[c-nsp] NAT problem on ISR 4331

Nick Cutting ncutting at edgetg.co.uk
Wed Mar 16 06:54:14 EDT 2016


Sorry Global table... not global vrf

Also - you may get more options using the NVI rather than ip nat inside / outside when the internet is in a vrf - but less when the internet is in the global table is involved.  I cannot remember the specifics - but stick to this rule.

This is on a router with ADSL default route in a VRF, and the guest wifi in the same VRF

interface GigabitEthernet0/0.201
 ip nat enable

ip nat source list GUEST-WIFI-NAT interface GigabitEthernet0/0.201 vrf ADSL overload 



-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Nick Cutting
Sent: 16 March 2016 10:37
To: Eugen Şerban; cnsp at marenda.net
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] NAT problem on ISR 4331

These routers are much closer to ASR than ISR - they have the same feature set. - e.g. VASI interfaces etc.

Juergen is right about the global VRF - that is where I keep the internet (default route), when implementing similar designs

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Eugen Serban
Sent: 16 March 2016 09:36
To: cnsp at marenda.net
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] NAT problem on ISR 4331

Hello Juergen,

Please find bellow the routing table for all VRFs.

The idea with this router is that in the future it might be used for "hybrid networks", "local internet breakout" (or however you'd like to call it). So we plan to use the default VRF for internal (trusted) traffic.

hostname#sh ip route
[...]

Gateway of last resort is not set

      192.168.0.0/16 is variably subnetted, 3 subnets, 3 masks
S        192.168.0.0/16 [1/0] via 192.168.37.1
C        192.168.37.0/26 is directly connected, GigabitEthernet0/0/1.1
L        192.168.37.56/32 is directly connected, GigabitEthernet0/0/1.1

hostname#sh ip route vrf internet

Routing Table: internet
[...]

Gateway of last resort is 1.2.3.89 to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 1.2.3.89, GigabitEthernet0/0/2
      1.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C        1.2.3.88/29 is directly connected, GigabitEthernet0/0/2
L        1.2.3.90/32 is directly connected, GigabitEthernet0/0/2
L        1.2.3.91/32 is directly connected, GigabitEthernet0/0/2
L        1.2.3.92/32 is directly connected, GigabitEthernet0/0/2
      14.0.0.0/32 is subnetted, 1 subnets
S        14.22.77.29 [1/0] via 1.2.3.89, GigabitEthernet0/0/2
      18.0.0.0/32 is subnetted, 1 subnets
S        18.33.25.41 [1/0] via 1.2.3.89, GigabitEthernet0/0/2

hostname#sh ip route vrf guest

Routing Table: guest
[...]

Gateway of last resort is 0.0.0.0 to network 0.0.0.0

S*    0.0.0.0/0 is directly connected, Tunnel400
      14.0.0.0/32 is subnetted, 1 subnets
B        14.22.77.29
           [20/0] via 1.2.3.89 (internet), 6d22h, GigabitEthernet0/0/2
      18.0.0.0/32 is subnetted, 1 subnets
B        18.33.25.41
           [20/0] via 1.2.3.89 (internet), 6d22h, GigabitEthernet0/0/2
      172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C        172.16.112.0/23 is directly connected, GigabitEthernet0/0/1.122
L        172.16.112.1/32 is directly connected, GigabitEthernet0/0/1.122


hostname#sh ip route vrf hotspot

Routing Table: hotspot
[...]

Gateway of last resort is 0.0.0.0 to network 0.0.0.0

S*    0.0.0.0/0 is directly connected, Tunnel600
      14.0.0.0/32 is subnetted, 1 subnets
B        14.22.77.29
           [20/0] via 1.2.3.89 (internet), 6d22h, GigabitEthernet0/0/2
      18.0.0.0/32 is subnetted, 1 subnets
B        18.33.25.41
           [20/0] via 1.2.3.89 (internet), 6d22h, GigabitEthernet0/0/2
      172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C        172.16.32.0/23 is directly connected, GigabitEthernet0/0/1.121
L        172.16.32.1/32 is directly connected, GigabitEthernet0/0/1.121



2016-03-15 19:58 GMT+01:00 Juergen Marenda <cnsp at marenda.net>:

> Hi,
>
> First of all, your routing statements would be from interest...
> For All mentioned VRFs and global, please.
>
> From my experience eith ISR1 Routers,
> "surf" nat outside interface almost always had to be the global vrf, 
> not "vrf internet" ; and you must pin the inside vrf's (default-)route 
> to the global (default-)gateway.
> (here, host-routes to your two special's should be sufficient)
>
> Finally I would tend to write " no ip virtual-reassembly " on nearly 
> every Interface to disable that miss-feature.
>
> Hope this help's,
>
> Juergen.
>
> -----Ursprüngliche Nachricht-----
> Von: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] Im Auftrag 
> von Eugen Serban
> Gesendet: Dienstag, 15. März 2016 16:23
> An: Nick Cutting
> Cc: cisco-nsp at puck.nether.net
> Betreff: Re: [c-nsp] NAT problem on ISR 4331
>
> Hello Nick,
>
> Thank you for the hint with monitor capture. I will try that one.
>
> to answer your questions, yes, it's because I need to present a 
> different IP for each VRF.
>
> I am trying to use two different IPs for the NAT (we pay for them, so 
> we might just use them), please see the conf.
>
>
> ip nat translation timeout 60
> ip nat translation tcp-timeout 60
> ip nat translation udp-timeout 60
> ip nat translation dns-timeout 60
> no ip nat service all-algs
> no ip nat service dns-reset-ttl
> !
> ip nat pool HotspotNAT 1.2.3.92 1.2.3.92 netmask 255.255.255.248 ip 
> nat pool GuestNAT 1.2.3.91 1.2.3.91 netmask 255.255.255.248 !
> ip nat inside source list Guest2Internet pool GuestNAT vrf guest 
> overload ip nat inside source list Hotspot2Internet pool HotspotNAT 
> vrf hotspot overload !
> ip access-list extended Guest2Internet  permit ip 172.16.112.0
> 0.0.1.255 host 14.22.77.29  permit ip 172.16.112.0 0.0.1.255 host
> 18.33.25.41 ip access-list extended Hotspot2Internet
>   permit ip 172.16.32.0 0.0.1.255 host 14.22.77.29
>   permit ip 172.16.32.0 0.0.1.255 host 18.33.25.41 !
> interface GigabitEthernet0/0/1.121
>  description Hotspot Vlan
>  encapsulation dot1Q 121
>  ip vrf forwarding hotspot
>  ip address 172.16.32.1 255.255.254.0
>  ip nat inside
>  no cdp enable
>  arp timeout 300
>  ip virtual-reassembly
> !
> interface GigabitEthernet0/0/1.122
>  description Guest Vlan
>  encapsulation dot1Q 122
>  ip vrf forwarding guest
>  ip address 172.16.112.1 255.255.254.0  ip nat inside  no cdp enable 
> arp timeout 300  ip virtual-reassembly !
> interface GigabitEthernet0/0/2
>  description WAN interface 1
>  ip vrf forwarding internet
>  ip address 1.2.3.91 255.255.255.248 secondary  ip address 1.2.3.92
> 255.255.255.248 secondary  ip address 1.2.3.90 255.255.255.248  no ip 
> redirects  no ip unreachables  no ip proxy-arp  ip nat outside  ip 
> verify unicast reverse-path 100  negotiation auto  no cdp enable  arp 
> timeout 300  ip virtual-reassembly !
> [...]
>
>
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/
_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/


More information about the cisco-nsp mailing list