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frame-relay static route problem

shaila_rox
Level 1
Level 1

hi, i have two routers connected via frame-relay switch (2522 router), the configuration on switch is correct as well as on both routers, i have made loopback interface on RB router i.e RB has 20.0.0.0/8, now at RA when i define the static router

ip route 20.0.0.0 0.255.255.255 serial 0

it was not able to send packets to 20.0.0.0/8 when i ran debug i got error like encapuslation failed, now when i replaced the static route with next hop ip it was working fine, why ???? can some1 tell me the reason that why was it not working when i gave its own interface in the static route ???

thanks in advance

1 Accepted Solution

Accepted Solutions

CSCO10892433
Level 4
Level 4

Hi,shaila

When a layer3 packet is going to be sent out, the router must know the layer 2 header to encapsulate the Layer3 packet.In this case, it must know which dlci number (as well as other layer2 information) to encap the IP packet. If you only indicate a connected interface for the static route, and there are many dlci numbers on this interface, the router will not know which dlci number to use and thus gives you a encapsulation failure message.

On the other hand, if you indicate a next-hop address on the static route and there is a frame-relay map which maps a dlci number to this next-hop address , the router will know the exact dlci number to encapsulate the ip packet and the packet will be sent out successfully.

HTH

SSLIN

View solution in original post

4 Replies 4

CSCO10892433
Level 4
Level 4

Hi,shaila

When a layer3 packet is going to be sent out, the router must know the layer 2 header to encapsulate the Layer3 packet.In this case, it must know which dlci number (as well as other layer2 information) to encap the IP packet. If you only indicate a connected interface for the static route, and there are many dlci numbers on this interface, the router will not know which dlci number to use and thus gives you a encapsulation failure message.

On the other hand, if you indicate a next-hop address on the static route and there is a frame-relay map which maps a dlci number to this next-hop address , the router will know the exact dlci number to encapsulate the ip packet and the packet will be sent out successfully.

HTH

SSLIN

Thank u very much SSLIN i got it..

plz tell me 1 thing more if u have any idea regarding ipv6, actually i m not getting very much understanding of it, like i dont know if i m writing a ipv6 address how much prefix length to chose, wat r the limitations of prefix length in ipv6 and other such issues, can u plz refer me any site or document that addresses these issues and give me a firm starting for ipv6 ???

i will be thankful to u

thanks again in advance

*Shaila* did it work what CSCO adviced u?

What i wanted to mention is that when ur using a static route u need to put a netmask and not a wildcard...

so try it again with 20.0.0.0 255.255.255.0 serial0

ciao flash

no it was a typing mistake i know a subnet mask is used, wat CSCO told is correct coz u know that if i really had entered the mistaken static route router would not have accepted it

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