08-23-2015 04:05 PM - edited 03-05-2019 02:08 AM
I was wondering if there is any support for virtual links in the IPv4 address family of OSPFv3. Has anyone seen it? I saw one article on Cisco's website that it isn't supported, but maybe it's an old article? Has anyone been able to make VL's work in this scenario?
http://www.cisco.com/en/US/docs/ios-xml/ios/ipv6/configuration/15-0sy/ip6-ospf.html
- Look at the Note under the OSPFv3 Virtual Links
Also, see below output. There is no option for virtual links!
PE1(config)#router ospfv3 1
PE1(config-router)#address-family ipv4
PE1(config-router-af)#area 1 ?
authentication Enable authentication
default-cost Set the summary default-cost of a NSSA/stub area
filter-list Filter networks between OSPFv3 areas
normal Specify a normal area type
nssa Specify a NSSA area
range Summarize routes matching address/mask (border routers only)
stub Specify a stub area
transit Use this router to transit data
08-23-2015 04:17 PM
Hi Tim,
Checked on my VIRL IOSv 15.5(3)M, no luck - the virtual link does not seem to be supported for IPv4 AF.
I am thinking whether there is some technical limitation that would actually prevent this virtual link from being established, or whether it is just a rarely-used feature for OSPFv3+IPv4 AF so Cisco didn't implement it. No firm ideas on this as of yet - I'll keep you posted if I have more details.
Best regards,
Peter
08-23-2015 04:19 PM
Hi Tim,
RFC5838 says:
OSPFv3 control packets sent over a virtual link are IPv6 packets and may traverse multiple hops. Therefore, there MUST be a global IPv6 address associated with the virtual link so that OSPFv3 control packets are forwarded correctly by the intermediate hops between virtual link endpoints. Although this requirement can be satisfied in IPv6 unicast AFs, it will not function in other AFs as there will not be a routable global IPv6 address or forwarding path. Therefore, virtual links are not supported in AFs other than IPv6 unicast.
So, it explains why it's not supported.
Thanks,
Mohammad
08-23-2015 06:12 PM
Thanks for the response. I was hoping that maybe creating an IPv6 VL would allow the IPv4 routes to be learned. But I tried earlier to create a virtual link on the IPv6 side, which I did successfully. However, that did not help my problem. I still could not learn the route from the area not connected to area 0. Thanks again.
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