multilink bundle-name authenticated

[sukesh tandon]

multilink bundle-name authenticated.... This command as mentioned in the cisco page is not shown in the running configuration.But i find in the running config of my router.

Can anyone explain the difference which the authenticated and endpoint keywords make with an example.???

Regards

Sukesh Tandon

[Peter Paluch]

Hi Sukesh,

This command is described in IOS Command Reference here:

http://www.cisco.com/c/en/us/td/docs/ios/dial/command/reference/dia-cr-book/dia_m2.html#wp1013395

This command basically influences how IOS locally names the created multilink bundles for local identification and management purposes. Consider two routers, R1 and R2, interconnected with two parallel serial links S1/0 and S1/1.

R1 is configured as a typical customer CPE:

interface Multilink1
 ip address negotiated
 ppp chap hostname PPPuser
 ppp chap password 0 PPPpassword
 ppp multilink
 ppp multilink group 1
 ppp multilink endpoint string MyR1EndID
!
interface Serial1/0
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1
!         
interface Serial1/1
 no ip address
 encapsulation ppp
 ppp multilink
 ppp multilink group 1

R2 is configured resembling an access concentrator at an ISP:

multilink virtual-template 1
!
username PPPuser password 0 PPPpassword
!
interface Loopback0
 ip address 10.255.255.2 255.255.255.255
!
interface Serial1/0
 no ip address
 encapsulation ppp
 ppp authentication chap
 ppp multilink
!         
interface Serial1/1
 no ip address
 encapsulation ppp
 ppp authentication chap
 ppp multilink
!
interface Virtual-Template1
 ip unnumbered Loopback0
 peer default ip address pool IPLocal
!         
ip local pool IPLocal 10.0.0.1 10.0.0.100

Basically, this configuration first authenticates anyone connecting to S1/0 or S1/1 on R2, and afterwards, if it is determined that the peer requests a MLPPP session, it will be created and the bundle will be terminated by a Virtual-Access interface whose configuration is cloned from the Virtual-Template1 interface.

With the multilink bundle-name authenticated, after R1 authenticates to R2 and creates a bundle, the show ppp multilink on R2 says:

R2(config)#do show ppp multilink

Virtual-Access3
  Bundle name: PPPuser
  Remote Username: PPPuser
  Remote Endpoint Discriminator: [1] MyR1EndID
  Local Username: R2
  Local Endpoint Discriminator: [1] R2
  Bundle up for 00:04:04, total bandwidth 3088, load 1/255
  Receive buffer limit 24384 bytes, frag timeout 1000 ms
    0/0 fragments/bytes in reassembly list
    0 lost fragments, 0 reordered
    0/0 discarded fragments/bytes, 0 lost received
    0x1 received sequence, 0x3 sent sequence
  Member links: 2 (max not set, min not set)
    Se1/0, since 00:04:05
    Se1/1, since 00:04:05
No inactive multilink interfaces

Note the Bundle name: line at the beginning of the output. Because the bundle naming is now configured to authenticated, the remote username is used to identify the bundle.

After changing the multilink bundle-name to endpoint and resetting the PPP session, show ppp multilink on R2 shows:

R2(config)#do show ppp multilink          

Virtual-Access2
  Bundle name: MyR1EndID
  Remote Username: PPPuser
  Remote Endpoint Discriminator: [1] MyR1EndID
  Local Username: R2
  Local Endpoint Discriminator: [1] R2
  Bundle up for 00:00:06, total bandwidth 3088, load 1/255
  Receive buffer limit 24384 bytes, frag timeout 1000 ms
    0/0 fragments/bytes in reassembly list
    0 lost fragments, 0 reordered
    0/0 discarded fragments/bytes, 0 lost received
    0x3 received sequence, 0x2 sent sequence
  Member links: 2 (max not set, min not set)
    Se1/0, since 00:00:04
    Se1/1, since 00:00:04
No inactive multilink interfaces

Notice now the Bundle name: it is set to MyR1EndID, the value configured on R1. Finally, if the bundle naming is set to both, this is the output:

R2(config)#do show ppp multilink      

Virtual-Access3
  Bundle name: PPPuser/MyR1EndID
  Remote Username: PPPuser
  Remote Endpoint Discriminator: [1] MyR1EndID
  Local Username: R2
  Local Endpoint Discriminator: [1] R2
  Bundle up for 00:00:03, total bandwidth 3088, load 1/255

There is even a setting of rfc available that appears to combine both remote username, remote endpoint discriminator, local username and local discriminator:

R2(config)#do show ppp multilink    

Virtual-Access2
  Bundle name: PPPuser/MyR1EndID/R2/R2
  Remote Username: PPPuser
  Remote Endpoint Discriminator: [1] MyR1EndID
  Local Username: R2
  Local Endpoint Discriminator: [1] R2
  Bundle up for 00:00:03, total bandwidth 3088, load 1/255

Nonetheless, this setting does not appear to influence any operations of the MLPPP bundle except the local naming of created bundles for management purposes.

Best regards,
Peter

[sukesh tandon]

Thanks buddy,

I just want to have an end to this by knowing whether it necessary for a multilink to have an IP address or there are some other ways to escape(As there is no ip address assigned to the multilink output  shown by you at the CE router). As per my knowledge we definitely need to have an IP address assigned to the multilink when running dynamic protocols such as OSPF..

[Peter Paluch]

Hi Sukesh,

You are welcome.

I just want to have an end to this by knowing whether it necessary for a multilink to have an IP address or there are some other ways to escape(As there is no ip address assigned to the multilink output  shown by you at the CE router).

When configuring a multilink, the physical interfaces do not have an IP address; however, either the Multilink interface or the Virtual-Template interface must have an IP address assigned in order to carry IP traffic. You are completely right. In my example above, R1 is configured with ip address negotiated on the Multilink1 interface, causing R1 to request an IP address dynamically from R2. On R2, the Virtual-Template1 interface is configured as IP Unnumbered interface, inheriting its IP address from the Loobpack0 interface. In any case, the virtual interfaces that terminate the MLPPP bundle on both routers have their IP address configured. Just as an example, R1's routing table looks as follows:

R1# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     10.0.0.0/32 is subnetted, 2 subnets
C       10.255.255.2 is directly connected, Multilink1
C       10.0.0.1 is directly connected, Multilink1

On R2, its routing table is:

R2# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     10.0.0.0/32 is subnetted, 2 subnets
C       10.255.255.2 is directly connected, Loopback0
C       10.0.0.1 is directly connected, Virtual-Access2

10.0.0.1 is R1's IP address assigned to it by R2. 10.255.255.2 is R2's IP address, originally configured on Loopback0 and shared by Virtual-Template1 for all terminated MLPPP sessions.

Best regards,
Peter