Unanswered Question
Oct 12th, 2008
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Hi all,

One of our clients has about 25 remote loactions connected to a central site using Frame relay and ISDN backup. The central site router is a 3845 and all branch routers are 1841s. As of now EIGRP is the routing protocol.The service provider here is switching over to MPLS (Layer 2 or Layer 3). So this clinet has to migrate from FR to MPLS. Basically as a part of this, migration the provider will place a Huawei switch the Customer central site. They will also place a Huawei switch at each remote loaction. The customer insists that he needs to use EIGRP and does not want to migrate to OSPF or static routing (Huawei ofcourse will not support EIGRP. Basically the connetction will be like this:-

6509 --- 3845 --- Huawei --- cloud --- Huawei---1841--- branch LAN

//other branch lans

The 3845 connection to huawei is via a fast ethernet port. My concern is:=

a) All the 1841s have to peer with central 3845 router by EIGRP and exchange routes. This will be through the Huawei layer 2 VPN.For this i think i will have to create sub interfaces on the 3845 fastethernet. eg

sub interface 1 remote loaction 1 ----

sub interface 2 ---- remote location 2


So when i give "show ip eigrp nei" on central 3845 i have to see ip's, etc as neighbors. On remote loaction 1 1841 when i give "show ip eigrp nei" i have to see only as neighbor but all eigrp routes should be there.

Will the 3841 and the branch 1841 peer like this through sub interfaces and provider L2 vpn (assuming correct configs on huawei? Could anyone who seen/worked on scenarios like this give some thought. Actually i have posted the same query in MPLS section ass well.

Thanks a lot in advance.


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Overall Rating: 5 (1 ratings)
Giuseppe Larosa Sun, 10/12/2008 - 03:26
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Hello Sonu,

the Central site will have one 802.1Q vlan/subif for each remote site.

The link of c3845 to the Huawei switch needs to be an 802.1Q trunk.

The L2 VPN service can be as simple as Vlan based EoMPLS point-to-point links: vlan 10 carried over EoMPLS LSP to remote branch office 1, vlan 11 to remote branch office 2 and so on.

on c3845

int fas0/0

no ip address

int fas0/0.10

enc dot1q 10

desc to remote side 1

ip addr

int fas0/0.20

enc dot1q 20

desc to remote side 2

ip addr

the huawei switch needs to xconnect vlan 10 to remote 1 vlan 10 and so on

on remote branch router you may need to use the same approach with a single subif (this depends on how the xconnect is made by Huawei if it uses the 802.1Q tag in and out)

The scenario should work fine and your understanding is correct about EIGRP neighborships over it.

Hope to help



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