Problems with 3G HWIC as Backup Interface

[Sailorderrick]

Good Afternoon

I am trying to configure a 3825 router and a 3G HWIC, with the gi0/0 WAN interface as primary and the cell0/2/0 as secondary. The gi0/1 interface is subdivided into approximately 10 sub-interfaces.

The primary interface works fine, and when the cellular interface takes over, it also works fine. The issue comes when the primary interface comes back online. For whatever reason, the primary interface does not route, and the internet drops.

I suspect I have something wrong in the routing table or the NAT.

Any help is GREATLY appreciated!

Rgds

[Richard Burts]

Derrick

I am puzzled about what is going on with 0/1/0 and 0/3/0. I have been thinking about how to get traffic from certain vlans to go out 192.168.5.1 while traffic from other vlans goes out 192.168.6.1. Normally we would use Policy Based Routing to achieve this. The challenge in this is that you only want PBR to work when the VSAT interfaces are active. I believe there is a way to achieve it using these steps:

1) choose some destination and set it up to be accessed using 0/1/0. This should not be a destination that you really care about accessing. Configure a permanent static route for this destination specifying both the outbound interface and the next hop.

2) Configure IP SLA to verify access to the address specified in 1).

3) Configure an extended access list which will permit traffic whose source address is in any of the subnets of the vlans that should use 0/1/0 and goes to any destination.

4) Configure a route map for PBR. The route map should have a match statement that matches to the access list in 3) and have a set statement that sets ip next-hop as the next hop address out 0/1/0 and includes the parameter verify-availability and uses the tracking set up in 2).

5) Assign the route map to the vlan interfaces whose traffic should use 0/1/0 using the command ip policy <route_map_name>

6) choose some destination and set it up to be accessed using 0/3/0. This should not be a destination that you really care about accessing. Configure a permanent static route for this destination specifying both the outbound interface and the next hop.

7) Configure IP SLA to verify access to the address specified in 6).

8) Configure an extended access list which will permit traffic whose source address is in one of the subnets of the vlans that should use 0/3/0 and goes to any destination.

9) Configure a route map for PBR. The route map should have a match statement that matches to the access list in 8) and have a set statement that sets ip next-hop as the next hop address out 0/3/0 and includes the parameter verify-availability and uses the tracking set up in 7).

10) Assign the route map to the vlan interfaces whose traffic should use 0/3/0 using the command ip policy <route_map_name>

HTH

Rick

[Sailorderrick]

Hi Rick

The 2951 arrived on Friday afternoon and I configured it over the weekend. I used conditional static routes to setup interfaces 0/0, 0/1 and 0/2 was setup as the internal interface. I checked to see if int 0/1 would come up if 0/0 went down and it did. It also relinquished control once 0/0 came back up. Then I added the cellular interface and things went a bit sideways. One of the reasons to upgrade to the 2951 was to give us access to 4G/LTE networks. So, there is a "new" EHWIC-4G-LTE-A module in the router, as opposed to the HWIC-3G that was in the 3825.

However, I am having issues getting it to connect. I have attached the config file, the debug file and the output of show cellular all. Hopefully, you can spot where I went wrong.

Cheers

Derrick

[Richard Burts]

Derrick

I am guessing that there are several things that we will be checking. So far I am noticing these things:

- Profile 1 is inactive. Not sure what is the deal about this and am looking.

- the cellular output seems unhappy about the dialer string. Not sure about that and am looking.

- your EHWIC-4G-LTE-A seems to be for ATT networks. Is your cellular service with ATT?

more later

HTH 

Rick

[Sailorderrick]

Hi Rick

I am told that AT&T and Bell are synonymous. Hopefully, the gentleman that told me that is correct.

Cheers

Derrick

[Sailorderrick]

Hi Rick

Found the dialer problem. I missed out a space in the dialer sequence. So that is fixed and it goes online and connects to the internet, as expected.  Now I need to get rid of all that timer nonsense in the line interface. 

Cheers

Derrick

[Sailorderrick]

Hey Rick

Is there a command, or series of commands, that would build in a delay to let the cellular interface come online before the V-Sat interfaces try to take over? I noticed that the time it takes for the cellular interface to come online seems to be too long and the V-Sat interface kicks in.

Cheers

Derrick

[Sailorderrick]

Hi Rick

Had a brain cramp yesterday. I realized that the timers showing up had to do with me turning on Debug and seeing the internal workings of things, and that I just had to turn off Debug. (Like I said, brain cramp) Anyway, I will deal with that shortly. We are starting to make some progress. I appreciate all this assistance.

Cheers

Derrick

[Richard Burts]

Derrick

Thanks for the update. Yes we do seem to be making progress. Glad you were able to resolve the issue with the dialer string. Pesky spaces !

Is there anything you need from me at this point? (not clear whether your comments about timers is resolved or not)

HTH

Rick

[Sailorderrick]

Hi Rick

OK, now that we have three auto negotiating Gi interfaces with the 2951, I need to get one of the other interfaces (only Gi) up and running. The timer issue is a matter of turning off the debug commands on the 4G card. Didn't have a chance to do that yesterday. Will do that in a few minutes.

I am going to re-read your mail from a few days ago about those cards and then do a bit of web research on some of the stuff you mentioned, as I have never done that kind of configuration before.

Cheers

Derrick

[Richard Burts]

Derrick

Thanks for the update. It will be a learning experience. If you need anything else let me know.

HTH

Rick