host. There's the IP address on the LAN-side of your router. There's the IP address on the WAN-side of your router. (*) There's the IP address on the WAN-side of the modem. (*) There's the IP address on the ISP-side of the modem. (*) You won't see this in a combo (router+modem). If I may nitpick just a bit, everything stated above is correct except that the modem also has a LANside and a WANside, rather than a WANside and an ISPside. (WANside and ISPside would refer to the same interface and are thus redundant.) Also, while the modem does have an IP address for its LANside interface and another IP address for its WANside interface, those IP addresses are not used to handle customer traffic. The modem's LANside IP address only connects to a web server interface, while the modem's WANside IP address can be used by the ISP to connect to a web server interface (different from the web server on the LANside), as well as some combination of TFTP, SNMP, SSH, and Telnet. TFTP is always included, (required by the DOCSIS standard and how the ISP delivers the modem's config file on every modem boot), while the rest can vary with the specific modem model. From the perspective of the customer's Internet traffic, inbound or outbound, the modem is mostly an Ethernet bridge, and thus transparent. Since it operates at OSI Layer 2 (MAC layer), versus Layer 3 (IP layer), IP addresses don't come into play. It's also why you'll see that the router's gateway IP is an interface on the ISP's CMTS and not an interface on the cable modem. Unless you configured your host with a static IP address, it is dynamically assigned by the DHCP server internal to the router. Correct. The router's WAN-side IP address gets dynamically assigned by the modem's internal DHCP server. No, the modem does have a DHCP server, but it gets disabled during modem startup. The router's WANside IP address (this is the Internet-facing interface) gets assigned by the ISPs CMTS, the same CMTS (usually) that becomes the router's next-hop gateway. The ISP-side IP address for the modem gets assigned by your ISP's DHCP server. Actually, that too is assigned by the CMTS, (the CMTS is very DHCP-like), but it doesn't matter because the customer usually can't determine what that address is, and even if they could, they couldn't make use of it in any way. It's only there to allow the ISP to have admin access to the modem from the WANside. Any other access is blocked by policy. Speaking of modem IP's, the modem's LANside IP address is hardcoded. It doesn't get assigned by DHCP or CMTS, it's simply hardcoded by the modem manufacturer into the modem's non-volatile config. Most modem makers have settled on 192.168.100.1 as their hardcoded LANside IP address, which works fine in every case except where the LAN is using 192.168.100.0/24 as its address scheme. In that case, everything will still be fine, except that you won't be able to access the modem's LANside web server if you use a router. The reason is probably obvious. I found your cable modem at with pics: https://www.amazon.com/MOTOROLA-Cert.../dp/B019ZY1ZWS The backside has only 1 Ethernet port, so it is usable with only a single intranet host Usually the case, but not strictly true. It used to be more common than it is now, but ISPs can assign a service profile that allows more than one routable IP address to be assigned from the CMTS. You'll usually see it in the modem config as the parameter "CPE Allowed: 2", which means the modem and one host, but there are service plans with a value of 3 or 5 that I know of, and possibly others that I haven't seen. When the CPE value is greater than 2, you can simply connect an Ethernet switch to the modem's single Ethernet port and all of the connected hosts, up to the CPE limit -1, will obtain a routable IP address from the CMTS. Side note regarding the point about "CPE Allowed" being greater than 2. You'd expect multiple hosts to pull down routable IPs from the same subnet, so that file sharing is easy and efficient, but the CMTS has no concept of multiple hosts at the same physical location, so you'd be just as likely to pull down routable IPs from different subnets. In that case, traffic from one host goes out through the modem to the CMTS or edge router, makes a hairpin turn and comes back through the modem to the other host. That wasn't a great situation, but it was wholly alleviated as consumer routers came onto the scene. or you connect it to a router to hookup multiple intranet hosts. Since it appears you are using a separate router, my guess is: - The WAN-side IP address of your router comes from the cable modem's internal DHCP server. As stated above, it's actually assigned by the ISPs CMTS. The cable modem's DHCP server is disabled during modem startup. - The ISP-side IP address of the cable modem comes from the ISP's DHCP server. Actually the CMTS, but I agree, it's very similar to DHCP. - Both those IP addresses come from your ISP's IP pool. The first will be routable, while the second _may_ be routable. I have diminished respect for ISPs that use routable IPs on the WANside of their cable modems. That's just wasteful. Non-routable IPs would work just as well, but inertia prevents them from making the change. Spectrum is one of the offenders, for example. - They need not be the same. They're never the same. They can't be. The cable modem's IP address allows tech to access the cable modem, like when provisioning it, not something beyond it. They probably don't care/support what you have on the other side of their modem. Agreed. Since the router and modem are separate network devices, they each need an IP address on their interface to connect to each other. The WAN-side IP address of the router connects to the WAN-side IP address of the modem. What you meant to say was that the WANside of the router connects to the LANside (not WANside) of the modem, but as stated above, that's not correct from a networking perspective. The modem behaves exactly like an Ethernet bridge. Traffic that appears on one interface is copied to the other interface. The modem operates at OSI Layer 2, the MAC layer, so the modem doesn't care about IP addresses, with one exception. The modem sniffs the outgoing traffic and looks for a destination IP that matches its hardcoded internal web server. That traffic is hijacked and directed to the modem's internal web server rather than pushed over the bridge. .---router----. |--LANsideIP | .----modem----. | WANsideIP--|---|--WANsideIP | '-------------' |ISPsideIP --| '-------------' Does your router report the modem's WAN-side IP address? I assume you mean LANside, and the answer will be no. The router's next hop gateway will be inside the ISPs network, usually the CMTS itself. The router's next hop gateway will never be the modem. If your router is configured for dynamic IP address assigned (from the modem's internal DHCP server) Not the modem's DHCP server, since it gets disabled during modem boot, but rather the ISPs CMTS. it should list what is its "gateway" IP address (where to find the modem but its IP address). Yes, and that will usually be the CMTS, never the modem. It could be an edge router rather than the CMTS, but it'll never be the modem. -- Char Jackson |
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Char Jackson wrote:
You'll have to power cycle the modem so it can learn your MAC address, and I recommend power cycling your PC, as well, although "ipconfig /release /renew" should also do the trick. Because of DHCP assignment of IP addresses, it is best to first bring up the host at the top end of the chain first so its DHCP server is ready when the next lower device comes up. Have DHCP ready to server the next downstream device. - Power down all devices. - Bring up modem. Let it settle. - Bring up router. Let it settle (much quicker than the modem). - Bring up hosts connected to router. With the simplified setup of just one host to the cable modem: - Power down all devices. - Bring up modem. - Bring up host. |
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Mark Lloyd wrote:
On 12/14/18 7:29 PM, David E. Ross wrote: [snip] I generally avoid combination devices -- router-modem, printer-scanner, etc -- because subcomponents rarely fail together. I am concerned that Southern California Edison's momentary spike might cause only the router part of a router-modem to fail. If that happens with separate modem and router, I could still connect directly to the modem until I can replace the router. This indeed happened. A printer-scanner does make it easy to make copies. Other than that, I avoid combination devices too, ESPECIALLY modem router. A modem (I have cable) is under the control of your ISP. A router is a part of YOUR network, and the ISP shouldn't have anything to do with that. Pretty hard to decide what modem you get unless you buy your own. ISPs tend to remove the old stock of modem and populate their inventory with a specific model. Eliminates them having to carry multiple models and have to support them. If you lease the modem from the ISP (most likely scenario), you get what they give you. You might have an old model for a while but when you go to trade it in (old one doesn't work, old one doesn't have enough channels for the increased speed tier), you'll get their newer model. You can always put your own router downstream of the cable modem. You will have to do that, anyway, if you have more wired hosts than the number of ports on the combo modem. You might also want to subnet your network, like having one for your host(s) and another for your family's host(s) to, for example, let them get to the Internet but block them from getting into your subnet. You might have to support your family as their computer/network guru but that doesn't mean you need to let them get at your hosts after they're infected because they clicked on a rogueware popup when they were web surfing. The combo modems usually don't have the same level of configurability as the stand-alone routers. However, when you call in for tech support, you better get your host wired directly to their combo modem because they won't support your router sitting between their combo modem and your host(s). If you buy your own modem, like to have it only a modem and not a router, your ISP's support ends at the service entry point to your home. Unless there's a cabling problem outside the house, you won't get any support from your ISP (other than they will [re]provision the modem). |
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