05-19-2010 04:12 PM - edited 03-04-2019 08:32 AM
Hy,
I have a 3725 router that i want to connect to another router on a fastethernet interface. Unfortunately i am out of fastethernet interfaces on my 3725 router, but i have a few serial interf. to spare. The other router has no serial interf free.
My solution was to interconnect the two routers via another router (a smaller c1721 with 2 serial and 2 fast interfaces avalable).
So the connections wil be as so: router c3725 - serial link -- router c1721 -- fastethernet link -- the other router (probably c3845).
Now my question is: can i configure the c1721 to forward all the traffic received from the serial interf. to the fastethernet interf., and vice-versa, without enabling the routing protocol??
Static routes are out of the question due to the complicate ip address design behind these routers.(I don't want to enable the routing protocol because the routing table is very large and i don't think that the small c1721 can handle it without introducing a significant delay).
thanks in advance.
Solved! Go to Solution.
05-20-2010 11:22 AM
Hi,
You can use bridging concept to acheive your goal. For example, consider the below topology,
R7-----------------R1-------------------R3
E0/1 F0/1 S2/2 S2/2
13.1.1.1/24 13.1.1.3/24
I have enabled CRB bridging on R1 and have both F0/1 and S2/2 on bridge-group 1. On R7 and R3, I have IRB enabled and have E0/1 of R7 and S2/2 of R3 on bridge-group 1. With this config, I can reach between E0/1 of R7 and S2/2 of R3.
Configs:
R1_Config:
========
!
no ip routing
!
bridge crb
!
interface FastEthernet0/1
no ip address
bridge-group 1
!
interface Serial2/2
no ip address
no ip directed-broadcast
no ip route-cache
serial restart-delay 0
bridge-group 1
!
bridge 1 protocol ieee
R3_Config:
========
!
ip cef
!
bridge irb
!
!
interface Serial2/2
no ip address
serial restart-delay 0
bridge-group 1
!
interface BVI1
ip address 13.1.1.3 255.255.255.0
!
bridge 1 protocol ieee
bridge 1 route ip
end
R7_Config:
========
!
ip cef
!
bridge irb
!
interface Ethernet0/1
no ip address
half-duplex
bridge-group 1
!
interface BVI1
ip address 13.1.1.1 255.255.255.0
!
bridge 1 protocol ieee
bridge 1 route ip
!
end
Please try the same and let us know if it solves your issue.
Regards,
Nagendra
05-20-2010 08:37 PM
Hi,
To my knowledge, number of prefix on routing table limitation depends on the memory installed. I guess 1721 supports upto 64 MB which is more than enough to handle 500 entries.
But you may have to take other factors (like volume of traffic/routing protocol/stability) into consideration while positioning 1721.
Regards,
Nagendra
05-19-2010 05:09 PM
policy route
interface serial 0
ip policy route-map testing
route-map testing
match ip address 10
set interface ethernet 0
access-list 10 perm any
05-20-2010 04:58 AM
hy r-godden thanks for your reply but it did't work (for what i needed - i wanted the c1721 router to act like a "media convertor" from serial to ethernet if this is even posible)
I think i will enable the routing protocol on the c1721. I don't have a general view of the c1721. Is a "500 entries routing table" a large routing table for the c1721??? can the router handle it??
05-20-2010 11:22 AM
Hi,
You can use bridging concept to acheive your goal. For example, consider the below topology,
R7-----------------R1-------------------R3
E0/1 F0/1 S2/2 S2/2
13.1.1.1/24 13.1.1.3/24
I have enabled CRB bridging on R1 and have both F0/1 and S2/2 on bridge-group 1. On R7 and R3, I have IRB enabled and have E0/1 of R7 and S2/2 of R3 on bridge-group 1. With this config, I can reach between E0/1 of R7 and S2/2 of R3.
Configs:
R1_Config:
========
!
no ip routing
!
bridge crb
!
interface FastEthernet0/1
no ip address
bridge-group 1
!
interface Serial2/2
no ip address
no ip directed-broadcast
no ip route-cache
serial restart-delay 0
bridge-group 1
!
bridge 1 protocol ieee
R3_Config:
========
!
ip cef
!
bridge irb
!
!
interface Serial2/2
no ip address
serial restart-delay 0
bridge-group 1
!
interface BVI1
ip address 13.1.1.3 255.255.255.0
!
bridge 1 protocol ieee
bridge 1 route ip
end
R7_Config:
========
!
ip cef
!
bridge irb
!
interface Ethernet0/1
no ip address
half-duplex
bridge-group 1
!
interface BVI1
ip address 13.1.1.1 255.255.255.0
!
bridge 1 protocol ieee
bridge 1 route ip
!
end
Please try the same and let us know if it solves your issue.
Regards,
Nagendra
05-20-2010 02:36 PM
hy naikumar,
IT WORKED!! thanks a lot.
regarding my last question (just curious): 500 entries in a routing table are too much for a c1721?? can this router handle it well (regarding the delay)??
05-20-2010 08:37 PM
Hi,
To my knowledge, number of prefix on routing table limitation depends on the memory installed. I guess 1721 supports upto 64 MB which is more than enough to handle 500 entries.
But you may have to take other factors (like volume of traffic/routing protocol/stability) into consideration while positioning 1721.
Regards,
Nagendra
05-21-2010 05:29 AM
aha ... I thought so... i was just curious for more opinions...
thank a lot again...
the solution presented by you above is just what i needed
best regards
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