06-23-2006 03:20 PM - edited 03-03-2019 01:06 PM
Hello,
I've a Cisco 3600 series router connected to two ISP via BGP. One being over satellite and the other through fiber. This is how the BGP config looks:
router bgp 100
bgp log-neighbor-changes
network 192.168.48.0
network 192.168.48.0 mask 255.255.240.0
aggregate-address 192.168.48.0 255.255.240.0 summary-only
neighbor 172.16.39.3 remote-as 200
neighbor 172.16.39.3 description Satellite BGP connection 2
neighbor 172.16.39.3 ebgp-multihop 10
neighbor 172.16.39.3 weight 100
neighbor 172.16.39.4 remote-as 200
neighbor 172.16.39.4 description Satellite BGP connection
neighbor 172.16.39.4 ebgp-multihop 10
neighbor 172.16.39.4 weight 100
neighbor 10.111.207.173 remote-as 300
neighbor 10.111.207.173 description Fiber BGP connection
neighbor 10.111.207.173 weight 200
Now the problem is even with the weight set to 200, downstream data is mostly comming (about 90%) comming through the satellite downlink. But I want to have
1. both the upload and download come through the fiber link first,
2. if fiber congested then load share with satellite
3. if fiber fails, switch to satellite.
Please suggest how to achieve the above.
Thanks in advance.
06-23-2006 09:36 PM
1. both the upload and download come through the fiber link first,
A1-you need to set high local preference updates coming in and lower med updates going out from fiber link.
A2- You can use route-map and set AS prepend to make a path connected to satelite as backup say for example
neighbor 172.16.39.3 remote-as 200 route-map foo out
!--- It appends AS 100 to the BGP updates sent to AS 400
!--- in order to make it a backup for the ISP-A to R1 path.
!
access-list 1 permit x.x.x.x
route-map foo permit 10
match ip address 1
set as-path prepend 100 100
2. if fiber congested then load share with satellite
A1- possible by running HSRP but in ur case you have only one router.
3. if fiber fails, switch to satellite.
by default it will happen if you have peership from both the link.
06-24-2006 12:38 AM
The weight configuration is to modify your inbound routing update, this will only affect your uplink traffic. To affect your downlink traffic, you need to modify your outbound routing update. With BGP, there 2 ways to do this, either using MED or using AS path prepend.
MED works only if both paths are to the same AS. AS path prepend is often the preferred option. A common question is how many number of AS number should be appended. You will need to monitor this, and change the number till you see a desired utilisation levels on your link.
Check the following link
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
2. To achieve this, consider running OER, Optimised Edge Routing. Check the following link.
http://www.cisco.com/en/US/netsol/ns471/networking_solutions_package.html
3. The former BGP configs will hsve achieved this.
06-24-2006 03:48 PM
Thank you Kamlesh and Olorunloba. I have used AS path prepend and achived about 33% of the traffic to come through the fiber link and the rest is still coming through the satellite. Also I have set local preference of 1000 to the fiber and 50 to the satellite inbound. Syncronization is on.
This is the new configuration:
router bgp 100
bgp log-neighbor-changes
network 192.168.48.0
network 192.168.48.0 mask 255.255.240.0
aggregate-address 192.168.48.0 255.255.240.0 summary-only
neighbor 172.16.39.3 remote-as 200
neighbor 172.16.39.3 description satellite BGP connection 2
neighbor 172.16.39.3 ebgp-multihop 10
neighbor 172.16.39.3 weight 100
neighbor 172.16.39.3 route-map satellite-in in
neighbor 172.16.39.3 route-map foo out
neighbor 172.16.39.4 remote-as 200
neighbor 172.16.39.4 description satellite BGP connection
neighbor 172.16.39.4 ebgp-multihop 10
neighbor 172.16.39.4 weight 100
no neighbor 172.16.39.4 activate
neighbor 10.111.207.173 remote-as 300
neighbor 10.111.207.173 description fiber BGP connection
neighbor 10.111.207.173 weight 200
neighbor 10.111.207.173 route-map fiber-in in
maximum-paths 4
!
route-map satellite-in permit 10
set local-preference 50
!
route-map fiber-in permit 10
set local-preference 1000
!
route-map foo permit 10
set as-path prepend 100 100 100 100 100 100 100 100 100 100
This the BGP trace from APNIC site:
From Brisbane:
Brisbane Local time [Sun Jun 25 09:34:22 2006]
BGP routing table entry for 202.92.48.0/20, version 23915362
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Not advertised to any peer
1221 4637 3356 200 100 100 100 100 100 100 100 100 100 100 100, (aggregated by 100 10.111.207.174)
203.14.8.16 (metric 2) from 203.14.8.16 (203.14.8.16)
Origin IGP, localpref 80, valid, external, atomic-aggregate
Dampinfo: penalty 192, flapped 3 times in 00:44:51
1221 4637 3356 200 100 100 100 100 100 100 100 100 100 100 100, (aggregated by 100 10.111.207.174)
202.12.29.79 (metric 2) from 202.12.29.79 (202.12.29.79)
Origin IGP, metric 0, localpref 500, valid, internal, atomic-aggregate, best
From Tokyo:
Brisbane Local time [Sun Jun 25 09:36:15 2006]
BGP routing table entry for 202.92.48.0/20, version 2540172
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
193.0.4.28 202.12.29.64 202.249.2.143 202.249.2.166
2497 6453 200 100 100 100 100 100 100 100 100 100 100 100, (aggregated by 100 10.111.207.174)
202.249.2.169 from 202.249.2.169 (202.232.1.98)
Origin IGP, localpref 100, valid, external, atomic-aggregate
2516 1239 702 702 300 100, (aggregated by 100 10.111.207.174)
202.249.2.110 from 202.249.2.110 (203.181.99.231)
Origin IGP, localpref 100, valid, external, atomic-aggregate, best
By the way I've IOS Version 12.1(5)T7, so no OER support.
Please suggest what should I do.
Thanks.
06-24-2006 09:30 PM
can you put your show ip bgp output so that we will be able to help you well.
i think you are done with your config.
As in your output given above shows from brisbon it is reachable via AS 200 but from tokyo it reachable via As 300.
this time your all the traffic should go to fiber link and coming from both the link just check.
please rate if helps
Kamlesh
06-25-2006 08:08 AM
Below are the results of ip bgp and neighbors
#sh ip bgp
BGP table version is 28, local router ID is 10.111.207.174
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 0.0.0.0 10.111.207.173 1000 200 300 702 i
* 172.16.39.3 50 100 200 i
s> 192.168.48.0 0.0.0.0 0 32768 i
*> 192.168.48.0/20 0.0.0.0 32768 i
#sh ip bgp neighbors 172.16.39.3
core-danl#sh ip bgp neighbors 172.16.39.3
BGP neighbor is 172.16.39.3, remote AS 200, external link
Description: satellite BGP connection 2
BGP version 4, remote router ID 172.16.39.3
BGP state = Established, up for 05:55:13
Last read 00:00:14, hold time is 180, keepalive interval is 60 seconds
Neighbor capabilities:
Route refresh: advertised and received(new)
Address family IPv4 Unicast: advertised and received
Received 1372 messages, 0 notifications, 0 in queue
Sent 1427 messages, 1 notifications, 0 in queue
Route refresh request: received 0, sent 8
Default minimum time between advertisement runs is 30 seconds
Default weight 100
For address family: IPv4 Unicast
BGP table version 28, neighbor version 28
Index 1, Offset 0, Mask 0x2
Inbound path policy configured
Outbound path policy configured
Route map for incoming advertisements is satellite-in
Route map for outgoing advertisements is foo
1 accepted prefixes consume 36 bytes
Prefix advertised 5, suppressed 0, withdrawn 1
Number of NLRIs in the update sent: max 1, min 0
Connections established 5; dropped 4
Last reset 11:53:04, due to Neighbor deleted
External BGP neighbor may be up to 10 hops away.
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Local host: 192.168.48.129, Local port: 179
Foreign host: 172.16.39.3, Foreign port: 48164
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x1A2D70A4):
Timer Starts Wakeups Next
Retrans 383 20 0x0
TimeWait 0 0 0x0
AckHold 361 177 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
iss: 93155242 snduna: 93162430 sndnxt: 93162430 sndwnd: 16384
irs: 3203800665 rcvnxt: 3203807597 rcvwnd: 16061 delrcvwnd: 323
SRTT: 709 ms, RTTO: 957 ms, RTV: 248 ms, KRTT: 0 ms
minRTT: 524 ms, maxRTT: 1068 ms, ACK hold: 200 ms
Flags: passive open, nagle, gen tcbs
Datagrams (max data segment is 536 bytes):
Rcvd: 731 (out of order: 0), with data: 361, total data bytes: 6931
Sent: 553 (retransmit: 20), with data: 362, total data bytes: 7187
06-25-2006 08:08 AM
#sh ip bgp neighbors 10.111.207.173
BGP neighbor is 10.111.207.173, remote AS 300, external link
Description: fiber BGP connection
BGP version 4, remote router ID 10.111.195.214
BGP state = Established, up for 00:15:50
Last read 00:00:09, hold time is 30, keepalive interval is 10 seconds
Neighbor capabilities:
Route refresh: advertised and received(new)
Address family IPv4 Unicast: advertised and received
Received 43895 messages, 5 notifications, 0 in queue
Sent 43947 messages, 14 notifications, 0 in queue
Route refresh request: received 0, sent 10
Default minimum time between advertisement runs is 30 seconds
Default weight 200
For address family: IPv4 Unicast
BGP table version 28, neighbor version 28
Index 2, Offset 0, Mask 0x4
Inbound path policy configured
Route map for incoming advertisements is fiber-in
1 accepted prefixes consume 36 bytes
Prefix advertised 58, suppressed 0, withdrawn 28
Number of NLRIs in the update sent: max 1, min 0
Connections established 24; dropped 23
Last reset 00:16:35, due to BGP Notification sent, hold time expired
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Local host: 10.111.207.174, Local port: 11045
Foreign host: 10.111.207.173, Foreign port: 179
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x1A2F1DDC):
Timer Starts Wakeups Next
Retrans 121 20 0x0
TimeWait 0 0 0x0
AckHold 100 42 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
iss: 2861998644 snduna: 2862000658 sndnxt: 2862000677 sndwnd: 15833
irs: 1678389569 rcvnxt: 1678391540 rcvwnd: 15909 delrcvwnd: 494
SRTT: 509 ms, RTTO: 1816 ms, RTV: 1307 ms, KRTT: 0 ms
minRTT: 0 ms, maxRTT: 1496 ms, ACK hold: 200 ms
Flags: higher precedence, nagle
Datagrams (max data segment is 1460 bytes):
Rcvd: 206 (out of order: 0), with data: 101, total data bytes: 1970
Sent: 167 (retransmit: 20), with data: 101, total data bytes: 2032
Thanks.
06-25-2006 06:56 AM
[quote]
neighbor 10.111.207.173 remote-as 300
neighbor 10.111.207.173 description fiber BGP connection
neighbor 10.111.207.173 weight 200
neighbor 10.111.207.173 route-map fiber-in in
[/quote]
You are missing 'ebgp-multihop' for this neighbor.
06-26-2006 12:36 AM
Is this BGP negihbour 172.16.39.4 up?.
You have two neighbours in As 200 i.e. 172.16.39.3 and 172.16.39.4. You however are prepending to 172.16.39.3 and not to 172.16.39.4. Depending on the setup of As 200, your prepending might not have the full desired result. Apply the foo route-map also to 172.16.39.4, and check again what your utilisation is.
06-26-2006 09:29 AM
Your all the traffic is going outside via fiber link only as default route is best and installed in routing table but i wondered why it is showing only 702 i AS no i suppose you have connectivity to MCI international. but if you have another ip block from VSNL or from other service provider your traffic for that ip block will always come from there link until and unless your link goes down conected to that provider. next i would like to know what traffic is coming in and what traffic is going out so that we can have broad view of traffic flow so that we will be able to differentiate what traffic should come froom where and where we need to have load balancing. waiting for ur input.
please rate if it helps
HTH
Kamlesh
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