[c-nsp] Fw: Re: ISIS P2P Behaviour with L2 Switch

[Dhamija Amit]

Hi Oliver

Not sure but just saw some wireshark output which shows the ethernet header in ISIS is IEEE 802.3 which doesn't have ethertype field and VLAN ID is not there.

Thanks
Amit Dhamija


 


--- On Wed, 1/16/13, Oliver Boehmer (oboehmer) <oboehmer at cisco.com> wrote:

> From: Oliver Boehmer (oboehmer) <oboehmer at cisco.com>
> Subject: Re: [c-nsp] Fw: Re:  ISIS P2P Behaviour with L2 Switch
> To: "Dhamija Amit" <amiitdhamija at yahoo.com>
> Cc: "alumbis at gmail.com" <alumbis at gmail.com>
> Date: Wednesday, January 16, 2013, 5:12 PM
> >
> >
> >
> >In my case router is sending vlan tags and is configured
> with dot1q three
> >seprate subinterfaces vlan 10,20 and 30 , three seprate
> p2p adjancies ,
> >Now connecting router port on switch is trunk port, How
> switch will
> >identify the hellos or distinguish hellos between three
> vlans , IIH pdus
> >carried on layer 2 frame doesn't have vlan information.
> 
> why do you say the hellos/IIH PDUs originated by R1 don't
> carry vlan tags?
> It's a trunk, so packets (incl. ISIS PDUs) will have a a
> dot1q tag?
> 
>     oli
> 
> >
> >From: Pete Lumbis <alumbis at gmail.com>
> >Date: Tue, 15 Jan 2013 22:17:19 -0500
> >To: Dhamija Amit<amiitdhamija at yahoo.com>
> >Subject: Re: [c-nsp] ISIS P2P Behaviour with L2 Switch
> >
> >
> >
> >Not sure I understand the entire question, but from a
> high level,
> >regardless of upper level information (ISIS PDU, IPv4
> Packet, IPv6
> >Packet, etc) the switch is unaware. When a frame arrives
> on the
> >switchport it is either put into the vlan that was
> assigned ot that port
> >(access port) or the native vlan (frame on a trunk port
> without a tag).
> >
> >
> >In this case, if R1 doesn't send tags, the switch will
> put the frame in
> >the native or access vlan for that port and switch the
> frame only in that
> >VLAN. If the mac address is an unknown unicast or
> multicast mac it will
> >be flooded to all ports within that vlan.
> >
> >
> >-Pete
> >
> >
> >
> >
> >On Tue, Jan 15, 2013 at 7:29 PM, Dhamija Amit <amiitdhamija at yahoo.com>
> >wrote:
> >
> >
> >When R1 sends ISIS hello ( let's say it's a P2P so it
> want to send hello
> >to R2 only which it includes in IPV4 interface address
> TLV), When it
> >comes to Switch , since ISIS Layer 2 Ethernet frame
> doesn't consists of
> >any specific VLAN header when frame comes on switch ,
> then from switch
> >point of view it has no means to identify it comes from
> R1 (Vlan 10) ,
> >then will this hello will be broadcast to all the
> remaining routers R2,R3
> >and R4 ( as destination address is fixed
> multicast-address and there is
> >no CAM table for it)  ?? or else how switch will
> ensure that this
> >specific hello packet is originated from vlan 10 and
> should only be send
> >to R2.??
> >
> >
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> 
>