Posted on December 1, 2020 3:11 am
 |  Asked by saverio giuntini
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I’m testing RFC5549 on vEOS. BGP sessions are up and IPv4 NLRIs are installed in the FIB:

Leaf-2#sh ip route

VRF: default
Codes: C – connected, S – static, K – kernel,
O – OSPF, IA – OSPF inter area, E1 – OSPF external type 1,
E2 – OSPF external type 2, N1 – OSPF NSSA external type 1,
N2 – OSPF NSSA external type2, B – BGP, B I – iBGP, B E – eBGP,
R – RIP, I L1 – IS-IS level 1, I L2 – IS-IS level 2,
O3 – OSPFv3, A B – BGP Aggregate, A O – OSPF Summary,
NG – Nexthop Group Static Route, V – VXLAN Control Service,
DH – DHCP client installed default route, M – Martian,
DP – Dynamic Policy Route, L – VRF Leaked,
RC – Route Cache Route

Gateway of last resort:
B E [200/0]
via fe80::e25:ceff:fe37:aa5d, Ethernet1
via fe80::e25:ceff:fecb:5018, Ethernet2



IPv4 Addressless Forwarding on IPv6 addressed Interfacesis enabled:

Leaf-2#sh ip

IP Routing : Enabled
IP Multicast Routing : Disabled
IPv6 Multicast Routing : Disabled
IPv6 Interfaces Forwarding : True

IPv6 Unicast Routing : Enabled


However, IPv4 traffic is not forwarded. Am I missing something?

Answered on December 1, 2020 3:21 am

Hi Saverio,

Thank you for contacting the forum. the RFC5549 is only supported in vEOS in multi-agent model.

Please note that Arista supports two models in which BGP is implemented: Ribd and ArBGP. In the case of ArBGP (multi-agent), check for “service routing protocols model multi-agent” in the running-config.


Answered on December 1, 2020 3:30 am

Hi Saverio,

Thanks for reaching out.

Is BGP running in Gated Mode(service routing protocols model ribd) or in ArBGP mode(service routing protocols model multi-agent)?

Because IPv4 over IPv6 forwarding (RFC5549) does not work on vEOS-lab in Gated mode.

You can refer to the limitations section in the below TOI:

"This feature is supported for all IPv6 BGP sessions, but only supported for IPv4 sessions on multi-agent, and that support is further limited to iBGP."




Posted by saverio giuntini
Answered on December 1, 2020 8:53 pm


Thanks! This solved the problem:

service routing protocols model multi-agent

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