[cisco-voip] asymetrical routing and voice - thoughts? requirements?

Nick Matthews matthnick at gmail.com
Thu Oct 14 15:06:23 EDT 2010


You could also use a BVI and put the two interfaces in a bridge group.  This
assumes you don't require 2 different IP addresses.

-nick


On Thu, Oct 14, 2010 at 1:19 PM, Lelio Fulgenzi <lelio at uoguelph.ca> wrote:

> I'm thinking in my situation this might not work. Because we're connected
> via an intermediary switch, if the upstream core router goes down, the
> interface will still be up.
>
>
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
> ------------------------------
> *From: *"Lelio Fulgenzi" <lelio at uoguelph.ca>
> *To: *"James Brown" <James.Brown at barclayswealth.com>
>
> *Cc: *cisco-voip at puck.nether.net
> *Sent: *Thursday, October 14, 2010 12:29:22 PM
>
> *Subject: *Re: [cisco-voip] asymetrical routing and voice - thoughts?
> requirements?
>
> someone else has mentioned the backup interface command. it didn't click
> until you put it in the config below, however.
>
> so essentially, on the VG224, i use the backup interface command and one of
> the interfaces will more than likely "go down" ?
>
> this should keep the upstream router from using that second interface
> correcT?
>
>
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
> ------------------------------
> *From: *"James Brown" <James.Brown at barclayswealth.com>
> *To: *lelio at uoguelph.ca
> *Cc: *cisco-voip at puck.nether.net
> *Sent: *Thursday, October 14, 2010 12:25:57 PM
> *Subject: *RE: [cisco-voip] asymetrical routing and voice - thoughts?
> requirements?
>
> Have you considered the backup interface command?
>
> !
> int fa0/0
>   backup interface Fast Ethernet 1/0
> !
>
> The only alternative I can think of  might involve attaching a route-map,
> but then you have to consider changing the metric of both inbound and
> outbound routes on a per-interface basis.
>
> Regards
>
> James.
>
>  ------------------------------
> *From:* cisco-voip-bounces at puck.nether.net [mailto:
> cisco-voip-bounces at puck.nether.net] *On Behalf Of *Lelio Fulgenzi
> *Sent:* 13 October 2010 21:48
> *To:* Wes Sisk
> *Cc:* voyp list
> *Subject:* Re: [cisco-voip] asymetrical routing and voice - thoughts?
> requirements?
>
>  a very rudimentary diagram follows.
>
> Essentially, any traffic that hits core-1 will go to the VG224:fa0/0
> interface and any traffic that hits core-2 will go to the VG224:fa0/1
> interface. That's because an interlink between the two cores (not pictured,
> sorry) increases the distance to the other side.
>
> We are using intermediary switches because there are not enough ports on
> the core switches/routers.
>
> The links are essentially layer three routed point-to-point links (through
> a layer two interface).
>
> The default route is sent to the VG224 using eigrp summary command and they
> are equally weighted. So traffic outbound from the VG224 will be random
> across both links. I can change this by using a delay command easily to
> prefer one route over the other. But again, this will affect outbound
> traffic only.
>
> I guess there's a difference between equal routes (which appear on the
> VG224) which means traffic to the same destination will traverse both links
> and with an asymetrical route which I understand as traffic to a device goes
> out one link and comes back on another. However, I can't guarantee that
> traffic from a device on the network will always choose core-1 or core-2, so
> it may be a case of inbound traffic coming in on either interface as well.
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
> ------------------------------
> *From: *"Wes Sisk" <wsisk at cisco.com>
> *To: *"Lelio Fulgenzi" <lelio at uoguelph.ca>
> *Cc: *"voyp list" <cisco-voip at puck.nether.net>
> *Sent: *Wednesday, October 13, 2010 4:29:18 PM
> *Subject: *Re: [cisco-voip] asymetrical routing and voice - thoughts?
> requirements?
>
> We're missing a bit of information like how you got asymmetrical routing to
> the router interfaces.  Care to share?
>
> Otherwise, in theoretical discussion, my peers agree that router will
> service traffic for any locally configured IP from any network interface.
>
> There are the classic issues of binding VOIP protocols to interfaces with
> routable IP addresses but that is a separate issue.
>
> /Wes
>
> Lelio Fulgenzi wrote:
>
> OK, not sure if this has been discussed before, but I just tried to get all
> my voice through one interface of my VG224 and in doing so, I lost the route
> to the other interface. We did this by using the delay command. Anything
> else I've been told, will take significant time to deploy.
>
> So the question is, in the case of end devices (mainly gateways) that have
> two uplinks, how important is it to ensure that only one side is always
> used? Is it a requirement or is it a nice to have? I'd rather not be
> introducing delay statements if I don't have to.
>
> Or is it all just to make troubleshooting easier?
>
> ---
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Cooking with unix is easy. You just sed it and forget it.
>                               - LFJ (with apologies to Mr. Popeil)
>
>
> ------------------------------
>
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> cisco-voip mailing listcisco-voip at puck.nether.nethttps://puck.nether.net/mailman/listinfo/cisco-voip
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