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-   -   Remote VLANs bridging over metro ethernet ... (http://www.velocityreviews.com/forums/t34549-remote-vlans-bridging-over-metro-ethernet.html)

Pedro Ribeiro 07-19-2004 11:40 PM

Remote VLANs bridging over metro ethernet ...
 
I have a problem to solve in the network design i'm doing for our
campuses across the city.

The WAN/MAN operator we are using have made us a good price for the
links at 10 and 100Mbit/s from the data/comm center to every school,
the circuits are terminated in 10BaseT/100BaseTX in the remote sides
and in 1000BaseT in the main site with the circuits arriving each in
his 802.1q VLAN. (In the remote side the frames are delivered
untagged).

The problem is that i need to pass VLANs across this links (Our VLANs
over the Operator VLANs) and the Operator imposes several restrictions
to traffic in the circuits:
The maximum frame size allowed: 1500 bytes.
Each circuit can only introduce 4 MAC addresses in each side.

I can't use IEEE802.1q over these circuits because:
- Maximum ethernet frames sent by machines (can't control MTU of
them) after adding the VLAN tag will be oversized frames in the
operators view and wil be discarded.
- Each machine will introduce his MAC violating again, now the MAC
limit.

ISL could solve this last problem because frames are tunneled between
switches point2point but the maximum frame size problem becomes bigger
as the ISL introduces big overhead in encapsulation.

Does anyone know any device (or IOS feature) that could transport
VLANs across these circuits? (Some kind of remote bridge doing
fragmentation & reassembly)

TIA.

Ivan Ostres 07-20-2004 04:53 AM

Re: Remote VLANs bridging over metro ethernet ...
 
In article <cbe495fa.0407191540.31a6f1cf@posting.google.com >, pribeiro-
newspost@net.ipl.pt says...
> I have a problem to solve in the network design i'm doing for our
> campuses across the city.
>
> The WAN/MAN operator we are using have made us a good price for the
> links at 10 and 100Mbit/s from the data/comm center to every school,
> the circuits are terminated in 10BaseT/100BaseTX in the remote sides
> and in 1000BaseT in the main site with the circuits arriving each in
> his 802.1q VLAN. (In the remote side the frames are delivered
> untagged).
>
> The problem is that i need to pass VLANs across this links (Our VLANs
> over the Operator VLANs) and the Operator imposes several restrictions
> to traffic in the circuits:
> The maximum frame size allowed: 1500 bytes.
> Each circuit can only introduce 4 MAC addresses in each side.
>
> I can't use IEEE802.1q over these circuits because:
> - Maximum ethernet frames sent by machines (can't control MTU of
> them) after adding the VLAN tag will be oversized frames in the
> operators view and wil be discarded.
> - Each machine will introduce his MAC violating again, now the MAC
> limit.
>
> ISL could solve this last problem because frames are tunneled between
> switches point2point but the maximum frame size problem becomes bigger
> as the ISL introduces big overhead in encapsulation.
>
> Does anyone know any device (or IOS feature) that could transport
> VLANs across these circuits? (Some kind of remote bridge doing
> fragmentation & reassembly)
>
> TIA.
>


Well, the only method I've ever seen (at networkers) is QinQ. That is
using dot1q inside of a dot1q.

Does this mean that you have a flat L2 network without routers on any
end?

--
-Ivan.

*** Use Rot13 to see my eMail address ***

Pedro Ribeiro 07-20-2004 01:36 PM

Re: Remote VLANs bridging over metro ethernet ...
 
Yes, L2 flat, but I can't use QinQ or ISLinQ because I have the frame
size and MAC limitations imposed by the operator ...

Ivan Ostres <vina.bfgerf@mt.ugarg.ue> wrote in message >

....

> Well, the only method I've ever seen (at networkers) is QinQ. That is
> using dot1q inside of a dot1q.
>
> Does this mean that you have a flat L2 network without routers on any
> end?


Gordon Smith 07-20-2004 09:45 PM

Re: Remote VLANs bridging over metro ethernet ...
 

"Ivan Ostres" <vina.bfgerf@mt.ugarg.ue> wrote in message
news:MPG.1b66c2fbbb84f5e99896a7@news.individual.ne t...
>
> Well, the only method I've ever seen (at networkers) is QinQ. That is
> using dot1q inside of a dot1q.
>
> Does this mean that you have a flat L2 network without routers on any
> end?
>
> --
> -Ivan.
>


Well... dare I say it :-)
Juniper routers have a feature called CCC (circuit cross-connect) that
allows you to bridge layer 2 over layer 3 very well. Quite useful in a
meshed & routed core network. It doesn't scale particularly well though, in
terms of the number of CCC's you can run.

Doing some form of bridging would keep the MAC count down across the
provider's links.
Unless their provider is running jumbo frames internally, delivering tagged
circuits will reduce the MTU of the payload anyway, although that shouldn't
be a real problem. There's a number of ways to get around that...




Erik Tamminga 07-21-2004 11:43 AM

Re: Remote VLANs bridging over metro ethernet ...
 
Hi,

Are you realy sure you need to pass your vlans over the operators vlans?
This is almost impossible (without spending huge amounts on specialized
equipment capable of handling the throughput and resulting in complex
setups). Example: setup an expensive router on either side, create a tunnel
setup over the operator's vlans (l2tp, gre, ....) and bridge local traffic
from local ethernet ports to the tunnels.

If you're not sure, I would suggest going the other way and create a routed
setup using layer-3 switches at either side of the link. (3550/3570 series?)

Erik

"Pedro Ribeiro" <pribeiro-newspost@net.ipl.pt> wrote in message
news:cbe495fa.0407191540.31a6f1cf@posting.google.c om...
> I have a problem to solve in the network design i'm doing for our
> campuses across the city.
>
> The WAN/MAN operator we are using have made us a good price for the
> links at 10 and 100Mbit/s from the data/comm center to every school,
> the circuits are terminated in 10BaseT/100BaseTX in the remote sides
> and in 1000BaseT in the main site with the circuits arriving each in
> his 802.1q VLAN. (In the remote side the frames are delivered
> untagged).
>
> The problem is that i need to pass VLANs across this links (Our VLANs
> over the Operator VLANs) and the Operator imposes several restrictions
> to traffic in the circuits:
> The maximum frame size allowed: 1500 bytes.
> Each circuit can only introduce 4 MAC addresses in each side.
>
> I can't use IEEE802.1q over these circuits because:
> - Maximum ethernet frames sent by machines (can't control MTU of
> them) after adding the VLAN tag will be oversized frames in the
> operators view and wil be discarded.
> - Each machine will introduce his MAC violating again, now the MAC
> limit.
>
> ISL could solve this last problem because frames are tunneled between
> switches point2point but the maximum frame size problem becomes bigger
> as the ISL introduces big overhead in encapsulation.
>
> Does anyone know any device (or IOS feature) that could transport
> VLANs across these circuits? (Some kind of remote bridge doing
> fragmentation & reassembly)
>
> TIA.





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