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

[Dhamija Amit]

--- On Wed, 1/16/13, Amit <amiitdhamija at yahoo.com> wrote:


From: Amit <amiitdhamija at yahoo.com>
Subject: Re: [c-nsp] ISIS P2P Behaviour with L2 Switch
To: "Pete Lumbis" <alumbis at gmail.com>
Date: Wednesday, January 16, 2013, 5:00 AM



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.
Thanks
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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.??