[quagga-dev 3895] Re: BGP 'next-hop' attribute with IPv6 - ignored ?

Paul Jakma paul at clubi.ie
Fri Dec 9 11:59:57 GMT 2005

On Fri, 9 Dec 2005, Hajnalka Köntös wrote:

> The 'next-hop' attribute of quagga BGP using IPv6 seems to be 
> ignored in bgp updates and not to be synchronized with the linux 
> routing table. I use quagga 0.98.3. Is it a bug? Is this problem 
> resolved in newer versions?

Depends whether it is a bug.

> If I define a route map for a bgp neighbor containing a next-hop 
> statement with a custom global IPv6 address (not the default, 
> interface address), then bgp database shows the next-hop as the 
> interface global IPv6 address, and the neighbor quagga bgp router's 
> routing table shows the next-hop as the interface link-local IPv6 
> address.

Well, the calculated addresses are not going to show what next-hops 
will be due to route-maps.

> routerA: I would like to set the 'next-hop' attribute for this
> neighbor to 2001:6:6:6::173.

> routerA: /etc/quagga/bgpd.conf:
> neighbor 2001:6:6:6::1 update-source 2001:6:6:6::172
> neighbor 2001:6:6:6::1 route-map set-nexthop out
> ! exit-address-family
> !
> ipv6 access-list all permit any
> !
> route-map set-nexthop permit 10
> match ipv6 address all

Just remove this line, then it matches everything.

> set ipv6 next-hop global 2001:6:6:6::173     <--- ignored in the bgp updates
> set ipv6 next-hop local fe80::ccc:ccc    <--- ignored in the bgp updates
> set ip next-hop

If the route went through and matched this route-map entry, then yes 
weird, and the questions would be:

- what went on the wire?
- is it a problem with 'ipv6 next-hop' on the speaker, or accepting
   next-hops on the receiver?

Also, why are you setting an IPv4 NEXT_HOP?

> Nexthop global: 2001:6:6:6::172        <----- interface address, not
> the configured value
> Nexthop local: fe80::20c:29ff:fe68:27ec <----- interface address, not
> the configured value

This seems correct. You are expecting it to show the values which 
would result from route-map manipulation, which is not possible to 

>   Network          Next Hop            Metric LocPrf Weight Path
> *>i2001:66:66:66::/64   2001:6:6:6::172          0    100      0 ?
> ...  <----- The next hop here is the neighbor's inteface global IPv6
> address, not the configured value

Hmm. Could be a bug, maybe. What was sent on the wire?

Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Many are cold, but few are frozen.

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