Allow_As, as-verride, SOO,bgp-backdoor

Hi,
Can any body pls share the above attribute usefullness & where we need/should to use the attirbute.
Pls share practival example.
Br/Subhojit

Hi Geert,
According to what i have read in CCIE Professional Development Routing TCPIP, Volume TWO.
The address specified by the network backboor command is not advertised to EBGP peers.

Similar Messages

BGP backdoor link

Dear Team,
Can u explain how does bgp backdoor link will work ,
Scenario :
Two customer sites connected different PE
CE1>>>PE1(mpls core )PE2>>>CE2 this CE 1 and CE2 have back to back connectivity with Eigrp , how does the loop avoidance happens here

Hello.
If CE-PE protocol is eBGP., then ISP would be using SOO as loop-prevention mechanism.
Also, if you have same AS for both CE-PE links, then your CE would prevent the prefix to be learnt due to self AS been found in AS-path.
PS: I hope this answers your question about loop-prevention mechanism on ISP side; If you have a question about CE network, then additional information needed - what is advertised via each links, what is routing policy (active/active or active/backup), what link is primary (MPLS or backdoor) and etc.

BGP BACKDOOR

From the documentation that i have read concerning bgp backdoor, i assume that a network marked as backdoor is NOT advertised:
network x.x.x.x backdoor
-> if network x.x.x.x is received from eBGP, its admin distance is changed to 200, to prefer an IGP learned network. However, network x.x.x.x is not advertised to BGP peers by this command, even if x.x.x.x has an exact match in our routing table. Correct ?
But what will happen in the following situation:
router eigrp 1
network x.x.x.x
router bgp 65000
network x.x.x.x backdoor
redistribute eigrp 1
neighbor y.y.y.y remote-as 65100
Will network x.x.x.x be advertised to AS65100 by the redistribute command ?? Or will the backdoor command prevent this ?? Will the backdoor command only work on received routes from AS65100 ???
Can someone shed some light on this ?? I am unable to test this in a lab at this time.
Regards,
Geert

Hi Geert,
According to what i have read in CCIE Professional Development Routing TCPIP, Volume TWO.
The address specified by the network backboor command is not advertised to EBGP peers.

JMS Routing over two AS Nodes

Hi,
Is it possible to have a single JMS/AQ point in front of a ACTIVE-ACTIVE AS cluster that routes to a single JMS inbound node?
Suppose you have two servers with an OC4J instance on each AS. You have a Cache objects running on each OC4J instance.
A single message is consumed , a MDB calls an EJB on each OC4J instance to check for instance presence in each cache. the JMS should be routed to the OC4J Node whose cache contains the instance.
Should it be feasible ??
how??
Please advise.
thanks
JO

The following document by Mr. Omar Santo should lead you on a correct path of Network salvation ;-)
https://supportforums.cisco.com/document/148471/what-bgp-backdoor-feature
Manish

Modifying iBGP distance for a Specific Prefix

Hi
I have scenario where I wish bgp backdoor could be used, but it can't in this case.
I have router learning a single prefix via EIGRP and iBGP. I would like it to prefer iBGP, but of course EIGRP wins due to distance (90).
I would like to modify a single prefix learned via iBGP to say 80 for example. So long as it wins over EIGRP.
I've researched few posts, but they point to eBGP. I would imagine the same could be acheived for iBGP. Has anyone done this and is there any other ways it can be acheived other than using ACL with distance command under BGP.
thank you

You may change the EIGRP AD for the specific prefix, as Julio outlines, it is probably best doing it this way than to play with BGP.
The way you can accomplish that is here:
R1 is advertising a connected network 1.1.1.0. There is an iBGP peering between R1 and R2. Also an EIGRP neighborship between them both. I want to influence R2's route to 1.1.1.0/24 to prefer iBGP (200) over eigrp (90).
Here is my current config and routes.
router eigrp 10
network 1.1.1.0 0.0.0.255
network 10.0.0.1 0.0.0.0
no auto-summary
router bgp 100
no synchronization
bgp router-id 10.0.0.1
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.0
neighbor 10.0.0.2 remote-as 100
no auto-summary
Rack1R2
router eigrp 10
network 10.0.0.2 0.0.0.0
no auto-summary
router bgp 100
no synchronization
bgp router-id 10.0.0.2
bgp log-neighbor-changes
neighbor 10.0.0.1 remote-as 100
no auto-summary
Rack1R2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
D 1.1.1.0 [90/409600] via 10.0.0.1, 00:06:30, FastEthernet0/0
10.0.0.0/30 is subnetted, 1 subnets
C 10.0.0.0 is directly connected, FastEthernet0/0
Rack1R2#
Rack1R2#show ip bgp
BGP table version is 4, local router ID is 10.0.0.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
r>i1.1.1.0/24 10.0.0.1 0 100 0 i
Rack1R2#
Now to modify the AD for the particular prefix in EIGRP.
Rack1R2(config)#router eigrp 10
Rack1R2(config-router)#distance ?
<1-255> Administrative distance
eigrp IP-EIGRP distance
Rack1R2(config-router)#distance 201 ? -Make it worse that iBGP
A.B.C.D IP Source address
Rack1R2(config-router)#distance 201 10.0.0.1 ? - Where you are learning the route from
A.B.C.D Wildcard bits
Rack1R2(config-router)#distance 201 10.0.0.1 0.0.0.0 1 - Followed by an ACL to match the prefix
Rack1R2(config)#ip access-list standard 1
Rack1R2(config-std-nacl)#permit 1.1.1.0
Rack1R2(config-std-nacl)#exit
Rack1R2(config)#
For me, it took effect immediately, but you may need to clear ip route x.x.x.x (i've experienced this before)
Rack1R2(config)#do show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [200/0] via 10.0.0.1, 00:03:28
10.0.0.0/30 is subnetted, 1 subnets
C 10.0.0.0 is directly connected, FastEthernet0/0
Now it has changed to prefer the iBGP route. Please take extra caution as doing this even with IGPs generally can cause routing loops.
hth.

Routing over LAN

I have two sites that each have a router and switching. I am going to connect these two sites through a fiber connection. The one subnet is 10.110.46.0/24 and the other site is 10.110.145.0/24.
Each router has a MPLS connection back to the corporate office that is using BGP to route. Since these sites will be able to connect via fiber I would like to route them over the LAN and not the wan.
Do I need to create a new interface on each router. So on the 10.110.145.254 router do I need to create a 10.110.46.X interface. And on the 10.110.46.254 router do I need to create a 10.110.145.x interface?
Once these are created as directly connected routes should they sites start talking to each other over the LAN as opposed to the WAN?
Also, all the switches live in the same VTP domain.
Thanks

The following document by Mr. Omar Santo should lead you on a correct path of Network salvation ;-)
https://supportforums.cisco.com/document/148471/what-bgp-backdoor-feature
Manish

BGP IPV4 soo community

Hi Guys ,
how can i configure bgp soo community in IPV4 network enviorment ? i have BGP IPv4 running in my network . no vrf's no vpnv4 bgp.. Simple IPv4 BGP with some IBGP and EBGP peers.i wanna advertise a network with soo community . how could i do this. any ideas please. and how can i verify that soo community is being advertised ..
here is what i tried.
address-family ipv4
neighbor x.x.x.x activate
neighbor x.x.x.x send-community both
neighbor x.x.x.x next-hop-self
neighbor x.x.x.x activate
neighbor x.x.x.x send-community both
neighbor x.x.x.x route-map med out
no auto-summary
network 10.1.75.0 mask 255.255.255.0 route-map extendcom
exit-address-family
route-map extendcom permit 30
set extcommunity soo 1001:1001
regards
amit

hello Amit,
see the answers in WAN ... forum
Best Regards
Giuseppe

SOO Site of origin!!... Clarification please!!

Hello to all, I'm having problems in understanding how bgp choose one route and discard other based in its SOO, for example
suppose this example
look at the network diagram in the link:
Figure 1 Network Diagram for SoO Example
(BGP per Neighbor SoO Configuration)
http://www.cisco.com/en/US/partner/products/ps6441/products_feature_guide09186a0080783eac.html
For my example I will tag the ingress router on PE1 from CPE1 with soo 65000:1, and I will tag again the ingress on PE2 from CPE2 with the same soo 65000:1, obvious that I'm using as-overide in this example....
My question is, suposse we are analising PE2, and from the left receive the routes of CPE2 tagged with soo through IGP and from EGP is receiving the routes directly from CPE2 tagged with the same soo... so the question is, because of the same SOO the PE2 have to choose a network path and discard other, how is the selection process, the PE2 look first at soo and after that makes a decision on external internal protocol or how is the algorithm in the decision for discarting, sorry if it seems banal, but I undertand the soo but I don't understand if we have two same soo network how to choose one and discard other?....
Best Regards!

Marcelo, neither PE1 or PE2 discards any route. The BGP decision making is also not altered, so when in the same example PE2 receives routes from PE1 with SOO tag, it runs the best path selection on the routes as usual, ignoring the SOO, when it receives these updates, now after receiving when it has to send these updates out that is when the SOO is helpful. So PE2 observes that his neighbor also has the same SOO tag, so he does not send those routes out to that neighbor. But PE2 very much has those routes in the BGP table.
One simple example why these routes are kept in the BGP table and not discarded is, on the same PE2 these may be CE3 also connected. But CE3 may not have a backdoor to CE1 or CE2, in that case the PE2 needs the routes so it can give it to CE3 which is not configured with the same SOO.
So its very much neighbor/site dependent, even if the neighbor(CE2) doesnt have a route still the PE2 will not send anything received from CE1/PE1.
So if implementing SOO, its as good as mandatory to have a IBGP mesh between your sites where you configure SOO.
HTH-Cheers,
Swaroop

BGP Selection .. Why Path #2 is better ! ?

I have a question please. For below output why 2nd output is considered best
According to my topology this is the right behavior however I am just curious why it is considered the best
Many Thanks
||||||||||||||
R9#show ip bgp vpnv4 vrf ABC 172.9.0.5
BGP routing table entry for 1009:9:172.9.0.5/32, version 142
Paths: (2 available, best #2, table ABC, RIB-failure(17) - next-hop mismatch)
Not advertised to any peer
Local
    172.9.195.15 from 0.0.0.0 (9.9.0.9)
      Origin incomplete, metric 2560077056, localpref 100, weight 32768, valid, sourced
      Extended Community: SoO:109:109 RT:1009:9
        Cost:pre-bestpath:129:2560077056 (default+412593409) 0x8800:0:9
        0x8801:100:77056 0x8802:259:2560000000 0x8803:257:1
        0x8804:1009:2886270986 0x8805:9:0
      mpls labels in/out 31/nolabel
9, imported path from 9:9:172.9.0.5/32
    9.9.0.8 (metric 30) from 9.9.0.8 (9.9.0.8)
      Origin IGP, metric 4125934090, localpref 100, valid, internal, best
      Extended Community: RT:9:9 OSPF DOMAIN ID:0x0005:0x0000006D0200
        OSPF RT:0.0.0.0:2:0 OSPF ROUTER ID:172.9.0.5:36783
      mpls labels in/out 31/62
R9#

The BGP cost community modifies the BGP path selection process.
the "pre-bestpath" point of insertion was introduced in the BGP Cost Community feature. This POI is applied automatically to EIGRP routes that are redistributed into BGP and carries the EIGRP route type and metric. This POI influences the best path calculation process by influencing BGP to consider this POI before any other comparison step effectivefly forcing BGP to use IGP-like selection rules.
https://supportforums.cisco.com/document/58226/dual-ce-pe-connection-and-eigrp
http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/s_bgpcc.html
http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.html#custom
Best Regards,
Bheem

Backdoor routes

We are starting a conversion of a rather large network from atm/frame to mpls. We will be managing the ce routers and talk bgp to the pe routers. Our current network is eigrp. We will have quite a few backdoor links in the network. Some will be backup only and not carry normal traffic, others such as the backdoor links between our data centers will be the primary path between the sites.
My question is what is the best way to handle the backdoor links. We are looking at:
1)running bgp on the backdoor links also and ibgp between the routers for the backdoor and the ce router.
2)running eigrp on the backdoor but under a seperate eigrp as number and redistributing into the primary eigrp as.
Both have their pros and cons. I was wondering which way other organization have gone and why.

Hello,
my 2 cents on the subject.
I haven´t been involved with a customer in the situation you are. So those are some thoughts on the subject not backed up by experience.
First, you need mutual redistribution BGP<->EIGRP on all CE routers.
Second, as EIGRP will always prefer internal routes over external ones, you need another protocol on the backdoor links, which should be really backdoor.
This said I would first select the links, which really shall be backup to the MPLS network. All other (prefered) links should be running EIGRP with main AS to reduce complexity.
So lets first look at the "MPLS is backup" scenario. You will have the same networks on the CE learned through EIGRP and eBGP. The latter having AD=20 is prefered, which is undesired in this case. Setting eBGP to AD=150 could fix this. Additionally you need to tag the EIGRP networks learned from BGP with a site specific tag, which would allow to exclude them from redistribution back into BGP once they are announced through EIGRP to another CE.
Generally a tag should indicate that this network was already passed through the MPLS VPN and thus MUST not be redistributed again.
Now lets have a look at the "MPLS is primary" scenario. As you already stated you need another routing protocol/EIGRP AS in this case. On the CE this would still work, because external EIGRP with AD=170 is worse than (modified) AD=150 of BGP.
What remains is again to set proper filters to avoid routing loops most likely again with tags and route-maps for scalability.
With all this mutual redistribution it is clear, that any mistake in configuration or design of the filters will result in a routing loop.
The other option would be BGP everywhere. Be aware however, that this will most likely not remove the redistribution and filter complexity.
What I do not quite understand is, how the physical design looks like, i.e. where you have BGP routers and where EIGRP (main AS). In case you don´t want to black hole yourself, you need to redistribute back into EIGRP in any case, or run an iBGP full mesh on most of your internal routers.
So in the end you have a lot of complexity in both solutions. Both of them can be implemented. From an operation point of view I would say, that my tendency would be towards EIGRP instead of BGP. But just because your staff might know the latter good enough to operate the whole thing without too much pain.
Looking from a distance:
1) Have you pushed the SP hard enough (=$$ ?) to allow EIGRP on the PE-CE link? This would simplify the whole situation.
2) Have you thought of pushing the SP into OSPF on PE-CE and convert everything to OSPF internally? This would also simplify things. OSPF is better prepared to handle routing loops in MPLS VPNs and also sham links allow for having backdoor links, when required.
Hope this helps! PLease rate all posts.
Regards, Martin

Configuring BGP and OSPF to BGP always prefer.

Hi,
I´m configuring a VPNv4 between two sites. In principal site I receive some prefixes through OSPF and in the backup site the same prefixes through OSPF. I´m redistributing OSPF routes through BGP to backup site.
In summary, in backup site the ASR9K receives the same prefixes through OSPF (local) and BGP but ASR must prefer BGP routes
instead of OSPF.
How can I configure it?.
Thanks.

Hi Jaime,
a L3 network topology would possibly help to understand your goals and challenges. In general, in scenarios with OSPF and VPNv4 there's a challenge, that OSPF prefixes will be preferred indeed, if the two sites have a backdoor link. To overcome this, there's a feature in OSPF called 'sham-link', which makes the prefixes learned across the backbone(and hence via MP-BGP) more prefrred.
HTH,
Ivan.

SoO and eBGP

SoO is used to prevent a route from being readvertised back to the site from which it originated...
but in following case when eBGP is the PE/CE routing protocol, PE3 will prefer the eBGP route from CE-2 instead of iBGP route from PE1 or PE2 unless routing loop is intentionally created by preferring the iBGP route through weight or other attributes....
so when does the SoO comes into play with eBGP....

Hi,
SoO is required with BGP when you also configured as-override. In this case the AS PATH can't be used anymore to detect loop so you need something else to identify from where this path is coming from.
In usual case, PE3 will send the update to CE2 which will drop it as it sees its own AS in the AS-PATH. With as-override, CE2 is not seeing its own AS anymore.
PE3 will still prefer its eBGP route from CE2 regardless if you configured SoO or not.
HTH
Laurent.

Hi apple team.. Am really disappointed by the performance of iOS7.. First of all the UI is soo cartoonish as a high school students have designed it..

Hi apple team.. Am really disappointed by the performance of iOS7.. First of all the UI is soo cartoonish as a high school students have designed it.. Secondly after upgrading my phone started to lag badly.. All my frnds r facing same problm.. Plz release a fix for this or let me knw how to downgrade to iOS6 i was very happy with that.. Even while typing this msg the keyboard is lagging badly.. Plz help..

Sorry, Apple has no approved method to downgrade the version of iOS on your iDevice. You can voice your displeasure with the iOS by leaving feedback at the appropriate subsection from the link below.
http://www.apple.com/feedback/

I am soo unhappy! Everyday I'm discovering what I cannot do on my iPhone 5s! Since September 20, I purchased the new 5s

I am soo unhappy! Everyday I am discovering what I cannot do on my iPhone 5s! Since September 20, I purchased the new 5s and iPad mini with Wi-fi and I have had nothing but trouble. I cannot use my iPad, it is worthless! My old iPad 3 worked better which I traded it in for. I cannot get Wi-fi to work properly on either device. I have to be standing next to my router for it to work. My router works fine and worked fine with my old iPad 3. The list is endless...... I am on my 3rd replacement for iPhone and still experiencing problems.
-Facetime just starts without me promting it
-I have almost every call I make drop
-Siri does not register with my voice, very frustrating!
-I have a new car and the 5s will not let me use my console phonebook favorites shortcuts
-I cannot attach a photo from a relpy or an email for that matter. WTH??? Why??
-I cannot scroll to the bottom of a page without playing "spin the wheel" and have the pop up screen come up and then accidentally hit private mode then miss phone calls. But I can scroll to the top with a couple of tries. I have small fingers so why is this so user unfriendly?
-My cellular connection notice keeps coming on? Why? Both on iPhone iPad
-My Wi-fi does not work I have to be standing next to my router for it to work for both my iPhone 5s and iPad mini. My router works fine and worked fine with my old iPad 3.
-My icloud is not saving my new phone numbers so each time I have received a new phone numbers get LOST!
- I now cannot look anything up while on the phone AND NO ONE TOLD ME THIS BEFORE I PURCHASED THIS PHONE! I really have needed it through all the time I have been on the phone with either Apple or Sprint! A total of of at least 40hours and I am not exaggerating!
-I have to switch to too many pages to write emails, texts or even phone calls! Not as easy as 1,2,3. WHY?
-Merging on iCloud can erase numbers be careful! What a nice option I thought. As my Android/Gmail basically threw up on my new iPhone. So I had multiple contacts of the same person. E.G. 5 Joe Smoo. All listed separately, one was an email,2nd was FB, 3rd Home phone, 4th cell and 5th fax or listed as other. Well, if someone has 2 cell phones or emails and you merge then iCloud takes the privilege of ERASING one of the 3s or contacts. Also, some of them were listed as other and that too got ERASED. Thank you iCloud! I only discovered this after merging at least 20 contacts because I was told I had to to manually go into my phonebook to try and fix the quadruplet or more names on my phonebook.
-There is more believe me! BTW I have been pretty dedicated to Apple (macbook, iMac and iPad), only I had an Android phone because my carrier didn't have iPhone & I did not want AT&T. This is turning me into sour grapes or should I say apples!!!!!!!!!!!!!!!!!
Please respond if you have similar problems or any because no one else seems to be experiencing such problems as I have. If you are an Apple employee then please have someone contact me.

Dude or hot-spur,
Not fishy at all!!!! You really think I would have taken any more of my time to post a bogus rant? We'll no, it is unfortunately all true. I want to hear from anyone who is experiencing such problems not anyone else that wants to put there two cents in. I really don't need anymore hate or negativity. Just people's experiences because I feel like I am the only one having so many problems. Thank you
Yes, I have had some unfortunate bad luck to have so many problems at the same time, but some of them are just things you cannot do on the new OS.
Thank you again

Multi-Instance BGP

BGP Multi-instance was supposed to be released in XR 4.2, I could not find any mention of it in the Release notes for 4.2, 4.3, & 5.1?
How do I find out if it was implemented and if so how to configure it, if not if it is still on the road map?
Thanks,
John

Hello,
It is in release note XR .4.2:
http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.2/general/release/notes/reln_a9k_42.html
And some writing on Cisco doc:
http://www.cisco.com/en/US/docs/routers/crs/software/crs_r4.2/routing/configuration/guide/b_routing_cg42crs_chapter_01.html#concept_E6B1D3D6B8CA4742AED837B3A94E826F
Below is the example what i did in my lab running 4.2.3:
RP/0/RSP1/CPU0:ASR-9006-01#show run router bgp
Fri Jan 31 21:05:02.170 UTC
router bgp 1 instance IPV4
bgp router-id 72.15.48.5
bgp graceful-restart
ibgp policy out enforce-modifications
address-family ipv4 unicast
redistribute connected
allocate-label all
address-family vpnv4 unicast
retain route-target all
neighbor 172.16.8.3
remote-as 1
update-source Loopback0
address-family ipv4 labeled-unicast
route-policy PASS in
route-policy PASS out
router bgp 1 instance IPV6
bgp router-id 99.2.3.4
address-family ipv6 unicast
redistribute connected
thanks,
rivalino

Allow_As, as-verride, SOO,bgp-backdoor

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