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New Member

A Static Route pointing behind the next-hop?

Hi,

I want to insert a host-route into my routing table for redistribution to other routers. I only get a summary route from my next-hop-router.

Is there any possiblity to insert a static route which points not to my real next-hop.

eg. I get 10.1.0.0 via eBGP from two eBGP-neighbors (for redundancy)

and I want to propagate the host-route 10.1.1.1 to special iBGP-neighbors

I tried the following: ip route 10.1.1.1 255.255.255.255 10.1.0.0

-> but this static entry is not installed in my routing table and so I am not able to propagate the host route separately

Any solution would help me,

Thanks Chris

10 REPLIES
New Member

Re: A Static Route pointing behind the next-hop?

Is the next-hop 10.1.0.0 reachable from your IGP routing table?

and why you want to use the 10.1.0.0 subnet address as your next-hop?

New Member

Re: A Static Route pointing behind the next-hop?

The 10.1.0.0 is in the routingtable through bgp.

It would be possible to use any address as long as the address is within 10.1/16 (eg. 10.1.0.1)

(I also tried: ip route 10.1.1.1 255.255.255.255 10.1.0.1)

Regards Chris

Re: A Static Route pointing behind the next-hop?

You may also try ip route 10.1.1.1 255.255.255.255 eth 0/0 10.1.x.x

New Member

Re: A Static Route pointing behind the next-hop?

Seems the entry is possible with this syntax. The route is installed in the routing table. But if the eth0/0 does not go down, the entry still stays in the routing table even if the bgp-summary-route (10.1.x.x) is no longer available over this interface.

But I want to reach the situation that independent of the interface the host-route is as long used as long as there is a way to 10.1.0.1 (the route behind next-hop over the BGP-summary-entry). The route behind the next-hop could be now on any other interface where the eBGP-summary comes now, but the static entry does not reflect to this change.

Is there no way to make a static route pointing only to a BGP-summary route?

Regards Chris

PS: my situation

ip route 10.1.1.1 255.255.255.255 10.1.0.1

(10.1.0.1 is no next-hop of this router but should be reachable over a second routing-table lookup because there is an eBGP-summary-route in the routing table which this address would be part of)

-> 10.1.0.1 is in my routing table within 10.1.0.0/16 known over ebgp (over two pathes)

Re: A Static Route pointing behind the next-hop?

Firstly make sure that the summary 10.1.0.0 is in your RIB, make sure that CEF has a valid cached adjacency for the summary and the local static, cause CEF will just punt it out the interface that the summary was recieved from.

I did this under EIGRP with a summary route and a static pointing out the summary route, as long as the summary was there all went well..

Use the cef tools available like sh ip cef exact-route

E.G:

R1 routing table ( just the summary)

D 100.0.0.0/8 is a summary, 00:13:14, Null0

R2:

ip route 10.5.5.5 255.255.255.255 10.1.0.0

XLDNR2#sh ip rout 10.5.5.5

Routing entry for 10.5.5.5/32

Known via "static", distance 1, metric 0

Routing Descriptor Blocks:

* 10.1.0.0

Route metric is 0, traffic share count is 1

XLDNR2#sh ip rout 10.1.0.0

Routing entry for 10.1.0.0/16

Known via "eigrp 100", distance 90, metric 3072, type internal

Redistributing via eigrp 100

Last update from 10.1.10.1 on Vlan10, 00:13:01 ago

Routing Descriptor Blocks:

* 10.1.10.1, from 10.1.10.1, 00:13:01 ago, via Vlan10

Route metric is 3072, traffic share count is 1

Total delay is 20 microseconds, minimum bandwidth is 1000000 Kbit

Reliability 255/255, minimum MTU 1500 bytes

Loading 1/255, Hops 1

XLDNR2#ping 10.5.5.5

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.5.5.5, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

New Member

Re: A Static Route pointing behind the next-hop?

Hi,

this is exactly what I thought that it should function, but it does not want ;-))

I have the following test environment (I tried the test with 210.210.0.0/16 with host 210.210.210.210)

==================================

Router ASBR1 is the router where the summary is created and the host exits

Router_ASBR1#sh ip rou

C 210.210.210.210 is directly connected, Loopback333

S 210.210.0.0 255.255.0.0 is directly connected, Null0

==================================

Router ASBR2 is the router where the static should be installed and then redistributed but the host-route does not exist in the routing table

Router_ASBR2#sh run | incl ip route

ip route 210.210.210.210 255.255.255.255 210.210.0.1

Router_ASBR2#sh ip rou 210.210.210.210

Routing entry for 210.210.0.0 255.255.0.0, supernet

Known via "bgp 200", distance 20, metric 0

Tag 100, type external

Last update from 100.100.100.111 00:07:50 ago

Routing Descriptor Blocks:

* 100.100.100.111, from 100.100.100.111, 00:07:50 ago

Route metric is 0, traffic share count is 1

AS Hops 1

Router_ASBR2#sh ip cef exact-route 172.20.1.2 210.210.210.210

172.20.1.2 -> 210.210.210.210: FastEthernet0/0 (next hop 172.20.1.1)

The IP routing table does not show the static route.

Any suggestions what could be wrong?

Regards,

Chris

Re: A Static Route pointing behind the next-hop?

Have you configured ip classless.. if you look at your routing table on ASBR2 you gave a /16 entry, this is the longest match and as such the router will direct traffic toward that route VIA an iBGP path 100.100.100.111.

New Member

Re: A Static Route pointing behind the next-hop?

Hi,

"ip classless" is configured.

The packets are going through this longest-match but I do not have an active static route in ASBR2.

PS: it is eBGP the process is 200 the distance is 20 (Known via "bgp 200", distance 20).

Regards,

Chris

Re: A Static Route pointing behind the next-hop?

Okay back at office now..:)

Yip, sorry i was a tad confused.. me did mean eBGP, could you paste your config's here or mail them.

You have configured a static route acting as a summary, now this summary is being seen on ASBR2.

I would clear that route out 1st then clear teh cef entry, in the past i have experienced a lot of problems with CEF and the RIB not being consitant.

New Member

Re: A Static Route pointing behind the next-hop?

u have given wromge command

actual ur command is like

ip route 10.1.1.0 255.255.255.0 10.1.0.XXX

here xxx will be ur home addrees.

note : hope address is its gatway address

it can be 1) ur serial interface

2) ur dialer interface

3) ur remote router serial interface ip address

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