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Anonymous
N/A

Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

Be most grateful if someone could check this out.

I have a (nuther make ) wireless router that I wish to attach to the 877 via one of the FA ports

877 has 12.4 Enterprise IOS /  256 RAM / 40 flash

( I would love to use an 877W -- but Cisco have not upgraded to Gigabit ports or 802.11n wireless yet )

I require the Cisco to treat this ONE port as a pure ADSL bridge ( passthrough ) -- No NAT or IP Routing

( the other wireless router will do this )

I am trying to bridge one FA port ( VLAN ) to the ATM interface using IRB

To do this I have a bridge-group set on the ATM (sub) interface as well as on the VLAN in question.

To complicate things I also have some PPPoE dialers to different ISP's using dynamic IP addressing PPP IPCP on the same ATM interface.

interface ATM0.1

  pppoe-client dial-pool-number 2

  pppoe-client dial-pool-number 1

  bridge-group 1

In this country we can only use ONE ATM PVC for  ADSL

I understand that you cannot bridge & route on the same interface.

As I understand it the PPPoE routing is taking place on the dialer interface so therefore bridging should be possible on the ATM (sub) interface

This does not appear to be working  ?   I have been advised by a Cisco "fundi"  that this scenario is not possible.

ie it is not possible to set up one port on the 877 for bridging ( the "modem" -- ATM)  and the others for routing.

I would appreciate it if someone could confirm this -- possible / not possible

If I am doing something wrong and have been misinformed I would appreciate it if someone could explain the correct way of doing this.

Thanks

chris@airphotoafrica.co.za

11 REPLIES
Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

No this cannot work.

If you want multiple ISPs get multiple ADSL circuits.

You are lucky aready that you have two PPPoE working on the same PVC, that is already probably unsupported.

If you want a router with gigabit and wireless N, upgrade to an bigger model.

Note gigabit and N are not really useful behind ADSL bottleneck.

Anonymous
N/A

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

f you want multiple ISPs get multiple ADSL circuits.

You are lucky aready that you have two PPPoE working on the same PVC, that is already probably unsupported.

If you want a router with gigabit and wireless N, upgrade to an bigger model.

Note gigabit and N are not really useful behind ADSL bottleneck.

===============

Aahh  my friend thanks for your reply

Please to check the latest data on new Cisco IOS versions.

Cisco can run MULTIPLE PPPoE sessions on ONE PVC   ( will get official link if you want it )

--------

OK -- to save you the time here is the Cisco link

Cisco IOS 12.4 (15) T

http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/mpppoec.html

------------

Reason for Gigabit and 802.11n

Now I can plug in AP ( 802.11n ) and NAS ( Gigabit )  and use on LAN + still use Internet  -- comprendo ?

877 has four integrated FA managed ports.

Please can someone from CISCO answer.

Message was edited by: Chris Moore

Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

Please to check the latest data on new Cisco IOS versions.

Cisco can run MULTIPLE PPPoE sessions on ONE PVC   ( will get official link if you want it )

--------

OK -- to save you the time here is the Cisco link

Cisco IOS 12.4 (15) T

http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/mpppoec.html

Thank you for the clarification - that features is to terminate multiple PPPoE sessions on same interface and PVC, in order to give you multiple public addresses by PPPoE constrained ISPs.

What you want (simultaneous termination for some session and bridging for others) is NOT possible because the router would not know when a packet comes in, if to terminate or bridge it.

Reason for Gigabit and 802.11n

Now I can plug in AP ( 802.11n ) and NAS ( Gigabit )  and use on LAN + still use Internet  -- comprendo ?

Plug everything into a gigabit switch and you will be fine.

Not only I "comprendo", but I speak it, do you ?

Regarding "someone from Cisco", I worked there 10 years, yet admit there is non Cisco people that know much more than me

Anonymous
N/A

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

What you want (simultaneous termination for some session and  bridging for others) is NOT possible because the router would not know  when a packet comes in, if to terminate or bridge it.

==========

Lo siento Amigo No hablo español

I am just a stupid Englishman that thinks everyone should speak English

Surely the router knows if a packet is coming in on the Dialer interface or the Bridge interface -- and then what to do with it ?

What about IRB used on other interfaces ( and other routers) -- I am sure it does this

Respect ........

But maybe one of the Cisco engineers can answer this -- I find it hard to believe that the all singing / all dancing Cisco cannot do this.

PS;  Have you seen the price of Cisco Gigabit switches

Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

Surely the router knows if a packet is coming in on the Dialer  interface or the Bridge interface -- and then what to do with it ?

No it does not, because the incoming interface is the same - ATM PVC.

What about IRB used on other interfaces ( and other routers) -- I am sure it does this

Bridging PPPoE is not a problem, simultaneous bridging and temination is, for the reason above. Moreover, all the MAC addresses involved are the same.

PS;  Have you seen the price of Cisco Gigabit switches

Yes, $90 for a 12 ports 2950G  on the leading auction site - not exactly intimidating.

Then there is also the choice of ex-linkysy line whatever is called now.

Anonymous
N/A

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

Thank you for your patience

With respect

The 2950 12 port switch has ONLY 10/100 ports

http://www.cisco.com/en/US/products/hw/switches/ps628/ps626/index.html

The 2950T has TWO Gigabit "uplink"  ports

IF Cisco upgraded the 800 series then the 877 would have FOUR Gigabit ports

I assume that if one had access to another ATM PVC then bridging and routing would be possible ?

( Bridging on the OTHER ATM sub-interface )

Sorry man I am kinda dissapointed -- I still cannot believe this

The ATM interface has TWO seperate and distinctive Dialers TWO ISP's coming in on the same interface which it has to distinguish between.

There HAS to be some logic on that interface.

I wonder -- does a Bridge Interface get a MAC address ?

Enough to know the difference between a routed stream and a bridged stream ?  ( I am not a Phd Electronics Networking engineer )

Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

Thank you for your patience

With respect

The 2950 12 port switch has ONLY 10/100 ports

http://www.cisco.com/en/US/products/hw/switches/ps628/ps626/index.html

The 2950T has TWO Gigabit "uplink"  ports

You are right. However in your case any cheap gigabit switch will work.

I assume that if one had access to another ATM PVC then bridging and routing would be possible ?

( Bridging on the OTHER ATM sub-interface )

Yes, it would. However I do not know of any ISP anywhere in the world where ADSL carry more than one PVC, and good reasons.

Sorry man I am kinda dissapointed -- I still cannot believe this

The  ATM interface has TWO seperate and distinctive Dialers TWO ISP's coming  in on the same interface which it has to distinguish between.

There HAS to be some logic on that interface.

Yes there is and is as follows: PPPoE enable on PVR or Ethernet == ALL PPPoE packets will be terminated in interface. End of processing.

I wonder -- does a Bridge Interface get a MAC address ?

Transparent bridges do not need MAC addresses of their own in order to process packets, however they need MAC address for the spanning thrre protocol - BTW all that is irrelevant to your case.

Enough to know the difference between a routed stream and a bridged stream ?  ( I am not a Phd Electronics Networking engineer

You are failing to indentify the real issue. It is not routing Vs switching. It is that PPPoE pre-empts bridging.

Anonymous
N/A

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

You are failing to indentify the real issue. It is not routing Vs switching. It is that PPPoE pre-empts bridging.

Aahh  OK thank you

I assume then that this would be the same for PPPoA ?

So is there ANY way to achieve what I was asking ........?

Bridge AND route on an ATM WAN interface ( single device / single line / single PVC )  ?

( any other combination of devices / interfaces )

Thank you for your input so far

Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

It would be even worst with PPPoA, as it not even bridgeable.

If you want to distribute different public addresses to different devices off the same ADSL circuit, choose an ISP that does not uses PPP at all. then you can use IRb for the purpose.

If you want everything to work with your current setup, get any gigabit switch for your LAN needs, and let the router do his work normally.

Anonymous
N/A

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

If you want to distribute different public addresses to different  devices off the same ADSL circuit, choose an ISP that does not uses PPP  at all. then you can use IRb for the purpose.

HHhmm   I will go and do some more reading about ADSL without PPP -- now I have a place to start working from.

Never a dull monent with Cisco

So much to learn -- so little time ( and so little "grey-matter" )

Thank you for your help

Hall of Fame Super Gold

Re: Cisco 877 IRB -- Bridge ATM & VLAN -- Possible Bug ?

You are welcome.

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