Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

APS and BGP

Hey Guys/Gals

I am installing a pair of 7600 for a customer and we are receiving at first a POS OC3 off a Sonet Ring. The issue (to me at least) is when we throw APS into the mix. The configs on the cisco web site have me a bit confused. This is the "simple Config" they list for Router A and Router B

Step 1 On router A, which contains the working interface, use the following configuration:

Router# configure terminal

Router(config)# interface loopback 1

Router(config-if)# ip address 7.7.7.7 255.255.255.0

Router(config)# exit

Router(config)# interface pos 2/0

Router(config-if)# aps working 1

router(config-if)# pos ais-shut

Router(config-if)# end

Router#

Step 2 On router B, which contains the protect interface, use the following configuration:

Router# configure terminal

Router(config)# interface loopback 2

Router(config-if)# ip address 7.7.7.6 255.255.255.0

Router(config)# exit

Router(config-if)# interface pos 3/0

Router(config-if)# aps protect 1 7.7.7.7

router(config-if)# pos ais-shut

Router(config-if)# end

Router#

Fine I could type all that but here are my questions, 1) Where is the tie in from the IP Stack on LoopBack 1's IP and the POS Interface? How does the Router A know to use that address and maybe not another Interfaces' IP Stack? or is it that the POS interface doesn't have or can't have an IP Stack on it? 2)Can I use This setup (once I understand the question #1) to setup BGP on this "Protected" and "Working" combo? Below is the link for the config above.

"http://www.cisco.com/en/US/customer/products/hw/routers/ps368/products_module_configuration_guide_chapter09186a008007cb49.html#1047749"

Felix

1 REPLY
Cisco Employee

Re: APS and BGP

Hi Felix,

I'm afraid they've done a dirty on you and not included all of the configuration.

They are missing:

-ip addresses on pos 2/0

-ip address on pos 3/0

-no keepalive on *both* pos 2/0 and 3/0

-aps group 1 on *both* pos 2/0 and 3/0

The ip address for the aps enabled interfaces are only required to be within the same subnet as each other. They may actually be the same address - a number of people do it this way for simplicity.

So, for question #1 - they must have an ip address for ip to work across those interfaces, and the routers will use the ip configured on the respective pos interface. The loopback ip addresses are used for the control communication between the working and protect routers and it is required that loopbacks be used.

For question #2, you may use BGP. If iBGP then you'll want to peer to the loopbacks anyway. If eBGP then you can either:

-use multihop to peer to the loopbacks which may prevent the session from dropping during an aps switch

-use regular eBGP to peer to the interface ip addresses - but then you will want to make sure that you are using the same ip address on both pos 2/0 and pos 3/0 so that your peering session will work once an aps switch has occured.

Hope this is helpful and sorry for the confusing information there. They were only trying to show what info you'd need to add to an already working set of interfaces in order to enable aps. However, I agree that this is a bit confusing.

-steve

216
Views
5
Helpful
1
Replies
CreatePlease to create content