Rip again!

Sun Aug 21 18:15:40 UTC 2005

In case no one else has suggested it: the source MAC address will
identify the source.

Chris 

> -----Original Message-----
> From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On 
> Behalf Of Scott Morris
> Sent: Sunday, August 21, 2005 9:21 AM
> To: 'Tom Sanders'; nanog at nanog.org
> Subject: RE: Rip again!
> 
> 
> How about the source IP?
> 
> RIP v1 is sent to 255.255.255.255 broadcast.  RIPv2 is sent 
> to 224.0.0.9 multicast.  Both are local-link only, so won't 
> go THROUGH a router.  The sending source IP will tell you 
> where they came from.
> 
> If you're using VLANs (trunks), there won't be any issues.  
> If you're using
> secondary addresses, this will depend on whose devices you 
> use.   In the
> Cisco world, packets will always be sourced from the primary 
> IP address on an interface.  And if the receiving router 
> doesn't have a subnet matching the sender, packets/updates 
> are ignored.  (Again, Cisco world you can use "no 
> validate-update-source" to override this check)
> 
> But that gives you a tracking method on packets.  
> 
> Scott 
> 
> -----Original Message-----
> From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On 
> Behalf Of Tom Sanders
> Sent: Sunday, August 21, 2005 12:13 PM
> To: nanog at nanog.org
> Subject: Rip again!
> 
> 
> Hi,
> 
> There isnt IMO a way in RIP to identify the source of the RIP 
> packet (the way we have Router ID in OSPF, system ID in ISIS, etc.)
> 
> Now assume we have 2 vlans defined on an ethernet. Thus we 
> would have two IP interfaces, 1.1.1.1/24 and 2.2.2.2/24 and 
> both using the same physical interface. RIP is running on 
> both these interfaces.
> 
> My doubt is that how will another router, which is configured 
> in the same way (2 vlans) be able to differentiate between 
> the RIP responses originated by 1.1.1.1 and 2.2.2.2?
> 
> Thanks,
> Toms
> 
> 