Help with dual homing vg224

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Jul 1st, 2008
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Hi All,

I have 60 vg224's installed and need to try and build some resilience into them by dual homing them to different switches.

Anybody got any ideas ?

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jasyoung Tue, 07/01/2008 - 08:40
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You'll need to dual-home them using layer 3 interfaces. You'll configure the two Ethernet interfaces on the VG224 in two different subnets and attach one link to each switch. Then you need to create a Loopback address on the VG224, have it participate in your IGP (EIGRP or OSPF) and announce that address. Optionally you can crank down the timers for your IGP's hello and dead intervals. Then you bind your signaling and control to that Loopback interface. The method for doing that varies depending on whether you're using H.323, MGCP or SCCP and you didn't mention which.

The best way to handle interface config and subnet allocation depend on what sort of VG224 density you have on each switch (are they spread out around a campus or is it a stack of VG224s going into one switch?) and what model switches you have. In general you might use "no-switchport" /30 subnet interfaces on IOS-based switches coupled to one or a few VG224s, or a larger VLAN-based subnet if you have a high density of VG224s connecting to one switch (or if you're using CatOS switches and you don't have a choice).

When the VG224 first started shipping, it supported OSPF but not EIGRP. I ran into that when I tried to deploy them in a redundant fashion like yours, in an environment where EIGRP was already prevalent. I had to work around it with route redistribution. I worked with a friend in TAC to get a bug filed, and EIGRP is now available on the VG224 as of IOS 12.3(13)T and later.

At the customer sites where we've done this (including the IGP timer tuning), we were able to pull out Ethernet links and carry on existing conversations with no more than a second or two interruption.

r.robins Wed, 07/02/2008 - 00:16
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Thanks for the information.

This is what I thought we would need to do but was hoping Cisco would have made things simpler.

I didnt really want to introduce any dynamic routing protocols as they are just not necessary any where else on the network.

The vg224's are all in 3 cabinets and I want to connect them into either a stck of 3750's or into 6 single 3560's. At least I know I need enhanced image for the switches now.

We are using mgcp to talk to the call manager, and I already use the Loopback address to register each of the gateways in DNS and CM.

Chad Stachowicz Wed, 07/16/2008 - 22:32
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so I was hoping to bind my SCCP on my VG224 to my loopback so that, if either cable broke it would be up, however unlike a CFB where I can register a name, the vg225 in ccm asks for a MAC Address, which does not exist on a loopback, how can I achieve this redundant registration...



rchaseling Wed, 11/16/2011 - 04:42
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Just wondering if this is possible at all also?

Registering a VG224 to CUCM using SCCP to a Loopback? Is the only option for redundancy a BVI since Port channel is not supported I believe.


BRUNO VAN DE VELDE Wed, 11/16/2011 - 05:16
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If you're looking for a simple config, AND if you can live with a failover-time of approx 30 secs, use the good old 'backup interface' command:

interface fastethernet 0/0

ip address A.B.C.D

backup interface fastethernet 0/1


interface fastethernet 0/1

ip address A.B.C.D    (because of the 'backup interface' command, you can put the same ip-address here

rchaseling Wed, 11/16/2011 - 06:36
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Thanks handy to know but not what I was after. Also this would change the MAC address I would assume & would cause it to unregister


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