set ip vs set ip next-hop

[Balajee Muggalla]

Hi,

   Following link says that "set ip next-hop" in policy-map sets the egress interface for a packet and prerequisite for this to work is that dest add of the packet must lie with the network of the same interface. My doubt is if the dest addr of the packet lies in the range of mentioned interface, then why do we need to define policy-map. Even without policy-map, it always follow the same interface, isn't it?

Link : https://supportforums.cisco.com/thread/2122056

Thanks,

Balajee

[cadet alain]

Hi,

What this means is that set interface will only work for point-to-point interfaces like PPP,HDLC, Frame-relay point-to-point but won't work for multipoint interfaces like ethernet, Frame-relay physical or multipoint subinterface.

Also in set ip next-hop the next hop must be adjacent otherwise you must use the set ip nex-hop recursive command

Regards

Alain

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[Balajee Muggalla]

Hi Alain,

    My bad, I gave wrong description. My doubt was about "set interface" , not about "set ip next-hop". Above link says, destination address of packet must be in the subnet of mentioned interface. If that is the case, why do we need policy-map? Without policy-map also, packet would egress the same interface na?

- Balajee

[cadet alain]

Hi,

Without PBR if you had multiple equal longest match routes (or even unequal with EIGRP if variance was set) then the forwarding would be taken care of by the switching process and per-flow( src ip-dst ip) load-sharing  would be in effect so some traffic would go out an interface and some other would take the other one. With PBR you can decide which outgoing interface will be used for all of some traffic.

Regards

Alain

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