question in the routing process in routers and MLS .

[Dr.X]

hi ,

i want to ask  a question about the router behavior when use the routing process ,

which one  is  checked first :

the longest match of the destination address  or the AD of the route of the destination address ???

does this differ when using rouer than using Multi layer switch ??

regards

[Raju Sekharan]

AD is compared only when the router installs the route in routing table. It is used if differnt routing protocols have same prefix with same subnet mask

When the router routes a packet, it always look longest match first.

Thanks

Raju

[Dr.X]

assume my topology below :

e2>--------R1--10.20.30.1/24----------------------------10.20.30.2/24---R2---------------

assume i put a route in R1 as====># ip route 10.20.30.5 255.255.255.255 null0

and a packet from e1 is goining to 10.20.30.5 through R1.

do you mean that the traffic will dropped  and will go to null0  ,because longest match that 10.20.30.0/24 ??

[Raju Sekharan]

Yes. it will get dropped

Thank you

Raju