Here is quick step to configure BGP multi-hop on Cisco CRS router.


CRS# conf t
CRS(config)# router bgp 65501

CRS(config-bgp)# neighbor
CRS(config-bgp-nbr)# remote-as 2000
CRS(config-bgp-nbr)# password <MD5 password>
CRS(config-bgp-nbr)# ebgp-multihop 2
CRS(config-bgp-nbr)# update-source loopback0
CRS(config-bgp-nbr)# address-family ipv4 unicast
CRS(config-bgp-nbr-af)# route-policy xxxxx in
CRS(config-bgp-nbr-af)# exit

CRS(config)#router static
CRS(config-static)#address-family ipv4 unicast
CRS(config-static-afi)# TenGigE0/1


Here is sample BGP configuration for Cisco CRS router with XR software


Cisco CRS# conf t
Cisco CRS(config)#
router bgp 65501

Cisco CRS(config-bgp)# neighbor
Cisco CRS(config-bgp-nbr)# remote-as 2000
Cisco CRS(config-bgp-nbr)# description "CRS BGP sample"
Cisco CRS(config-bgp-nbr)# password xxxxx
Cisco CRS(config-bgp-nbr)# address-family ipv4 unicast
Cisco CRS(config-bgp-nbr-af)# route-policy xxxx in
Cisco CRS(config-bgp-nbr-af)# maximum-prefix 5000 75
Cisco CRS(config-bgp-nbr-af)# commit


Last Updated (Friday, 14 May 2010 21:44)

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We know how to change peer ASN without changing BGP processor ID which might be private ASN. That is local-as commands is the one to replace ASN for outside of world. However, your BGP peer keep on sending private ASN or current BGP processor ID. Here is the magic command to fix it.

"neighbor x.x.x.x local-as yyy no-prepend replace-as"

From below example, we will use ASN 100 on R1 to peer with R5. After configured R1, we got following output.



Last Updated (Monday, 10 May 2010 15:11)

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This is the one of famous question my customers asking all the time. How to configure secure BGP? There are few ways to make robust BGP session. Keep it in your mind, ISP doesn't provide all below commands (Don't wasting time). They would configure MD5 hash for your link. 

1. Using MD5 password

MD5 setting is common and easy to implement.

Cisco_Router(config-router)#neighbor x.x.x.x password c1sc0


Last Updated (Monday, 21 September 2009 21:51)

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Most of the decent size of ISP provides BGP community string for their customer. By using icon_BGP.pngBGP community string, you can control our announcement globally and it instantly affects your inbound traffic. In these days, modifying backbone routing policy in ISP is common. They don't want to loose their customer's traffic, so they apply BGP attribute to customer's announcement to avoid those traffic is leaving their backbone.



Last Updated (Wednesday, 06 January 2010 14:41)

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