CE7855 outgoing interface static route packet loss

Latest reply: Dec 24, 2018 01:33:40 245 1 0 0
Issue Description


Customer complaining that after inserting a /32 static route only with outgoing interface and without specifying the next-hop, packet loss occur. 



transparent.gif Handling Process

Requested from customer the following output: 

       <Huawei> display diagnostic-information

transparent.gif Solution

#

interface 40GE1/0/6:4

 undo portswitch

 ip address 172.X.38.22 255.255.255.0

 device transceiver 40GBASE-COPPER

#

Customer
configuration was before like this :

[ac-2-1] ip route-static 172.X.38.18 255.255.255.255 40GE1/0/6:4

After configuring the static route in this way problem was solved:

[ac-2-1] ip route-static 172.X.38.18 255.255.255.255 40GE1/0/6:4 172.X.38.18  

[ac-2-1] ip route-static 172.X.38.18 255.255.255.255 172.X.38.18  

If we do not configure next-hop for a static route with a multi-access outgoing interface like Ethernet, it will be considered an incomplete route
entry.

If the next-hop is not specified in the static route, the next-hop in FIB it will be the interface’s address as the next-hop, in our case 172.X.38.22, which is not a valid next-hop or forwarding path.

When the packet is received for that destination it will be sent to CPU for further processing, because the route it matches does not have a next-hop and because Ethernet it’s a multi-access network segment, so it can’t rewrite the packet because it is missing Layer 2 information for the next-hop.  

Next-hop is required to be configured on multi-access interfaces like Ethernet in this case for the CE to be able to rewrite the packets at Layer 2 correctly.

So, missing next-hop in your configuration caused unexpected behavior on the CE so from here is also the packet loss..

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xiaomumu
Created Dec 24, 2018 01:33:40 Helpful(0) Helpful(0)

Learn more, great
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