Connection drop with Cisco Router

Problem - Canopy wireless connection drop about a minute later after changing static route in 2 Cisco routers.

Prior to this, the 2 routers are using a 128kbps leased line and ISDN BRI line as backup. There is no problem pinging from both routers.

This is what I have done. I have configured 2 Cisco routers to use Canopy wireless connection as the primary connection.

Router A-------------------------------------Router B
Eth 0 (10.30.1.1/16)------------------------Eth 0 (10.40.1.1/16)
Ser 0 (10.130.40.1/30)<— 128kbps —>Ser 0 (10.130.40.2/30)
Eth 1 (10.130.40.9/29)---------------------Eth 1 (10.130.40.12/29)
Canopy A (10.130.40.10/29) ~~~~~~~ Canopy B (10.130.40.11/29)

Canopy A is connected to Eth 1 of Router A.
Canopy B is connected to Eth 1 of Router B.

From Router A, there is no problem pinging Canopy B’s IP and vice versa.

The problem happens when I change static route into Router A & B.

Original Routing Router A: -
ip route 10.40.0.0 255.255.0.0 10.130.40.[u:b40pcmk4]2[/u:b40pcmk4]
ip route 10.40.0.0 255.255.0.0 BRI3/0 150 (ISDN backup)

New Routing Router A: -
ip route 10.40.0.0 255.255.0.0 10.130.40.[u:b40pcmk4]12[/u:b40pcmk4]
ip route 10.40.0.0 255.255.0.0 BRI3/0 150 (ISDN backup)


Original Routing Router B: -
ip route 0.0.0.0 255.255.0.0 10.130.40.[u:b40pcmk4]1[/u:b40pcmk4]
ip route 0.0.0.0 255.255.0.0 10.130.40.5 150 (ISDN backup)

New Routing Router B: -
ip route 0.0.0.0 255.255.0.0 10.130.40.[u:b40pcmk4]9[/u:b40pcmk4]
ip route 0.0.0.0 255.255.0.0 10.130.40.5 150 (ISDN backup)

After changing the routing, my ping from 10.30.1.1 to 10.40.1.1 continues to work fine for about a minute. It fails after that.

Appreciate any help.

Thanks in advance.

Believe if you check carefully you will see that your eth1 interfaces and your Canopy units are all in the same IP subnet, whereas your ser0 links are a separate (/30) subnet. Since to the router it appears that the “remote” (Canopy B) is part of the same network it will not forward the packets. Either change the subnet or make the Canopy units a separate “network” and believe it will start working…

Larry Smith
ECSIS.NET

Based on your addressing for your Eth1 interfaces on both routers, the IP range with a /29 subnet mask is 8-15, your usable addresses being 9-14.

So yes, your Eth1 interfaces and your Canopy units are on the same subnet but that should not matter because the Canopy devices are not Layer-3 devices. You are not using them to formally “route” to the other side of the hop. The routers are used to “route” to the other side of the hop, the Canopy units are simply the phyiscal medium that connects the routers.

I am unfamiliar with the 0.0.0.0 255.255.0.0 notation in your routes in router B. I have only ever used the quad-zero route notation without a subnet mask, e.g. ip route 0.0.0.0 0.0.0.0 <interface> as a default route. What exactly does 0.0.0.0 255.255.0.0 mean?

I would try adding these static routes:

In Router A:

ip route 10.130.40.12 255.255.255.255 eth1

In Router B:

ip route 10.130.40.9 255.255.255.255 eth1

I would also try replacing your 0.0.0.0 255.255.0.0 in router B with 10.30.0.0 255.255.0.0. Until I understand that 0.0.0.0 255.255.0.0 means I am sort of in the dark.

I am assuming that your Canopy units are BH’s. I would also change the Bridge Timeout entry parameter in the units to 1440. This will keep ARP bridging entries in the ARP table of the units for 24 hours.

Keep me posted, I like troubleshooting routers and subnetting issues.

My typing mistake msmith.

In Router B, it is supposed to be -
Original Routing: -
ip route 0.0.0.0 0.0.0.0 10.130.40.1
ip route 0.0.0.0 0.0.0.0 10.130.40.5 150 (ISDN backup)

New Routing Router B: -
ip route 0.0.0.0 0.0.0.0 10.130.40.9
ip route 0.0.0.0 0.0.0.0 10.130.40.5 150 (ISDN backup)

Yes, the Canopy units are BH’s and the Bridge Timeout entry has been set to 1440.

After changing the Bridge Timeout from 25 to 1440 and rebooting, my ping connection to both Canopy died. I can’t access to the Canopy from IE anymore.

Pls help!

Ah… it’s working again. Don’t know why the canopy took so long (more than 10 minutes) to work again after rebooting.

After some more changes to the route in both routers, I managed to get the canopy connection to work. I could ping each other and the connection is now stable.

My problem now is how to get the ISDN connection to start when the canopy connection fails. The ISDN is suppose to provide the backup. Previously, when my ISDN was used to backup serial leased line, it was working fine. The ISDN line was activated when serial leased line failed (i.e. Line Protocol is DOWN).

Can someone advise me the changes necessary to my cisco routers to get the ISDN working? Can ISDN BRI be used to provide backup for Ethernet Canopy connection? To my knowledge, ISDN backup only works with Serial port connection.

Thanks.

Glad it is working.

So what do your routes in both routers look like now?

It’s the same as before.

Router A
ip route 10.40.0.0 255.255.0.0 10.130.40.12
ip route 10.40.0.0 255.255.0.0 BRI3/0 150

Router B
ip route 0.0.0.0 0.0.0.0 10.130.40.9
ip route 0.0.0.0 0.0.0.0 10.130.40.5 150

But now, I have also change some other routes in Router A (see below), which I think might be the caused of my connection drop problem.

ip route 10.41.0.0 255.255.0.0 10.130.40.12
ip route 10.42.0.0 255.255.0.0 10.130.40.12
ip route 10.42.0.0 255.255.0.0 BRI3/0 150
ip route 10.43.0.0 255.255.0.0 10.130.40.12
ip route 10.43.0.0 255.255.0.0 BRI3/0 150
ip route 10.44.0.0 255.255.0.0 10.40.1.1


Thanks.