From: Sean C (Upp_and_Upp@hotmail.com)
Date: Tue Apr 12 2005 - 12:36:09 GMT-3
Hi Tim,
One of the mentioned reasons for Multilink Frame is (per CCO): Greater
Service Resilience When Links Fail - Greater service resilience is provided
when multiple physical interfaces are provisioned as a single bundle. When a
link fails, the bundle continues to support the Frame Relay service by
transmitting across the remaining bundle links.
So, if using Multilink FR, and using the scenario I mentioned below: unless
both T1s are advertising all DLCIs, how will the carrier let a circuit carry
non-native DLCIs. IOW, from my example below, if the 2nd T1 fails, how does
the carrier allow the 1st T1 to handle DLCIs 4, 5, 6. Won't DLCIs 4, 5 and
6 need to be configured on the 1st T1. I can't just hope the carrier knows
to allow DLCIs 4, 5 and 6 on the 1st T1. What happens now if I tried to
configure DLCIs on a circuit where they are not provisioned - nothing. So,
how does the carrier carry all DLCIs. Do both circuits need to carry all 6
DLCIs? Or, from what Jaffe mentioned in a different email, the carrier is
also responsible for creating a virtual interface on their equipment and all
DLCIs ride on the Virtual interface, not on the physical circuits.
Hope this makes sense and appreciate your comments,
Sean
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "'Sean C'" <Upp_and_Upp@hotmail.com>; "'Group Study'"
<ccielab@groupstudy.com>
Sent: Tuesday, April 12, 2005 11:13 AM
Subject: RE: Realworld use of Multilink Frame Relay
> I'm not sure I completely understand your question, but if I do, it seems
> to
> me that multilink is independent of how the f/r switches behave.
>
> The way I think of it, multilink is to serial interfaces what etherchannel
> is to ethernet links - it's just a way to aggregate links. I don't think
> or
> see any reason for the behavior of the f/r switches to do anything
> differently just because you decided to aggregate multiple links running
> f/r
> encap.
>
> Of course, the routers on each side have to know what's going on so they
> can
> re-assemble fragmented packets if any, but you're use of multilink should
> be
> transparent to the carrier, I think.
>
> Maybe someone knows differently.
>
> Tim
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Sean
> C
> Sent: Tuesday, April 12, 2005 9:01 AM
> To: Group Study
> Subject: OT: Realworld use of Multilink Frame Relay
>
> Hello,
>
> When implementing Multilink Frame Relay (FRF.16) - I'm trying to
> understand
> how the carrier advertises PVCs. My question is this: does the carrier
> advertise all PVCs on each T1?
>
> IOW - if an original implementation of FR had 2 T1s with the 1st T1
> utilizing
> PVCs # 1, 2 & 3 and the 2nd T1 utilizing PVCs # 4, 5 & 6. If wishing to
> utilize Multilink FR, does the carrier now need to advertise all PVCs on
> both
> T1s? IOW - will the 1st T1 now carry PVCs # 1, 2, 3, 4, 5 & 6 and the 2nd
> T1
> will carry the same PVCs #1, 2, 3, 4, 5, & 6? It's the only way I can see
> this happening because I can't figure out if the 2nd T1 fails, how the 1st
> T1
> will be able to support PVCs 4, 5 & 6.
>
> I appreciate any answer supplied. I hope my question is stated simply
> enough.
> I had searched on CCO:
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122
> t
> /122t8/ft_mfr.htm
> and Googled some but have not found the appropriate answer.
>
> Thanks in advance,
> Sean
>
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